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 {
     //檢查請求是否是multipart，像檔案上傳這些，如果是通過MultipartResolver進行解析
         processedRequest = checkMultipart(request);
multipartRequestParsed = (processedRequest != request);
    //通過getHandler()方法，使用HandlerMapping完成請求到處理器的對映，獲取到HandlerExecutionChain 
// Determine handler for the current request.
mappedHandler = getHandler(processedRequest);
         if (mappedHandler == null || mappedHandler.getHandler() == null) {
            noHandlerFound(processedRequest, response);
            return;
}
    //將獲取到的Handler處理器進行適配，用響應的HandlerAdapter進行包裝
// Determine handler adapter for the current request.
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 (logger.isDebugEnabled()) {
logger.debug("Last-Modified value for [" + getRequestUri(request) + "] is: " + lastModified);
}
if (new ServletWebRequest(request, response).checkNotModified(lastModified) && isGet) {
return;
}
         }
      //如果設定了攔截器，那麼在執行handler處理器方法處理之前，進行攔截器預處理
if (!mappedHandler.applyPreHandle(processedRequest, response)) {
return;
}
      //通過介面卡呼叫執行處理器的相關功能處理方法，返回ModelAndView物件，包含檢視和Model資料
// Actually invoke the handler.
mv = ha.handle(processedRequest, response, mappedHandler.getHandler());

         if (asyncManager.isConcurrentHandlingStarted()) {
return;
}

         applyDefaultViewName(request, mv);
     //如果設定了攔截器，那麼在執行handler處理器方法處理之後，進行攔截器後處理
mappedHandler.applyPostHandle(processedRequest, response, mv);
}
catch (Exception ex) {
         dispatchException = ex;
}
//這裡處理請求結果，在個函式中，將判斷是否有dispatchException，如果有，將通過ExceptionResolver進行解析處理。然後由ViewResolver解析View ，最後對View進行渲染呈現檢視
      processDispatchResult(processedRequest, response, mappedHandler, mv, dispatchException);
}
catch (Exception ex) {
      triggerAfterCompletion(processedRequest, response, mappedHandler, ex);
}
catch (Error err) {
      triggerAfterCompletionWithError(processedRequest, response, mappedHandler, err);
}
finally {
if (asyncManager.isConcurrentHandlingStarted()) {
// Instead of postHandle and afterCompletion
if (mappedHandler != null) {
            mappedHandler.applyAfterConcurrentHandlingStarted(processedRequest, response);
}
      }
else {
       //如果請求是multipart，那麼這裡進行資源清理操作

// Clean up any resources used by a multipart request.
if (multipartRequestParsed) {
            cleanupMultipart(processedRequest);
}
      }
   }
}