...大约 111 分钟
45、web实验-抽取公共页面
- 公共页面
/templates/common.html
<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org"><!--注意要添加xmlns:th才能添加thymeleaf的标签-->
<head th:fragment="commonheader">
<!--common-->
<link href="css/style.css" th:href="@{/css/style.css}" rel="stylesheet">
<link href="css/style-responsive.css" th:href="@{/css/style-responsive.css}" rel="stylesheet">
...
</head>
<body>
<!-- left side start-->
<div id="leftmenu" class="left-side sticky-left-side">
...
<div class="left-side-inner">
...
<!--sidebar nav start-->
<ul class="nav nav-pills nav-stacked custom-nav">
<li><a th:href="@{/main.html}"><i class="fa fa-home"></i> <span>Dashboard</span></a></li>
...
<li class="menu-list nav-active"><a href="#"><i class="fa fa-th-list"></i> <span>Data Tables</span></a>
<ul class="sub-menu-list">
<li><a th:href="@{/basic_table}"> Basic Table</a></li>
<li><a th:href="@{/dynamic_table}"> Advanced Table</a></li>
<li><a th:href="@{/responsive_table}"> Responsive Table</a></li>
<li><a th:href="@{/editable_table}"> Edit Table</a></li>
</ul>
</li>
...
</ul>
<!--sidebar nav end-->
</div>
</div>
<!-- left side end-->
<!-- header section start-->
<div th:fragment="headermenu" class="header-section">
<!--toggle button start-->
<a class="toggle-btn"><i class="fa fa-bars"></i></a>
<!--toggle button end-->
...
</div>
<!-- header section end-->
<div id="commonscript">
<!-- Placed js at the end of the document so the pages load faster -->
<script th:src="@{/js/jquery-1.10.2.min.js}"></script>
<script th:src="@{/js/jquery-ui-1.9.2.custom.min.js}"></script>
<script th:src="@{/js/jquery-migrate-1.2.1.min.js}"></script>
<script th:src="@{/js/bootstrap.min.js}"></script>
<script th:src="@{/js/modernizr.min.js}"></script>
<script th:src="@{/js/jquery.nicescroll.js}"></script>
<!--common scripts for all pages-->
<script th:src="@{/js/scripts.js}"></script>
</div>
</body>
</html>
/templates/table/basic_table.html
<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0">
<meta name="description" content="">
<meta name="author" content="ThemeBucket">
<link rel="shortcut icon" href="#" type="image/png">
<title>Basic Table</title>
<div th:include="common :: commonheader"> </div><!--将common.html的代码段 插进来-->
</head>
<body class="sticky-header">
<section>
<div th:replace="common :: #leftmenu"></div>
<!-- main content start-->
<div class="main-content" >
<div th:replace="common :: headermenu"></div>
...
</div>
<!-- main content end-->
</section>
<!-- Placed js at the end of the document so the pages load faster -->
<div th:replace="common :: #commonscript"></div>
</body>
</html>
Difference between th:insert and th:replace (and th:include)
46、web实验-遍历数据与页面bug修改
控制层代码：
@GetMapping("/dynamic_table")
public String dynamic_table(Model model){
//表格内容的遍历
List<User> users = Arrays.asList(new User("zhangsan", "123456"),
new User("lisi", "123444"),
new User("haha", "aaaaa"),
new User("hehe ", "aaddd"));
model.addAttribute("users",users);
return "table/dynamic_table";
}
页面代码：
<table class="display table table-bordered" id="hidden-table-info">
<thead>
<tr>
<th>#</th>
<th>用户名</th>
<th>密码</th>
</tr>
</thead>
<tbody>
<tr class="gradeX" th:each="user,stats:${users}">
<td th:text="${stats.count}">Trident</td>
<td th:text="${user.userName}">Internet</td>
<td >[[${user.password}]]</td>
</tr>
</tbody>
</table>
47、视图解析-【源码分析】-视图解析器与视图
视图解析原理流程：
- 目标方法处理的过程中（阅读
DispatcherServlet源码），所有数据都会被放在ModelAndViewContainer里面，其中包括数据和视图地址。 - 方法的参数是一个自定义类型对象（从请求参数中确定的），把他重新放在
ModelAndViewContainer。 - 任何目标方法执行完成以后都会返回
ModelAndView（数据和视图地址）。 processDispatchResult()处理派发结果（页面改如何响应）render(mv, request, response);进行页面渲染逻辑- 根据方法的
String返回值得到View对象【定义了页面的渲染逻辑】
- 所有的视图解析器尝试是否能根据当前返回值得到
View对象 - 得到了
redirect:/main.html --> Thymeleaf new RedirectView()。 ContentNegotiationViewResolver里面包含了下面所有的视图解析器，内部还是利用下面所有视图解析器得到视图对象。view.render(mv.getModelInternal(), request, response);视图对象调用自定义的render进行页面渲染工作。
RedirectView如何渲染【重定向到一个页面】- 获取目标url地址
response.sendRedirect(encodedURL);
- 根据方法的
视图解析：
- 返回值以
forward:开始：new InternalResourceView(forwardUrl);--> 转发request.getRequestDispatcher(path).forward(request, response); - 返回值以
redirect:开始：new RedirectView()--> render就是重定向response.sendRedirect(encodedURL); - 返回值是普通字符串：
new ThymeleafView()--->
在 http://localhost:8080/ 页面里，输入用户名和密码，点击登录
首先mappedHandler = getHandler(processedRequest);寻找哪个handler (controller.method())能够处理该请求
HandlerAdapter ha = getHandlerAdapter(mappedHandler.getHandler());寻找哪个处理器适配器能够处理该请求
mv = ha.handle(processedRequest, response, mappedHandler.getHandler());真正执行handler
无论是否是异步，都会执行mav = invokeHandlerMethod(request, response, handlerMethod);，但如果是异步执行会使用同步代码块来执行。执行完后会返回一个ModelAndView，用于返回模型和视图
然后把argumentResolvers里所有的参数解析器和returnValueHandlers里所有的返回值处理器都设置给invocableMethod
然后调用invocableMethod.invokeAndHandle(webRequest, mavContainer);，准备执行目标方法
Object returnValue = invokeForRequest(webRequest, mavContainer, providedArgs);会执行目标方法，并获得目标方法的返回值
执行目标方法
获得返回值
然后调用返回值处理器，查看哪个handler来进行处理
调用selectHandler(returnValue, returnType);方法，选择一个合适的handler
匹配到了ViewNameMethodReturnValueHandler
ViewNameMethodReturnValueHandler支持的返回类型位void 或字符序列，所以匹配到了
然后调用ViewNameMethodReturnValueHandler这个类的handleReturnValue(returnValue, returnType, mavContainer, webRequest);处理返回值
首先将返回的字符串设置位ModelAndViewContainer的视图名，然后判断是不是重定向的视图，然后将ModelAndViewContainer设置为重定向模型场景
这个判断是不是重定向也很简单，判断是否匹配redirectPatterns或是否以redirect:开头
由于前面的这些方法都没有返回值，因此就来到了RequestMappingHandlerAdapter类的invokeHandlerMethod方法的这里（这个方法就是我们之前向invocableMethod设置所有参数解析器和返回值处理器，然后调用invocableMethod.invokeAndHandle(webRequest, mavContainer);方法准备执行目标方法的方法）
由于当前这个invokeHandlerMethod方法后面执行的方法都会带上mavContainer参数，最后在ViewNameMethodReturnValueHandler修改了mavContainer的数据，所以等后面的方法都执行完后，此时能获取到修改后的mavContainer （当然如果使用@ResponseBody这类的注解，不会设置mavContainer的视图名，后面会给一个默认的视图名）
当然这个mavContainer也会在defaultModel里保存执行目标方法时传递的参数和BindingResult，因此在使用全局异常的时候可以传一个BindingResult，从而获取到错误的详细信息
把ModelAndViewContainer里的model和viewName封装到ModelAndView里去，然后判断是不是重定向，如果是重定向则在model里获取一闪而过的属性（只能获取一次的属性），并把它们放到OutputFlashMap里。可以在目标方法添加RedirectAttributes类的参数，然后调用addFlashAttribute方法添加改类型的属性。常用于登录校验失败后，重定向到登录页面时给与提示( redirectAttributes.addFlashAttribute("message", "username/password invalid");)。
调用applyDefaultViewName(processedRequest, mv);方法，如果没有设置视图名，则会给一个默认的视图名，默认的视图名为视图的前缀 + 当前目标方法的请求映射 + 视图的后缀
然后调用processDispatchResult(processedRequest, response, mappedHandler, mv, dispatchException);处理派发结果
如果ModelAndView不为空，则调用render(mv, request, response);准备渲染页面
首先根据返回的String解析出对应的视图名
此时ContentNegotiatingViewResolver(内容协商视图解析器)可以解析该视图，并返回RedirectView(重定向视图)
先获取所有候选的视图
InternalResourceViewResolver内部资源视图解析器会解析该视图名返回RedirectView重定向视图
此时根据视图名redirect:/main.html来生成视图。（注意重启项目已清除缓存）
该方法会删除前面的redirect:
遍历ContentNegotiatingViewResolver内部的视图解析器，判断哪些视图可以解析。这里不同的是找到可以解析的视图后并不直接return，而是继续遍历，从而找到所有的。(这三层for循环效率是不是有点低，不过spring做的缓存挺好的)
然后获得最佳匹配的视图
首先判断是不是RedirectView重定向视图，如果是重定向视图直接返回。如果不是重定向视图则判断要求的媒体类型和候选视图的媒体类型是否匹配，如果匹配则返回。
获得到最佳的视图后会返回最佳的视图
获得最佳视图后，DispatcherServlet类的render方法会调用view.render(mv.getModelInternal(), request, response);进行页面渲染
然后调用renderMergedOutputModel(mergedModel, getRequestToExpose(request), response);渲染并合并输出模型。
RedirectView如何渲染
首先会调用
其实就是调用本类的getUrl()方法，如果还有公开的模型属性还会将其拼接到url后面。（类似于/main.html?id=1&sort=2）
拿到目标的url后，执行sendRedirect(request, response, targetUrl, this.http10Compatible);执行重定向
对url进行编码后，调用原生的response.sendRedirect(encodedURL);进行重定向
总结
重定向：
如果是重定向使用的视图是RedirectView
其最终调用的是原生的response.sendRedirect(encodedURL);
请求转发：
如果是重定向使用的视图是InternalResourceView
其最终调用的是原生的request.getRequestDispatcher(path).forward(request, response);
阅读源码：最好自己在IDE，打断点，且Debug模式运行实例，这样比较没那么沉闷。
48、拦截器-登录检查与静态资源放行
编写一个拦截器实现
HandlerInterceptor接口拦截器注册到容器中（实现
WebMvcConfigurer的addInterceptors()）指定拦截规则（注意，如果是拦截所有，静态资源也会被拦截】
编写一个实现HandlerInterceptor接口的拦截器：
@Slf4j
public class LoginInterceptor implements HandlerInterceptor {
/**
* 目标方法执行之前
*/
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
String requestURI = request.getRequestURI();
log.info("preHandle拦截的请求路径是{}",requestURI);
//登录检查逻辑
HttpSession session = request.getSession();
Object loginUser = session.getAttribute("loginUser");
if(loginUser != null){
//放行
return true;
}
//拦截住。未登录。跳转到登录页
request.setAttribute("msg","请先登录");
// re.sendRedirect("/");
request.getRequestDispatcher("/").forward(request,response);
return false;
}
/**
* 目标方法执行完成以后
*/
@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
log.info("postHandle执行{}",modelAndView);
}
/**
* 页面渲染以后
*/
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
log.info("afterCompletion执行异常{}",ex);
}
}
拦截器注册到容器中 && 指定拦截规则：
@Configuration
public class AdminWebConfig implements WebMvcConfigurer{
@Override
public void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(new LoginInterceptor())//拦截器注册到容器中
.addPathPatterns("/**") //所有请求都被拦截包括静态资源
.excludePathPatterns("/","/login","/css/**","/fonts/**","/images/**",
"/js/**","/aa/**"); //放行的请求
}
}
49、拦截器-【源码分析】-拦截器的执行时机和原理
- 根据当前请求，找到
HandlerExecutionChain（可以处理请求的handler以及handler的所有 拦截器） - 先来顺序执行 所有拦截器的
preHandle()方法。- 如果当前拦截器
preHandle()返回为true。则执行下一个拦截器的preHandle() - 如果当前拦截器返回为
false。直接倒序执行所有已经执行了的拦截器的afterCompletion();。
- 如果当前拦截器
- 如果任何一个拦截器返回
false，直接跳出不执行目标方法。 - 所有拦截器都返回
true，才执行目标方法。 - 倒序执行所有拦截器的
postHandle()方法。 - 前面的步骤有任何异常都会直接倒序触发
afterCompletion()。 - 页面成功渲染完成以后，也会倒序触发
afterCompletion()。
调用getHandler(processedRequest);方法返回的HandlerExecutionChain处理器执行链里不仅有处理该请求的handler，还有所有的interceptor拦截器
在执行目标方法之前会应用PreHandle，如果返回false，则直接return，不进行后续处理。
在目标方法执行之前会遍历所有的拦截器，调用其preHandle方法。如果有任何一个拦截器拦截了该请求，则直接返回false，后面的拦截器就不会执行。
boolean applyPreHandle(HttpServletRequest request, HttpServletResponse response) throws Exception {
HandlerInterceptor[] interceptors = getInterceptors();
if (!ObjectUtils.isEmpty(interceptors)) {
for (int i = 0; i < interceptors.length; i++) {
HandlerInterceptor interceptor = interceptors[i];
if (!interceptor.preHandle(request, response, this.handler)) {
triggerAfterCompletion(request, response, null);
return false;
}
// interceptorIndex默认为-1，只有当前拦截器放行请求后才将`interceptorIndex`赋为当前拦截器的索引
this.interceptorIndex = i;
}
}
return true;
}
如果被请求被拦截了，会倒序执行前面已经放行的拦截器的afterCompletion方法（只有当前拦截器放行请求后才将interceptorIndex赋为当前拦截器的索引，所以把当前请求拦截的拦截器不会执行其afterCompletion方法）
void triggerAfterCompletion(HttpServletRequest request, HttpServletResponse response, @Nullable Exception ex)
throws Exception {
HandlerInterceptor[] interceptors = getInterceptors();
if (!ObjectUtils.isEmpty(interceptors)) {
for (int i = this.interceptorIndex; i >= 0; i--) {
HandlerInterceptor interceptor = interceptors[i];
try {
interceptor.afterCompletion(request, response, this.handler, ex);
}
catch (Throwable ex2) {
logger.error("HandlerInterceptor.afterCompletion threw exception", ex2);
}
}
}
}
目标方法执行完后，就会应用PostHandle
这个方法就是倒序执行所有拦截器的postHandle方法
void applyPostHandle(HttpServletRequest request, HttpServletResponse response, @Nullable ModelAndView mv)
throws Exception {
HandlerInterceptor[] interceptors = getInterceptors();
if (!ObjectUtils.isEmpty(interceptors)) {
for (int i = interceptors.length - 1; i >= 0; i--) {
HandlerInterceptor interceptor = interceptors[i];
interceptor.postHandle(request, response, this.handler, mv);
}
}
}
然后进入到响应结果，返回页面
调用render(mv, request, response);页面渲染完后，还会倒序执行triggerAfterCompletion方法
这个triggerAfterCompletion方法，就是如果拦截器将拦截器拦截后调用的triggerAfterCompletion方法
而且就算前面执行的任何方法有任何异常也会执行triggerAfterCompletion方法
DispatcherServlet中涉及到HandlerInterceptor的地方：
public class DispatcherServlet extends FrameworkServlet {
...
protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception {
HttpServletRequest processedRequest = request;
HandlerExecutionChain mappedHandler = null;
boolean multipartRequestParsed = false;
WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request);
try {
ModelAndView mv = null;
Exception dispatchException = null;
...
//该方法内调用HandlerInterceptor的preHandle()
if (!mappedHandler.applyPreHandle(processedRequest, response)) {
return;
}
// Actually invoke the handler.
mv = ha.handle(processedRequest, response, mappedHandler.getHandler());
...
//该方法内调用HandlerInterceptor的postHandle()
mappedHandler.applyPostHandle(processedRequest, response, mv);
}
processDispatchResult(processedRequest, response, mappedHandler, mv, dispatchException);
}
catch (Exception ex) {
//该方法内调用HandlerInterceptor接口的afterCompletion方法
triggerAfterCompletion(processedRequest, response, mappedHandler, ex);
}
catch (Throwable err) {
//该方法内调用HandlerInterceptor接口的afterCompletion方法
triggerAfterCompletion(processedRequest, response, mappedHandler,
new NestedServletException("Handler processing failed", err));
}
finally {
...
}
}
private void triggerAfterCompletion(HttpServletRequest request, HttpServletResponse response,
@Nullable HandlerExecutionChain mappedHandler, Exception ex) throws Exception {
if (mappedHandler != null) {
//该方法内调用HandlerInterceptor接口的afterCompletion方法
mappedHandler.triggerAfterCompletion(request, response, ex);
}
throw ex;
}
private void processDispatchResult(HttpServletRequest request, HttpServletResponse response,
@Nullable HandlerExecutionChain mappedHandler, @Nullable ModelAndView mv,
@Nullable Exception exception) throws Exception {
...
if (mappedHandler != null) {
//该方法内调用HandlerInterceptor接口的afterCompletion方法
// Exception (if any) is already handled..
mappedHandler.triggerAfterCompletion(request, response, null);
}
}
}
public class HandlerExecutionChain {
...
boolean applyPreHandle(HttpServletRequest request, HttpServletResponse response) throws Exception {
for (int i = 0; i < this.interceptorList.size(); i++) {
HandlerInterceptor interceptor = this.interceptorList.get(i);
//HandlerInterceptor的preHandle方法
if (!interceptor.preHandle(request, response, this.handler)) {
triggerAfterCompletion(request, response, null);
return false;
}
this.interceptorIndex = i;
}
return true;
}
void applyPostHandle(HttpServletRequest request, HttpServletResponse response, @Nullable ModelAndView mv)
throws Exception {
for (int i = this.interceptorList.size() - 1; i >= 0; i--) {
HandlerInterceptor interceptor = this.interceptorList.get(i);
//HandlerInterceptor接口的postHandle方法
interceptor.postHandle(request, response, this.handler, mv);
}
}
void triggerAfterCompletion(HttpServletRequest request, HttpServletResponse response, @Nullable Exception ex) {
for (int i = this.interceptorIndex; i >= 0; i--) {
HandlerInterceptor interceptor = this.interceptorList.get(i);
try {
//HandlerInterceptor接口的afterCompletion方法
interceptor.afterCompletion(request, response, this.handler, ex);
}
catch (Throwable ex2) {
logger.error("HandlerInterceptor.afterCompletion threw exception", ex2);
}
}
}
}
50、文件上传-单文件与多文件上传的使用
- 页面代码
/static/form/form_layouts.html
<form role="form" th:action="@{/upload}" method="post" enctype="multipart/form-data">
<div class="form-group">
<label for="exampleInputEmail1">邮箱</label>
<input type="email" name="email" class="form-control" id="exampleInputEmail1" placeholder="Enter email">
</div>
<div class="form-group">
<label for="exampleInputPassword1">名字</label>
<input type="text" name="username" class="form-control" id="exampleInputPassword1" placeholder="Password">
</div>
<div class="form-group">
<label for="exampleInputFile">头像</label>
<input type="file" name="headerImg" id="exampleInputFile">
</div>
<div class="form-group">
<label for="exampleInputFile">生活照</label>
<input type="file" name="photos" multiple>
</div>
<div class="checkbox">
<label>
<input type="checkbox"> Check me out
</label>
</div>
<button type="submit" class="btn btn-primary">提交</button>
</form>
- 控制层代码
@Slf4j
@Controller
public class FormTestController {
@GetMapping("/form_layouts")
public String form_layouts(){
return "form/form_layouts";
}
@PostMapping("/upload")
public String upload(@RequestParam("email") String email,
@RequestParam("username") String username,
@RequestPart("headerImg") MultipartFile headerImg,
@RequestPart("photos") MultipartFile[] photos) throws IOException {
log.info("上传的信息：email={}，username={}，headerImg={}，photos={}",
email,username,headerImg.getSize(),photos.length);
if(!headerImg.isEmpty()){
//保存到文件服务器，OSS服务器
String originalFilename = headerImg.getOriginalFilename();
headerImg.transferTo(new File("H:\\cache\\"+originalFilename));
}
if(photos.length > 0){
for (MultipartFile photo : photos) {
if(!photo.isEmpty()){
String originalFilename = photo.getOriginalFilename();
photo.transferTo(new File("H:\\cache\\"+originalFilename));
}
}
}
return "main";
}
}
文件上传相关的配置类：
org.springframework.boot.autoconfigure.web.servlet.MultipartAutoConfigurationorg.springframework.boot.autoconfigure.web.servlet.MultipartProperties
文件大小相关配置项：
spring.servlet.multipart.max-file-size=10MB
spring.servlet.multipart.max-request-size=100MB
51、文件上传-【源码流程】文件上传参数解析器
首先将multipartRequestParsed设置为false，表示未解析到文件上传请求
检查是不是文件上传请求，如果是文件上传请求会对该请求进行包装
protected HttpServletRequest checkMultipart(HttpServletRequest request) throws MultipartException {
if (this.multipartResolver != null && this.multipartResolver.isMultipart(request)) {
if (WebUtils.getNativeRequest(request, MultipartHttpServletRequest.class) != null) {
if (request.getDispatcherType().equals(DispatcherType.REQUEST)) {
logger.trace("Request already resolved to MultipartHttpServletRequest, e.g. by MultipartFilter");
}
}
else if (hasMultipartException(request)) {
logger.debug("Multipart resolution previously failed for current request - " +
"skipping re-resolution for undisturbed error rendering");
}
else {
try {
return this.multipartResolver.resolveMultipart(request);
}
catch (MultipartException ex) {
if (request.getAttribute(WebUtils.ERROR_EXCEPTION_ATTRIBUTE) != null) {
logger.debug("Multipart resolution failed for error dispatch", ex);
// Keep processing error dispatch with regular request handle below
}
else {
throw ex;
}
}
}
}
// If not returned before: return original request.
return request;
}
首先会调用MultipartResolver的isMultipart()方法
该方法会判断该请求的ContentType是不是以multipart/开头
@Override
public boolean isMultipart(HttpServletRequest request) {
return StringUtils.startsWithIgnoreCase(request.getContentType(), "multipart/");
}
如果是文件上传，就返回this.multipartResolver.resolveMultipart(request);
其会将该请求封装为StandardMultipartHttpServletRequest
@Override
public MultipartHttpServletRequest resolveMultipart(HttpServletRequest request) throws MultipartException {
return new StandardMultipartHttpServletRequest(request, this.resolveLazily);
}
然后判断如果processedRequest不是原生的HttpServletRequest就将multipartRequestParsed设为true，表示解析到文件上传请求
然后执行目标请求
然后会调用handleInternal(request, response, (HandlerMethod) handler);
然后调用invokeHandlerMethod(request, response, handlerMethod);
然后准备执行目标方法
调用invokeForRequest(webRequest, mavContainer, providedArgs);方法，然后准备确定每个参数的值
调用getMethodArgumentValues(request, mavContainer, providedArgs);方法，确定每一个参数的值
然后查看参数解析器支不支持该类型
可以看到RequestPartMethodArgumentResolver支持该参数
当标注了@RequestPart注解，该方法的返回值就为true
@Override
public boolean supportsParameter(MethodParameter parameter) {
if (parameter.hasParameterAnnotation(RequestPart.class)) {
return true;
}
else {
if (parameter.hasParameterAnnotation(RequestParam.class)) {
return false;
}
return MultipartResolutionDelegate.isMultipartArgument(parameter.nestedIfOptional());
}
}
如果有参数解析器支持解析该参数，就准备解析该参数
该方法还会调用getArgumentResolver(parameter);方法，不过此时argumentResolverCache里已经有该参数对应的解析器了，直接就返回了，不用再次遍历
然后委派给MultipartResolutionDelegate类的resolveMultipartArgument方法
如果是单个的文件就会根据文件名返回一个StandardMultipartHttpServletRequest
如果是多个文件就根据name属性名，获取该输入框选择的所有文件
这些信息都存到multipartFiles里取了，直接获取就行了
@Override
public List<MultipartFile> getFiles(String name) {
List<MultipartFile> multipartFiles = getMultipartFiles().get(name);
if (multipartFiles != null) {
return multipartFiles;
}
else {
return Collections.emptyList();
}
}
文件上传相关的自动配置类MultipartAutoConfiguration有创建文件上传参数解析器StandardServletMultipartResolver。
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass({ Servlet.class, StandardServletMultipartResolver.class, MultipartConfigElement.class })
@ConditionalOnProperty(prefix = "spring.servlet.multipart", name = "enabled", matchIfMissing = true)
@ConditionalOnWebApplication(type = Type.SERVLET)
@EnableConfigurationProperties(MultipartProperties.class)
public class MultipartAutoConfiguration {
private final MultipartProperties multipartProperties;
public MultipartAutoConfiguration(MultipartProperties multipartProperties) {
this.multipartProperties = multipartProperties;
}
@Bean
@ConditionalOnMissingBean({ MultipartConfigElement.class, CommonsMultipartResolver.class })
public MultipartConfigElement multipartConfigElement() {
return this.multipartProperties.createMultipartConfig();
}
@Bean(name = DispatcherServlet.MULTIPART_RESOLVER_BEAN_NAME)
@ConditionalOnMissingBean(MultipartResolver.class)
public StandardServletMultipartResolver multipartResolver() {
//配置好文件上传解析器
StandardServletMultipartResolver multipartResolver = new StandardServletMultipartResolver();
multipartResolver.setResolveLazily(this.multipartProperties.isResolveLazily());
return multipartResolver;
}
}
//文件上传解析器
public class StandardServletMultipartResolver implements MultipartResolver {
private boolean resolveLazily = false;
public void setResolveLazily(boolean resolveLazily) {
this.resolveLazily = resolveLazily;
}
@Override
public boolean isMultipart(HttpServletRequest request) {
return StringUtils.startsWithIgnoreCase(request.getContentType(), "multipart/");
}
@Override
public MultipartHttpServletRequest resolveMultipart(HttpServletRequest request) throws MultipartException {
return new StandardMultipartHttpServletRequest(request, this.resolveLazily);
}
@Override
public void cleanupMultipart(MultipartHttpServletRequest request) {
if (!(request instanceof AbstractMultipartHttpServletRequest) ||
((AbstractMultipartHttpServletRequest) request).isResolved()) {
// To be on the safe side: explicitly delete the parts,
// but only actual file parts (for Resin compatibility)
try {
for (Part part : request.getParts()) {
if (request.getFile(part.getName()) != null) {
part.delete();
}
}
}
catch (Throwable ex) {
LogFactory.getLog(getClass()).warn("Failed to perform cleanup of multipart items", ex);
}
}
}
}
public class DispatcherServlet extends FrameworkServlet {
@Nullable
private MultipartResolver multipartResolver;
private void initMultipartResolver(ApplicationContext context) {
...
//这个就是配置类配置的StandardServletMultipartResolver文件上传解析器
this.multipartResolver = context.getBean(MULTIPART_RESOLVER_BEAN_NAME, MultipartResolver.class);
...
}
protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception {
HttpServletRequest processedRequest = request;
HandlerExecutionChain mappedHandler = null;
boolean multipartRequestParsed = false;//最后finally的回收flag
...
try {
ModelAndView mv = null;
Exception dispatchException = null;
try {
//做预处理,如果有上传文件 就new StandardMultipartHttpServletRequest包装类
processedRequest = checkMultipart(request);
multipartRequestParsed = (processedRequest != request);
// Determine handler for the current request.
mappedHandler = getHandler(processedRequest);
...
// Determine handler adapter for the current request.
HandlerAdapter ha = getHandlerAdapter(mappedHandler.getHandler());
...
// Actually invoke the handler.
mv = ha.handle(processedRequest, response, mappedHandler.getHandler());
}
....
finally {
...
if (multipartRequestParsed) {
cleanupMultipart(processedRequest);
}
}
}
protected HttpServletRequest checkMultipart(HttpServletRequest request) throws MultipartException {
if (this.multipartResolver != null && this.multipartResolver.isMultipart(request)) {
...
return this.multipartResolver.resolveMultipart(request);
...
}
}
protected void cleanupMultipart(HttpServletRequest request) {
if (this.multipartResolver != null) {
MultipartHttpServletRequest multipartRequest =
WebUtils.getNativeRequest(request, MultipartHttpServletRequest.class);
if (multipartRequest != null) {
this.multipartResolver.cleanupMultipart(multipartRequest);
}
}
}
}
mv = ha.handle(processedRequest, response, mappedHandler.getHandler());跳到以下的类
public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter
implements BeanFactoryAware, InitializingBean {
@Override
protected ModelAndView handleInternal(HttpServletRequest request,
HttpServletResponse response, HandlerMethod handlerMethod) throws Exception {
ModelAndView mav;
...
mav = invokeHandlerMethod(request, response, handlerMethod);
...
return mav;
}
@Nullable
protected ModelAndView invokeHandlerMethod(HttpServletRequest request,
HttpServletResponse response, HandlerMethod handlerMethod) throws Exception {
ServletWebRequest webRequest = new ServletWebRequest(request, response);
try {
WebDataBinderFactory binderFactory = getDataBinderFactory(handlerMethod);
ModelFactory modelFactory = getModelFactory(handlerMethod, binderFactory);
ServletInvocableHandlerMethod invocableMethod = createInvocableHandlerMethod(handlerMethod);
if (this.argumentResolvers != null) {//关注点
invocableMethod.setHandlerMethodArgumentResolvers(this.argumentResolvers);
}
...
invocableMethod.invokeAndHandle(webRequest, mavContainer);
...
return getModelAndView(mavContainer, modelFactory, webRequest);
}
finally {
webRequest.requestCompleted();
}
}
}
this.argumentResolvers其中主角类RequestPartMethodArgumentResolver用来生成
public class ServletInvocableHandlerMethod extends InvocableHandlerMethod {
...
public void invokeAndHandle(ServletWebRequest webRequest, ModelAndViewContainer mavContainer,
Object... providedArgs) throws Exception {
Object returnValue = invokeForRequest(webRequest, mavContainer, providedArgs);
...
}
@Nullable
public Object invokeForRequest(NativeWebRequest request, @Nullable ModelAndViewContainer mavContainer,
Object... providedArgs) throws Exception {
Object[] args = getMethodArgumentValues(request, mavContainer, providedArgs);
...
return doInvoke(args);//反射调用
}
@Nullable
protected Object doInvoke(Object... args) throws Exception {
Method method = getBridgedMethod();
ReflectionUtils.makeAccessible(method);
return method.invoke(getBean(), args);
...
}
//处理得出multipart参数，准备稍后的反射调用（@PostMapping标记的上传方法）
protected Object[] getMethodArgumentValues(NativeWebRequest request, @Nullable ModelAndViewContainer mavContainer,
Object... providedArgs) throws Exception {
MethodParameter[] parameters = getMethodParameters();
...
Object[] args = new Object[parameters.length];
for (int i = 0; i < parameters.length; i++) {
MethodParameter parameter = parameters[i];
parameter.initParameterNameDiscovery(this.parameterNameDiscoverer);
args[i] = findProvidedArgument(parameter, providedArgs);
if (args[i] != null) {
continue;
}
//关注点1
if (!this.resolvers.supportsParameter(parameter)) {
throw new IllegalStateException(formatArgumentError(parameter, "No suitable resolver"));
}
try {
//关注点2
args[i] = this.resolvers.resolveArgument(parameter, mavContainer, request, this.dataBinderFactory);
}
catch (Exception ex) {
...
}
}
return args;
}
}
public class RequestPartMethodArgumentResolver extends AbstractMessageConverterMethodArgumentResolver {
//对应上面代码关注点1
@Override
public boolean supportsParameter(MethodParameter parameter) {
//标注@RequestPart的参数
if (parameter.hasParameterAnnotation(RequestPart.class)) {
return true;
}
else {
if (parameter.hasParameterAnnotation(RequestParam.class)) {
return false;
}
return MultipartResolutionDelegate.isMultipartArgument(parameter.nestedIfOptional());
}
}
//对应上面代码关注点2
@Override
@Nullable
public Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
NativeWebRequest request, @Nullable WebDataBinderFactory binderFactory) throws Exception {
HttpServletRequest servletRequest = request.getNativeRequest(HttpServletRequest.class);
Assert.state(servletRequest != null, "No HttpServletRequest");
RequestPart requestPart = parameter.getParameterAnnotation(RequestPart.class);
boolean isRequired = ((requestPart == null || requestPart.required()) && !parameter.isOptional());
String name = getPartName(parameter, requestPart);
parameter = parameter.nestedIfOptional();
Object arg = null;
//封装成MultipartFile类型的对象作参数
Object mpArg = MultipartResolutionDelegate.resolveMultipartArgument(name, parameter, servletRequest);
if (mpArg != MultipartResolutionDelegate.UNRESOLVABLE) {
arg = mpArg;
}
...
return adaptArgumentIfNecessary(arg, parameter);
}
}
public final class MultipartResolutionDelegate {
...
@Nullable
public static Object resolveMultipartArgument(String name, MethodParameter parameter, HttpServletRequest request)
throws Exception {
MultipartHttpServletRequest multipartRequest =
WebUtils.getNativeRequest(request, MultipartHttpServletRequest.class);
boolean isMultipart = (multipartRequest != null || isMultipartContent(request));
if (MultipartFile.class == parameter.getNestedParameterType()) {
if (!isMultipart) {
return null;
}
if (multipartRequest == null) {
multipartRequest = new StandardMultipartHttpServletRequest(request);
}
return multipartRequest.getFile(name);
}
else if (isMultipartFileCollection(parameter)) {
if (!isMultipart) {
return null;
}
if (multipartRequest == null) {
multipartRequest = new StandardMultipartHttpServletRequest(request);
}
List<MultipartFile> files = multipartRequest.getFiles(name);
return (!files.isEmpty() ? files : null);
}
else if (isMultipartFileArray(parameter)) {
if (!isMultipart) {
return null;
}
if (multipartRequest == null) {
multipartRequest = new StandardMultipartHttpServletRequest(request);
}
List<MultipartFile> files = multipartRequest.getFiles(name);
return (!files.isEmpty() ? files.toArray(new MultipartFile[0]) : null);
}
else if (Part.class == parameter.getNestedParameterType()) {
if (!isMultipart) {
return null;
}
return request.getPart(name);
}
else if (isPartCollection(parameter)) {
if (!isMultipart) {
return null;
}
List<Part> parts = resolvePartList(request, name);
return (!parts.isEmpty() ? parts : null);
}
else if (isPartArray(parameter)) {
if (!isMultipart) {
return null;
}
List<Part> parts = resolvePartList(request, name);
return (!parts.isEmpty() ? parts.toArray(new Part[0]) : null);
}
else {
return UNRESOLVABLE;
}
}
...
}
52、错误处理-SpringBoot默认错误处理机制
Spring Boot官方文档 - Error Handling
默认规则：
默认情况下，Spring Boot提供
/error处理所有错误的映射机器客户端，它将生成JSON响应，其中包含错误，HTTP状态和异常消息的详细信息。对于浏览器客户端，响应一个
whitelabel错误视图，以HTML格式呈现相同的数据
{
"timestamp": "2020-11-22T05:53:28.416+00:00",
"status": 404,
"error": "Not Found",
"message": "No message available",
"path": "/asadada"
}
- 要对其进行自定义，添加
View解析为error要完全替换默认行为，可以实现
ErrorController并注册该类型的Bean定义，或添加ErrorAttributes类型的组件以使用现有机制但替换其内容。/error下的4xx，5xx页面会被自动解析（比如放在src/resources/public/error/404.html里，如果文件名为4xx.html则4开头的错误都能够由该页面处理）
53、错误处理-【源码分析】底层组件功能分析
ErrorMvcAutoConfiguration自动配置异常处理规则- 容器中的组件：类型：
DefaultErrorAttributes-> id：errorAttributes public class DefaultErrorAttributes implements ErrorAttributes, HandlerExceptionResolverDefaultErrorAttributes：定义错误页面中可以包含数据（异常明细，堆栈信息等）。
- 容器中的组件：类型：
BasicErrorController--> id：basicErrorController（json+白页 适配响应） - 处理默认
/error路径的请求，页面响应new ModelAndView("error", model);- 容器中有组件
View->id是error；（响应默认错误页） - 容器中放组件
BeanNameViewResolver（视图解析器）；按照返回的视图名作为组件的id去容器中找View对象。
- 容器中有组件
- 容器中的组件：类型：
DefaultErrorViewResolver-> id：conventionErrorViewResolver - 如果发生异常错误，会以HTTP的状态码 作为视图页地址（viewName），找到真正的页面（主要作用）。
- error/404、5xx.html
- 如果想要返回页面，就会找error视图（
StaticView默认是一个白页）。
总结：
DefaultErrorAttributes：设置错误包含的信息
BasicErrorController：根据内容协商要求的媒体类型返回不同类型的数据(html或json)
DefaultErrorViewResolver：错误页面访问的路径
ErrorMvcAutoConfiguration
错误处理相关的配置在org.springframework.boot.autoconfigure.web.servlet.error.ErrorMvcAutoConfiguration里
DefaultErrorAttributes
DefaultErrorAttributes类定义错误页面中可以包含哪些数据
ErrorMvcAutoConfiguration向容器中放了一个类型为DefaultErrorAttributes的errorAttributes (如果@Bean没有指定名称，默认把方法名作为该bean的名称)，
@Bean
@ConditionalOnMissingBean(value = ErrorAttributes.class, search = SearchStrategy.CURRENT)
public DefaultErrorAttributes errorAttributes() {
return new DefaultErrorAttributes();
}
其实现了ErrorAttributes、HandlerExceptionResolver、Ordered
public class DefaultErrorAttributes implements ErrorAttributes, HandlerExceptionResolver, Ordered
其主要代码为：
@Order(Ordered.HIGHEST_PRECEDENCE)
public class DefaultErrorAttributes implements ErrorAttributes, HandlerExceptionResolver, Ordered {
private static final String ERROR_ATTRIBUTE = DefaultErrorAttributes.class.getName() + ".ERROR";
...
@Override
public ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) {
storeErrorAttributes(request, ex);
return null;
}
private void storeErrorAttributes(HttpServletRequest request, Exception ex) {
request.setAttribute(ERROR_ATTRIBUTE, ex);
}
@Override
public Map<String, Object> getErrorAttributes(WebRequest webRequest, ErrorAttributeOptions options) {
Map<String, Object> errorAttributes = getErrorAttributes(webRequest, options.isIncluded(Include.STACK_TRACE));
if (Boolean.TRUE.equals(this.includeException)) {
options = options.including(Include.EXCEPTION);
}
if (!options.isIncluded(Include.EXCEPTION)) {
errorAttributes.remove("exception");
}
if (!options.isIncluded(Include.STACK_TRACE)) {
errorAttributes.remove("trace");
}
if (!options.isIncluded(Include.MESSAGE) && errorAttributes.get("message") != null) {
errorAttributes.put("message", "");
}
if (!options.isIncluded(Include.BINDING_ERRORS)) {
errorAttributes.remove("errors");
}
return errorAttributes;
}
@Override
@Deprecated
public Map<String, Object> getErrorAttributes(WebRequest webRequest, boolean includeStackTrace) {
Map<String, Object> errorAttributes = new LinkedHashMap<>();
errorAttributes.put("timestamp", new Date());
addStatus(errorAttributes, webRequest);
addErrorDetails(errorAttributes, webRequest, includeStackTrace);
addPath(errorAttributes, webRequest);
return errorAttributes;
}
...
}
BasicErrorController
BasicErrorController类根据内容协商要求返回的媒体类型来显示不同格式的错误数据，浏览器返回白页、非浏览器返回json
ErrorMvcAutoConfiguration向容器中放了一个BasicErrorController类型的basicErrorController，用于对浏览器（白页）和非浏览器（json）返回不同媒体类型的错误信息
@Bean
@ConditionalOnMissingBean(value = ErrorController.class, search = SearchStrategy.CURRENT)
public BasicErrorController basicErrorController(ErrorAttributes errorAttributes,
ObjectProvider<ErrorViewResolver> errorViewResolvers) {
return new BasicErrorController(errorAttributes, this.serverProperties.getError(),
errorViewResolvers.orderedStream().collect(Collectors.toList()));
}
该类主要代码：
@Controller
@RequestMapping("${server.error.path:${error.path:/error}}")
public class BasicErrorController extends AbstractErrorController {
...
@RequestMapping(produces = MediaType.TEXT_HTML_VALUE)
public ModelAndView errorHtml(HttpServletRequest request, HttpServletResponse response) {
HttpStatus status = getStatus(request);
Map<String, Object> model = Collections
.unmodifiableMap(getErrorAttributes(request, getErrorAttributeOptions(request, MediaType.TEXT_HTML)));
response.setStatus(status.value());
ModelAndView modelAndView = resolveErrorView(request, response, status, model);
return (modelAndView != null) ? modelAndView : new ModelAndView("error", model);
}
@RequestMapping
public ResponseEntity<Map<String, Object>> error(HttpServletRequest request) {
HttpStatus status = getStatus(request);
if (status == HttpStatus.NO_CONTENT) {
return new ResponseEntity<>(status);
}
Map<String, Object> body = getErrorAttributes(request, getErrorAttributeOptions(request, MediaType.ALL));
return new ResponseEntity<>(body, status);
}
@ExceptionHandler(HttpMediaTypeNotAcceptableException.class)
public ResponseEntity<String> mediaTypeNotAcceptable(HttpServletRequest request) {
HttpStatus status = getStatus(request);
return ResponseEntity.status(status).build();
}
...
}
@RequestMapping("${server.error.path:${error.path:/error}}")
该类有个RequestMapping的注解，其映射的路径先获取配置文件中的server.error.path，如果该值不存在再获取error.path，如果还不存在则给默认值/error，这就是上面官网中所说的处理默认/error路径下的请求。
该类中也给我们配置了默认的响应，分别为默认的白页数据和默认的json数据。当是浏览器访问时会给返回一个ModelAndView view的名称为error，当不是浏览器访问时则返回json数据。
还对HttpMediaTypeNotAcceptableException（没有可接受的html媒体类型异常）误进行了处理
ErrorPageCustomizer
ErrorMvcAutoConfiguration向容器中放了一个类型为ErrorPageCustomizer的errorPageCustomizer，可以对错误页面定制化
@Bean
public ErrorPageCustomizer errorPageCustomizer(DispatcherServletPath dispatcherServletPath) {
return new ErrorPageCustomizer(this.serverProperties, dispatcherServletPath);
}
defaultErrorView
ErrorMvcAutoConfiguration类的静态内部类WhitelabelErrorViewConfiguration放了一个名为error的View，这个error视图就是前面浏览器访问错误后返回的ModelAndView里的view。同时还配了一个BeanNameViewResolver bean名称视图解析器，根据bean的名称在容器中查找对应的视图对象
@Configuration(proxyBeanMethods = false)
@ConditionalOnWebApplication(type = Type.SERVLET)
@ConditionalOnClass({ Servlet.class, DispatcherServlet.class })
// Load before the main WebMvcAutoConfiguration so that the error View is available
@AutoConfigureBefore(WebMvcAutoConfiguration.class)
@EnableConfigurationProperties({ ServerProperties.class, ResourceProperties.class, WebMvcProperties.class })
public class ErrorMvcAutoConfiguration {
...
@Configuration(proxyBeanMethods = false)
@ConditionalOnProperty(prefix = "server.error.whitelabel", name = "enabled", matchIfMissing = true)
@Conditional(ErrorTemplateMissingCondition.class)
protected static class WhitelabelErrorViewConfiguration {
private final StaticView defaultErrorView = new StaticView();
@Bean(name = "error")
@ConditionalOnMissingBean(name = "error")
public View defaultErrorView() {
return this.defaultErrorView;
}
// If the user adds @EnableWebMvc then the bean name view resolver from
// WebMvcAutoConfiguration disappears, so add it back in to avoid disappointment.
@Bean
@ConditionalOnMissingBean
public BeanNameViewResolver beanNameViewResolver() {
BeanNameViewResolver resolver = new BeanNameViewResolver();
resolver.setOrder(Ordered.LOWEST_PRECEDENCE - 10);
return resolver;
}
}
...
}
默认视图StaticView类的render方法如下图所示，就是返回一个html页面
private static class StaticView implements View {
private static final MediaType TEXT_HTML_UTF8 = new MediaType("text", "html", StandardCharsets.UTF_8);
private static final Log logger = LogFactory.getLog(StaticView.class);
@Override
public void render(Map<String, ?> model, HttpServletRequest request, HttpServletResponse response)
throws Exception {
if (response.isCommitted()) {
String message = getMessage(model);
logger.error(message);
return;
}
response.setContentType(TEXT_HTML_UTF8.toString());
StringBuilder builder = new StringBuilder();
Object timestamp = model.get("timestamp");
Object message = model.get("message");
Object trace = model.get("trace");
if (response.getContentType() == null) {
response.setContentType(getContentType());
}
builder.append("<html><body><h1>Whitelabel Error Page</h1>").append(
"<p>This application has no explicit mapping for /error, so you are seeing this as a fallback.</p>")
.append("<div id='created'>").append(timestamp).append("</div>")
.append("<div>There was an unexpected error (type=").append(htmlEscape(model.get("error")))
.append(", status=").append(htmlEscape(model.get("status"))).append(").</div>");
if (message != null) {
builder.append("<div>").append(htmlEscape(message)).append("</div>");
}
if (trace != null) {
builder.append("<div style='white-space:pre-wrap;'>").append(htmlEscape(trace)).append("</div>");
}
builder.append("</body></html>");
response.getWriter().append(builder.toString());
}
...
}
主要代码
@Configuration(proxyBeanMethods = false)
@ConditionalOnWebApplication(type = Type.SERVLET)
@ConditionalOnClass({ Servlet.class, DispatcherServlet.class })
// Load before the main WebMvcAutoConfiguration so that the error View is available
@AutoConfigureBefore(WebMvcAutoConfiguration.class)
@EnableConfigurationProperties({ ServerProperties.class, ResourceProperties.class, WebMvcProperties.class })
public class ErrorMvcAutoConfiguration {
...
@Bean
@ConditionalOnMissingBean(value = ErrorAttributes.class, search = SearchStrategy.CURRENT)
public DefaultErrorAttributes errorAttributes() {
return new DefaultErrorAttributes();
}
@Bean
@ConditionalOnMissingBean(value = ErrorController.class, search = SearchStrategy.CURRENT)
public BasicErrorController basicErrorController(ErrorAttributes errorAttributes,
ObjectProvider<ErrorViewResolver> errorViewResolvers) {
return new BasicErrorController(errorAttributes, this.serverProperties.getError(),
errorViewResolvers.orderedStream().collect(Collectors.toList()));
}
@Bean
public ErrorPageCustomizer errorPageCustomizer(DispatcherServletPath dispatcherServletPath) {
return new ErrorPageCustomizer(this.serverProperties, dispatcherServletPath);
}
...
@Configuration(proxyBeanMethods = false)
@ConditionalOnProperty(prefix = "server.error.whitelabel", name = "enabled", matchIfMissing = true)
@Conditional(ErrorTemplateMissingCondition.class)
protected static class WhitelabelErrorViewConfiguration {
private final StaticView defaultErrorView = new StaticView();
@Bean(name = "error")
@ConditionalOnMissingBean(name = "error")
public View defaultErrorView() {
return this.defaultErrorView;
}
// If the user adds @EnableWebMvc then the bean name view resolver from
// WebMvcAutoConfiguration disappears, so add it back in to avoid disappointment.
@Bean
@ConditionalOnMissingBean
public BeanNameViewResolver beanNameViewResolver() {
BeanNameViewResolver resolver = new BeanNameViewResolver();
resolver.setOrder(Ordered.LOWEST_PRECEDENCE - 10);
return resolver;
}
}
/**
* Simple {@link View} implementation that writes a default HTML error page.
*/
private static class StaticView implements View {
private static final MediaType TEXT_HTML_UTF8 = new MediaType("text", "html", StandardCharsets.UTF_8);
private static final Log logger = LogFactory.getLog(StaticView.class);
@Override
public void render(Map<String, ?> model, HttpServletRequest request, HttpServletResponse response)
throws Exception {
if (response.isCommitted()) {
String message = getMessage(model);
logger.error(message);
return;
}
response.setContentType(TEXT_HTML_UTF8.toString());
StringBuilder builder = new StringBuilder();
Object timestamp = model.get("timestamp");
Object message = model.get("message");
Object trace = model.get("trace");
if (response.getContentType() == null) {
response.setContentType(getContentType());
}
builder.append("<html><body><h1>Whitelabel Error Page</h1>").append(
"<p>This application has no explicit mapping for /error, so you are seeing this as a fallback.</p>")
.append("<div id='created'>").append(timestamp).append("</div>")
.append("<div>There was an unexpected error (type=").append(htmlEscape(model.get("error")))
.append(", status=").append(htmlEscape(model.get("status"))).append(").</div>");
if (message != null) {
builder.append("<div>").append(htmlEscape(message)).append("</div>");
}
if (trace != null) {
builder.append("<div style='white-space:pre-wrap;'>").append(htmlEscape(trace)).append("</div>");
}
builder.append("</body></html>");
response.getWriter().append(builder.toString());
}
...
}
}
DefaultErrorViewResolver
DefaultErrorViewResolver类规定了错误页面的路径
/**
* Default {@link ErrorViewResolver} implementation that attempts to resolve error views
* using well known conventions. Will search for templates and static assets under
* {@code '/error'} using the {@link HttpStatus status code} and the
* {@link HttpStatus#series() status series}.
* <p>
* For example, an {@code HTTP 404} will search (in the specific order):
* <ul>
* <li>{@code '/<templates>/error/404.<ext>'}</li>
* <li>{@code '/<static>/error/404.html'}</li>
* <li>{@code '/<templates>/error/4xx.<ext>'}</li>
* <li>{@code '/<static>/error/4xx.html'}</li>
* </ul>
*
* @author Phillip Webb
* @author Andy Wilkinson
* @since 1.4.0
*/
public class DefaultErrorViewResolver implements ErrorViewResolver, Ordered {
private static final Map<Series, String> SERIES_VIEWS;
static {
Map<Series, String> views = new EnumMap<>(Series.class);
views.put(Series.CLIENT_ERROR, "4xx");
views.put(Series.SERVER_ERROR, "5xx");
SERIES_VIEWS = Collections.unmodifiableMap(views);
}
...
@Override
public ModelAndView resolveErrorView(HttpServletRequest request, HttpStatus status, Map<String, Object> model) {
ModelAndView modelAndView = resolve(String.valueOf(status.value()), model);
if (modelAndView == null && SERIES_VIEWS.containsKey(status.series())) {
modelAndView = resolve(SERIES_VIEWS.get(status.series()), model);
}
return modelAndView;
}
private ModelAndView resolve(String viewName, Map<String, Object> model) {
String errorViewName = "error/" + viewName;
TemplateAvailabilityProvider provider = this.templateAvailabilityProviders.getProvider(errorViewName,
this.applicationContext);
if (provider != null) {
return new ModelAndView(errorViewName, model);
}
return resolveResource(errorViewName, model);
}
...
}
例如，HTTP 404 将搜索（按特定顺序）：
/<templates>/error/404.<ext> （Extended file system：延伸文件系统，缩写为 ext或 ext1）
/<static>/error/404.html
/<templates>error4xx.<ext> （Extended file system：延伸文件系统，缩写为 ext或 ext1）
/<static>/error/4xx.html
CLIENT_ERROR客户端错误会找4xx的bean，SERVER_ERROR服务端错误会找5xx的bean
resolveErrorView解析错误视图会调用resolve方法，传递一个状态码，然后把状态码作为视图名，errorViewName错误的视图名赋值为"error/" + viewName;
54、错误处理-【源码流程】异常处理流程
譬如写一个会抛出异常的控制层：
@Controller
public class HelloController {
@ResponseBody
@GetMapping("/hello")
public String hello() {
int i = 10 / 0;
return "hello";
}
}
调用ha.handle(processedRequest, response, mappedHandler.getHandler());，正真的执行目标代码，期间报任何异常都会被捕获，并赋值给Exception类型的dispatchException
执行到下一个断点，跳到int i = 10 / 0;这里
然后点击Step Over F8，执行下一行，就被InvocableHandlerMethod类的doInvoke方法捕获了InvocationTargetException类型的异常，然后判断是不是运行时异常，如果是运行时异常则强转为运行时异常再抛出该异常
@Nullable
protected Object doInvoke(Object... args) throws Exception {
ReflectionUtils.makeAccessible(getBridgedMethod());
try {
return getBridgedMethod().invoke(getBean(), args);
}
catch (IllegalArgumentException ex) {
assertTargetBean(getBridgedMethod(), getBean(), args);
String text = (ex.getMessage() != null ? ex.getMessage() : "Illegal argument");
throw new IllegalStateException(formatInvokeError(text, args), ex);
}
catch (InvocationTargetException ex) {
// Unwrap for HandlerExceptionResolvers ...
Throwable targetException = ex.getTargetException();
if (targetException instanceof RuntimeException) {
throw (RuntimeException) targetException;
}
else if (targetException instanceof Error) {
throw (Error) targetException;
}
else if (targetException instanceof Exception) {
throw (Exception) targetException;
}
else {
throw new IllegalStateException(formatInvokeError("Invocation failure", args), targetException);
}
}
}
然后执行RequestMappingHandlerAdapter类的invokeHandlerMethod方法的finally里的webRequest.requestCompleted();，表明该请求已经执行完了 （这个方法就是向invocableMethod里设置argumentResolvers参数解析器和returnValueHandlers返回值处理器的方法）
由于出现了异常，所以就被捕获了
捕获后就进入到了视图解析流程，此时由于出现了异常所以mv为null即没有返回模型和视图，dispatchException显示为/ by zero异常（如果视图解析出现异常，则会继续被捕获，捕获后调用所有已运行放行该请求的interceptor的afterCompletion返回视图后的处理方法）
如果出现异常先判断是不是ModelAndViewDefiningException异常，如果不是则获得处理该请求的handler即com.atguigu.boot.controller.HelloController#hello()，然后调用processHandlerException(request, response, handler, exception);来处理Handler异常，处理完后返回一个ModelAndView
handlerExceptionResolvers类型为List<HandlerExceptionResolver>，其保存了所有处理器异常解析器，其中就有前面我们提到的DefaultErrorAttributes
@Nullable
protected ModelAndView processHandlerException(HttpServletRequest request, HttpServletResponse response,
@Nullable Object handler, Exception ex) throws Exception {
// Success and error responses may use different content types
request.removeAttribute(HandlerMapping.PRODUCIBLE_MEDIA_TYPES_ATTRIBUTE);
// Check registered HandlerExceptionResolvers...
ModelAndView exMv = null;
if (this.handlerExceptionResolvers != null) {
for (HandlerExceptionResolver resolver : this.handlerExceptionResolvers) {
exMv = resolver.resolveException(request, response, handler, ex);
if (exMv != null) {
break;
}
}
}
if (exMv != null) {
...
WebUtils.exposeErrorRequestAttributes(request, ex, getServletName());
return exMv;
}
throw ex;
}
DefaultErrorAttributes类的resolveException方法就是把异常放到key为org.springframework.boot.web.servlet.error.DefaultErrorAttributes.ERROR的请求域中，然后直接返回null了，并没有返回ModelAndView
@Order(Ordered.HIGHEST_PRECEDENCE)
public class DefaultErrorAttributes implements ErrorAttributes, HandlerExceptionResolver, Ordered {
private static final String ERROR_ATTRIBUTE = DefaultErrorAttributes.class.getName() + ".ERROR";
...
@Override
public ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response, Object handler,
Exception ex) {
storeErrorAttributes(request, ex);
return null;
}
private void storeErrorAttributes(HttpServletRequest request, Exception ex) {
request.setAttribute(ERROR_ATTRIBUTE, ex);
}
}
由于DefaultErrorAttributes解析后返回null，所以又遍历到下一个解析器HandlerExceptionResolverComposite，该解析是处理器异常解析器组合，里面包含3个解析器，这三个都是web场景相关的异常解析器，都不能解析/ by zero异常
ExceptionHandlerExceptionResolver：标注@ExceptionHandler
ResponseStatusExceptionResolver： 标注@ResponseStatus
DefaultHandlerExceptionResolver：主要处理常见的web相关的异常
@Override
@Nullable
public ModelAndView resolveException(
HttpServletRequest request, HttpServletResponse response, @Nullable Object handler, Exception ex) {
if (this.resolvers != null) {
for (HandlerExceptionResolver handlerExceptionResolver : this.resolvers) {
ModelAndView mav = handlerExceptionResolver.resolveException(request, response, handler, ex);
if (mav != null) {
return mav;
}
}
}
return null;
}
由于没有任何异常解析器能够处理，因此就将这个异常抛出去了
然后就捕获到了该异常，最后调用triggerAfterCompletion(processedRequest, response, mappedHandler, ex);方法，这个方法就是返回视图后倒序调用已放行该请求的所有拦截器的afterCompletion方法
然后来到了finally，执行完后该方法就没有了
此时控制台已经报了/ by zero异常
2022-09-27 20:23:58.930 DEBUG 16856 --- [nio-8080-exec-1] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped to com.atguigu.boot.controller.HelloController#hello()
2022-09-27 20:24:05.377 DEBUG 16856 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet : Failed to complete request: java.lang.ArithmeticException: / by zero
2022-09-27 20:24:05.382 ERROR 16856 --- [nio-8080-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.lang.ArithmeticException: / by zero] with root cause
java.lang.ArithmeticException: / by zero
at com.atguigu.boot.controller.HelloController.hello(HelloController.java:27) ~[classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_301]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_301]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_301]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_301]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105) ~[spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
在doDispatch的第一行打个断点，点击Resume Program F9跳转到下一个断点，然后就会发现tomcat底层会再发送一个/error请求，BasicErrorController类就专门处理error请求。(也就是我们以前用tomcat做服务器，写Java web的时候，代码写错了，此时就会返回一个错误页，这个错误页就是tomcat重新发送了一个`/erro)
然后查到HandlerExecutionChain with [org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController#errorHtml(HttpServletRequest, HttpServletResponse)] and 2 interceptors能处理
然后执行BasicErrorController的errorHtml(HttpServletRequest, HttpServletResponse)方法
在BasicErrorController类的errorHtml方法的第一行打上断点，点击Resume Program F9跳转到下一个断点，就来到了该方法
@RequestMapping(produces = MediaType.TEXT_HTML_VALUE)
public ModelAndView errorHtml(HttpServletRequest request, HttpServletResponse response) {
HttpStatus status = getStatus(request);
Map<String, Object> model = Collections
.unmodifiableMap(getErrorAttributes(request, getErrorAttributeOptions(request, MediaType.TEXT_HTML)));
response.setStatus(status.value());
ModelAndView modelAndView = resolveErrorView(request, response, status, model);
return (modelAndView != null) ? modelAndView : new ModelAndView("error", model);
}
老师的可以拿到上个请求的/ by zero异常，但是我拿不到，我只能拿到上次发生异常的请求路径/hello
然后遍历errorViewResolvers，不过里面只有一个我们前面提到的DefaultErrorViewResolver
resolver.resolveErrorView(request, status, model)方法的过程如下
@Override
public ModelAndView resolveErrorView(HttpServletRequest request, HttpStatus status, Map<String, Object> model) {
// status.value() 获得状态字为500,把500当作viewName，然后获取ModelAndView
ModelAndView modelAndView = resolve(String.valueOf(status.value()), model);
if (modelAndView == null && SERIES_VIEWS.containsKey(status.series())) {
modelAndView = resolve(SERIES_VIEWS.get(status.series()), model);
}
return modelAndView;
}
//ModelAndView modelAndView = resolve(String.valueOf(status.value()), model);方法调用时的值
private ModelAndView resolve(String viewName, Map<String, Object> model) {
// errorViewName变为 error/500
String errorViewName = "error/" + viewName;
// 查看模板引擎有没有 error/500 页面
TemplateAvailabilityProvider provider = this.templateAvailabilityProviders.getProvider(errorViewName,
this.applicationContext);
// 如果查看模板引擎有 error/500 页面，直接返回该页面
if (provider != null) {
return new ModelAndView(errorViewName, model);
}
// 如果没有调用 resolveResource 方法
return resolveResource(errorViewName, model);
}
@Override
public ModelAndView resolveErrorView(HttpServletRequest request, HttpStatus status, Map<String, Object> model) {
// status.value() 获得状态字为500,把500当作viewName，然后获取ModelAndView
ModelAndView modelAndView = resolve(String.valueOf(status.value()), model);
// 如果modelAndView并且SERIES_VIEWS里面有key为{name=SERVER_ERROR,value=5,ordinal=4}的值
if (modelAndView == null && SERIES_VIEWS.containsKey(status.series())) {
// SERIES_VIEWS.get(SERVER_ERROR) = 5xx
modelAndView = resolve(SERIES_VIEWS.get(status.series()), model);
}
return modelAndView;
}
//modelAndView = resolve(SERIES_VIEWS.get(status.series()), model);方法调用时的值
private ModelAndView resolve(String viewName, Map<String, Object> model) {
// errorViewName变为 error/5xx
String errorViewName = "error/" + viewName;
// 查看模板引擎有没有 error/5xx 页面
TemplateAvailabilityProvider provider = this.templateAvailabilityProviders.getProvider(errorViewName,
this.applicationContext);
// 如果查看模板引擎有 error/5xx 页面，直接返回该页面
if (provider != null) {
return new ModelAndView(errorViewName, model);
}
// 如果没有调用 resolveResource 方法
return resolveResource(errorViewName, model);
}
private ModelAndView resolveResource(String viewName, Map<String, Object> model) {
// this.resourceProperties.getStaticLocations()方法获取spring.resources.static-locations配置的静态资源位置（默认为："classpath:/META-INF/resources/","classpath:/resources/", "classpath:/static/", "classpath:/public/"）
for (String location : this.resourceProperties.getStaticLocations()) {
try {
//获取到静态资源路径
Resource resource = this.applicationContext.getResource(location);
//查看里面的error文件夹下有没有5xx.html页面
resource = resource.createRelative(viewName + ".html");
if (resource.exists()) {
// 如果有该页面，返回该页面的ModelAndView
return new ModelAndView(new HtmlResourceView(resource), model);
}
}
catch (Exception ex) {
}
}
return null;
}
根据以上代码可以看到如果有精确错误的页面(例如classpath:/static/error/500.html)就返回该页面，如果没有精确错误的页面就找模糊错误的页面(例如classpath:/static/error/5xx.html)
纯文字描述：
当浏览器发出/hello请求，DispatcherServlet的doDispatch()的mv = ha.handle(processedRequest, response, mappedHandler.getHandler());将会抛出ArithmeticException。
public class DispatcherServlet extends FrameworkServlet {
...
protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception {
...
// Actually invoke the handler.
//将会抛出ArithmeticException
mv = ha.handle(processedRequest, response, mappedHandler.getHandler());
applyDefaultViewName(processedRequest, mv);
mappedHandler.applyPostHandle(processedRequest, response, mv);
}
catch (Exception ex) {
//将会捕捉ArithmeticException
dispatchException = ex;
}
catch (Throwable err) {
...
}
//捕捉后，继续运行
processDispatchResult(processedRequest, response, mappedHandler, mv, dispatchException);
}
catch (Exception ex) {
triggerAfterCompletion(processedRequest, response, mappedHandler, ex);
}
catch (Throwable err) {
triggerAfterCompletion(processedRequest, response, mappedHandler,
new NestedServletException("Handler processing failed", err));
}
finally {
...
}
}
private void processDispatchResult(HttpServletRequest request, HttpServletResponse response,
@Nullable HandlerExecutionChain mappedHandler, @Nullable ModelAndView mv,
@Nullable Exception exception) throws Exception {
boolean errorView = false;
if (exception != null) {
if (exception instanceof ModelAndViewDefiningException) {
...
}
else {
Object handler = (mappedHandler != null ? mappedHandler.getHandler() : null);
//ArithmeticException将在这处理
mv = processHandlerException(request, response, handler, exception);
errorView = (mv != null);
}
}
...
}
protected ModelAndView processHandlerException(HttpServletRequest request, HttpServletResponse response,
@Nullable Object handler, Exception ex) throws Exception {
// Success and error responses may use different content types
request.removeAttribute(HandlerMapping.PRODUCIBLE_MEDIA_TYPES_ATTRIBUTE);
// Check registered HandlerExceptionResolvers...
ModelAndView exMv = null;
if (this.handlerExceptionResolvers != null) {
//遍历所有的 handlerExceptionResolvers，看谁能处理当前异常HandlerExceptionResolver处理器异常解析器
for (HandlerExceptionResolver resolver : this.handlerExceptionResolvers) {
exMv = resolver.resolveException(request, response, handler, ex);
if (exMv != null) {
break;
}
}
}
...
//若只有系统的自带的异常解析器（没有自定义的），异常还是会抛出
throw ex;
}
}
系统自带的异常解析器：
DefaultErrorAttributes先来处理异常，它主要功能把异常信息保存到request域，并且返回null。
public class DefaultErrorAttributes implements ErrorAttributes, HandlerExceptionResolver, Ordered {
...
public ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) {
this.storeErrorAttributes(request, ex);
return null;
}
private void storeErrorAttributes(HttpServletRequest request, Exception ex) {
request.setAttribute(ERROR_ATTRIBUTE, ex);//把异常信息保存到request域
}
...
}
默认没有任何解析器（上图的
HandlerExceptionResolverComposite）能处理异常，所以最后异常会被抛出。最终底层就会转发
/error请求。会被底层的BasicErrorController处理。
@Controller
@RequestMapping("${server.error.path:${error.path:/error}}")
public class BasicErrorController extends AbstractErrorController {
@RequestMapping(produces = MediaType.TEXT_HTML_VALUE)
public ModelAndView errorHtml(HttpServletRequest request, HttpServletResponse response) {
HttpStatus status = getStatus(request);
Map<String, Object> model = Collections
.unmodifiableMap(getErrorAttributes(request, getErrorAttributeOptions(request, MediaType.TEXT_HTML)));
response.setStatus(status.value());
ModelAndView modelAndView = resolveErrorView(request, response, status, model);
//如果/template/error内没有4**.html或5**.html，
//modelAndView为空，最终还是返回viewName为error的modelAndView
return (modelAndView != null) ? modelAndView : new ModelAndView("error", model);
}
...
}
protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception {
...
protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception {
...
// Actually invoke the handler.
mv = ha.handle(processedRequest, response, mappedHandler.getHandler());
...
//渲染页面
processDispatchResult(processedRequest, response, mappedHandler, mv, dispatchException);
...
}
private void processDispatchResult(HttpServletRequest request, HttpServletResponse response,
@Nullable HandlerExecutionChain mappedHandler, @Nullable ModelAndView mv,
@Nullable Exception exception) throws Exception {
boolean errorView = false;
...
// Did the handler return a view to render?
if (mv != null && !mv.wasCleared()) {
render(mv, request, response);
if (errorView) {
WebUtils.clearErrorRequestAttributes(request);
}
}
...
}
protected void render(ModelAndView mv, HttpServletRequest request, HttpServletResponse response) throws Exception {
...
View view;
String viewName = mv.getViewName();
if (viewName != null) {
// We need to resolve the view name.
//找出合适error的View，如果/template/error内没有4**.html或5**.html，
//将会返回默认异常页面ErrorMvcAutoConfiguration.StaticView
//这里按需深究代码吧！
view = resolveViewName(viewName, mv.getModelInternal(), locale, request);
...
}
...
try {
if (mv.getStatus() != null) {
response.setStatus(mv.getStatus().value());
}
//看下面代码块的StaticView的render块
view.render(mv.getModelInternal(), request, response);
}
catch (Exception ex) {
...
}
}
}
@Configuration(proxyBeanMethods = false)
@ConditionalOnWebApplication(type = Type.SERVLET)
@ConditionalOnClass({ Servlet.class, DispatcherServlet.class })
// Load before the main WebMvcAutoConfiguration so that the error View is available
@AutoConfigureBefore(WebMvcAutoConfiguration.class)
@EnableConfigurationProperties({ ServerProperties.class, ResourceProperties.class, WebMvcProperties.class })
public class ErrorMvcAutoConfiguration {
...
@Configuration(proxyBeanMethods = false)
@ConditionalOnProperty(prefix = "server.error.whitelabel", name = "enabled", matchIfMissing = true)
@Conditional(ErrorTemplateMissingCondition.class)
protected static class WhitelabelErrorViewConfiguration {
//将创建一个名为error的系统默认异常页面View的Bean
private final StaticView defaultErrorView = new StaticView();
@Bean(name = "error")
@ConditionalOnMissingBean(name = "error")
public View defaultErrorView() {
return this.defaultErrorView;
}
// If the user adds @EnableWebMvc then the bean name view resolver from
// WebMvcAutoConfiguration disappears, so add it back in to avoid disappointment.
@Bean
@ConditionalOnMissingBean
public BeanNameViewResolver beanNameViewResolver() {
BeanNameViewResolver resolver = new BeanNameViewResolver();
resolver.setOrder(Ordered.LOWEST_PRECEDENCE - 10);
return resolver;
}
}
private static class StaticView implements View {
private static final MediaType TEXT_HTML_UTF8 = new MediaType("text", "html", StandardCharsets.UTF_8);
private static final Log logger = LogFactory.getLog(StaticView.class);
@Override
public void render(Map<String, ?> model, HttpServletRequest request, HttpServletResponse response)
throws Exception {
if (response.isCommitted()) {
String message = getMessage(model);
logger.error(message);
return;
}
response.setContentType(TEXT_HTML_UTF8.toString());
StringBuilder builder = new StringBuilder();
Object timestamp = model.get("timestamp");
Object message = model.get("message");
Object trace = model.get("trace");
if (response.getContentType() == null) {
response.setContentType(getContentType());
}
//系统默认异常页面html代码
builder.append("<html><body><h1>Whitelabel Error Page</h1>").append(
"<p>This application has no explicit mapping for /error, so you are seeing this as a fallback.</p>")
.append("<div id='created'>").append(timestamp).append("</div>")
.append("<div>There was an unexpected error (type=").append(htmlEscape(model.get("error")))
.append(", status=").append(htmlEscape(model.get("status"))).append(").</div>");
if (message != null) {
builder.append("<div>").append(htmlEscape(message)).append("</div>");
}
if (trace != null) {
builder.append("<div style='white-space:pre-wrap;'>").append(htmlEscape(trace)).append("</div>");
}
builder.append("</body></html>");
response.getWriter().append(builder.toString());
}
private String htmlEscape(Object input) {
return (input != null) ? HtmlUtils.htmlEscape(input.toString()) : null;
}
private String getMessage(Map<String, ?> model) {
Object path = model.get("path");
String message = "Cannot render error page for request [" + path + "]";
if (model.get("message") != null) {
message += " and exception [" + model.get("message") + "]";
}
message += " as the response has already been committed.";
message += " As a result, the response may have the wrong status code.";
return message;
}
@Override
public String getContentType() {
return "text/html";
}
}
}
55、错误处理-【源码流程】几种异常处理原理
1. 自定义错误页
- 自定义错误页
error/404.html error/5xx.html；有精确的错误状态码页面就匹配精确，没有就找 4xx.html；如果都没有就触发白页
image-20220927212117539
2. @ControllerAdvice+@ExceptionHandler
@ControllerAdvice+@ExceptionHandler处理全局异常；底层是ExceptionHandlerExceptionResolver支持的
@Slf4j
@ControllerAdvice
public class GlobalExceptionHandler {
@ExceptionHandler({ArithmeticException.class,NullPointerException.class}) //处理异常
public String handleArithException(Exception e){
log.error("异常是：{}",e);
return "login"; //视图地址
}
}
DefaultErrorAttributes类只是把错误放到请求域中，并不能返回ModelAndView，让其执行到HandlerExceptionResolverComposite
此时HandlerExceptionResolverComposite里的ExceptionHandlerExceptionResolver就能解析了
得到ModelAndView后就执行正常的逻辑，调用render(mv, request, response);渲染页面
3. @ResponseStatus+自定义异常
自定义异常
@ResponseStatus+自定义异常 ；底层是ResponseStatusExceptionResolver，把responseStatus注解的信息底层调用response.sendError(statusCode, resolvedReason)，tomcat发送的/error
@ResponseStatus(value= HttpStatus.FORBIDDEN,reason = "用户数量太多")
public class UserTooManyException extends RuntimeException {
public UserTooManyException(){
}
public UserTooManyException(String message){
super(message);
}
}
@Controller
public class TableController {
@GetMapping("/dynamic_table")
public String dynamic_table(@RequestParam(value="pn",defaultValue = "1") Integer pn,Model model){
//表格内容的遍历
List<User> users = Arrays.asList(new User("zhangsan", "123456"),
new User("lisi", "123444"),
new User("haha", "aaaaa"),
new User("hehe ", "aaddd"));
model.addAttribute("users",users);
if(users.size()>3){
throw new UserTooManyException();//抛出自定义异常
}
return "table/dynamic_table";
}
}
此时ResponseStatusExceptionResolver能够返回ModelAndView
然后调用doResolveException(request, response, handler, ex);做解析流程
@Override
@Nullable
public ModelAndView resolveException(
HttpServletRequest request, HttpServletResponse response, @Nullable Object handler, Exception ex) {
if (shouldApplyTo(request, handler)) {
prepareResponse(ex, response);
ModelAndView result = doResolveException(request, response, handler, ex);
if (result != null) {
// Print debug message when warn logger is not enabled.
if (logger.isDebugEnabled() && (this.warnLogger == null || !this.warnLogger.isWarnEnabled())) {
logger.debug("Resolved [" + ex + "]" + (result.isEmpty() ? "" : " to " + result));
}
// Explicitly configured warn logger in logException method.
logException(ex, request);
}
return result;
}
else {
return null;
}
}
首先判断该异常是否继承ResponseStatusException类，如果没有继承ResponseStatusException类则判断这个异常类是否标注了@ResponseStatus注解
@Override
@Nullable
protected ModelAndView doResolveException(
HttpServletRequest request, HttpServletResponse response, @Nullable Object handler, Exception ex) {
try {
if (ex instanceof ResponseStatusException) {
return resolveResponseStatusException((ResponseStatusException) ex, request, response, handler);
}
ResponseStatus status = AnnotatedElementUtils.findMergedAnnotation(ex.getClass(), ResponseStatus.class);
if (status != null) {
return resolveResponseStatus(status, request, response, handler, ex);
}
if (ex.getCause() instanceof Exception) {
return doResolveException(request, response, handler, (Exception) ex.getCause());
}
}
catch (Exception resolveEx) {
if (logger.isWarnEnabled()) {
logger.warn("Failure while trying to resolve exception [" + ex.getClass().getName() + "]", resolveEx);
}
}
return null;
}
然后把statusCode状态码、reason原因应用上去
protected ModelAndView resolveResponseStatus(ResponseStatus responseStatus, HttpServletRequest request,
HttpServletResponse response, @Nullable Object handler, Exception ex) throws Exception {
int statusCode = responseStatus.code().value();
String reason = responseStatus.reason();
return applyStatusAndReason(statusCode, reason, response);
}
然后调用 response.sendError(statusCode, resolvedReason);直接让tomcat发送/error请求，这次请求就结束了，然后ModelAndView的内容都是空的，所有的视图解析器都解析不了
protected ModelAndView applyStatusAndReason(int statusCode, @Nullable String reason, HttpServletResponse response)
throws IOException {
if (!StringUtils.hasLength(reason)) {
response.sendError(statusCode);
}
else {
String resolvedReason = (this.messageSource != null ?
this.messageSource.getMessage(reason, null, reason, LocaleContextHolder.getLocale()) :
reason);
response.sendError(statusCode, resolvedReason);
}
return new ModelAndView();
}
Spring的异常
- Spring自家异常如
org.springframework.web.bind.MissingServletRequestParameterException，DefaultHandlerExceptionResolver处理Spring自家异常。response.sendError(HttpServletResponse.SC_BAD_REQUEST/*400*/, ex.getMessage());
@ResponseBody
@GetMapping("/hehe")
public String hello(@RequestParam String a) {
return "hello"+a;
}
发送 http://localhost:8080/hehe 请求，此时不携带参数
此时HandlerExceptionResolverComposite里的DefaultHandlerExceptionResolver能够解析，并返回内容为空的ModelAndView
由于我们缺少必要的参数，因此异常为MissingServletRequestParameterException
重定向到400的错误页面
完整代码：
可以看到基本上都是web相关的异常，而且都是response.sendError(HttpServletResponse.SC_BAD_REQUEST, ex.getMessage()); return new ModelAndView(); 重定向后返回空视图
public class DefaultHandlerExceptionResolver extends AbstractHandlerExceptionResolver {
public static final String PAGE_NOT_FOUND_LOG_CATEGORY = "org.springframework.web.servlet.PageNotFound";
protected static final Log pageNotFoundLogger = LogFactory.getLog(PAGE_NOT_FOUND_LOG_CATEGORY);
public DefaultHandlerExceptionResolver() {
setOrder(Ordered.LOWEST_PRECEDENCE);
setWarnLogCategory(getClass().getName());
}
@Override
@Nullable
protected ModelAndView doResolveException(
HttpServletRequest request, HttpServletResponse response, @Nullable Object handler, Exception ex) {
try {
if (ex instanceof HttpRequestMethodNotSupportedException) {
return handleHttpRequestMethodNotSupported(
(HttpRequestMethodNotSupportedException) ex, request, response, handler);
}
else if (ex instanceof HttpMediaTypeNotSupportedException) {
return handleHttpMediaTypeNotSupported(
(HttpMediaTypeNotSupportedException) ex, request, response, handler);
}
else if (ex instanceof HttpMediaTypeNotAcceptableException) {
return handleHttpMediaTypeNotAcceptable(
(HttpMediaTypeNotAcceptableException) ex, request, response, handler);
}
else if (ex instanceof MissingPathVariableException) {
return handleMissingPathVariable(
(MissingPathVariableException) ex, request, response, handler);
}
else if (ex instanceof MissingServletRequestParameterException) {
return handleMissingServletRequestParameter(
(MissingServletRequestParameterException) ex, request, response, handler);
}
else if (ex instanceof ServletRequestBindingException) {
return handleServletRequestBindingException(
(ServletRequestBindingException) ex, request, response, handler);
}
else if (ex instanceof ConversionNotSupportedException) {
return handleConversionNotSupported(
(ConversionNotSupportedException) ex, request, response, handler);
}
else if (ex instanceof TypeMismatchException) {
return handleTypeMismatch(
(TypeMismatchException) ex, request, response, handler);
}
else if (ex instanceof HttpMessageNotReadableException) {
return handleHttpMessageNotReadable(
(HttpMessageNotReadableException) ex, request, response, handler);
}
else if (ex instanceof HttpMessageNotWritableException) {
return handleHttpMessageNotWritable(
(HttpMessageNotWritableException) ex, request, response, handler);
}
else if (ex instanceof MethodArgumentNotValidException) {
return handleMethodArgumentNotValidException(
(MethodArgumentNotValidException) ex, request, response, handler);
}
else if (ex instanceof MissingServletRequestPartException) {
return handleMissingServletRequestPartException(
(MissingServletRequestPartException) ex, request, response, handler);
}
else if (ex instanceof BindException) {
return handleBindException((BindException) ex, request, response, handler);
}
else if (ex instanceof NoHandlerFoundException) {
return handleNoHandlerFoundException(
(NoHandlerFoundException) ex, request, response, handler);
}
else if (ex instanceof AsyncRequestTimeoutException) {
return handleAsyncRequestTimeoutException(
(AsyncRequestTimeoutException) ex, request, response, handler);
}
}
catch (Exception handlerEx) {
if (logger.isWarnEnabled()) {
logger.warn("Failure while trying to resolve exception [" + ex.getClass().getName() + "]", handlerEx);
}
}
return null;
}
protected ModelAndView handleHttpRequestMethodNotSupported(HttpRequestMethodNotSupportedException ex,
HttpServletRequest request, HttpServletResponse response, @Nullable Object handler) throws IOException {
String[] supportedMethods = ex.getSupportedMethods();
if (supportedMethods != null) {
response.setHeader("Allow", StringUtils.arrayToDelimitedString(supportedMethods, ", "));
}
response.sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED, ex.getMessage());
return new ModelAndView();
}
protected ModelAndView handleHttpMediaTypeNotSupported(HttpMediaTypeNotSupportedException ex,
HttpServletRequest request, HttpServletResponse response, @Nullable Object handler) throws IOException {
response.sendError(HttpServletResponse.SC_UNSUPPORTED_MEDIA_TYPE);
List<MediaType> mediaTypes = ex.getSupportedMediaTypes();
if (!CollectionUtils.isEmpty(mediaTypes)) {
response.setHeader("Accept", MediaType.toString(mediaTypes));
}
return new ModelAndView();
}
protected ModelAndView handleHttpMediaTypeNotAcceptable(HttpMediaTypeNotAcceptableException ex,
HttpServletRequest request, HttpServletResponse response, @Nullable Object handler) throws IOException {
response.sendError(HttpServletResponse.SC_NOT_ACCEPTABLE);
return new ModelAndView();
}
protected ModelAndView handleMissingPathVariable(MissingPathVariableException ex,
HttpServletRequest request, HttpServletResponse response, @Nullable Object handler) throws IOException {
response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, ex.getMessage());
return new ModelAndView();
}
protected ModelAndView handleMissingServletRequestParameter(MissingServletRequestParameterException ex,
HttpServletRequest request, HttpServletResponse response, @Nullable Object handler) throws IOException {
response.sendError(HttpServletResponse.SC_BAD_REQUEST, ex.getMessage());
return new ModelAndView();
}
protected ModelAndView handleServletRequestBindingException(ServletRequestBindingException ex,
HttpServletRequest request, HttpServletResponse response, @Nullable Object handler) throws IOException {
response.sendError(HttpServletResponse.SC_BAD_REQUEST, ex.getMessage());
return new ModelAndView();
}
protected ModelAndView handleConversionNotSupported(ConversionNotSupportedException ex,
HttpServletRequest request, HttpServletResponse response, @Nullable Object handler) throws IOException {
sendServerError(ex, request, response);
return new ModelAndView();
}
protected ModelAndView handleTypeMismatch(TypeMismatchException ex,
HttpServletRequest request, HttpServletResponse response, @Nullable Object handler) throws IOException {
response.sendError(HttpServletResponse.SC_BAD_REQUEST);
return new ModelAndView();
}
protected ModelAndView handleHttpMessageNotReadable(HttpMessageNotReadableException ex,
HttpServletRequest request, HttpServletResponse response, @Nullable Object handler) throws IOException {
response.sendError(HttpServletResponse.SC_BAD_REQUEST);
return new ModelAndView();
}
protected ModelAndView handleHttpMessageNotWritable(HttpMessageNotWritableException ex,
HttpServletRequest request, HttpServletResponse response, @Nullable Object handler) throws IOException {
sendServerError(ex, request, response);
return new ModelAndView();
}
protected ModelAndView handleMethodArgumentNotValidException(MethodArgumentNotValidException ex,
HttpServletRequest request, HttpServletResponse response, @Nullable Object handler) throws IOException {
response.sendError(HttpServletResponse.SC_BAD_REQUEST);
return new ModelAndView();
}
protected ModelAndView handleMissingServletRequestPartException(MissingServletRequestPartException ex,
HttpServletRequest request, HttpServletResponse response, @Nullable Object handler) throws IOException {
response.sendError(HttpServletResponse.SC_BAD_REQUEST, ex.getMessage());
return new ModelAndView();
}
protected ModelAndView handleBindException(BindException ex, HttpServletRequest request,
HttpServletResponse response, @Nullable Object handler) throws IOException {
response.sendError(HttpServletResponse.SC_BAD_REQUEST);
return new ModelAndView();
}
protected ModelAndView handleNoHandlerFoundException(NoHandlerFoundException ex,
HttpServletRequest request, HttpServletResponse response, @Nullable Object handler) throws IOException {
pageNotFoundLogger.warn(ex.getMessage());
response.sendError(HttpServletResponse.SC_NOT_FOUND);
return new ModelAndView();
}
protected ModelAndView handleAsyncRequestTimeoutException(AsyncRequestTimeoutException ex,
HttpServletRequest request, HttpServletResponse response, @Nullable Object handler) throws IOException {
if (!response.isCommitted()) {
response.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE);
}
else {
logger.warn("Async request timed out");
}
return new ModelAndView();
}
protected void sendServerError(Exception ex, HttpServletRequest request, HttpServletResponse response)
throws IOException {
request.setAttribute("javax.servlet.error.exception", ex);
response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
}
}
4. 自定义 HandlerExceptionResolver
- 自定义实现
HandlerExceptionResolver处理异常；可以作为默认的全局异常处理规则
前面几个异常处理解析器都实现了HandlerExceptionResolver接口，因此我们也可以实现HandlerExceptionResolver接口创建自定义的异常解析器
@Order(value= Ordered.HIGHEST_PRECEDENCE) //设置优先级为0x80000000=-2^31 ( 1000 0000 0000 0000 0000 0000 0000 0000 )，数字越小优先级越高，默认为0x7fffffff=2^31-1 ( 0111 1111 1111 1111 1111 1111 1111 1111 )
@Component
public class CustomerHandlerExceptionResolver implements HandlerExceptionResolver {
@Override
public ModelAndView resolveException(HttpServletRequest request,
HttpServletResponse response,
Object handler, Exception ex) {
try {
response.sendError(511,"我喜欢的错误");
} catch (IOException e) {
e.printStackTrace();
}
return new ModelAndView();
}
}
使用此方式需要注意解析器的执行顺序，如果没加@Order(value= Ordered.HIGHEST_PRECEDENCE)，则CustomerHandlerExceptionResolver自定义的处理器异常解析器在最后面，解析到DefaultHandlerExceptionResolver时，由于其能够处理，所以直接就返回了，就执行不到我们自定义的异常解析器了
加入@Order(value= Ordered.HIGHEST_PRECEDENCE)后，此时我们的CustomerHandlerExceptionResolver就到最前面了
然后我们就可以像前面的一样重定向到页面，然后返回空内容的ModelAndView （不过由于优先级太高，前面所有的错误都能被我们写的自定义处理器异常解析器解析，导致都由该类解析了）
5. 实现 ErrorViewResolver
ErrorViewResolver实现自定义处理异常response.sendError()，error请求就会转给controller。- 你的异常没有任何人能处理，tomcat底层调用
response.sendError()，error请求就会转给controller。 basicErrorController要去的页面地址是ErrorViewResolver。
@Controller
@RequestMapping("${server.error.path:${error.path:/error}}")
public class BasicErrorController extends AbstractErrorController {
...
@RequestMapping(produces = MediaType.TEXT_HTML_VALUE)
public ModelAndView errorHtml(HttpServletRequest request, HttpServletResponse response) {
HttpStatus status = getStatus(request);
Map<String, Object> model = Collections
.unmodifiableMap(getErrorAttributes(request, getErrorAttributeOptions(request, MediaType.TEXT_HTML)));
response.setStatus(status.value());
ModelAndView modelAndView = resolveErrorView(request, response, status, model);
return (modelAndView != null) ? modelAndView : new ModelAndView("error", model);
}
protected ModelAndView resolveErrorView(HttpServletRequest request, HttpServletResponse response, HttpStatus status,
Map<String, Object> model) {
//这里用到ErrorViewResolver接口
for (ErrorViewResolver resolver : this.errorViewResolvers) {
ModelAndView modelAndView = resolver.resolveErrorView(request, status, model);
if (modelAndView != null) {
return modelAndView;
}
}
return null;
}
...
}
@FunctionalInterface
public interface ErrorViewResolver {
ModelAndView resolveErrorView(HttpServletRequest request, HttpStatus status, Map<String, Object> model);
}
56、原生组件注入-原生注解与Spring方式注入
官方文档 - Servlets, Filters, and listeners
@WebServlet,@WebFilter, and@WebListenerannotated classes can be automatically registered with an embedded servlet container by annotating a@Configurationclass with@ServletComponentScanand specifying the package(s) containing the components that you want to register. By default,@ServletComponentScanscans from the package of the annotated class.
使用原生的注解
使用原生的HttpServlet不会执行DispatcherServlet的doDispatch方法，即Spring的HandlerInterceptor拦截器都不会执行，该请求直接由原生的tomcat处理 (过滤器为javax.servlet.Filter类，不是spring提供的功能，原生tomcat本来就能执行过滤器)
@WebServlet(urlPatterns = "/test/my")
public class MyServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
resp.getWriter().write("66666");
}
}
@Slf4j
@WebFilter(urlPatterns={"/css/*","/images/*","/test/*"}) // servlet规范里的/*类似于spring里面的/**
public class MyFilter implements Filter {
@Override
public void init(FilterConfig filterConfig) throws ServletException {
log.info("MyFilter初始化完成");
}
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
log.info("MyFilter工作");
chain.doFilter(request,response);
}
@Override
public void destroy() {
log.info("MyFilter销毁");
}
}
@Slf4j
@WebListener
public class MyServletContextListener implements ServletContextListener {
@Override
public void contextInitialized(ServletContextEvent sce) {
log.info("MyServletContextListener监听到项目初始化完成");
}
@Override
public void contextDestroyed(ServletContextEvent sce) {
log.info("MyServletContextListener监听到项目销毁");
}
}
最后还要在主启动上类添加注解@ServletComponentScan (默认扫描当前类所在的本包和其子包)
@ServletComponentScan(basePackages = "com.atguigu.boot")
@SpringBootApplication(exclude = RedisAutoConfiguration.class)
public class Boot05WebAdminApplication {
public static void main(String[] args) {
SpringApplication.run(Boot05WebAdminApplication.class, args);
}
}
Spring方式注入
注释掉@WebFilter、@WebListener、@WebServlet后新建一个配置类放入以下bean
ServletRegistrationBean, FilterRegistrationBean, and ServletListenerRegistrationBean
使用如下方式仍然只有原生的Filter生效，spring提供的HandlerInterceptor不生效
@Configuration(proxyBeanMethods = true) //需要开启代理，保证依赖的组件始终是dan'li
public class MyRegistrationConfig {
@Bean
public ServletRegistrationBean<Servlet> myServlet(){
MyServlet myServlet = new MyServlet();
return new ServletRegistrationBean<>(myServlet,"/test/my","/test/my02");
}
@Bean
public FilterRegistrationBean<Filter> myFilter(){
MyFilter myFilter = new MyFilter();
//return new FilterRegistrationBean(myFilter,myServlet(),myServlet2(),myServlet3());
FilterRegistrationBean<Filter> filterRegistrationBean = new FilterRegistrationBean<>(myFilter);
filterRegistrationBean.setUrlPatterns(Arrays.asList("/test/my","/css/*"));
return filterRegistrationBean;
}
@Bean
public ServletListenerRegistrationBean<EventListener> myListener(){
MyListener myServletContextListener = new MyListener();
return new ServletListenerRegistrationBean<>(myServletContextListener);
}
}
57、原生组件注入-【源码分析】DispatcherServlet注入原理
org.springframework.boot.autoconfigure.web.servlet.DispatcherServletAutoConfiguration配置类
@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE)
@Configuration(proxyBeanMethods = false)
@ConditionalOnWebApplication(type = Type.SERVLET)
@ConditionalOnClass(DispatcherServlet.class)
@AutoConfigureAfter(ServletWebServerFactoryAutoConfiguration.class)
public class DispatcherServletAutoConfiguration {
/*
* The bean name for a DispatcherServlet that will be mapped to the root URL "/"
*/
public static final String DEFAULT_DISPATCHER_SERVLET_BEAN_NAME = "dispatcherServlet";
/*
* The bean name for a ServletRegistrationBean for the DispatcherServlet "/"
*/
public static final String DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME = "dispatcherServletRegistration";
@Configuration(proxyBeanMethods = false)
@Conditional(DefaultDispatcherServletCondition.class)
@ConditionalOnClass(ServletRegistration.class)
@EnableConfigurationProperties(WebMvcProperties.class)
protected static class DispatcherServletConfiguration {
//创建DispatcherServlet类的Bean
@Bean(name = DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)
public DispatcherServlet dispatcherServlet(WebMvcProperties webMvcProperties) {
DispatcherServlet dispatcherServlet = new DispatcherServlet();
dispatcherServlet.setDispatchOptionsRequest(webMvcProperties.isDispatchOptionsRequest());
dispatcherServlet.setDispatchTraceRequest(webMvcProperties.isDispatchTraceRequest());
dispatcherServlet.setThrowExceptionIfNoHandlerFound(webMvcProperties.isThrowExceptionIfNoHandlerFound());
dispatcherServlet.setPublishEvents(webMvcProperties.isPublishRequestHandledEvents());
dispatcherServlet.setEnableLoggingRequestDetails(webMvcProperties.isLogRequestDetails());
return dispatcherServlet;
}
@Bean
@ConditionalOnBean(MultipartResolver.class)
@ConditionalOnMissingBean(name = DispatcherServlet.MULTIPART_RESOLVER_BEAN_NAME)
public MultipartResolver multipartResolver(MultipartResolver resolver) {
// Detect if the user has created a MultipartResolver but named it incorrectly
return resolver;
}
}
@Configuration(proxyBeanMethods = false)
@Conditional(DispatcherServletRegistrationCondition.class)
@ConditionalOnClass(ServletRegistration.class)
@EnableConfigurationProperties(WebMvcProperties.class)
@Import(DispatcherServletConfiguration.class)
protected static class DispatcherServletRegistrationConfiguration {
//注册DispatcherServlet类
@Bean(name = DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME)
@ConditionalOnBean(value = DispatcherServlet.class, name = DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)
public DispatcherServletRegistrationBean dispatcherServletRegistration(DispatcherServlet dispatcherServlet,
WebMvcProperties webMvcProperties, ObjectProvider<MultipartConfigElement> multipartConfig) {
DispatcherServletRegistrationBean registration = new DispatcherServletRegistrationBean(dispatcherServlet,
webMvcProperties.getServlet().getPath());
registration.setName(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME);
registration.setLoadOnStartup(webMvcProperties.getServlet().getLoadOnStartup());
multipartConfig.ifAvailable(registration::setMultipartConfig);
return registration;
}
}
...
}
DispatcherServlet默认映射的是 / 路径，可以通过在配置文件修改spring.mvc.servlet.path=/mvc。
在DispatcherServletAutoConfiguration的内部类DispatcherServletConfiguration里面首先配置类DispatcherServlet
public class DispatcherServletAutoConfiguration {
/*
* The bean name for a DispatcherServlet that will be mapped to the root URL "/"
*/
public static final String DEFAULT_DISPATCHER_SERVLET_BEAN_NAME = "dispatcherServlet";
/*
* The bean name for a ServletRegistrationBean for the DispatcherServlet "/"
*/
public static final String DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME = "dispatcherServletRegistration";
@Configuration(proxyBeanMethods = false)
@Conditional(DefaultDispatcherServletCondition.class)
@ConditionalOnClass(ServletRegistration.class)
@EnableConfigurationProperties(WebMvcProperties.class)
protected static class DispatcherServletConfiguration {
@Bean(name = DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)
public DispatcherServlet dispatcherServlet(WebMvcProperties webMvcProperties) {
DispatcherServlet dispatcherServlet = new DispatcherServlet();
dispatcherServlet.setDispatchOptionsRequest(webMvcProperties.isDispatchOptionsRequest());
dispatcherServlet.setDispatchTraceRequest(webMvcProperties.isDispatchTraceRequest());
dispatcherServlet.setThrowExceptionIfNoHandlerFound(webMvcProperties.isThrowExceptionIfNoHandlerFound());
dispatcherServlet.setPublishEvents(webMvcProperties.isPublishRequestHandledEvents());
dispatcherServlet.setEnableLoggingRequestDetails(webMvcProperties.isLogRequestDetails());
return dispatcherServlet;
}
...
}
然后是文件上传解析器
@Bean
@ConditionalOnBean(MultipartResolver.class)
@ConditionalOnMissingBean(name = DispatcherServlet.MULTIPART_RESOLVER_BEAN_NAME)
public MultipartResolver multipartResolver(MultipartResolver resolver) {
// Detect if the user has created a MultipartResolver but named it incorrectly
return resolver;
}
内部类DispatcherServletRegistrationConfiguration配置类
public class DispatcherServletAutoConfiguration {
...
@Configuration(proxyBeanMethods = false)
@Conditional(DispatcherServletRegistrationCondition.class)
@ConditionalOnClass(ServletRegistration.class)
@EnableConfigurationProperties(WebMvcProperties.class)
@Import(DispatcherServletConfiguration.class)
protected static class DispatcherServletRegistrationConfiguration {
@Bean(name = DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME)
@ConditionalOnBean(value = DispatcherServlet.class, name = DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)
public DispatcherServletRegistrationBean dispatcherServletRegistration(DispatcherServlet dispatcherServlet,
WebMvcProperties webMvcProperties, ObjectProvider<MultipartConfigElement> multipartConfig) {
DispatcherServletRegistrationBean registration = new DispatcherServletRegistrationBean(dispatcherServlet,
webMvcProperties.getServlet().getPath());
registration.setName(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME);
registration.setLoadOnStartup(webMvcProperties.getServlet().getLoadOnStartup());
multipartConfig.ifAvailable(registration::setMultipartConfig);
return registration;
}
}
...
}
而DispatcherServletRegistrationBean继承ServletRegistrationBean（ServletRegistrationBean就是前面通过原生注解注入时提到的）
public class DispatcherServletRegistrationBean extends ServletRegistrationBean<DispatcherServlet>
implements DispatcherServletPath {
...
}
在创建DispatcherServletRegistrationBean时会从容器中拿dispatcherServlet、webMvcProperties、multipartConfig，然后根据webMvcProperties.getServlet().getPath()的值注册为该Servlet路径
该配置位于org.springframework.boot.autoconfigure.web.servlet.WebMvcProperties类里，默认的路径为/，由于我们配置的路径为/test/my，而spring配置的路径为/，根据tomcat的最长匹配优先原则，如果访问/test/my会由/test/my来处理，不会通过spring，因此只有原生tomcat具有的功能才会生效
@ConfigurationProperties(prefix = "spring.mvc")
public class WebMvcProperties {
...
public static class Servlet {
/**
* Path of the dispatcher servlet.
*/
private String path = "/";
/**
* Load on startup priority of the dispatcher servlet.
*/
private int loadOnStartup = -1;
public String getPath() {
return this.path;
}
}
...
}
根据上面的配置文件，可以修改spring.mvc.servlet.path=/，来改变默认路径
58、嵌入式Servlet容器-【源码分析】切换web服务器与定制化
默认支持的WebServer
Tomcat,Jetty, orUndertow。ServletWebServerApplicationContext容器启动寻找ServletWebServerFactory并引导创建服务器。
原理
- SpringBoot应用启动发现当前是Web应用，web场景包-导入tomcat。
- web应用会创建一个web版的IOC容器
ServletWebServerApplicationContext。 ServletWebServerApplicationContext启动的时候寻找ServletWebServerFactory（Servlet 的web服务器工厂——>Servlet 的web服务器）。- SpringBoot底层默认有很多的WebServer工厂（
ServletWebServerFactoryConfiguration内创建Bean），如：TomcatServletWebServerFactoryJettyServletWebServerFactoryUndertowServletWebServerFactory
- 底层直接会有一个自动配置类
ServletWebServerFactoryAutoConfiguration。 ServletWebServerFactoryAutoConfiguration导入了ServletWebServerFactoryConfiguration（配置类）。ServletWebServerFactoryConfiguration根据动态判断系统中到底导入了那个Web服务器的包。（默认是web-starter导入tomcat包），容器中就有TomcatServletWebServerFactoryTomcatServletWebServerFactory创建出Tomcat服务器并启动；TomcatWebServer的构造器拥有初始化方法initialize——this.tomcat.start();- 内嵌服务器，与以前手动把启动服务器相比，改成现在使用代码启动（tomcat核心jar包存在）。
Spring Boot默认使用Tomcat服务器，若需更改其他服务器，则修改工程pom.xml：
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<exclusions>
<exclusion>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jetty</artifactId>
</dependency>
The ServletWebServerApplicationContext
Under the hood, Spring Boot uses a different type of
ApplicationContextfor embedded servlet container support. TheServletWebServerApplicationContextis a special type ofWebApplicationContextthat bootstraps itself by searching for a singleServletWebServerFactorybean. Usually aTomcatServletWebServerFactory,JettyServletWebServerFactory, orUndertowServletWebServerFactoryhas been auto-configured.
在底层，Spring Boot 使用不同类型的 ApplicationContext 来支持嵌入式 servlet 容器。 ServletWebServerApplicationContext 是一种特殊类型的 WebApplicationContext，它通过搜索单个 ServletWebServerFactory bean 来引导自身。通常已自动配置了 TomcatServletWebServerFactory、JettyServletWebServerFactory 或 UndertowServletWebServerFactory。
其继承关系如下图所示：
public class ServletWebServerApplicationContext extends GenericWebApplicationContext
implements ConfigurableWebServerApplicationContext
public class GenericWebApplicationContext extends GenericApplicationContext
implements ConfigurableWebApplicationContext, ThemeSource
public class GenericApplicationContext extends AbstractApplicationContext implements BeanDefinitionRegistry
public abstract class AbstractApplicationContext extends DefaultResourceLoader
implements ConfigurableApplicationContext
public interface ConfigurableApplicationContext extends ApplicationContext, Lifecycle, Closeable
根据官方文档that bootstraps itself by searching for a single ServletWebServerFactory bean.，查看该类，可以发现它导入了ServletWebServerFactoryConfiguration.EmbeddedTomcat.class、ServletWebServerFactoryConfiguration.EmbeddedJetty.class、ServletWebServerFactoryConfiguration.EmbeddedUndertow.class
@Configuration(proxyBeanMethods = false)
@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE)
@ConditionalOnClass(ServletRequest.class)
@ConditionalOnWebApplication(type = Type.SERVLET)
@EnableConfigurationProperties(ServerProperties.class)
@Import({ ServletWebServerFactoryAutoConfiguration.BeanPostProcessorsRegistrar.class,
ServletWebServerFactoryConfiguration.EmbeddedTomcat.class,
ServletWebServerFactoryConfiguration.EmbeddedJetty.class,
ServletWebServerFactoryConfiguration.EmbeddedUndertow.class })
public class ServletWebServerFactoryAutoConfiguration {
@Bean
public ServletWebServerFactoryCustomizer servletWebServerFactoryCustomizer(ServerProperties serverProperties) {
return new ServletWebServerFactoryCustomizer(serverProperties);
}
@Bean
@ConditionalOnClass(name = "org.apache.catalina.startup.Tomcat")
public TomcatServletWebServerFactoryCustomizer tomcatServletWebServerFactoryCustomizer(
ServerProperties serverProperties) {
return new TomcatServletWebServerFactoryCustomizer(serverProperties);
}
...
}
在org.springframework.boot.autoconfigure.web.servlet.ServletWebServerFactoryConfiguration类里如果存在对应的类，就会把TomcatServletWebServerFactory、JettyServletWebServerFactory、UndertowServletWebServerFactory其中的一个放到ioc容器中
@Configuration(proxyBeanMethods = false)
class ServletWebServerFactoryConfiguration {
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass({ Servlet.class, Tomcat.class, UpgradeProtocol.class })
@ConditionalOnMissingBean(value = ServletWebServerFactory.class, search = SearchStrategy.CURRENT)
static class EmbeddedTomcat {
@Bean
TomcatServletWebServerFactory tomcatServletWebServerFactory(
ObjectProvider<TomcatConnectorCustomizer> connectorCustomizers,
ObjectProvider<TomcatContextCustomizer> contextCustomizers,
ObjectProvider<TomcatProtocolHandlerCustomizer<?>> protocolHandlerCustomizers) {
TomcatServletWebServerFactory factory = new TomcatServletWebServerFactory();
factory.getTomcatConnectorCustomizers()
.addAll(connectorCustomizers.orderedStream().collect(Collectors.toList()));
factory.getTomcatContextCustomizers()
.addAll(contextCustomizers.orderedStream().collect(Collectors.toList()));
factory.getTomcatProtocolHandlerCustomizers()
.addAll(protocolHandlerCustomizers.orderedStream().collect(Collectors.toList()));
return factory;
}
}
/**
* Nested configuration if Jetty is being used.
*/
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass({ Servlet.class, Server.class, Loader.class, WebAppContext.class })
@ConditionalOnMissingBean(value = ServletWebServerFactory.class, search = SearchStrategy.CURRENT)
static class EmbeddedJetty {
@Bean
JettyServletWebServerFactory JettyServletWebServerFactory(
ObjectProvider<JettyServerCustomizer> serverCustomizers) {
JettyServletWebServerFactory factory = new JettyServletWebServerFactory();
factory.getServerCustomizers().addAll(serverCustomizers.orderedStream().collect(Collectors.toList()));
return factory;
}
}
/**
* Nested configuration if Undertow is being used.
*/
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass({ Servlet.class, Undertow.class, SslClientAuthMode.class })
@ConditionalOnMissingBean(value = ServletWebServerFactory.class, search = SearchStrategy.CURRENT)
static class EmbeddedUndertow {
@Bean
UndertowServletWebServerFactory undertowServletWebServerFactory(
ObjectProvider<UndertowDeploymentInfoCustomizer> deploymentInfoCustomizers,
ObjectProvider<UndertowBuilderCustomizer> builderCustomizers) {
UndertowServletWebServerFactory factory = new UndertowServletWebServerFactory();
factory.getDeploymentInfoCustomizers()
.addAll(deploymentInfoCustomizers.orderedStream().collect(Collectors.toList()));
factory.getBuilderCustomizers().addAll(builderCustomizers.orderedStream().collect(Collectors.toList()));
return factory;
}
}
}
准备好服务器后，就开始调用createWebServer()方法创建Web服务
首先会调用getWebServerFactory()方法，从容器中找WebServer工厂
private void createWebServer() {
WebServer webServer = this.webServer;
ServletContext servletContext = getServletContext();
if (webServer == null && servletContext == null) {
ServletWebServerFactory factory = getWebServerFactory();
this.webServer = factory.getWebServer(getSelfInitializer());
getBeanFactory().registerSingleton("webServerGracefulShutdown",
new WebServerGracefulShutdownLifecycle(this.webServer));
getBeanFactory().registerSingleton("webServerStartStop",
new WebServerStartStopLifecycle(this, this.webServer));
}
else if (servletContext != null) {
try {
getSelfInitializer().onStartup(servletContext);
}
catch (ServletException ex) {
throw new ApplicationContextException("Cannot initialize servlet context", ex);
}
}
initPropertySources();
}
该方法首先会重容器中寻找实现了ServletWebServerFactory接口的bean的名字，如果没有找到就抛ServletWebServerFactory bean异常，找到多个就抛multiple ServletWebServerFactory beans异常，如果只存在一个则返回该工厂
我们此时就只有一个为tomcatServletWebServerFactory的工厂，该类也就是前面提到的ServletWebServerFactory 会自动配置TomcatServletWebServerFactory、JettyServletWebServerFactory 、UndertowServletWebServerFactory中的TomcatServletWebServerFactory
protected ServletWebServerFactory getWebServerFactory() {
// Use bean names so that we don't consider the hierarchy
String[] beanNames = getBeanFactory().getBeanNamesForType(ServletWebServerFactory.class);
if (beanNames.length == 0) {
throw new ApplicationContextException("Unable to start ServletWebServerApplicationContext due to missing "
+ "ServletWebServerFactory bean.");
}
if (beanNames.length > 1) {
throw new ApplicationContextException("Unable to start ServletWebServerApplicationContext due to multiple "
+ "ServletWebServerFactory beans : " + StringUtils.arrayToCommaDelimitedString(beanNames));
}
return getBeanFactory().getBean(beanNames[0], ServletWebServerFactory.class);
}
ServletWebServerFactory得到以后就会调用getWebServer方法获取Web服务器
在getWebServer方法里会创建Tomcat容器，然后调用getTomcatWebServer(tomcat)返回WebServer接口
@Override
public WebServer getWebServer(ServletContextInitializer... initializers) {
if (this.disableMBeanRegistry) {
Registry.disableRegistry();
}
Tomcat tomcat = new Tomcat();
File baseDir = (this.baseDirectory != null) ? this.baseDirectory : createTempDir("tomcat");
tomcat.setBaseDir(baseDir.getAbsolutePath());
// 通过 org.apache.coyote.http11.Http11NioProtocol 协议建立连接
Connector connector = new Connector(this.protocol);
connector.setThrowOnFailure(true);
tomcat.getService().addConnector(connector);
customizeConnector(connector);
tomcat.setConnector(connector);
tomcat.getHost().setAutoDeploy(false);
configureEngine(tomcat.getEngine());
for (Connector additionalConnector : this.additionalTomcatConnectors) {
tomcat.getService().addConnector(additionalConnector);
}
prepareContext(tomcat.getHost(), initializers);
return getTomcatWebServer(tomcat);
}
WebServer接口定义了启动服务器的start()方法
点击start()方法左侧按钮，可以看到支持Jetty、Netty、Tomcat、Undertow这四种类型的服务器
getTomcatWebServer(tomcat)方法会创建TomcatWebServer
protected TomcatWebServer getTomcatWebServer(Tomcat tomcat) {
return new TomcatWebServer(tomcat, getPort() >= 0, getShutdown());
}
在该构造器中会调用initialize();方法
public TomcatWebServer(Tomcat tomcat, boolean autoStart, Shutdown shutdown) {
Assert.notNull(tomcat, "Tomcat Server must not be null");
this.tomcat = tomcat;
this.autoStart = autoStart;
this.gracefulShutdown = (shutdown == Shutdown.GRACEFUL) ? new GracefulShutdown(tomcat) : null;
initialize();
}
initialize()方法会调用this.tomcat.start();方法
private void initialize() throws WebServerException {
logger.info("Tomcat initialized with port(s): " + getPortsDescription(false));
synchronized (this.monitor) {
try {
addInstanceIdToEngineName();
Context context = findContext();
context.addLifecycleListener((event) -> {
if (context.equals(event.getSource()) && Lifecycle.START_EVENT.equals(event.getType())) {
// Remove service connectors so that protocol binding doesn't
// happen when the service is started.
removeServiceConnectors();
}
});
// Start the server to trigger initialization listeners
this.tomcat.start();
// We can re-throw failure exception directly in the main thread
rethrowDeferredStartupExceptions();
try {
ContextBindings.bindClassLoader(context, context.getNamingToken(), getClass().getClassLoader());
}
catch (NamingException ex) {
// Naming is not enabled. Continue
}
// Unlike Jetty, all Tomcat threads are daemon threads. We create a
// blocking non-daemon to stop immediate shutdown
startDaemonAwaitThread();
}
catch (Exception ex) {
stopSilently();
destroySilently();
throw new WebServerException("Unable to start embedded Tomcat", ex);
}
}
}
该this.tomcat.start();就是原生的org.apache.catalina.startup.Tomcat包下的start()方法
修改使用的服务器
可以配置的服务器Starters如下图所示
| Name | Description |
|---|---|
spring-boot-starter-jetty | Starter for using Jetty as the embedded servlet container. An alternative to spring-boot-starter-tomcat |
spring-boot-starter-log4j2 | Starter for using Log4j2 for logging. An alternative to spring-boot-starter-logging |
spring-boot-starter-logging | Starter for logging using Logback. Default logging starter |
spring-boot-starter-reactor-netty | Starter for using Reactor Netty as the embedded reactive HTTP server. |
spring-boot-starter-tomcat | Starter for using Tomcat as the embedded servlet container. Default servlet container starter used by spring-boot-starter-web |
spring-boot-starter-undertow | Starter for using Undertow as the embedded servlet container. An alternative to spring-boot-starter-tomcat |
由于我们引入了spring-boot-starter-web场景
该场景导入了spring-boot-starter-tomcat
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
<version>2.3.4.RELEASE</version>
<scope>compile</scope>
</dependency>
因此修改使用的服务器非常简单，只需排除spring-boot-starter-tomcat，加入其他服务器的starter即可
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<exclusions>
<exclusion>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-undertow</artifactId>
</dependency>
此时Undertow就启动起来了
定制Servlet容器
实现
WebServerFactoryCustomizer<ConfigurableServletWebServerFactory>- 把配置文件的值和
ServletWebServerFactory进行绑定
- 把配置文件的值和
修改配置文件
server.xxx直接自定义
ConfigurableServletWebServerFactory
xxxxxCustomizer：定制化器，可以改变xxxx的默认规则
import org.springframework.boot.web.server.WebServerFactoryCustomizer;
import org.springframework.boot.web.servlet.server.ConfigurableServletWebServerFactory;
import org.springframework.stereotype.Component;
@Component
public class CustomizationBean implements WebServerFactoryCustomizer<ConfigurableServletWebServerFactory> {
@Override
public void customize(ConfigurableServletWebServerFactory server) {
server.setPort(9000);
}
}
7.4.4. Customizing Embedded Servlet Containers
Common servlet container settings can be configured by using Spring
Environmentproperties. Usually, you would define the properties in yourapplication.propertiesfile.Common server settings include:
- Network settings: Listen port for incoming HTTP requests (
server.port), interface address to bind toserver.address, and so on.- Session settings: Whether the session is persistent (
server.servlet.session.persistent), session timeout (server.servlet.session.timeout), location of session data (server.servlet.session.store-dir), and session-cookie configuration (server.servlet.session.cookie.*).- Error management: Location of the error page (
server.error.path) and so on.- SSL
- HTTP compression
Spring Boot tries as much as possible to expose common settings, but this is not always possible. For those cases, dedicated namespaces offer server-specific customizations (see
server.tomcatandserver.undertow). For instance, access logs can be configured with specific features of the embedded servlet container.See the
ServerPropertiesclass for a complete list.Programmatic Customization
If you need to programmatically configure your embedded servlet container, you can register a Spring bean that implements the
WebServerFactoryCustomizerinterface.WebServerFactoryCustomizerprovides access to theConfigurableServletWebServerFactory, which includes numerous customization setter methods. The following example shows programmatically setting the port:import org.springframework.boot.web.server.WebServerFactoryCustomizer; import org.springframework.boot.web.servlet.server.ConfigurableServletWebServerFactory; import org.springframework.stereotype.Component; @Component public class CustomizationBean implements WebServerFactoryCustomizer<ConfigurableServletWebServerFactory> { @Override public void customize(ConfigurableServletWebServerFactory server) { server.setPort(9000); } }
TomcatServletWebServerFactory,JettyServletWebServerFactoryandUndertowServletWebServerFactoryare dedicated variants ofConfigurableServletWebServerFactorythat have additional customization setter methods for Tomcat, Jetty and Undertow respectively.Customizing ConfigurableServletWebServerFactory Directly
If the preceding customization techniques are too limited, you can register the
TomcatServletWebServerFactory,JettyServletWebServerFactory, orUndertowServletWebServerFactorybean yourself.@Bean public ConfigurableServletWebServerFactory webServerFactory() { TomcatServletWebServerFactory factory = new TomcatServletWebServerFactory(); factory.setPort(9000); factory.setSessionTimeout(10, TimeUnit.MINUTES); factory.addErrorPages(new ErrorPage(HttpStatus.NOT_FOUND, "/notfound.html")); return factory; }Setters are provided for many configuration options. Several protected method “hooks” are also provided should you need to do something more exotic. See the source code documentation for details.
- ServerProperties配置文件
ServletWebServerFactoryAutoConfiguration类引入的ServerProperties配置类，因此可以通过该配置类配置绝大部分功能
- 传入
ServletWebServerFactoryCustomizer需要的ConfigurableServletWebServerFactory
也可以使用ServletWebServerFactory的ConfigurableServletWebServerFactory来进行自定义的配置
ConfigurableServletWebServerFactory类的配置也会在ServletWebServerFactoryCustomizer中应用
public class ServletWebServerFactoryCustomizer
implements WebServerFactoryCustomizer<ConfigurableServletWebServerFactory>, Ordered {
private final ServerProperties serverProperties;
public ServletWebServerFactoryCustomizer(ServerProperties serverProperties) {
this.serverProperties = serverProperties;
}
@Override
public int getOrder() {
return 0;
}
@Override
public void customize(ConfigurableServletWebServerFactory factory) {
PropertyMapper map = PropertyMapper.get().alwaysApplyingWhenNonNull();
map.from(this.serverProperties::getPort).to(factory::setPort);
map.from(this.serverProperties::getAddress).to(factory::setAddress);
map.from(this.serverProperties.getServlet()::getContextPath).to(factory::setContextPath);
map.from(this.serverProperties.getServlet()::getApplicationDisplayName).to(factory::setDisplayName);
map.from(this.serverProperties.getServlet()::isRegisterDefaultServlet).to(factory::setRegisterDefaultServlet);
map.from(this.serverProperties.getServlet()::getSession).to(factory::setSession);
map.from(this.serverProperties::getSsl).to(factory::setSsl);
map.from(this.serverProperties.getServlet()::getJsp).to(factory::setJsp);
map.from(this.serverProperties::getCompression).to(factory::setCompression);
map.from(this.serverProperties::getHttp2).to(factory::setHttp2);
map.from(this.serverProperties::getServerHeader).to(factory::setServerHeader);
map.from(this.serverProperties.getServlet()::getContextParameters).to(factory::setInitParameters);
map.from(this.serverProperties.getShutdown()).to(factory::setShutdown);
}
}
然后ServletWebServerFactoryAutoConfiguration会将ServletWebServerFactoryCustomizer放入容器中（当然也可以直接向容器中放入ServletWebServerFactoryCustomizer来实现定制化）
3、放入TomcatServletWebServerFactoryCustomizer
ServletWebServerFactoryAutoConfiguration类会向容器中放TomcatServletWebServerFactoryCustomizer，因此也可以自己在容器中放TomcatServletWebServerFactoryCustomizer来实现定制化
59、定制化原理-SpringBoot定制化组件的几种方式（小结）
定制化的常见方式
修改配置文件
xxxxxCustomizer编写自定义的配置类
xxxConfiguration+@Bean替换、增加容器中默认组件，视图解析器Web应用 编写一个配置类实现
WebMvcConfigurer即可定制化web功能 +@Bean给容器中再扩展一些组件
@Configuration
public class AdminWebConfig implements WebMvcConfigurer{
}
@EnableWebMvc+WebMvcConfigurer—@Bean可以全面接管SpringMVC，所有规则全部自己重新配置； 实现定制和扩展功能（高级功能，初学者退避三舍）。- 原理：
WebMvcAutoConfiguration默认的SpringMVC的自动配置功能类，如静态资源、欢迎页等。- 一旦使用
@EnableWebMvc，会@Import(DelegatingWebMvcConfiguration.class)。 DelegatingWebMvcConfiguration的作用，只保证SpringMVC最基本的使用- 把所有系统中的
WebMvcConfigurer拿过来，所有功能的定制都是这些WebMvcConfigurer合起来一起生效。 - 自动配置了一些非常底层的组件，如
RequestMappingHandlerMapping，这些组件依赖的组件都是从容器中获取如。 public class DelegatingWebMvcConfiguration extends WebMvcConfigurationSupport。
- 把所有系统中的
WebMvcAutoConfiguration里面的配置要能生效必须@ConditionalOnMissingBean(WebMvcConfigurationSupport.class)。- @EnableWebMvc 导致了WebMvcAutoConfiguration 没有生效。
- 原理：
Spring MVC Auto-configuration
Spring Boot provides auto-configuration for Spring MVC that works well with most applications.
The auto-configuration adds the following features on top of Spring’s defaults:
- Inclusion of
ContentNegotiatingViewResolverandBeanNameViewResolverbeans.- Support for serving static resources, including support for WebJars (covered later in this document).
- Automatic registration of
Converter,GenericConverter, andFormatterbeans.- Support for
HttpMessageConverters(covered later in this document).- Automatic registration of
MessageCodesResolver(covered later in this document).- Static
index.htmlsupport.- Automatic use of a
ConfigurableWebBindingInitializerbean (covered later in this document).If you want to keep those Spring Boot MVC customizations and make more MVC customizations (interceptors, formatters, view controllers, and other features), you can add your own
@Configurationclass of typeWebMvcConfigurerbut without@EnableWebMvc.If you want to provide custom instances of
RequestMappingHandlerMapping,RequestMappingHandlerAdapter, orExceptionHandlerExceptionResolver, and still keep the Spring Boot MVC customizations, you can declare a bean of typeWebMvcRegistrationsand use it to provide custom instances of those components.If you want to take complete control of Spring MVC, you can add your own
@Configurationannotated with@EnableWebMvc, or alternatively add your own@Configuration-annotatedDelegatingWebMvcConfigurationas described in the Javadoc of@EnableWebMvc.
@EnableWebMvc原理
EnableWebMvc注解会导入DelegatingWebMvcConfiguration
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Documented
@Import(DelegatingWebMvcConfiguration.class)
public @interface EnableWebMvc {
}
DelegatingWebMvcConfiguration类中的setConfigurers方法会拿到所有的WebMvcConfigurer，然后再配置其他功能
@Configuration(proxyBeanMethods = false)
public class DelegatingWebMvcConfiguration extends WebMvcConfigurationSupport {
private final WebMvcConfigurerComposite configurers = new WebMvcConfigurerComposite();
@Autowired(required = false)
public void setConfigurers(List<WebMvcConfigurer> configurers) {
if (!CollectionUtils.isEmpty(configurers)) {
this.configurers.addWebMvcConfigurers(configurers);
}
}
...
}
DelegatingWebMvcConfiguration类继承的WebMvcConfigurationSupport也会配置一些非常底层的组件
之所以使用@EnableWebMvc注解后WebMvcAutoConfiguration不生效，就是因为WebMvcAutoConfiguration类上添加了@ConditionalOnMissingBean(WebMvcConfigurationSupport.class)，当WebMvcConfigurationSupport不存在时WebMvcAutoConfiguration才生效。
@Configuration(proxyBeanMethods = false)
@ConditionalOnWebApplication(type = Type.SERVLET)
@ConditionalOnClass({ Servlet.class, DispatcherServlet.class, WebMvcConfigurer.class })
@ConditionalOnMissingBean(WebMvcConfigurationSupport.class)
@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE + 10)
@AutoConfigureAfter({ DispatcherServletAutoConfiguration.class, TaskExecutionAutoConfiguration.class,
ValidationAutoConfiguration.class })
public class WebMvcAutoConfiguration {
...
}
原理分析套路
场景starter - xxxxAutoConfiguration - 导入xxx组件 - 绑定xxxProperties - 绑定配置文件项。
60、数据访问-数据库场景的自动配置分析与整合测试
导入JDBC场景
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jdbc</artifactId>
</dependency>
接着导入数据库驱动包（MySQL为例）。
<!--默认版本：-->
<mysql.version>8.0.22</mysql.version>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<!--<version>5.1.49</version>-->
</dependency>
<!--
想要修改版本
1、直接依赖引入具体版本（maven的就近依赖原则）
2、重新声明版本（maven的属性的就近优先原则）
-->
<properties>
<java.version>1.8</java.version>
<mysql.version>5.1.49</mysql.version>
</properties>
相关数据源配置类
DataSourceAutoConfiguration： 数据源的自动配置。- 修改数据源相关的配置：
spring.datasource。 - 数据库连接池的配置，是自己容器中没有DataSource才自动配置的。
- 底层配置好的连接池是：
HikariDataSource。
- 修改数据源相关的配置：
DataSourceTransactionManagerAutoConfiguration： 事务管理器的自动配置。JdbcTemplateAutoConfiguration：JdbcTemplate的自动配置，可以来对数据库进行CRUD。- 可以修改前缀为
spring.jdbc的配置项来修改JdbcTemplate。 @Bean @Primary JdbcTemplate：Spring容器中有这个JdbcTemplate组件，使用@Autowired。
- 可以修改前缀为
JndiDataSourceAutoConfiguration： JNDI的自动配置。XADataSourceAutoConfiguration： 分布式事务相关的。
DataSourceAutoConfiguration
DataSourceAutoConfiguration会导入常见的数据源
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass({ DataSource.class, EmbeddedDatabaseType.class })
@ConditionalOnMissingBean(type = "io.r2dbc.spi.ConnectionFactory")
@EnableConfigurationProperties(DataSourceProperties.class)
@Import({ DataSourcePoolMetadataProvidersConfiguration.class, DataSourceInitializationConfiguration.class })
public class DataSourceAutoConfiguration {
@Configuration(proxyBeanMethods = false)
@Conditional(EmbeddedDatabaseCondition.class)
@ConditionalOnMissingBean({ DataSource.class, XADataSource.class })
@Import(EmbeddedDataSourceConfiguration.class)
protected static class EmbeddedDatabaseConfiguration {
}
@Configuration(proxyBeanMethods = false)
@Conditional(PooledDataSourceCondition.class)
@ConditionalOnMissingBean({ DataSource.class, XADataSource.class })
@Import({ DataSourceConfiguration.Hikari.class, DataSourceConfiguration.Tomcat.class,
DataSourceConfiguration.Dbcp2.class, DataSourceConfiguration.Generic.class,
DataSourceJmxConfiguration.class })
protected static class PooledDataSourceConfiguration {
}
...
}
通过@ConditionalOnClass(HikariDataSource.class)来判断要使用的数据源，如果配置了多个数据源可以通过spring.datasource.type配置来指定使用的数据源
abstract class DataSourceConfiguration {
@SuppressWarnings("unchecked")
protected static <T> T createDataSource(DataSourceProperties properties, Class<? extends DataSource> type) {
return (T) properties.initializeDataSourceBuilder().type(type).build();
}
/**
* Tomcat Pool DataSource configuration.
*/
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass(org.apache.tomcat.jdbc.pool.DataSource.class)
@ConditionalOnMissingBean(DataSource.class)
@ConditionalOnProperty(name = "spring.datasource.type", havingValue = "org.apache.tomcat.jdbc.pool.DataSource",
matchIfMissing = true)
static class Tomcat {
@Bean
@ConfigurationProperties(prefix = "spring.datasource.tomcat")
org.apache.tomcat.jdbc.pool.DataSource dataSource(DataSourceProperties properties) {
org.apache.tomcat.jdbc.pool.DataSource dataSource = createDataSource(properties,
org.apache.tomcat.jdbc.pool.DataSource.class);
DatabaseDriver databaseDriver = DatabaseDriver.fromJdbcUrl(properties.determineUrl());
String validationQuery = databaseDriver.getValidationQuery();
if (validationQuery != null) {
dataSource.setTestOnBorrow(true);
dataSource.setValidationQuery(validationQuery);
}
return dataSource;
}
}
/**
* Hikari DataSource configuration.
*/
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass(HikariDataSource.class)
@ConditionalOnMissingBean(DataSource.class)
@ConditionalOnProperty(name = "spring.datasource.type", havingValue = "com.zaxxer.hikari.HikariDataSource",
matchIfMissing = true)
static class Hikari {
@Bean
@ConfigurationProperties(prefix = "spring.datasource.hikari")
HikariDataSource dataSource(DataSourceProperties properties) {
HikariDataSource dataSource = createDataSource(properties, HikariDataSource.class);
if (StringUtils.hasText(properties.getName())) {
dataSource.setPoolName(properties.getName());
}
return dataSource;
}
}
/**
* DBCP DataSource configuration.
*/
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass(org.apache.commons.dbcp2.BasicDataSource.class)
@ConditionalOnMissingBean(DataSource.class)
@ConditionalOnProperty(name = "spring.datasource.type", havingValue = "org.apache.commons.dbcp2.BasicDataSource",
matchIfMissing = true)
static class Dbcp2 {
@Bean
@ConfigurationProperties(prefix = "spring.datasource.dbcp2")
org.apache.commons.dbcp2.BasicDataSource dataSource(DataSourceProperties properties) {
return createDataSource(properties, org.apache.commons.dbcp2.BasicDataSource.class);
}
}
/**
* Generic DataSource configuration.
*/
@Configuration(proxyBeanMethods = false)
@ConditionalOnMissingBean(DataSource.class)
@ConditionalOnProperty(name = "spring.datasource.type")
static class Generic {
@Bean
DataSource dataSource(DataSourceProperties properties) {
return properties.initializeDataSourceBuilder().build();
}
}
}
JdbcTemplateAutoConfiguration
JdbcTemplateAutoConfiguration导入了JdbcTemplateConfiguration
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass({ DataSource.class, JdbcTemplate.class })
@ConditionalOnSingleCandidate(DataSource.class)
@AutoConfigureAfter(DataSourceAutoConfiguration.class)
@EnableConfigurationProperties(JdbcProperties.class)
@Import({ JdbcTemplateConfiguration.class, NamedParameterJdbcTemplateConfiguration.class })
public class JdbcTemplateAutoConfiguration {
}
JdbcTemplateConfiguration向容器中放入了JdbcTemplate，在JdbcProperties类里可以配置数据源大小、查询超时时间等
@Configuration(proxyBeanMethods = false)
@ConditionalOnMissingBean(JdbcOperations.class)
class JdbcTemplateConfiguration {
@Bean
@Primary
JdbcTemplate jdbcTemplate(DataSource dataSource, JdbcProperties properties) {
JdbcTemplate jdbcTemplate = new JdbcTemplate(dataSource);
JdbcProperties.Template template = properties.getTemplate();
jdbcTemplate.setFetchSize(template.getFetchSize());
jdbcTemplate.setMaxRows(template.getMaxRows());
if (template.getQueryTimeout() != null) {
jdbcTemplate.setQueryTimeout((int) template.getQueryTimeout().getSeconds());
}
return jdbcTemplate;
}
}
修改配置项
spring:
datasource:
url: jdbc:mysql://localhost:3306/db_account
username: root
password: 123456
driver-class-name: com.mysql.jdbc.Driver
单元测试数据源
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.jdbc.core.JdbcTemplate;
@SpringBootTest
class Boot05WebAdminApplicationTests {
@Autowired
JdbcTemplate jdbcTemplate;
@Test//用@org.junit.Test会报空指针异常，可能跟JUnit新版本有关
void contextLoads() {
// jdbcTemplate.queryForObject("select * from account_tbl")
// jdbcTemplate.queryForList("select * from account_tbl",)
Long aLong = jdbcTemplate.queryForObject("select count(*) from account_tbl", Long.class);
log.info("记录总数：{}",aLong);
}
}
61、数据访问-自定义方式整合druid数据源
Druid是什么？
它是数据库连接池，它能够提供强大的监控和扩展功能。
Spring Boot整合第三方技术的两种方式：
自定义
找starter场景
自定义方式
添加依赖：
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>1.1.17</version>
</dependency>
配置Druid数据源：
由于容器中没有DataSource类才会配置相应的数据源，因此自己在容器中放入DataSource
@Configuration
public class MyConfig {
@Bean
@ConfigurationProperties("spring.datasource")//复用配置文件的数据源配置
public DataSource dataSource() throws SQLException {
DruidDataSource druidDataSource = new DruidDataSource();
// druidDataSource.setUrl();
// druidDataSource.setUsername();
// druidDataSource.setPassword();
return druidDataSource;
}
}
配置Druid的监控页功能：
Druid内置提供了一个
StatViewServlet用于展示Druid的统计信息。官方文档 - 配置_StatViewServlet配置。这个StatViewServlet的用途包括：- 提供监控信息展示的html页面
- 提供监控信息的JSON API
Druid内置提供一个
StatFilter，用于统计监控信息。官方文档 - 配置_StatFilterWebStatFilter用于采集web-jdbc关联监控的数据，如SQL监控、URI监控。官方文档 - 配置_配置WebStatFilterDruid提供了
WallFilter，它是基于SQL语义分析来实现防御SQL注入攻击的。官方文档 - 配置 wallfilter
@Configuration
public class MyConfig {
@Bean
@ConfigurationProperties("spring.datasource")
public DataSource dataSource() throws SQLException {
DruidDataSource druidDataSource = new DruidDataSource();
//加入监控和防火墙功能功能
druidDataSource.setFilters("stat,wall");
return druidDataSource;
}
/**
* 配置 druid的监控页功能
* @return
*/
@Bean
public ServletRegistrationBean statViewServlet(){
StatViewServlet statViewServlet = new StatViewServlet();
ServletRegistrationBean<StatViewServlet> registrationBean =
new ServletRegistrationBean<>(statViewServlet, "/druid/*");
//监控页账号密码：
registrationBean.addInitParameter("loginUsername","admin");
registrationBean.addInitParameter("loginPassword","123456");
return registrationBean;
}
/**
* WebStatFilter 用于采集web-jdbc关联监控的数据。
*/
@Bean
public FilterRegistrationBean webStatFilter(){
WebStatFilter webStatFilter = new WebStatFilter();
FilterRegistrationBean<WebStatFilter> filterRegistrationBean = new FilterRegistrationBean<>(webStatFilter);
filterRegistrationBean.setUrlPatterns(Arrays.asList("/*"));
filterRegistrationBean.addInitParameter("exclusions","*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*");
return filterRegistrationBean;
}
}
62、数据访问-druid数据源starter整合方式
官方文档 - Druid Spring Boot Starter
引入依赖：
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid-spring-boot-starter</artifactId>
<version>1.1.17</version>
</dependency>
分析自动配置：
- 扩展配置项
spring.datasource.druid - 自动配置类
DruidDataSourceAutoConfigure DruidSpringAopConfiguration.class, 监控SpringBean的；配置项：spring.datasource.druid.aop-patternsDruidStatViewServletConfiguration.class, 监控页的配置。spring.datasource.druid.stat-view-servlet默认开启。DruidWebStatFilterConfiguration.class，web监控配置。spring.datasource.druid.web-stat-filter默认开启。DruidFilterConfiguration.class所有Druid的filter的配置：
private static final String FILTER_STAT_PREFIX = "spring.datasource.druid.filter.stat";
private static final String FILTER_CONFIG_PREFIX = "spring.datasource.druid.filter.config";
private static final String FILTER_ENCODING_PREFIX = "spring.datasource.druid.filter.encoding";
private static final String FILTER_SLF4J_PREFIX = "spring.datasource.druid.filter.slf4j";
private static final String FILTER_LOG4J_PREFIX = "spring.datasource.druid.filter.log4j";
private static final String FILTER_LOG4J2_PREFIX = "spring.datasource.druid.filter.log4j2";
private static final String FILTER_COMMONS_LOG_PREFIX = "spring.datasource.druid.filter.commons-log";
private static final String FILTER_WALL_PREFIX = "spring.datasource.druid.filter.wall";
配置示例：
spring:
datasource:
url: jdbc:mysql://localhost:3306/db_account
username: root
password: 123456
driver-class-name: com.mysql.jdbc.Driver
druid:
aop-patterns: com.atguigu.admin.* #监控SpringBean
filters: stat,wall # 底层开启功能，stat（sql监控），wall（防火墙）
stat-view-servlet: # 配置监控页功能
enabled: true
login-username: admin
login-password: admin
resetEnable: false
web-stat-filter: # 监控web
enabled: true
urlPattern: /*
exclusions: '*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*'
filter:
stat: # 对上面filters里面的stat的详细配置
slow-sql-millis: 1000
logSlowSql: true
enabled: true
wall:
enabled: true
config:
drop-table-allow: false
63、数据访问-整合MyBatis-配置版
starter的命名方式：
- SpringBoot官方的Starter：
spring-boot-starter-* - 第三方的：
*-spring-boot-starter
引入依赖：
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>2.1.4</version>
</dependency>
配置模式:
全局配置文件
image-20221109165108122 SqlSessionFactory：自动配置好了
image-20221109165016891 SqlSession：自动配置了SqlSessionTemplate组合了SqlSession
image-20221109194712730 
image-20221109194716980 @Import(AutoConfiguredMapperScannerRegistrar.class)
image-20221109194840245 Mapper： 只要我们写的操作MyBatis的接口标准了@Mapper就会被自动扫描进来
@EnableConfigurationProperties(MybatisProperties.class) ： MyBatis配置项绑定类。
@AutoConfigureAfter({ DataSourceAutoConfiguration.class, MybatisLanguageDriverAutoConfiguration.class })
public class MybatisAutoConfiguration{
...
}
@ConfigurationProperties(prefix = "mybatis")
public class MybatisProperties{
...
}
配置文件：
spring:
datasource:
username: root
password: 1234
url: jdbc:mysql://localhost:3306/my
driver-class-name: com.mysql.jdbc.Driver
# 配置mybatis规则
mybatis:
config-location: classpath:mybatis/mybatis-config.xml #全局配置文件位置
mapper-locations: classpath:mybatis/*.xml #sql映射文件位置
mybatis-config.xml:
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<!-- 由于Spring Boot自动配置缘故，此处不必配置，只用来做做样。-->
</configuration>
Mapper接口：
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.lun.boot.mapper.UserMapper">
<select id="getUser" resultType="com.lun.boot.bean.User">
select * from user where id=#{id}
</select>
</mapper>
import com.lun.boot.bean.User;
import org.apache.ibatis.annotations.Mapper;
@Mapper
public interface UserMapper {
public User getUser(Integer id);
}
POJO：
public class User {
private Integer id;
private String name;
//getters and setters...
}
DB：
CREATE TABLE `user` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(45) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8mb4;
Controller and Service：
@Controller
public class UserController {
@Autowired
private UserService userService;
@ResponseBody
@GetMapping("/user/{id}")
public User getUser(@PathVariable("id") Integer id){
return userService.getUser(id);
}
}
@Service
public class UserService {
@Autowired
private UserMapper userMapper;//IDEA下标红线，可忽视这红线
public User getUser(Integer id){
return userMapper.getUser(id);
}
}
配置private Configuration configuration; 也就是配置mybatis.configuration相关的，就是相当于改mybatis全局配置文件中的值。（也就是说配置了mybatis.configuration，就不需配置mybatis全局配置文件了）
## 配置mybatis规则
mybatis:
mapper-locations: classpath:mybatis/mapper/*.xml
# 可以不写全局配置文件，所有全局配置文件的配置都放在configuration配置项中了。
# config-location: classpath:mybatis/mybatis-config.xml
type-aliases-package: com.atguigu.boot.mapper # 起别名
configuration:
map-underscore-to-camel-case: true
小结
- 导入MyBatis官方Starter。
- 编写Mapper接口，需
@Mapper注解。 - 编写SQL映射文件并绑定Mapper接口。
- 在
application.yaml中指定Mapper配置文件的所处位置，以及指定全局配置文件的信息 （建议：配置在mybatis.configuration）。
64、数据访问-整合MyBatis-注解配置混合版
你可以通过Spring Initializr添加MyBatis的Starer。
注解与配置混合搭配，干活不累：
@Mapper
public interface UserMapper {
public User getUser(Integer id);
@Select("select * from user where id=#{id}")
public User getUser2(Integer id);
public void saveUser(User user);
@Insert("insert into user(`name`) values(#{name})")
@Options(useGeneratedKeys = true, keyProperty = "id")
public void saveUser2(User user);
}
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.lun.boot.mapper.UserMapper">
<select id="getUser" resultType="com.lun.boot.bean.User">
select * from user where id=#{id}
</select>
<insert id="saveUser" useGeneratedKeys="true" keyProperty="id">
insert into user(`name`) values(#{name})
</insert>
</mapper>
简单DAO方法就写在注解上。复杂的就写在配置文件里。
使用
@MapperScan("com.lun.boot.mapper")简化，Mapper接口就可以不用标注@Mapper注解。
@MapperScan("com.lun.boot.mapper")
@SpringBootApplication
public class MainApplication {
public static void main(String[] args) {
SpringApplication.run(MainApplication.class, args);
}
}
65、数据访问-整合MyBatisPlus操作数据库
MyBatisPlus是什么
MyBatis-Plus（简称 MP）是一个 MyBatis的增强工具，在 MyBatis 的基础上只做增强不做改变，为简化开发、提高效率而生。
添加依赖：
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus-boot-starter</artifactId>
<version>3.4.1</version>
</dependency>
MybatisPlusAutoConfiguration配置类，MybatisPlusProperties配置项绑定。SqlSessionFactory自动配置好，底层是容器中默认的数据源。mapperLocations自动配置好的，有默认值classpath*:/mapper/**/*.xml，这表示任意包的类路径下的所有mapper文件夹下任意路径下的所有xml都是sql映射文件。 建议以后sql映射文件放在 mapper下。容器中也自动配置好了
SqlSessionTemplate。@Mapper标注的接口也会被自动扫描，建议直接@MapperScan("com.lun.boot.mapper")批量扫描。MyBatisPlus优点之一：只需要我们的Mapper继承MyBatisPlus的
BaseMapper就可以拥有CRUD能力，减轻开发工作。
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.lun.hellomybatisplus.model.User;
public interface UserMapper extends BaseMapper<User> {
}
66、数据访问-CRUD实验-数据列表展示
使用MyBatis Plus提供的IService，ServiceImpl，减轻Service层开发工作。
import com.lun.hellomybatisplus.model.User;
import com.baomidou.mybatisplus.extension.service.IService;
import java.util.List;
/**
* Service 的CRUD也不用写了
*/
public interface UserService extends IService<User> {
//此处故意为空
}
import com.lun.hellomybatisplus.model.User;
import com.lun.hellomybatisplus.mapper.UserMapper;
import com.lun.hellomybatisplus.service.UserService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.List;
@Service
public class UserServiceImpl extends ServiceImpl<UserMapper,User> implements UserService {
//此处故意为空
}
与下一节联合在一起
67、数据访问-CRUD实验-分页数据展示
与下一节联合在一起
68、数据访问-CRUD实验-删除用户完成
添加分页插件：
@Configuration
public class MyBatisConfig {
/**
* MybatisPlusInterceptor
* @return
*/
@Bean
public MybatisPlusInterceptor paginationInterceptor() {
MybatisPlusInterceptor mybatisPlusInterceptor = new MybatisPlusInterceptor();
// 设置请求的页面大于最大页后操作， true调回到首页，false 继续请求 默认false
// paginationInterceptor.setOverflow(false);
// 设置最大单页限制数量，默认 500 条，-1 不受限制
// paginationInterceptor.setLimit(500);
// 开启 count 的 join 优化,只针对部分 left join
//这是分页拦截器
PaginationInnerInterceptor paginationInnerInterceptor = new PaginationInnerInterceptor();
paginationInnerInterceptor.setOverflow(true);
paginationInnerInterceptor.setMaxLimit(500L);
mybatisPlusInterceptor.addInnerInterceptor(paginationInnerInterceptor);
return mybatisPlusInterceptor;
}
}
<table class="display table table-bordered table-striped" id="dynamic-table">
<thead>
<tr>
<th>#</th>
<th>name</th>
<th>age</th>
<th>email</th>
<th>操作</th>
</tr>
</thead>
<tbody>
<tr class="gradeX" th:each="user: ${users.records}">
<td th:text="${user.id}"></td>
<td>[[${user.name}]]</td>
<td th:text="${user.age}">Win 95+</td>
<td th:text="${user.email}">4</td>
<td>
<a th:href="@{/user/delete/{id}(id=${user.id},pn=${users.current})}"
class="btn btn-danger btn-sm" type="button">删除</a>
</td>
</tr>
</tfoot>
</table>
<div class="row-fluid">
<div class="span6">
<div class="dataTables_info" id="dynamic-table_info">
当前第[[${users.current}]]页 总计 [[${users.pages}]]页 共[[${users.total}]]条记录
</div>
</div>
<div class="span6">
<div class="dataTables_paginate paging_bootstrap pagination">
<ul>
<li class="prev disabled"><a href="#">← 前一页</a></li>
<li th:class="${num == users.current?'active':''}"
th:each="num:${#numbers.sequence(1,users.pages)}" >
<a th:href="@{/dynamic_table(pn=${num})}">[[${num}]]</a>
</li>
<li class="next disabled"><a href="#">下一页 → </a></li>
</ul>
</div>
</div>
</div>
#numbers表示methods for formatting numeric objects.link
@GetMapping("/user/delete/{id}")
public String deleteUser(@PathVariable("id") Long id,
@RequestParam(value = "pn",defaultValue = "1")Integer pn,
RedirectAttributes ra){
userService.removeById(id);
ra.addAttribute("pn",pn);
return "redirect:/dynamic_table";
}
@GetMapping("/dynamic_table")
public String dynamic_table(@RequestParam(value="pn",defaultValue = "1") Integer pn,Model model){
//表格内容的遍历
//从数据库中查出user表中的用户进行展示
//构造分页参数
Page<User> page = new Page<>(pn, 2);
//调用page进行分页
Page<User> userPage = userService.page(page, null);
model.addAttribute("users",userPage);
return "table/dynamic_table";
}
69、数据访问-准备阿里云Redis环境
添加依赖：
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
<!--导入jedis-->
<dependency>
<groupId>redis.clients</groupId>
<artifactId>jedis</artifactId>
</dependency>
RedisAutoConfiguration自动配置类，RedisProperties 属性类 --> spring.redis.xxx是对redis的配置。- 连接工厂
LettuceConnectionConfiguration、JedisConnectionConfiguration是准备好的。 - 自动注入了
RedisTemplate<Object, Object>，xxxTemplate。 - 自动注入了
StringRedisTemplate，key，value都是String - 底层只要我们使用
StringRedisTemplate、RedisTemplate就可以操作Redis。
外网Redis环境搭建：
- 阿里云按量付费Redis，其中选择经典网络。
- 申请Redis的公网连接地址。
- 修改白名单，允许
0.0.0.0/0访问。
RedisAutoConfiguration导入了LettuceConnectionConfiguration作为操作redis的客户端
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass(RedisOperations.class)
@EnableConfigurationProperties(RedisProperties.class)
@Import({ LettuceConnectionConfiguration.class, JedisConnectionConfiguration.class })
public class RedisAutoConfiguration {
@Bean
@ConditionalOnMissingBean(name = "redisTemplate")
public RedisTemplate<Object, Object> redisTemplate(RedisConnectionFactory redisConnectionFactory)
throws UnknownHostException {
RedisTemplate<Object, Object> template = new RedisTemplate<>();
template.setConnectionFactory(redisConnectionFactory);
return template;
}
@Bean
@ConditionalOnMissingBean
public StringRedisTemplate stringRedisTemplate(RedisConnectionFactory redisConnectionFactory)
throws UnknownHostException {
StringRedisTemplate template = new StringRedisTemplate();
template.setConnectionFactory(redisConnectionFactory);
return template;
}
}
LettuceConnectionConfiguration里也配置了LettuceConnectionFactory
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass(RedisClient.class)
class LettuceConnectionConfiguration extends RedisConnectionConfiguration {
LettuceConnectionConfiguration(RedisProperties properties,
ObjectProvider<RedisSentinelConfiguration> sentinelConfigurationProvider,
ObjectProvider<RedisClusterConfiguration> clusterConfigurationProvider) {
super(properties, sentinelConfigurationProvider, clusterConfigurationProvider);
}
@Bean(destroyMethod = "shutdown")
@ConditionalOnMissingBean(ClientResources.class)
DefaultClientResources lettuceClientResources() {
return DefaultClientResources.create();
}
@Bean
@ConditionalOnMissingBean(RedisConnectionFactory.class)
LettuceConnectionFactory redisConnectionFactory(
ObjectProvider<LettuceClientConfigurationBuilderCustomizer> builderCustomizers,
ClientResources clientResources) throws UnknownHostException {
LettuceClientConfiguration clientConfig = getLettuceClientConfiguration(builderCustomizers, clientResources,
getProperties().getLettuce().getPool());
return createLettuceConnectionFactory(clientConfig);
}
private LettuceConnectionFactory createLettuceConnectionFactory(LettuceClientConfiguration clientConfiguration) {
if (getSentinelConfig() != null) {
return new LettuceConnectionFactory(getSentinelConfig(), clientConfiguration);
}
if (getClusterConfiguration() != null) {
return new LettuceConnectionFactory(getClusterConfiguration(), clientConfiguration);
}
return new LettuceConnectionFactory(getStandaloneConfig(), clientConfiguration);
}
...
}
70、数据访问-Redis操作与统计小实验
相关Redis配置：
spring:
redis:
## url: redis://lfy:Lfy123456@r-bp1nc7reqesxisgxpipd.redis.rds.aliyuncs.com:6379
host: r-bp1nc7reqesxisgxpipd.redis.rds.aliyuncs.com
port: 6379
password: lfy:Lfy123456
client-type: jedis
jedis:
pool:
max-active: 10
## lettuce:# 另一个用来连接redis的java框架
## pool:
## max-active: 10
## min-idle: 5
测试Redis连接：
@SpringBootTest
public class Boot05WebAdminApplicationTests {
@Autowired
StringRedisTemplate redisTemplate;
@Autowired
RedisConnectionFactory redisConnectionFactory;
@Test
void testRedis(){
ValueOperations<String, String> operations = redisTemplate.opsForValue();
operations.set("hello","world");
String hello = operations.get("hello");
System.out.println(hello);
System.out.println(redisConnectionFactory.getClass());
}
}
Redis Desktop Manager：可视化Redis管理软件。
URL统计拦截器：
@Component
public class RedisUrlCountInterceptor implements HandlerInterceptor {
@Autowired
StringRedisTemplate redisTemplate;
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
String uri = request.getRequestURI();
//默认每次访问当前uri就会计数+1
redisTemplate.opsForValue().increment(uri);
return true;
}
}
注册URL统计拦截器：
@Configuration
public class AdminWebConfig implements WebMvcConfigurer{
@Autowired
RedisUrlCountInterceptor redisUrlCountInterceptor;
@Override
public void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(redisUrlCountInterceptor)
.addPathPatterns("/**")
.excludePathPatterns("/","/login","/css/**","/fonts/**","/images/**",
"/js/**","/aa/**");
}
}
Filter、Interceptor 几乎拥有相同的功能？
- Filter是Servlet定义的原生组件，它的好处是脱离Spring应用也能使用。
- Interceptor是Spring定义的接口，可以使用Spring的自动装配等功能。
调用Redis内的统计数据：
@Slf4j
@Controller
public class IndexController {
@Autowired
StringRedisTemplate redisTemplate;
@GetMapping("/main.html")
public String mainPage(HttpSession session,Model model){
log.info("当前方法是：{}","mainPage");
ValueOperations<String, String> opsForValue =
redisTemplate.opsForValue();
String s = opsForValue.get("/main.html");
String s1 = opsForValue.get("/sql");
model.addAttribute("mainCount",s);
model.addAttribute("sqlCount",s1);
return "main";
}
}
71、单元测试-JUnit5简介
Spring Boot 2.2.0 版本开始引入 JUnit 5 作为单元测试默认库
作为最新版本的JUnit框架，JUnit5与之前版本的JUnit框架有很大的不同。由三个不同子项目的几个不同模块组成。
JUnit 5 = JUnit Platform + JUnit Jupiter + JUnit Vintage
JUnit Platform: Junit Platform是在JVM上启动测试框架的基础，不仅支持Junit自制的测试引擎，其他测试引擎也都可以接入。
JUnit Jupiter: JUnit Jupiter提供了JUnit5的新的编程模型，是JUnit5新特性的核心。内部包含了一个测试引擎，用于在Junit Platform上运行。
JUnit Vintage: 由于JUint已经发展多年，为了照顾老的项目，JUnit Vintage提供了兼容JUnit4.x，JUnit3.x的测试引擎。
注意：
SpringBoot 2.4 以上版本移除了默认对 Vintage 的依赖。如果需要兼容JUnit4需要自行引入（不能使用JUnit4的功能 @Test）
JUnit 5’s Vintage已经从
spring-boot-starter-test从移除。如果需要继续兼容Junit4需要自行引入Vintage依赖：
<dependency>
<groupId>org.junit.vintage</groupId>
<artifactId>junit-vintage-engine</artifactId>
<scope>test</scope>
<exclusions>
<exclusion>
<groupId>org.hamcrest</groupId>
<artifactId>hamcrest-core</artifactId>
</exclusion>
</exclusions>
</dependency>
- 使用添加JUnit 5，添加对应的starter：
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
- Spring的JUnit 5的基本单元测试模板（Spring的JUnit4的是
@SpringBootTest+@RunWith(SpringRunner.class)）：
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;//注意不是org.junit.Test（这是JUnit4版本的）
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
@SpringBootTest
class SpringBootApplicationTests {
@Autowired
private Component component;
@Test
//@Transactional 标注后连接数据库有回滚功能
public void contextLoads() {
Assertions.assertEquals(5, component.getFive());
}
}
Jupiter
英 [ˈdʒuːpɪtə(r)] 美 [ˈdʒuːpɪtər]
n. 木星(太阳系中最大的行星)
vintage
英 [ˈvɪntɪdʒ] 美 [ˈvɪntɪdʒ]
n. 特定年份(或地方)酿制的酒;酿造年份;采摘葡萄酿酒的期间(或季节);葡萄收获期(或季节)
adj. (指葡萄酒)优质的，上等的，佳酿的;古色古香的(指1917–1930年间制造，车型和品味受人青睐的);(过去某个时期)典型的，优质的;(某人的)最佳作品的
72、单元测试-常用测试注解
- @Test：表示方法是测试方法。但是与JUnit4的@Test不同，他的职责非常单一不能声明任何属性，拓展的测试将会由Jupiter提供额外测试
- @ParameterizedTest：表示方法是参数化测试。
- @RepeatedTest：表示方法可重复执行。（
@RepeatedTest(5)：重复测试5次） - @DisplayName：为测试类或者测试方法设置展示名称。
- @BeforeEach：表示在每个单元测试之前执行。(执行单个测试方法之前)
- @AfterEach：表示在每个单元测试之后执行。 (执行单个测试方法之后)
- @BeforeAll：表示在所有单元测试之前执行。 (执行测试类之前)（执行测试类会执行该类的所有测试方法，此时只会执行一次
BeforeAll和AfterAll。而BeforeEach/BeforeEach会在该测试类的每个方法之前/之后执行） - @AfterAll：表示在所有单元测试之后执行。 (执行测试类之后)
- @Tag：表示单元测试类别，类似于JUnit4中的@Categories。
- @Disabled：表示测试类或测试方法不执行，类似于JUnit4中的@Ignore。(执行测试类时不执行该测试方法)
- @Timeout：表示测试方法运行如果超过了指定时间将会返回错误。
- @ExtendWith：为测试类或测试方法提供扩展类引用。
@ExtendWith类似于junit4的RunWith，可以指定使用Spring的测试驱动
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@BootstrapWith(SpringBootTestContextBootstrapper.class)
@ExtendWith(SpringExtension.class)
public @interface SpringBootTest {
...
}
import org.junit.jupiter.api.*;
@DisplayName("junit5功能测试类")
public class Junit5Test {
@DisplayName("测试displayname注解")
@Test
void testDisplayName() {
System.out.println(1);
System.out.println(jdbcTemplate);
}
@ParameterizedTest
@ValueSource(strings = { "racecar", "radar", "able was I ere I saw elba" })
void palindromes(String candidate) {
assertTrue(StringUtils.isPalindrome(candidate));
}
@Disabled
@DisplayName("测试方法2")
@Test
void test2() {
System.out.println(2);
}
@RepeatedTest(5)
@Test
void test3() {
System.out.println(5);
}
/**
* 规定方法超时时间。超出时间测试出异常
*
* @throws InterruptedException
*/
@Timeout(value = 500, unit = TimeUnit.MILLISECONDS)
@Test
void testTimeout() throws InterruptedException {
Thread.sleep(600);
}
@BeforeEach
void testBeforeEach() {
System.out.println("测试就要开始了...");
}
@AfterEach
void testAfterEach() {
System.out.println("测试结束了...");
}
@BeforeAll
static void testBeforeAll() {
System.out.println("所有测试就要开始了...");
}
@AfterAll
static void testAfterAll() {
System.out.println("所有测试以及结束了...");
}
}
73、单元测试-断言机制
断言Assertion是测试方法中的核心部分，用来对测试需要满足的条件进行验证。这些断言方法都是org.junit.jupiter.api.Assertions的静态方法。检查业务逻辑返回的数据是否合理。所有的测试运行结束以后，会有一个详细的测试报告。如果断言失败，该方法后面的所有代码都不会执行。
JUnit 5 内置的断言可以分成如下几个类别：
简单断言
用来对单个值进行简单的验证。如：
| 方法 | 说明 |
|---|---|
| assertEquals | 判断两个对象或两个原始类型是否相等 |
| assertNotEquals | 判断两个对象或两个原始类型是否不相等 |
| assertSame | 判断两个对象引用是否指向同一个对象 |
| assertNotSame | 判断两个对象引用是否指向不同的对象 |
| assertTrue | 判断给定的布尔值是否为 true |
| assertFalse | 判断给定的布尔值是否为 false |
| assertNull | 判断给定的对象引用是否为 null |
| assertNotNull | 判断给定的对象引用是否不为 null |
import static org.junit.jupiter.api.Assertions.*;
@Test
@DisplayName("simple assertion")
public void simple() {
assertEquals(3, 1 + 2, "simple math");
assertNotEquals(3, 1 + 1);
assertNotSame(new Object(), new Object());
Object obj = new Object();
assertSame(obj, obj);
assertFalse(1 > 2);
assertTrue(1 < 2);
assertNull(null);
assertNotNull(new Object());
}
数组断言
通过 assertArrayEquals 方法来判断两个对象或原始类型的数组是否相等。
@Test
@DisplayName("array assertion")
public void array() {
assertArrayEquals(new int[]{1, 2}, new int[] {1, 2});
}
组合断言
assertAll()方法接受多个 org.junit.jupiter.api.Executable 函数式接口的实例作为要验证的断言，可以通过 lambda 表达式很容易的提供这些断言。
@Test
@DisplayName("assert all")
public void all() {
assertAll("Math",
() -> assertEquals(2, 1 + 1),
() -> assertTrue(1 > 0)
);
}
异常断言
在JUnit4时期，想要测试方法的异常情况时，需要用@Rule注解的ExpectedException变量还是比较麻烦的。而JUnit5提供了一种新的断言方式Assertions.assertThrows()，配合函数式编程就可以进行使用。
@Test
@DisplayName("异常测试")
public void exceptionTest() {
ArithmeticException exception = Assertions.assertThrows(
//抛出数学运算异常
ArithmeticException.class, () -> System.out.println(1 % 0));
}
超时断言
JUnit5还提供了Assertions.assertTimeout()为测试方法设置了超时时间。
@Test
@DisplayName("超时测试")
public void timeoutTest() {
//如果测试方法时间超过1s将会异常
Assertions.assertTimeout(Duration.ofMillis(1000), () -> Thread.sleep(500));
}
快速失败
通过 fail 方法直接使得测试失败。
@Test
@DisplayName("fail")
public void shouldFail() {
if(true){
fail("This should fail");
}
}
74、单元测试-前置条件
Unit 5 中的前置条件（assumptions【假设】）类似于断言，不同之处在于不满足的断言assertions会使得测试方法失败，而不满足的前置条件只会使得测试方法的执行终止。
前置条件可以看成是测试方法执行的前提，当该前提不满足时，就没有继续执行的必要。
@DisplayName("前置条件")
public class AssumptionsTest {
private final String environment = "DEV";
@Test
@DisplayName("simple")
public void simpleAssume() {
assumeTrue(Objects.equals(this.environment, "DEV"));
assumeFalse(() -> Objects.equals(this.environment, "PROD"));
}
@Test
@DisplayName("assume then do")
public void assumeThenDo() {
assumingThat(
Objects.equals(this.environment, "DEV"),
() -> System.out.println("In DEV")
);
}
}
assumeTrue 和 assumFalse 确保给定的条件为 true 或 false，不满足条件会使得测试执行终止。
assumingThat 的参数是表示条件的布尔值和对应的 Executable 接口的实现对象。只有条件满足时，Executable 对象才会被执行；当条件不满足时，测试执行并不会终止。
75、单元测试-嵌套测试
JUnit 5 可以通过 Java 中的内部类和@Nested 注解实现嵌套测试，从而可以更好的把相关的测试方法组织在一起。在内部类中可以使用@BeforeEach 和@AfterEach注解，而且嵌套的层次没有限制。
@DisplayName("A stack")
class TestingAStackDemo {
Stack<Object> stack;
@Test
@DisplayName("is instantiated with new Stack()")
void isInstantiatedWithNew() {
new Stack<>();
}
@Nested
@DisplayName("when new")
class WhenNew {
@BeforeEach
void createNewStack() {
stack = new Stack<>();
}
@Test
@DisplayName("is empty")
void isEmpty() {
assertTrue(stack.isEmpty());
}
@Test
@DisplayName("throws EmptyStackException when popped")
void throwsExceptionWhenPopped() {
assertThrows(EmptyStackException.class, stack::pop);
}
@Test
@DisplayName("throws EmptyStackException when peeked")
void throwsExceptionWhenPeeked() {
assertThrows(EmptyStackException.class, stack::peek);
}
@Nested
@DisplayName("after pushing an element")
class AfterPushing {
String anElement = "an element";
@BeforeEach
void pushAnElement() {
stack.push(anElement);
}
@Test
@DisplayName("it is no longer empty")
void isNotEmpty() {
assertFalse(stack.isEmpty());
}
@Test
@DisplayName("returns the element when popped and is empty")
void returnElementWhenPopped() {
assertEquals(anElement, stack.pop());
assertTrue(stack.isEmpty());
}
@Test
@DisplayName("returns the element when peeked but remains not empty")
void returnElementWhenPeeked() {
assertEquals(anElement, stack.peek());
assertFalse(stack.isEmpty());
}
}
}
}
76、单元测试-参数化测试
参数化测试是JUnit5很重要的一个新特性，它使得用不同的参数多次运行测试成为了可能，也为我们的单元测试带来许多便利。
利用@ValueSource等注解，指定入参，我们将可以使用不同的参数进行多次单元测试，而不需要每新增一个参数就新增一个单元测试，省去了很多冗余代码。
利用**@ValueSource**等注解，指定入参，我们将可以使用不同的参数进行多次单元测试，而不需要每新增一个参数就新增一个单元测试，省去了很多冗余代码。
- @ValueSource: 为参数化测试指定入参来源，支持八大基础类以及String类型,Class类型
- @NullSource: 表示为参数化测试提供一个null的入参
- @EnumSource: 表示为参数化测试提供一个枚举入参
- @CsvFileSource：表示读取指定CSV文件内容作为参数化测试入参
- @MethodSource：表示读取指定方法的返回值作为参数化测试入参(注意方法返回需要是一个流)
当然如果参数化测试仅仅只能做到指定普通的入参还达不到让我觉得惊艳的地步。让我真正感到他的强大之处的地方在于他可以支持外部的各类入参。如:CSV,YML,JSON 文件甚至方法的返回值也可以作为入参。只需要去实现**ArgumentsProvider**接口，任何外部文件都可以作为它的入参。
@ParameterizedTest
@ValueSource(strings = {"one", "two", "three"})
@DisplayName("参数化测试1")
public void parameterizedTest1(String string) {
System.out.println(string);
Assertions.assertTrue(StringUtils.isNotBlank(string));
}
@ParameterizedTest
@MethodSource("method") //指定方法名
@DisplayName("方法来源参数")
public void testWithExplicitLocalMethodSource(String name) {
System.out.println(name);
Assertions.assertNotNull(name);
}
static Stream<String> method() {
return Stream.of("apple", "banana");
}
迁移指南
在进行迁移的时候需要注意如下的变化：
- 注解在
org.junit.jupiter.api包中，断言在org.junit.jupiter.api.Assertions类中，前置条件在org.junit.jupiter.api.Assumptions类中。 - 把
@Before和@After替换成@BeforeEach和@AfterEach。 - 把
@BeforeClass和@AfterClass替换成@BeforeAll和@AfterAll。 - 把
@Ignore替换成@Disabled。 - 把
@Category替换成@Tag。 - 把
@RunWith、@Rule和@ClassRule替换成@ExtendWith。
77、指标监控-SpringBoot Actuator与Endpoint
未来每一个微服务在云上部署以后，我们都需要对其进行监控、追踪、审计、控制等。SpringBoot就抽取了Actuator场景，使得我们每个微服务快速引用即可获得生产级别的应用监控、审计等功能。
官方文档 - Spring Boot Actuator: Production-ready Features
1.x与2.x的不同：
SpringBoot Actuator 1.x
- 支持SpringMVC
- 基于继承方式进行扩展
- 层级Metrics配置
- 自定义Metrics收集
- 默认较少的安全策略
SpringBoot Actuator 2.x
- 支持SpringMVC、JAX-RS以及Webflux
- 注解驱动进行扩展
- 层级&名称空间Metrics
- 底层使用MicroMeter，强大、便捷默认丰富的安全策略
如何使用
- 添加依赖：
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
- 访问
http://localhost:8080/actuator/**。 - 暴露所有监控信息为HTTP。
management:
endpoints:
enabled-by-default: true #暴露所有端点信息
web:
exposure:
include: '*' #以web方式暴露
- 测试例子 http://localhost:8080/actuator/metrics/endpointName/detailPath
- http://localhost:8080/actuator/beans
- http://localhost:8080/actuator/configprops
- http://localhost:8080/actuator/metrics
- http://localhost:8080/actuator/metrics/jvm.gc.pause
actuator
英 [ˈæktjʊeɪtə] 美 [ˈæktjuˌeɪtər]
n. 致动（促动，激励，调节）器；传动（装置，机构）；拖动装置；马达；操作机构；执行机构（元件）；（电磁铁）螺线管；操纵装置（阀门）；调速控制器；往复运动油（气）缸；作动筒
metric
英 [ˈmetrɪk] 美 [ˈmetrɪk]
adj. 米制的;公制的;按公制制作的;用公制测量的
n. 度量标准;[数学]度量;诗体;韵文;诗韵
78、指标监控-常使用的端点及开启与禁用
常使用的端点
| ID | 描述 |
|---|---|
auditevents | 暴露当前应用程序的审核事件信息。需要一个AuditEventRepository组件。 |
beans | 显示应用程序中所有Spring Bean的完整列表。 |
caches | 暴露可用的缓存。 |
conditions | 显示自动配置的所有条件信息，包括匹配或不匹配的原因。 |
configprops | 显示所有@ConfigurationProperties。 |
env | 暴露Spring的属性ConfigurableEnvironment |
flyway | 显示已应用的所有Flyway数据库迁移。 需要一个或多个Flyway组件。 |
health | 显示应用程序运行状况信息。 |
httptrace | 显示HTTP跟踪信息（默认情况下，最近100个HTTP请求-响应）。需要一个HttpTraceRepository组件。 |
info | 显示应用程序信息。 |
integrationgraph | 显示Spring integrationgraph 。需要依赖spring-integration-core。 |
loggers | 显示和修改应用程序中日志的配置。 |
liquibase | 显示已应用的所有Liquibase数据库迁移。需要一个或多个Liquibase组件。 |
metrics | 显示当前应用程序的“指标”信息。 |
mappings | 显示所有@RequestMapping路径列表。 |
scheduledtasks | 显示应用程序中的计划任务。 |
sessions | 允许从Spring Session支持的会话存储中检索和删除用户会话。需要使用Spring Session的基于Servlet的Web应用程序。 |
shutdown | 使应用程序正常关闭。默认禁用。 |
startup | 显示由ApplicationStartup收集的启动步骤数据。需要使用SpringApplication进行配置BufferingApplicationStartup。 |
threaddump | 执行线程转储。 |
如果您的应用程序是Web应用程序（Spring MVC，Spring WebFlux或Jersey），则可以使用以下附加端点：
| ID | 描述 |
|---|---|
heapdump | 返回hprof堆转储文件。 |
jolokia | 通过HTTP暴露JMX bean（需要引入Jolokia，不适用于WebFlux）。需要引入依赖jolokia-core。 |
logfile | 返回日志文件的内容（如果已设置logging.file.name或logging.file.path属性）。支持使用HTTPRange标头来检索部分日志文件的内容。 |
prometheus | 以Prometheus服务器可以抓取的格式公开指标。需要依赖micrometer-registry-prometheus。 |
其中最常用的Endpoint：
- Health：监控状况
- Metrics：运行时指标
- Loggers：日志记录
Health Endpoint
健康检查端点，我们一般用于在云平台，平台会定时的检查应用的健康状况，我们就需要Health Endpoint可以为平台返回当前应用的一系列组件健康状况的集合。
重要的几点：
- health endpoint返回的结果，应该是一系列健康检查后的一个汇总报告。
- 很多的健康检查默认已经自动配置好了，比如：数据库、redis等。
- 可以很容易的添加自定义的健康检查机制。
Metrics Endpoint
提供详细的、层级的、空间指标信息，这些信息可以被pull（主动推送）或者push（被动获取）方式得到：
- 通过Metrics对接多种监控系统。
- 简化核心Metrics开发。
- 添加自定义Metrics或者扩展已有Metrics。
开启与禁用Endpoints
- 默认所有的Endpoint除过shutdown都是开启的。
- 需要开启或者禁用某个Endpoint。配置模式为
management.endpoint.<endpointName>.enabled = true
management:
endpoint:
beans:
enabled: true
- 或者禁用所有的Endpoint然后手动开启指定的Endpoint。
management:
endpoints:
enabled-by-default: false
endpoint:
beans:
enabled: true
health:
enabled: true
暴露Endpoints
支持的暴露方式
- HTTP：默认只暴露health和info。
- JMX：默认暴露所有Endpoint。
- 除过health和info，剩下的Endpoint都应该进行保护访问。如果引入Spring Security，则会默认配置安全访问规则。
| ID | JMX | Web |
|---|---|---|
auditevents | Yes | No |
beans | Yes | No |
caches | Yes | No |
conditions | Yes | No |
configprops | Yes | No |
env | Yes | No |
flyway | Yes | No |
health | Yes | Yes |
heapdump | N/A | No |
httptrace | Yes | No |
info | Yes | Yes |
integrationgraph | Yes | No |
jolokia | N/A | No |
logfile | N/A | No |
loggers | Yes | No |
liquibase | Yes | No |
metrics | Yes | No |
mappings | Yes | No |
prometheus | N/A | No |
scheduledtasks | Yes | No |
sessions | Yes | No |
shutdown | Yes | No |
startup | Yes | No |
threaddump | Yes | No |
若要更改公开的Endpoint，请配置以下的包含和排除属性：
| Property | Default |
|---|---|
management.endpoints.jmx.exposure.exclude | |
management.endpoints.jmx.exposure.include | * |
management.endpoints.web.exposure.exclude | |
management.endpoints.web.exposure.include | info, health |
79、指标监控-定制Endpoint
http://localhost:8080/actuator 查看可查看的信息
定制 Health 信息
management:
health:
enabled: true
show-details: always #总是显示详细信息。可显示每个模块的状态信息
通过实现HealthIndicator 接口，或继承MyComHealthIndicator 类。
通过 http://localhost:8080/actuator/health 访问，MyHealthIndicator中的my即为返回结果中JSON.components里的名
import org.springframework.boot.actuate.health.Health;
import org.springframework.boot.actuate.health.HealthIndicator;
import org.springframework.stereotype.Component;
@Component
public class MyHealthIndicator implements HealthIndicator {
@Override
public Health health() {
int errorCode = check(); // perform some specific health check
if (errorCode != 0) {
return Health.down().withDetail("Error Code", errorCode).build();
}
return Health.up().build();
}
}
/*
构建Health
Health build = Health.down()
.withDetail("msg", "error service")
.withDetail("code", "500")
.withException(new RuntimeException())
.build();
*/
通过 http://localhost:8080/actuator/health 访问，MyComHealthIndicator中的myCom即为返回结果中JSON.components里的名
@Component
public class MyComHealthIndicator extends AbstractHealthIndicator {
/**
* 真实的检查方法
* @param builder
* @throws Exception
*/
@Override
protected void doHealthCheck(Health.Builder builder) throws Exception {
//mongodb 获取连接进行测试
Map<String,Object> map = new HashMap<>();
// 检查完成
if(1 == 2){
// builder.up(); //健康
builder.status(Status.UP);
map.put("count",1);
map.put("ms",100);
}else {
// builder.down();
builder.status(Status.OUT_OF_SERVICE);
map.put("err","连接超时");
map.put("ms",3000);
}
builder.withDetail("code",100)
.withDetails(map);
}
}
定制info信息
http://localhost:8080/actuator/info 会输出以上方式返回的所有info信息
常用两种方式：
- 编写配置文件
info:
appName: boot-admin
version: 2.0.1
mavenProjectName: @project.artifactId@ #使用@@可以获取maven的pom文件值
mavenProjectVersion: @project.version@
- 编写InfoContributor
import java.util.Collections;
import org.springframework.boot.actuate.info.Info;
import org.springframework.boot.actuate.info.InfoContributor;
import org.springframework.stereotype.Component;
@Component
public class ExampleInfoContributor implements InfoContributor {
@Override
public void contribute(Info.Builder builder) {
builder.withDetail("example",
Collections.singletonMap("key", "value"));
}
}
定制Metrics信息
http://localhost:8080/actuator/metrics 可以查看可访问的指标监控信息，在后面添加/{name}即可访问具体的信息
增加定制Metrics：
http://localhost:8080/actuator/metrics/myservice.method.running.counter
@Service
class MyService{
Counter counter;
// 在自己的业务逻辑类中通过构造方法注入 MeterRegistry
public MyService(MeterRegistry meterRegistry){
counter = meterRegistry.counter("myservice.method.running.counter");
}
public void hello() {
// 调用 counter 的 increment()方法就可以增加被调用的次数
counter.increment();
}
}
http://localhost:8080/actuator/metrics/queueSize
//也可以使用下面的方式
@Bean
MeterBinder queueSize() {
return (registry) -> Gauge.builder("queueSize", ()->200).register(registry);
}
定制Endpoint
http://localhost:8080/actuator/container
@Component
@Endpoint(id = "container")
public class DockerEndpoint {
//端点的du操作
@ReadOperation
public Map getDockerInfo(){
return Collections.singletonMap("info","docker started...");
}
//端点的写操作
@WriteOperation
private void restartDocker(){
System.out.println("docker restarted....");
}
}
场景：
- 开发ReadinessEndpoint来管理程序是否就绪。
- 开发LivenessEndpoint来管理程序是否存活。
80、指标监控-Boot Admin Server
可视化指标监控
What is Spring Boot Admin?
codecentric’s Spring Boot Admin is a community project to manage and monitor your Spring Boot ® applications. The applications register with our Spring Boot Admin Client (via HTTP) or are discovered using Spring Cloud ® (e.g. Eureka, Consul). The UI is just a Vue.js application on top of the Spring Boot Actuator endpoints.
Getting started
2.1. Setting up Spring Boot Admin Server
First, you need to setup your server. To do this just setup a simple boot project (using start.spring.io). As Spring Boot Admin Server is capable of running as servlet or webflux application, you need to decide on this and add the according Spring Boot Starter. In this example we’re using the servlet web starter.
Add Spring Boot Admin Server starter to your dependencies:
pom.xml
<dependency> <groupId>de.codecentric</groupId> <artifactId>spring-boot-admin-starter-server</artifactId> <version>2.3.1</version> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency>Pull in the Spring Boot Admin Server configuration via adding
@EnableAdminServerto your configuration:@Configuration @EnableAutoConfiguration @EnableAdminServer public class SpringBootAdminApplication { public static void main(String[] args) { SpringApplication.run(SpringBootAdminApplication.class, args); } }
If you want to setup the Spring Boot Admin Server via war-deployment in a servlet-container, please have a look at the spring-boot-admin-sample-war.
See also the spring-boot-admin-sample-servlet project, which also adds security.
2.2. Registering Client Applications
To register your application at the SBA Server, you can either include the SBA Client or use Spring Cloud Discovery (e.g. Eureka, Consul, …). There is also a simple option using a static configuration on the SBA Server side.
2.2.1. Spring Boot Admin Client
Each application that wants to register has to include the Spring Boot Admin Client. In order to secure the endpoints, also add the spring-boot-starter-security.
Add spring-boot-admin-starter-client to your dependencies:
pom.xml
<dependency> <groupId>de.codecentric</groupId> <artifactId>spring-boot-admin-starter-client</artifactId> <version>2.3.1</version> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-security</artifactId> </dependency>Enable the SBA Client by configuring the URL of the Spring Boot Admin Server:
application.properties
spring.boot.admin.client.url=http://localhost:8080 management.endpoints.web.exposure.include=*1. The URL of the Spring Boot Admin Server to register at.
2. As with Spring Boot 2 most of the endpoints aren’t exposed via http by default, we expose all of them. For production you should carefully choose which endpoints to expose.
Make the actuator endpoints accessible:
@Configuration public static class SecurityPermitAllConfig extends WebSecurityConfigurerAdapter { @Override protected void configure(HttpSecurity http) throws Exception { http.authorizeRequests().anyRequest().permitAll() .and().csrf().disable(); } }
For the sake of brevity we’re disabling the security for now. Have a look at the security section on how to deal with secured endpoints.
81、高级特性-Profile环境切换
为了方便多环境适配，Spring Boot简化了profile功能。
- 默认配置文件
application.yaml任何时候都会加载。 - 指定环境配置文件
application-{env}.yaml，env通常为prod、test， - 激活指定环境
- 配置文件激活：
spring.profiles.active=prod - 命令行激活：
java -jar xxx.jar --spring.profiles.active=prod --person.name=haha（修改配置文件的任意值，命令行优先）
- 配置文件激活：
- 默认配置与环境配置同时生效
- 同名配置项，profile配置优先
@Profile条件装配功能
@Data
@Component
@ConfigurationProperties("person")//在配置文件中配置
public class Person{
private String name;
private Integer age;
}
application.properties
person:
name: lun
age: 8
public interface Person {
String getName();
Integer getAge();
}
@Profile("test")//加载application-test.yaml里的
@Component
@ConfigurationProperties("person")
@Data
public class Worker implements Person {
private String name;
private Integer age;
}
@Profile(value = {"prod","default"})//加载application-prod.yaml里的
@Component
@ConfigurationProperties("person")
@Data
public class Boss implements Person {
private String name;
private Integer age;
}
application-test.yaml
person:
name: test-张三
server:
port: 7000
application-prod.yaml
person:
name: prod-张三
server:
port: 8000
application.properties
## 激活prod配置文件
spring.profiles.active=prod
@Autowired
private Person person;
@GetMapping("/")
public String hello(){
//激活了prod，则返回Boss；激活了test，则返回Worker
return person.getClass().toString();
}
@Profile还可以修饰在方法上：
class Color {
}
@Configuration- +
public class MyConfig {
@Profile("prod")
@Bean
public Color red(){
return new Color();
}
@Profile("test")
@Bean
public Color green(){
return new Color();
}
}
可以激活一组：
## 激活名为 production 的组
spring.profiles.active=production
## application-proddb.properties
spring.profiles.group.production[0]=proddb
## application-prodmq.properties
spring.profiles.group.production[1]=prodmq
82、高级特性-配置加载优先级
外部化配置
官方文档 - Externalized Configuration
Spring Boot uses a very particular PropertySource order that is designed to allow sensible overriding of values. Properties are considered in the following order (with values from lower items overriding earlier ones)（1优先级最低，14优先级最高，后面的配置会覆盖前面的配置）:
- Default properties (specified by setting
SpringApplication.setDefaultProperties). @PropertySourceannotations on your@Configurationclasses. Please note that such property sources are not added to theEnvironmentuntil the application context is being refreshed. This is too late to configure certain properties such aslogging.*andspring.main.*which are read before refresh begins.- Config data (such as
application.propertiesfiles) - A
RandomValuePropertySourcethat has properties only inrandom.*. - OS environment variables.
- Java System properties (
System.getProperties()). - JNDI attributes from
java:comp/env. ServletContextinit parameters.ServletConfiginit parameters.- Properties from
SPRING_APPLICATION_JSON(inline JSON embedded in an environment variable or system property). - Command line arguments.
propertiesattribute on your tests. Available on@SpringBootTestand the test annotations for testing a particular slice of your application.@TestPropertySourceannotations on your tests.- Devtools global settings properties in the
$HOME/.config/spring-bootdirectory when devtools is active.
import org.springframework.stereotype.*;
import org.springframework.beans.factory.annotation.*;
@Component
public class MyBean {
@Value("${name}")//以这种方式可以获得配置值
private String name;
// ...
}
- 外部配置源
- Java属性文件。
- YAML文件。
- 环境变量。
- 命令行参数。
- 配置文件查找位置
classpath根路径。classpath根路径下config目录。jar包当前目录。jar包当前目录的config目录。/config子目录的直接子目录。(linux系统下/config目录，即根目录下的config目录。如果是Windows可以放在某个盘符下的config文件夹下，比如D:\config下)
- 配置文件加载顺序：
- 当前jar包内部的
application.properties和application.yml。 - 当前jar包内部的
application-{profile}.properties和application-{profile}.yml。 - 引用的外部jar包的
application.properties和application.yml。 - 引用的外部jar包的
application-{profile}.properties和application-{profile}.yml。
- 当前jar包内部的
- 指定环境优先，外部优先，后面的可以覆盖前面的同名配置项。
由于后面的配置会覆盖前面的配置，所以同级目录各文件类型的优先级：properties > yaml > yml
总结：
不同位置配置文件执行顺序：
classpath根路径 ->classpath根路径下config目录 ->jar包当前目录 ->jar包当前目录的config目录 ->/config子目录的直接子目录相同位置不同配置文件类型执行顺序：
yml->yaml->properties相同位置相同配置文件类型不同文件名执行顺序：
application.yml->application-{profile}.yml
后面执行的配置会覆盖前面执行的配置
83、高级特性-自定义starter细节
starter启动原理
- starter的pom.xml引入autoconfigure依赖
graph LR
A[starter] -->B[autoconfigure]
B --> C[spring-boot-starter]
autoconfigure包中配置使用
META-INF/spring.factories中EnableAutoConfiguration的值，使得项目启动加载指定的自动配置类编写自动配置类
xxxAutoConfiguration->xxxxProperties@Configuration
@Conditional@EnableConfigurationProperties@Bean......
引入starter ---
xxxAutoConfiguration--- 容器中放入组件 ----绑定xxxProperties---- 配置项
自定义starter
目标：创建
HelloService的自定义starter。创建两个工程，分别命名为
hello-spring-boot-starter（普通Maven工程），hello-spring-boot-starter-autoconfigure（需用用到Spring Initializr创建的Maven工程）。hello-spring-boot-starter无需编写什么代码，只需让该工程引入hello-spring-boot-starter-autoconfigure依赖：
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.lun</groupId>
<artifactId>hello-spring-boot-starter</artifactId>
<version>1.0.0-SNAPSHOT</version>
<dependencies>
<dependency>
<groupId>com.lun</groupId>
<artifactId>hello-spring-boot-starter-autoconfigure</artifactId>
<version>1.0.0-SNAPSHOT</version>
</dependency>
</dependencies>
</project>
hello-spring-boot-starter-autoconfigure的pom.xml如下：
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.4.2</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.lun</groupId>
<artifactId>hello-spring-boot-starter-autoconfigure</artifactId>
<version>1.0.0-SNAPSHOT</version>
<name>hello-spring-boot-starter-autoconfigure</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
</dependencies>
</project>
- 创建4个文件：
com/lun/hello/auto/HelloServiceAutoConfigurationcom/lun/hello/bean/HelloPropertiescom/lun/hello/service/HelloServicesrc/main/resources/META-INF/spring.factories
import com.lun.hello.bean.HelloProperties;
import com.lun.hello.service.HelloService;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
@ConditionalOnMissingBean(HelloService.class)
@EnableConfigurationProperties(HelloProperties.class)//默认HelloProperties放在容器中
public class HelloServiceAutoConfiguration {
@Bean
public HelloService helloService(){
return new HelloService();
}
}
import org.springframework.boot.context.properties.ConfigurationProperties;
@ConfigurationProperties("hello")
public class HelloProperties {
private String prefix;
private String suffix;
public String getPrefix() {
return prefix;
}
public void setPrefix(String prefix) {
this.prefix = prefix;
}
public String getSuffix() {
return suffix;
}
public void setSuffix(String suffix) {
this.suffix = suffix;
}
}
import com.lun.hello.bean.HelloProperties;
import org.springframework.beans.factory.annotation.Autowired;
/**
* 默认不要放在容器中
*/
public class HelloService {
@Autowired
private HelloProperties helloProperties;
public String sayHello(String userName){
return helloProperties.getPrefix() + ": " + userName + " > " + helloProperties.getSuffix();
}
}
## Auto Configure
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
com.lun.hello.auto.HelloServiceAutoConfiguration
用maven插件，将两工程install到本地。
接下来，测试使用自定义starter，用Spring Initializr创建名为
hello-spring-boot-starter-test工程，引入hello-spring-boot-starter依赖，其pom.xml如下：
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.4.2</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.lun</groupId>
<artifactId>hello-spring-boot-starter-test</artifactId>
<version>1.0.0-SNAPSHOT</version>
<name>hello-spring-boot-starter-test</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<!-- 引入`hello-spring-boot-starter`依赖 -->
<dependency>
<groupId>com.lun</groupId>
<artifactId>hello-spring-boot-starter</artifactId>
<version>1.0.0-SNAPSHOT</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
- 添加配置文件
application.properties：
hello.prefix=hello
hello.suffix=666
- 添加单元测试类：
import com.lun.hello.service.HelloService;//来自自定义starter
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
@SpringBootTest
class HelloSpringBootStarterTestApplicationTests {
@Autowired
private HelloService helloService;
@Test
void contextLoads() {
// System.out.println(helloService.sayHello("lun"));
Assertions.assertEquals("hello: lun > 666", helloService.sayHello("lun"));
}
}
84、原理解析-SpringApplication创建初始化流程
SpringBoot启动过程
Spring Boot应用的启动类：
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class HelloSpringBootStarterTestApplication {
public static void main(String[] args) {
SpringApplication.run(HelloSpringBootStarterTestApplication.class, args);
}
}
public class SpringApplication {
...
public static ConfigurableApplicationContext run(Class<?> primarySource, String... args) {
return run(new Class<?>[] { primarySource }, args);
}
public static ConfigurableApplicationContext run(Class<?>[] primarySources, String[] args) {
return new SpringApplication(primarySources).run(args);
}
//先看看new SpringApplication(primarySources)，下一节再看看run()
public SpringApplication(Class<?>... primarySources) {
this(null, primarySources);
}
public SpringApplication(ResourceLoader resourceLoader, Class<?>... primarySources) {
this.resourceLoader = resourceLoader;
Assert.notNull(primarySources, "PrimarySources must not be null");
this.primarySources = new LinkedHashSet<>(Arrays.asList(primarySources));
//WebApplicationType是枚举类，有NONE,SERVLET,REACTIVE,下行webApplicationType是SERVLET
this.webApplicationType = WebApplicationType.deduceFromClasspath();
//初始启动引导器，去spring.factories文件中找org.springframework.boot.Bootstrapper，但我找不到实现Bootstrapper接口的类
this.bootstrappers = new ArrayList<>(getSpringFactoriesInstances(Bootstrapper.class));
//去spring.factories找 ApplicationContextInitializer
setInitializers((Collection) getSpringFactoriesInstances(ApplicationContextInitializer.class));
//去spring.factories找 ApplicationListener
setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));
this.mainApplicationClass = deduceMainApplicationClass();
}
private Class<?> deduceMainApplicationClass() {
try {
StackTraceElement[] stackTrace = new RuntimeException().getStackTrace();
for (StackTraceElement stackTraceElement : stackTrace) {
if ("main".equals(stackTraceElement.getMethodName())) {
return Class.forName(stackTraceElement.getClassName());
}
}
}
catch (ClassNotFoundException ex) {
// Swallow and continue
}
return null;
}
...
}
spring.factories：
...
## Application Context Initializers
org.springframework.context.ApplicationContextInitializer=\
org.springframework.boot.context.ConfigurationWarningsApplicationContextInitializer,\
org.springframework.boot.context.ContextIdApplicationContextInitializer,\
org.springframework.boot.context.config.DelegatingApplicationContextInitializer,\
org.springframework.boot.rsocket.context.RSocketPortInfoApplicationContextInitializer,\
org.springframework.boot.web.context.ServerPortInfoApplicationContextInitializer
## Application Listeners
org.springframework.context.ApplicationListener=\
org.springframework.boot.ClearCachesApplicationListener,\
org.springframework.boot.builder.ParentContextCloserApplicationListener,\
org.springframework.boot.context.FileEncodingApplicationListener,\
org.springframework.boot.context.config.AnsiOutputApplicationListener,\
org.springframework.boot.context.config.DelegatingApplicationListener,\
org.springframework.boot.context.logging.LoggingApplicationListener,\
org.springframework.boot.env.EnvironmentPostProcessorApplicationListener,\
org.springframework.boot.liquibase.LiquibaseServiceLocatorApplicationListener
...
SpringBoot启动原理：
首先调用SpringApplication的run(Class<?> primarySource, String... args)方法
@SpringBootApplication
public class MainApplication {
public static void main(String[] args) {
SpringApplication.run(MainApplication.class,args);
}
}
然后调用另一个run(Class<?>[] primarySources, String[] args)方法
public static ConfigurableApplicationContext run(Class<?> primarySource, String... args) {
return run(new Class<?>[] { primarySource }, args);
}
然后创建SpringApplication对象，并调用run(String... args)方法
public static ConfigurableApplicationContext run(Class<?>[] primarySources, String[] args) {
return new SpringApplication(primarySources).run(args);
}
构造方法会调用另一个构造方法
public SpringApplication(Class<?>... primarySources) {
this(null, primarySources);
}
@SuppressWarnings({ "unchecked", "rawtypes" })
public SpringApplication(ResourceLoader resourceLoader, Class<?>... primarySources) {
// 定义一个值为null的资源加载器
this.resourceLoader = resourceLoader;
// 断言主配置类不为空 ( com.atguigu.boot.MainApplication )
Assert.notNull(primarySources, "PrimarySources must not be null");
this.primarySources = new LinkedHashSet<>(Arrays.asList(primarySources));
// 判断web应用的类型
this.webApplicationType = WebApplicationType.deduceFromClasspath();
// 应用上下文初始化器
setInitializers((Collection) getSpringFactoriesInstances(ApplicationContextInitializer.class));
// 应用监听器
setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));
// 决定哪个是主程序
this.mainApplicationClass = deduceMainApplicationClass();
}
判断当前应用是servlet 或reactive 类型的web应用，或当前应用不是一个web应用
private static final String[] SERVLET_INDICATOR_CLASSES = { "javax.servlet.Servlet",
"org.springframework.web.context.ConfigurableWebApplicationContext" };
private static final String WEBMVC_INDICATOR_CLASS = "org.springframework.web.servlet.DispatcherServlet";
private static final String WEBFLUX_INDICATOR_CLASS = "org.springframework.web.reactive.DispatcherHandler";
private static final String JERSEY_INDICATOR_CLASS = "org.glassfish.jersey.servlet.ServletContainer";
private static final String SERVLET_APPLICATION_CONTEXT_CLASS = "org.springframework.web.context.WebApplicationContext";
private static final String REACTIVE_APPLICATION_CONTEXT_CLASS = "org.springframework.boot.web.reactive.context.ReactiveWebApplicationContext";
static WebApplicationType deduceFromClasspath() {
if (ClassUtils.isPresent(WEBFLUX_INDICATOR_CLASS, null) && !ClassUtils.isPresent(WEBMVC_INDICATOR_CLASS, null)
&& !ClassUtils.isPresent(JERSEY_INDICATOR_CLASS, null)) {
return WebApplicationType.REACTIVE;
}
for (String className : SERVLET_INDICATOR_CLASSES) {
if (!ClassUtils.isPresent(className, null)) {
return WebApplicationType.NONE;
}
}
return WebApplicationType.SERVLET;
}
然后获取应用上下文初始化器，并存入initializers中
读取spring.factory文件里ApplicationContextInitializer的配置，共7个
private <T> Collection<T> getSpringFactoriesInstances(Class<T> type) {
return getSpringFactoriesInstances(type, new Class<?>[] {});
}
private <T> Collection<T> getSpringFactoriesInstances(Class<T> type, Class<?>[] parameterTypes, Object... args) {
ClassLoader classLoader = getClassLoader();
// Use names and ensure unique to protect against duplicates
// 读取spring.factory文件中org.springframework.context.ApplicationContextInitializer的配置
Set<String> names = new LinkedHashSet<>(SpringFactoriesLoader.loadFactoryNames(type, classLoader));
List<T> instances = createSpringFactoriesInstances(type, parameterTypes, classLoader, args, names);
AnnotationAwareOrderComparator.sort(instances);
return instances;
}
也就是各jar包中META-INF/spring.factories文件里的ApplicationContextInitializer的配置
可以看到这5个类的确在initializers里
然后寻找应用的监听器，这个方法也是读取spring.factory文件里ApplicationListener的配置，并存入listeners里
然后调用deduceMainApplicationClass()决定哪个是主程序
该方法就是获取栈元素，然后找到第一个名为main的方法，最后返回该方法所在的类
private Class<?> deduceMainApplicationClass() {
try {
StackTraceElement[] stackTrace = new RuntimeException().getStackTrace();
for (StackTraceElement stackTraceElement : stackTrace) {
if ("main".equals(stackTraceElement.getMethodName())) {
// com.atguigu.boot.MainApplication
return Class.forName(stackTraceElement.getClassName());
}
}
}
catch (ClassNotFoundException ex) {
// Swallow and continue
}
return null;
}
85、原理解析-SpringBoot完整启动过程
继续上一节，接着讨论return new SpringApplication(primarySources).run(args)的run方法
public class SpringApplication {
...
public ConfigurableApplicationContext run(String... args) {
StopWatch stopWatch = new StopWatch();//开始计时器
stopWatch.start();//开始计时
//1.
//创建引导上下文（Context环境）createBootstrapContext()
//获取到所有之前的 bootstrappers 挨个执行 intitialize() 来完成对引导启动器上下文环境设置
DefaultBootstrapContext bootstrapContext = createBootstrapContext();
//2.到最后该方法会返回这context
ConfigurableApplicationContext context = null;
//3.让当前应用进入headless模式
configureHeadlessProperty();
//4.获取所有 RunListener（运行监听器）,为了方便所有Listener进行事件感知
SpringApplicationRunListeners listeners = getRunListeners(args);
//5. 遍历 SpringApplicationRunListener 调用 starting 方法；
// 相当于通知所有感兴趣系统正在启动过程的人，项目正在 starting。
listeners.starting(bootstrapContext, this.mainApplicationClass);
try {
//6.保存命令行参数 ApplicationArguments
ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);
//7.准备环境
ConfigurableEnvironment environment = prepareEnvironment(listeners, bootstrapContext, applicationArguments);
configureIgnoreBeanInfo(environment);
/*打印标志
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v2.4.2)
*/
Banner printedBanner = printBanner(environment);
// 创建IOC容器（createApplicationContext（））
// 根据项目类型webApplicationType（NONE,SERVLET,REACTIVE）创建容器，
// 当前会创建 AnnotationConfigServletWebServerApplicationContext
context = createApplicationContext();
context.setApplicationStartup(this.applicationStartup);
//8.准备ApplicationContext IOC容器的基本信息
prepareContext(bootstrapContext, context, environment, listeners, applicationArguments, printedBanner);
//9.刷新IOC容器,创建容器中的所有组件,Spring框架的内容
refreshContext(context);
//该方法没内容，大概为将来填入
afterRefresh(context, applicationArguments);
stopWatch.stop();//停止计时
if (this.logStartupInfo) {//this.logStartupInfo默认是true
new StartupInfoLogger(this.mainApplicationClass).logStarted(getApplicationLog(), stopWatch);
}
//10.
listeners.started(context);
//11.调用所有runners
callRunners(context, applicationArguments);
}
catch (Throwable ex) {
//13.
handleRunFailure(context, ex, listeners);
throw new IllegalStateException(ex);
}
try {
//12.
listeners.running(context);
}
catch (Throwable ex) {
//13.
handleRunFailure(context, ex, null);
throw new IllegalStateException(ex);
}
return context;
}
//1.
private DefaultBootstrapContext createBootstrapContext() {
DefaultBootstrapContext bootstrapContext = new DefaultBootstrapContext();
this.bootstrappers.forEach((initializer) -> initializer.intitialize(bootstrapContext));
return bootstrapContext;
}
//3.
private void configureHeadlessProperty() {
//this.headless默认为true
System.setProperty(SYSTEM_PROPERTY_JAVA_AWT_HEADLESS,
System.getProperty(SYSTEM_PROPERTY_JAVA_AWT_HEADLESS, Boolean.toString(this.headless)));
}
private static final String SYSTEM_PROPERTY_JAVA_AWT_HEADLESS = "java.awt.headless";
//4.
private SpringApplicationRunListeners getRunListeners(String[] args) {
Class<?>[] types = new Class<?>[] { SpringApplication.class, String[].class };
//getSpringFactoriesInstances 去 spring.factories 找 SpringApplicationRunListener
return new SpringApplicationRunListeners(logger,
getSpringFactoriesInstances(SpringApplicationRunListener.class, types, this, args),
this.applicationStartup);
}
//7.准备环境
private ConfigurableEnvironment prepareEnvironment(SpringApplicationRunListeners listeners,
DefaultBootstrapContext bootstrapContext, ApplicationArguments applicationArguments) {
// Create and configure the environment
//返回或者创建基础环境信息对象，如：StandardServletEnvironment, StandardReactiveWebEnvironment
ConfigurableEnvironment environment = getOrCreateEnvironment();
//配置环境信息对象,读取所有的配置源的配置属性值。
configureEnvironment(environment, applicationArguments.getSourceArgs());
//绑定环境信息
ConfigurationPropertySources.attach(environment);
//7.1 通知所有的监听器当前环境准备完成
listeners.environmentPrepared(bootstrapContext, environment);
DefaultPropertiesPropertySource.moveToEnd(environment);
configureAdditionalProfiles(environment);
bindToSpringApplication(environment);
if (!this.isCustomEnvironment) {
environment = new EnvironmentConverter(getClassLoader()).convertEnvironmentIfNecessary(environment,
deduceEnvironmentClass());
}
ConfigurationPropertySources.attach(environment);
return environment;
}
//8.
private void prepareContext(DefaultBootstrapContext bootstrapContext, ConfigurableApplicationContext context,
ConfigurableEnvironment environment, SpringApplicationRunListeners listeners,
ApplicationArguments applicationArguments, Banner printedBanner) {
//保存环境信息
context.setEnvironment(environment);
//IOC容器的后置处理流程
postProcessApplicationContext(context);
//应用初始化器
applyInitializers(context);
//8.1 遍历所有的 listener 调用 contextPrepared。
//EventPublishRunListenr通知所有的监听器contextPrepared
listeners.contextPrepared(context);
bootstrapContext.close(context);
if (this.logStartupInfo) {
logStartupInfo(context.getParent() == null);
logStartupProfileInfo(context);
}
// Add boot specific singleton beans
ConfigurableListableBeanFactory beanFactory = context.getBeanFactory();
beanFactory.registerSingleton("springApplicationArguments", applicationArguments);
if (printedBanner != null) {
beanFactory.registerSingleton("springBootBanner", printedBanner);
}
if (beanFactory instanceof DefaultListableBeanFactory) {
((DefaultListableBeanFactory) beanFactory)
.setAllowBeanDefinitionOverriding(this.allowBeanDefinitionOverriding);
}
if (this.lazyInitialization) {
context.addBeanFactoryPostProcessor(new LazyInitializationBeanFactoryPostProcessor());
}
// Load the sources
Set<Object> sources = getAllSources();
Assert.notEmpty(sources, "Sources must not be empty");
load(context, sources.toArray(new Object[0]));
//8.2
listeners.contextLoaded(context);
}
//11.调用所有runners
private void callRunners(ApplicationContext context, ApplicationArguments args) {
List<Object> runners = new ArrayList<>();
//获取容器中的 ApplicationRunner
runners.addAll(context.getBeansOfType(ApplicationRunner.class).values());
//获取容器中的 CommandLineRunner
runners.addAll(context.getBeansOfType(CommandLineRunner.class).values());
//合并所有runner并且按照@Order进行排序
AnnotationAwareOrderComparator.sort(runners);
//遍历所有的runner。调用 run 方法
for (Object runner : new LinkedHashSet<>(runners)) {
if (runner instanceof ApplicationRunner) {
callRunner((ApplicationRunner) runner, args);
}
if (runner instanceof CommandLineRunner) {
callRunner((CommandLineRunner) runner, args);
}
}
}
//13.
private void handleRunFailure(ConfigurableApplicationContext context, Throwable exception,
SpringApplicationRunListeners listeners) {
try {
try {
handleExitCode(context, exception);
if (listeners != null) {
//14.
listeners.failed(context, exception);
}
}
finally {
reportFailure(getExceptionReporters(context), exception);
if (context != null) {
context.close();
}
}
}
catch (Exception ex) {
logger.warn("Unable to close ApplicationContext", ex);
}
ReflectionUtils.rethrowRuntimeException(exception);
}
...
}
//2. new SpringApplication(primarySources).run(args) 最后返回的接口类型
public interface ConfigurableApplicationContext extends ApplicationContext, Lifecycle, Closeable {
String CONFIG_LOCATION_DELIMITERS = ",; \t\n";
String CONVERSION_SERVICE_BEAN_NAME = "conversionService";
String LOAD_TIME_WEAVER_BEAN_NAME = "loadTimeWeaver";
String ENVIRONMENT_BEAN_NAME = "environment";
String SYSTEM_PROPERTIES_BEAN_NAME = "systemProperties";
String SYSTEM_ENVIRONMENT_BEAN_NAME = "systemEnvironment";
String APPLICATION_STARTUP_BEAN_NAME = "applicationStartup";
String SHUTDOWN_HOOK_THREAD_NAME = "SpringContextShutdownHook";
void setId(String var1);
void setParent(@Nullable ApplicationContext var1);
void setEnvironment(ConfigurableEnvironment var1);
ConfigurableEnvironment getEnvironment();
void setApplicationStartup(ApplicationStartup var1);
ApplicationStartup getApplicationStartup();
void addBeanFactoryPostProcessor(BeanFactoryPostProcessor var1);
void addApplicationListener(ApplicationListener<?> var1);
void setClassLoader(ClassLoader var1);
void addProtocolResolver(ProtocolResolver var1);
void refresh() throws BeansException, IllegalStateException;
void registerShutdownHook();
void close();
boolean isActive();
ConfigurableListableBeanFactory getBeanFactory() throws IllegalStateException;
}
#4.
#spring.factories
## Run Listeners
org.springframework.boot.SpringApplicationRunListener=\
org.springframework.boot.context.event.EventPublishingRunListener
class SpringApplicationRunListeners {
private final Log log;
private final List<SpringApplicationRunListener> listeners;
private final ApplicationStartup applicationStartup;
SpringApplicationRunListeners(Log log, Collection<? extends SpringApplicationRunListener> listeners,
ApplicationStartup applicationStartup) {
this.log = log;
this.listeners = new ArrayList<>(listeners);
this.applicationStartup = applicationStartup;
}
//5.遍历 SpringApplicationRunListener 调用 starting 方法；
//相当于通知所有感兴趣系统正在启动过程的人，项目正在 starting。
void starting(ConfigurableBootstrapContext bootstrapContext, Class<?> mainApplicationClass) {
doWithListeners("spring.boot.application.starting", (listener) -> listener.starting(bootstrapContext),
(step) -> {
if (mainApplicationClass != null) {
step.tag("mainApplicationClass", mainApplicationClass.getName());
}
});
}
//7.1
void environmentPrepared(ConfigurableBootstrapContext bootstrapContext, ConfigurableEnvironment environment) {
doWithListeners("spring.boot.application.environment-prepared",
(listener) -> listener.environmentPrepared(bootstrapContext, environment));
}
//8.1
void contextPrepared(ConfigurableApplicationContext context) {
doWithListeners("spring.boot.application.context-prepared", (listener) -> listener.contextPrepared(context));
}
//8.2
void contextLoaded(ConfigurableApplicationContext context) {
doWithListeners("spring.boot.application.context-loaded", (listener) -> listener.contextLoaded(context));
}
//10.
void started(ConfigurableApplicationContext context) {
doWithListeners("spring.boot.application.started", (listener) -> listener.started(context));
}
//12.
void running(ConfigurableApplicationContext context) {
doWithListeners("spring.boot.application.running", (listener) -> listener.running(context));
}
//14.
void failed(ConfigurableApplicationContext context, Throwable exception) {
doWithListeners("spring.boot.application.failed",
(listener) -> callFailedListener(listener, context, exception), (step) -> {
step.tag("exception", exception.getClass().toString());
step.tag("message", exception.getMessage());
});
}
private void doWithListeners(String stepName, Consumer<SpringApplicationRunListener> listenerAction,
Consumer<StartupStep> stepAction) {
StartupStep step = this.applicationStartup.start(stepName);
this.listeners.forEach(listenerAction);
if (stepAction != null) {
stepAction.accept(step);
}
step.end();
}
...
}
接下来看run(args)方法，这个args就是main方法里传来的args
public ConfigurableApplicationContext run(String... args) {
// 创建停止监听器
StopWatch stopWatch = new StopWatch();
// 调用停机监听器的start()方法
stopWatch.start();
ConfigurableApplicationContext context = null;
Collection<SpringBootExceptionReporter> exceptionReporters = new ArrayList<>();
configureHeadlessProperty();
// 获取想监听项目启动状态的所有listener
SpringApplicationRunListeners listeners = getRunListeners(args);
// 遍历调用各listener的starting()方法
listeners.starting();
try {
// 创建应用参数
ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);
ConfigurableEnvironment environment = prepareEnvironment(listeners, applicationArguments);
configureIgnoreBeanInfo(environment);
Banner printedBanner = printBanner(environment);
context = createApplicationContext();
exceptionReporters = getSpringFactoriesInstances(SpringBootExceptionReporter.class,
new Class[] { ConfigurableApplicationContext.class }, context);
prepareContext(context, environment, listeners, applicationArguments, printedBanner);
refreshContext(context);
afterRefresh(context, applicationArguments);
stopWatch.stop();
if (this.logStartupInfo) {
new StartupInfoLogger(this.mainApplicationClass).logStarted(getApplicationLog(), stopWatch);
}
listeners.started(context);
callRunners(context, applicationArguments);
}
catch (Throwable ex) {
handleRunFailure(context, ex, exceptionReporters, listeners);
throw new IllegalStateException(ex);
}
try {
listeners.running(context);
}
catch (Throwable ex) {
handleRunFailure(context, ex, exceptionReporters, null);
throw new IllegalStateException(ex);
}
return context;
}
start()方法调用start("")方法
public void start() throws IllegalStateException {
start("");
}
该start(String taskName)方法记录了一下进程名和开始时间
public void start(String taskName) throws IllegalStateException {
if (this.currentTaskName != null) {
throw new IllegalStateException("Can't start StopWatch: it's already running");
}
this.currentTaskName = taskName;
this.startTimeNanos = System.nanoTime();
}
然后调用configureHeadlessProperty();方法
在这里面设置headless模式（在系统可能缺少显示设备、键盘或鼠标这些外设的情况下，但又需要使用他们提供的功能，生成相应的数据，以提供给客户端时可以使用该模式。比如远程连接服务器时，想使用服务器键盘、鼠标等功能，但是又没有这些设备）
private void configureHeadlessProperty() {
System.setProperty(SYSTEM_PROPERTY_JAVA_AWT_HEADLESS,
System.getProperty(SYSTEM_PROPERTY_JAVA_AWT_HEADLESS, Boolean.toString(this.headless)));
}
获取运行时监听器
还是调用getSpringFactoriesInstances()方法，从spring.factory文件里获取SpringApplicationRunListener的配置
private SpringApplicationRunListeners getRunListeners(String[] args) {
Class<?>[] types = new Class<?>[] { SpringApplication.class, String[].class };
return new SpringApplicationRunListeners(logger,
getSpringFactoriesInstances(SpringApplicationRunListener.class, types, this, args));
}
找到一个名为EventPublishingRunListener的listener，然后调用listeners.starting();方法
该方法会调用所有listener的starting()方法，即告诉关心项目启动状态的监听器
void starting() {
for (SpringApplicationRunListener listener : this.listeners) {
listener.starting();
}
}
创建应用参数后，调用prepareEnvironment(listeners, applicationArguments)方法，把listeners和applicationArguments都传进去
获取或创建环境信息
private ConfigurableEnvironment prepareEnvironment(SpringApplicationRunListeners listeners,
ApplicationArguments applicationArguments) {
// Create and configure the environment
// 如果有环境信息就使用该环境，没有就创建
ConfigurableEnvironment environment = getOrCreateEnvironment();
configureEnvironment(environment, applicationArguments.getSourceArgs());
ConfigurationPropertySources.attach(environment);
listeners.environmentPrepared(environment);
bindToSpringApplication(environment);
if (!this.isCustomEnvironment) {
environment = new EnvironmentConverter(getClassLoader()).convertEnvironmentIfNecessary(environment,
deduceEnvironmentClass());
}
ConfigurationPropertySources.attach(environment);
return environment;
}
当前是Servlet应用，所以创建StandardServletEnvironment()
private ConfigurableEnvironment getOrCreateEnvironment() {
if (this.environment != null) {
return this.environment;
}
switch (this.webApplicationType) {
case SERVLET:
return new StandardServletEnvironment();
case REACTIVE:
return new StandardReactiveWebEnvironment();
default:
return new StandardEnvironment();
}
}
得到基础环境信息后，再配置基础环境信息
配置环境信息
protected void configureEnvironment(ConfigurableEnvironment environment, String[] args) {
if (this.addConversionService) {
// 类型转换器 (比如String转Integer等，读取配置文件需要把String转成Integer、Date等)
ConversionService conversionService = ApplicationConversionService.getSharedInstance();
environment.setConversionService((ConfigurableConversionService) conversionService);
}
// 加载外部配置源
configurePropertySources(environment, args);
configureProfiles(environment, args);
}
加载外部配置源
protected void configurePropertySources(ConfigurableEnvironment environment, String[] args) {
// 获取环境中的所有配置源 (比如：使用@PropertySource指定的配置源)
// 例子 @PropertySource("classpath:/com/myco/app.properties") or @PropertySource("file:/path/to/file.xml")
MutablePropertySources sources = environment.getPropertySources();
if (this.defaultProperties != null && !this.defaultProperties.isEmpty()) {
sources.addLast(new MapPropertySource("defaultProperties", this.defaultProperties));
}
// 添加命令行信息
if (this.addCommandLineProperties && args.length > 0) {
String name = CommandLinePropertySource.COMMAND_LINE_PROPERTY_SOURCE_NAME;
if (sources.contains(name)) {
PropertySource<?> source = sources.get(name);
CompositePropertySource composite = new CompositePropertySource(name);
composite.addPropertySource(
new SimpleCommandLinePropertySource("springApplicationCommandLineArgs", args));
composite.addPropertySource(source);
sources.replace(name, composite);
}
else {
sources.addFirst(new SimpleCommandLinePropertySource(args));
}
}
}
激活profile环境
由于没有配置spring.profiles.active，所以这里面没有数据
protected void configureProfiles(ConfigurableEnvironment environment, String[] args) {
Set<String> profiles = new LinkedHashSet<>(this.additionalProfiles);
profiles.addAll(Arrays.asList(environment.getActiveProfiles()));
environment.setActiveProfiles(StringUtils.toStringArray(profiles));
}
绑定完所有的环境信息后，调用listeners.environmentPrepared(environment);方法
private ConfigurableEnvironment prepareEnvironment(SpringApplicationRunListeners listeners,
ApplicationArguments applicationArguments) {
// Create and configure the environment
ConfigurableEnvironment environment = getOrCreateEnvironment();
configureEnvironment(environment, applicationArguments.getSourceArgs());
ConfigurationPropertySources.attach(environment);
listeners.environmentPrepared(environment);
bindToSpringApplication(environment);
if (!this.isCustomEnvironment) {
environment = new EnvironmentConverter(getClassLoader()).convertEnvironmentIfNecessary(environment,
deduceEnvironmentClass());
}
ConfigurationPropertySources.attach(environment);
return environment;
}
listeners.environmentPrepared(environment);方法就是遍历所有的listener，调用其environmentPrepared方法。通知所有的监听器当前环境已准备完成。
void environmentPrepared(ConfigurableEnvironment environment) {
for (SpringApplicationRunListener listener : this.listeners) {
listener.environmentPrepared(environment);
}
}
这些都是在准备一些环境信息。
准备创建应用上下文 ( IOC容器 )
public ConfigurableApplicationContext run(String... args) {
...
try {
ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);
ConfigurableEnvironment environment = prepareEnvironment(listeners, applicationArguments);
// 配置忽略的Bean信息
configureIgnoreBeanInfo(environment);
// 打印banner (就是那个Spring的logo图标)
Banner printedBanner = printBanner(environment);
// 创建应用上下文
context = createApplicationContext();
exceptionReporters = getSpringFactoriesInstances(SpringBootExceptionReporter.class,
new Class[] { ConfigurableApplicationContext.class }, context);
...
}
catch (Throwable ex) {
...
}
...
return context;
}
首先检查当前是sevlet或reactive类型的Web应用，或者不是一个Web应用
protected ConfigurableApplicationContext createApplicationContext() {
Class<?> contextClass = this.applicationContextClass;
if (contextClass == null) {
try {
switch (this.webApplicationType) {
case SERVLET:
contextClass = Class.forName(DEFAULT_SERVLET_WEB_CONTEXT_CLASS);
break;
case REACTIVE:
contextClass = Class.forName(DEFAULT_REACTIVE_WEB_CONTEXT_CLASS);
break;
default:
contextClass = Class.forName(DEFAULT_CONTEXT_CLASS);
}
}
catch (ClassNotFoundException ex) {
throw new IllegalStateException(
"Unable create a default ApplicationContext, please specify an ApplicationContextClass", ex);
}
}
return (ConfigurableApplicationContext) BeanUtils.instantiateClass(contextClass);
}
准备IOC容器的信息
private void prepareContext(ConfigurableApplicationContext context, ConfigurableEnvironment environment,
SpringApplicationRunListeners listeners, ApplicationArguments applicationArguments, Banner printedBanner) {
// 设置ioc容器的环境信息
context.setEnvironment(environment);
// 后置处理ioc容器
postProcessApplicationContext(context);
// 应用初始化器
applyInitializers(context);
listeners.contextPrepared(context);
if (this.logStartupInfo) {
logStartupInfo(context.getParent() == null);
logStartupProfileInfo(context);
}
// Add boot specific singleton beans
// 获取bean工厂
ConfigurableListableBeanFactory beanFactory = context.getBeanFactory();
// 注册一个springApplicationArguments的组件，值为命令行参数信息
beanFactory.registerSingleton("springApplicationArguments", applicationArguments);
if (printedBanner != null) {
//
beanFactory.registerSingleton("springBootBanner", printedBanner);
}
if (beanFactory instanceof DefaultListableBeanFactory) {
((DefaultListableBeanFactory) beanFactory)
.setAllowBeanDefinitionOverriding(this.allowBeanDefinitionOverriding);
}
if (this.lazyInitialization) {
context.addBeanFactoryPostProcessor(new LazyInitializationBeanFactoryPostProcessor());
}
// Load the sources
Set<Object> sources = getAllSources();
Assert.notEmpty(sources, "Sources must not be empty");
load(context, sources.toArray(new Object[0]));
listeners.contextLoaded(context);
}
遍历所有ApplicationContextInitializer，调用其initialize(context)方法来对ioc容器进行初始化扩展。
@SuppressWarnings({ "rawtypes", "unchecked" })
protected void applyInitializers(ConfigurableApplicationContext context) {
for (ApplicationContextInitializer initializer : getInitializers()) {
Class<?> requiredType = GenericTypeResolver.resolveTypeArgument(initializer.getClass(),
ApplicationContextInitializer.class);
Assert.isInstanceOf(requiredType, context, "Unable to call initializer.");
initializer.initialize(context);
}
}
这个ApplicationContextInitializer就是前面说的7个在spring.factory里配置的该类引入的那个几个类
然后调用listeners的contextPrepared(context)方法，告诉这些监听器ioc上下文环境已近准备就绪了
private void prepareContext(ConfigurableApplicationContext context, ConfigurableEnvironment environment,
SpringApplicationRunListeners listeners, ApplicationArguments applicationArguments, Banner printedBanner) {
context.setEnvironment(environment);
postProcessApplicationContext(context);
applyInitializers(context);
listeners.contextPrepared(context);
if (this.logStartupInfo) {
logStartupInfo(context.getParent() == null);
logStartupProfileInfo(context);
}
...
}
该方法就是遍历listener，调用其contextPrepared方法，此时只有一个EventPublishingRunListener事件发布的运行时监听器
void contextPrepared(ConfigurableApplicationContext context) {
for (SpringApplicationRunListener listener : this.listeners) {
listener.contextPrepared(context);
}
}
准备完以后，会调用listeners的contextLoaded(context)，告诉所有的监听器上下文已经加载完毕
遍历所有listener，调用其contextLoaded(context)方法，至此准备工作也就完成了
void contextLoaded(ConfigurableApplicationContext context) {
for (SpringApplicationRunListener listener : this.listeners) {
listener.contextLoaded(context);
}
}
然后调用refreshContext(context);
调用 refresh((ApplicationContext) context)方法
private void refreshContext(ConfigurableApplicationContext context) {
// 调用refresh方法
refresh((ApplicationContext) context);
if (this.registerShutdownHook) {
try {
// 注册一个shutdown的钩子
context.registerShutdownHook();
}
catch (AccessControlException ex) {
// Not allowed in some environments.
}
}
}
调用refresh((ConfigurableApplicationContext) applicationContext);方法 （该方法标注了@Deprecated，表示当前方法已经过时了，不推荐继续使用）
@Deprecated
protected void refresh(ApplicationContext applicationContext) {
// 断定applicationContext对象是ConfigurableApplicationContext类型
Assert.isInstanceOf(ConfigurableApplicationContext.class, applicationContext);
refresh((ConfigurableApplicationContext) applicationContext);
}
然后调用调用applicationContext的refresh()方法
protected void refresh(ConfigurableApplicationContext applicationContext) {
applicationContext.refresh();
}
然后调用super.refresh()，调用父类的refresh()方法
@Override
public final void refresh() throws BeansException, IllegalStateException {
try {
super.refresh();
}
catch (RuntimeException ex) {
WebServer webServer = this.webServer;
if (webServer != null) {
webServer.stop();
}
throw ex;
}
}
接下来就是Spring经典的初始化过程，创建Spring IOC容器中的所有组件，如果在配置文件中配置了debug=true，此时控制台就会输出所有启用的组件和没有启用的组件
@Override
public void refresh() throws BeansException, IllegalStateException {
synchronized (this.startupShutdownMonitor) {
// Prepare this context for refreshing.
prepareRefresh();
// Tell the subclass to refresh the internal bean factory.
ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
// Prepare the bean factory for use in this context.
prepareBeanFactory(beanFactory);
try {
// Allows post-processing of the bean factory in context subclasses.
postProcessBeanFactory(beanFactory);
// Invoke factory processors registered as beans in the context.
invokeBeanFactoryPostProcessors(beanFactory);
// Register bean processors that intercept bean creation.
registerBeanPostProcessors(beanFactory);
// Initialize message source for this context.
initMessageSource();
// Initialize event multicaster for this context.
initApplicationEventMulticaster();
// Initialize other special beans in specific context subclasses.
onRefresh();
// Check for listener beans and register them.
registerListeners();
// Instantiate all remaining (non-lazy-init) singletons.
// 获取所有组件
finishBeanFactoryInitialization(beanFactory);
// Last step: publish corresponding event.
finishRefresh();
}
catch (BeansException ex) {
if (logger.isWarnEnabled()) {
logger.warn("Exception encountered during context initialization - " +
"cancelling refresh attempt: " + ex);
}
// Destroy already created singletons to avoid dangling resources.
destroyBeans();
// Reset 'active' flag.
cancelRefresh(ex);
// Propagate exception to caller.
throw ex;
}
finally {
// Reset common introspection caches in Spring's core, since we
// might not ever need metadata for singleton beans anymore...
resetCommonCaches();
}
}
}
获取启动所需要的时间，调用所有监听器的started(context)方法，调用Runners
public ConfigurableApplicationContext run(String... args) {
...
SpringApplicationRunListeners listeners = getRunListeners(args);
listeners.starting();
try {
...
refreshContext(context);
afterRefresh(context, applicationArguments);
// 获取启动所需要的时间
stopWatch.stop();
if (this.logStartupInfo) {
new StartupInfoLogger(this.mainApplicationClass).logStarted(getApplicationLog(), stopWatch);
}
// 调用所有监听器的started(context)方法
listeners.started(context);
callRunners(context, applicationArguments);
}
catch (Throwable ex) {
...
}
...
return context;
}
private void callRunners(ApplicationContext context, ApplicationArguments args) {
List<Object> runners = new ArrayList<>();
// 获取 ApplicationRunner
runners.addAll(context.getBeansOfType(ApplicationRunner.class).values());
// 获取 CommandLineRunner
runners.addAll(context.getBeansOfType(CommandLineRunner.class).values());
// 然后对收集到的runners 按照 @Order 进行排序
AnnotationAwareOrderComparator.sort(runners);
for (Object runner : new LinkedHashSet<>(runners)) {
if (runner instanceof ApplicationRunner) {
callRunner((ApplicationRunner) runner, args);
}
if (runner instanceof CommandLineRunner) {
callRunner((CommandLineRunner) runner, args);
}
}
}
这个callRunner()就是调用对应类型的run(args)方法
private void callRunner(ApplicationRunner runner, ApplicationArguments args) {
try {
(runner).run(args);
}
catch (Exception ex) {
throw new IllegalStateException("Failed to execute ApplicationRunner", ex);
}
}
private void callRunner(CommandLineRunner runner, ApplicationArguments args) {
try {
(runner).run(args.getSourceArgs());
}
catch (Exception ex) {
throw new IllegalStateException("Failed to execute CommandLineRunner", ex);
}
}
ApplicationRunner接口只有一个run方法
@FunctionalInterface
public interface ApplicationRunner {
/**
* Callback used to run the bean.
* @param args incoming application arguments
* @throws Exception on error
*/
void run(ApplicationArguments args) throws Exception;
}
CommandLineRunner接口也只有一个run方法
@FunctionalInterface
public interface CommandLineRunner {
/**
* Callback used to run the bean.
* @param args incoming main method arguments
* @throws Exception on error
*/
void run(String... args) throws Exception;
}
如果有异常，还会处理异常
public ConfigurableApplicationContext run(String... args) {
...
try {
...
listeners.started(context);
callRunners(context, applicationArguments);
}
catch (Throwable ex) {
handleRunFailure(context, ex, exceptionReporters, listeners);
throw new IllegalStateException(ex);
}
try {
listeners.running(context);
}
catch (Throwable ex) {
handleRunFailure(context, ex, exceptionReporters, null);
throw new IllegalStateException(ex);
}
return context;
}
处理异常就是调用所有listener的failed方法、调用 context.close()方法
private void handleRunFailure(ConfigurableApplicationContext context, Throwable exception,
Collection<SpringBootExceptionReporter> exceptionReporters, SpringApplicationRunListeners listeners) {
try {
try {
handleExitCode(context, exception);
if (listeners != null) {
listeners.failed(context, exception);
}
}
finally {
reportFailure(exceptionReporters, exception);
if (context != null) {
context.close();
}
}
}
catch (Exception ex) {
logger.warn("Unable to close ApplicationContext", ex);
}
ReflectionUtils.rethrowRuntimeException(exception);
}
然后尝试调用listeners.running(context);方法，如果有问题还是调用所有listener的failed方法、调用 context.close()方法
86、原理解析-自定义事件监听组件
SpringBoot原理
Spring原理【Spring注解】、SpringMVC原理、自动配置原理、SpringBoot原理
1、SpringBoot启动过程
创建 SpringApplication
- 保存一些信息。
判定当前应用的类型。ClassUtils。Servlet
bootstrappers：初始启动引导器（
List<Bootstrapper>）：去spring.factories文件中找org.springframework.boot.Bootstrapper找 ApplicationContextInitializer；去spring.factories找ApplicationContextInitializer
List<ApplicationContextInitializer<?>> initializers
- 找 ApplicationListener ；应用监听器。去spring.factories找 ApplicationListener
List<ApplicationListener<?>> listeners
运行 SpringApplication
- StopWatch
记录应用的启动时间
创建引导上下文（Context环境）createBootstrapContext()
- 获取到所有之前的 bootstrappers 挨个执行 intitialize() 来完成对引导启动器上下文环境设置
- 让当前应用进入headless模式。java.awt.headless
获取所有 RunListener（运行监听器）【为了方便所有Listener进行事件感知】
- getSpringFactoriesInstances 去spring.factories找 SpringApplicationRunListener.
- 遍历 SpringApplicationRunListener 调用 starting 方法；
- 相当于通知所有感兴趣系统正在启动过程的人，项目正在 starting。
- 保存命令行参数；ApplicationArguments
准备环境 prepareEnvironment（）;
- 返回或者创建基础环境信息对象。StandardServletEnvironment
配置环境信息对象。
- 读取所有的配置源的配置属性值。
- 绑定环境信息
监听器调用 listener.environmentPrepared()；通知所有的监听器当前环境准备完成
- 创建IOC容器（createApplicationContext（））
- 根据项目类型（Servlet）创建容器，
当前会创建 AnnotationConfigServletWebServerApplicationContext
- 准备ApplicationContext IOC容器的基本信息 prepareContext()
- 保存环境信息
IOC容器的后置处理流程。
应用初始化器；applyInitializers；
- 遍历所有的 ApplicationContextInitializer 。调用 initialize.。来对ioc容器进行初始化扩展功能
遍历所有的 listener 调用 contextPrepared。EventPublishRunListenr；通知所有的监听器 contextPrepared
- 所有的监听器 调用 contextLoaded。通知所有的监听器 contextLoaded；
- **刷新IOC容器。**refreshContext
- 创建容器中的所有组件（Spring注解）
- 容器刷新完成后工作？afterRefresh
所有监听 器 调用 listeners.started(context); 通知所有的监听器 started
**调用所有runners；**callRunners()
- 获取容器中的 ApplicationRunner
获取容器中的 CommandLineRunner
合并所有runner并且按照@Order进行排序
遍历所有的runner。调用 run 方法
- 如果以上有异常，
- 调用Listener 的 failed
- 调用所有监听器的 running 方法 listeners.running(context); 通知所有的监听器 running
MyApplicationContextInitializer.java
import org.springframework.context.ApplicationContextInitializer;
import org.springframework.context.ConfigurableApplicationContext;
public class MyApplicationContextInitializer implements ApplicationContextInitializer {
@Override
public void initialize(ConfigurableApplicationContext applicationContext) {
System.out.println("MyApplicationContextInitializer ....initialize.... ");
}
}
MyApplicationListener.java
import org.springframework.context.ApplicationEvent;
import org.springframework.context.ApplicationListener;
public class MyApplicationListener implements ApplicationListener {
@Override
public void onApplicationEvent(ApplicationEvent event) {
System.out.println("MyApplicationListener.....onApplicationEvent...");
}
}
MyApplicationRunner.java
import org.springframework.boot.ApplicationArguments;
import org.springframework.boot.ApplicationRunner;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;
@Order(1)
@Component//放入容器
public class MyApplicationRunner implements ApplicationRunner {
@Override
public void run(ApplicationArguments args) throws Exception {
System.out.println("MyApplicationRunner...run...");
}
}
MyCommandLineRunner.java
import org.springframework.boot.CommandLineRunner;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;
/**
* 应用启动做一个一次性事情
*/
@Order(2)
@Component//放入容器
public class MyCommandLineRunner implements CommandLineRunner {
@Override
public void run(String... args) throws Exception {
System.out.println("MyCommandLineRunner....run....");
}
}
MySpringApplicationRunListener.java
import org.springframework.boot.ConfigurableBootstrapContext;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.SpringApplicationRunListener;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.core.env.ConfigurableEnvironment;
public class MySpringApplicationRunListener implements SpringApplicationRunListener {
private SpringApplication application;
public MySpringApplicationRunListener(SpringApplication application, String[] args){
this.application = application;
}
@Override
public void starting(ConfigurableBootstrapContext bootstrapContext) {
System.out.println("MySpringApplicationRunListener....starting....");
}
@Override
public void environmentPrepared(ConfigurableBootstrapContext bootstrapContext, ConfigurableEnvironment environment) {
System.out.println("MySpringApplicationRunListener....environmentPrepared....");
}
@Override
public void contextPrepared(ConfigurableApplicationContext context) {
System.out.println("MySpringApplicationRunListener....contextPrepared....");
}
@Override
public void contextLoaded(ConfigurableApplicationContext context) {
System.out.println("MySpringApplicationRunListener....contextLoaded....");
}
@Override
public void started(ConfigurableApplicationContext context) {
System.out.println("MySpringApplicationRunListener....started....");
}
@Override
public void running(ConfigurableApplicationContext context) {
System.out.println("MySpringApplicationRunListener....running....");
}
@Override
public void failed(ConfigurableApplicationContext context, Throwable exception) {
System.out.println("MySpringApplicationRunListener....failed....");
}
}
注册MyApplicationContextInitializer，MyApplicationListener，MySpringApplicationRunListener:
resources / META-INF / spring.factories:
org.springframework.context.ApplicationContextInitializer=\
com.lun.boot.listener.MyApplicationContextInitializer
org.springframework.context.ApplicationListener=\
com.lun.boot.listener.MyApplicationListener
org.springframework.boot.SpringApplicationRunListener=\
com.lun.boot.listener.MySpringApplicationRunListener
87、后会有期
路漫漫其修远兮，吾将上下而求索。
纸上得来终觉浅，绝知此事要躬行。
Spring Boot 2 场景整合篇
- 虚拟化技术
- 安全控制
- 缓存技术
- 消息中间件
- 对象存储
- 定时调度
- 异步任务
- 分布式系统
Spring Boot 2 响应式编程
- 响应式编程基础
- Webflux开发Web应用
- 响应式访问持久化层
- 响应式安全开发
- 响应式原理
Powered by Waline v3.0.0-alpha.8