- 调整日志级别为trace
- 执行过程
- 跟踪源码
在springboot工程文件application-dev.yml中添加代码
logging:
level:
web: trace
启动项目,对url进行请求,可以看到更多日志,方便跟踪源码.
2021-11-08 17:43:02.075 INFO 5884 --- [nio-8081-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring DispatcherServlet 'dispatcherServlet'
2021-11-08 17:43:02.075 INFO 5884 --- [nio-8081-exec-1] o.s.web.servlet.DispatcherServlet : Initializing Servlet 'dispatcherServlet'
2021-11-08 17:43:02.075 TRACE 5884 --- [nio-8081-exec-1] o.s.web.servlet.DispatcherServlet : Detected org.springframework.web.multipart.support.StandardServletMultipartResolver@417a2f69
2021-11-08 17:43:02.076 TRACE 5884 --- [nio-8081-exec-1] o.s.web.servlet.DispatcherServlet : No LocaleResolver 'localeResolver': using default [AcceptHeaderLocaleResolver]
2021-11-08 17:43:02.077 TRACE 5884 --- [nio-8081-exec-1] o.s.web.servlet.DispatcherServlet : No ThemeResolver 'themeResolver': using default [FixedThemeResolver]
2021-11-08 17:43:02.079 TRACE 5884 --- [nio-8081-exec-1] o.s.web.servlet.DispatcherServlet : No RequestToViewNameTranslator 'viewNameTranslator': using default [DefaultRequestToViewNameTranslator]
2021-11-08 17:43:02.082 TRACE 5884 --- [nio-8081-exec-1] o.s.web.servlet.DispatcherServlet : No FlashMapManager 'flashMapManager': using default [SessionFlashMapManager]
2021-11-08 17:43:02.082 DEBUG 5884 --- [nio-8081-exec-1] o.s.web.servlet.DispatcherServlet : enableLoggingRequestDetails='false': request parameters and headers will be masked to prevent unsafe logging of potentially sensitive data
2021-11-08 17:43:02.082 INFO 5884 --- [nio-8081-exec-1] o.s.web.servlet.DispatcherServlet : Completed initialization in 7 ms
2021-11-08 17:43:02.093 TRACE 5884 --- [nio-8081-exec-1] o.s.web.servlet.DispatcherServlet : GET "/test/test", parameters={}, headers={masked} in DispatcherServlet 'dispatcherServlet'
2021-11-08 17:43:02.098 TRACE 5884 --- [nio-8081-exec-1] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped to public java.lang.String com.demo.test.controller.TestController.test()
2021-11-08 17:43:02.106 TRACE 5884 --- [nio-8081-exec-1] .w.s.m.m.a.ServletInvocableHandlerMethod : Arguments: []
2021-11-08 17:43:02.123 DEBUG 5884 --- [nio-8081-exec-1] m.m.a.RequestResponseBodyMethodProcessor : Using 'text/html', given [text/html, application/xhtml+xml, image/avif, image/webp, image/apng, application/xml;q=0.9, application/signed-exchange;v=b3;q=0.9, **, text/plain, */*, application/json, application/*+json, application/json, application/*+json]
2021-11-08 17:43:02.124 TRACE 5884 --- [nio-8081-exec-1] m.m.a.RequestResponseBodyMethodProcessor : Writing ["8081: springboot-demo1"]
2021-11-08 17:43:02.131 TRACE 5884 --- [nio-8081-exec-1] o.s.web.servlet.DispatcherServlet : No view rendering, null ModelAndView returned.
2021-11-08 17:43:02.131 DEBUG 5884 --- [nio-8081-exec-1] o.s.web.servlet.DispatcherServlet : Completed 200 OK, headers={masked}
执行过程
- 用户发送请求至前端控制器DispatcherServlet, 调用方法doDispatch.
- DispatcherServlet收到请求调用处理器映射器HandlerMapping.
- 处理器映射器根据请求url找到具体的处理器，生成处理器执行链HandlerExecutionChain(包括处理器对象和处理器拦截器)一并返回给DispatcherServlet.
- DispatcherServlet根据处理器Handler获取处理器适配器HandlerAdapter执行HandlerAdapter处理一系列的操作，如：参数封装，数据格式转换，数据验证等操作.
- 执行处理器Handler(Controller，也叫页面控制器).
- Handler执行完成返回ModelAndView.
- HandlerAdapter将Handler执行结果ModelAndView返回到DispatcherServlet.
- DispatcherServlet将ModelAndView传给ViewReslover视图解析器.
- ViewReslover解析后返回具体View.
- DispatcherServlet对View进行渲染视图（即将模型数据model填充至视图中）.
- DispatcherServlet响应用户.
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;
try {
processedRequest = checkMultipart(request);
multipartRequestParsed = (processedRequest != request);
// 获取程序执行链.
mappedHandler = getHandler(processedRequest);
if (mappedHandler == null) {
noHandlerFound(processedRequest, response);
return;
}
// 获取HandlerAdapter.
HandlerAdapter ha = getHandlerAdapter(mappedHandler.getHandler());
// Process last-modified header, if supported by the handler.
String method = request.getMethod();
boolean isGet = "GET".equals(method);
if (isGet || "HEAD".equals(method)) {
long lastModified = ha.getLastModified(request, mappedHandler.getHandler());
if (new ServletWebRequest(request, response).checkNotModified(lastModified) && isGet) {
return;
}
}
if (!mappedHandler.applyPreHandle(processedRequest, response)) {
return;
}
// 获取ModelAndView.
mv = ha.handle(processedRequest, response, mappedHandler.getHandler());
if (asyncManager.isConcurrentHandlingStarted()) {
return;
}
applyDefaultViewName(processedRequest, mv);
mappedHandler.applyPostHandle(processedRequest, response, mv);
}
catch (Exception ex) {
dispatchException = ex;
}
catch (Throwable err) {
// As of 4.3, we're processing Errors thrown from handler methods as well,
// making them available for @ExceptionHandler methods and other scenarios.
dispatchException = new NestedServletException("Handler dispatch failed", err);
}
// 处理请求
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 {
if (asyncManager.isConcurrentHandlingStarted()) {
// Instead of postHandle and afterCompletion
if (mappedHandler != null) {
mappedHandler.applyAfterConcurrentHandlingStarted(processedRequest, response);
}
}
else {
// Clean up any resources used by a multipart request.
if (multipartRequestParsed) {
cleanupMultipart(processedRequest);
}
}
}
}
参考链接: https://www.jianshu.com/p/8a20c547e245.
