springmvc源码要点1-创新互联
前置 : 版本4.1.2
成都创新互联公司于2013年成立,先为蓟州等服务建站,蓟州等地企业,进行企业商务咨询服务。为蓟州企业网站制作PC+手机+微官网三网同步一站式服务解决您的所有建站问题。请求如何定位到对应的处理方法?
a. 入口 DispatcherServlet的 doService方法
doDispatch(request, response);
b. 解析路径
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); // Determine handler for the current request. mappedHandler = getHandler(processedRequest); ----------------步骤1 if (mappedHandler == null || mappedHandler.getHandler() == null) { noHandlerFound(processedRequest, response); return; } // Determine handler adapter for the current request. HandlerAdapter ha = getHandlerAdapter(mappedHandler.getHandler()); ---------步骤2 // 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; } } if (!mappedHandler.applyPreHandle(processedRequest, response)) { return; } // Actually invoke the handler. mv = ha.handle(processedRequest, response, mappedHandler.getHandler()); ----- 步骤3 if (asyncManager.isConcurrentHandlingStarted()) { return; } applyDefaultViewName(request, mv); mappedHandler.applyPostHandle(processedRequest, response, mv); } catch (Exception ex) { dispatchException = ex; } 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 { // Clean up any resources used by a multipart request. if (multipartRequestParsed) { cleanupMultipart(processedRequest); } } } }
步骤1,点入内部,最终在AbstractHandlerMethodMapping的lookupHandlerMethod找到匹配方法
先完整匹配url,不行则正则匹配
注意步骤1中 返回的是HandlerExecutionChain , 在getHandler里同时也放入了拦截器链
步骤2 找到合适的处理请求的适配器
debug 得到是RequestMappingHandlerAdapter
步骤3 RequestMappingHandlerAdapter的handler在AbstractHandlerMethodAdapter类种
public final ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { return handleInternal(request, response, (HandlerMethod) handler);
里面的复杂逻辑目前不关心,只关注如何调用实际的方法
3. 返回值的处理
RequestMappingHandlerAdapter的invokeHandleMethod方法中,找到
requestMappingMethod.invokeAndHandle(webRequest, mavContainer); --》 进入 -- 》 Object returnValue = invokeForRequest(webRequest, mavContainer, providedArgs);
这里方法里包含了我们在controller里写的方法:
public final Object invokeForRequest(NativeWebRequest request, ModelAndViewContainer mavContainer, Object... providedArgs) throws Exception { Object[] args = getMethodArgumentValues(request, mavContainer, providedArgs); if (logger.isTraceEnabled()) { StringBuilder sb = new StringBuilder("Invoking ["); sb.append(getBeanType().getSimpleName()).append("."); sb.append(getMethod().getName()).append("] method with arguments "); sb.append(Arrays.asList(args)); logger.trace(sb.toString()); } Object returnValue = invoke(args); if (logger.isTraceEnabled()) { logger.trace("Method [" + getMethod().getName() + "] returned [" + returnValue + "]"); } return returnValue; }
回到invokeAndHandle方法,看这句话:
this.returnValueHandlers.handleReturnValue(returnValue, getReturnValueType(returnValue), mavContainer, webRequest);
RequestResponseBodyMethodProcessor 负责处理
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文章标题:springmvc源码要点1-创新互联
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