SpringMVC学习——组件解析

不念不忘少年蓝@ 2022-05-29 10:47 179阅读 0赞

## SpringMVC学习——组件解析 ##

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**Spring MVC框架结构图**

[![SpringMVC学习——组件解析][SpringMVC]][SpringMVC_SpringMVC]

**前端控制器（DispatcherServlet）**  
[![SpringMVC学习——组件解析][SpringMVC 1]][SpringMVC_SpringMVC 1]

**控制器组件（Controller）**  
[![SpringMVC学习——组件解析][SpringMVC 2]][SpringMVC_SpringMVC 2]

**处理器映射器组件（HandlerMapping）**  
[![SpringMVC学习——组件解析][SpringMVC 3]][SpringMVC_SpringMVC 3]

**处理器适配器组件（HandlerAdapter）**

[![SpringMVC学习——组件解析][SpringMVC 4]][SpringMVC_SpringMVC 4]

**拦截器组件（HandlerInterceptor）**  
[![SpringMVC学习——组件解析][SpringMVC 5]][SpringMVC_SpringMVC 5]

**视图解析器组件（ViewResolver）**  
[![SpringMVC学习——组件解析][SpringMVC 6]][SpringMVC_SpringMVC 6]

**视图组件（View）**  
[![SpringMVC学习——组件解析][SpringMVC 7]][SpringMVC_SpringMVC 7]  
  
**前端控制器流程处理关键方法（doDispatch）源码解析：**

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 \{

// 检查并且包装multipart/form-data请求

processedRequest = checkMultipart(request);

multipartRequestParsed = processedRequest != request;

// 根据请求去匹配HandlerMapping，并且通过HandlerMapping返回HandlerExecutionChain

mappedHandler = getHandler(processedRequest, false);

if (mappedHandler == null || mappedHandler.getHandler() == null) \{

noHandlerFound(processedRequest, response);

return;

// 根据Handler匹配HandlerAdapter

HandlerAdapter ha = getHandlerAdapter(mappedHandler.getHandler());

// 验证HTTP头部last-modified

String method = request.getMethod();

boolean isGet = "GET".equals(method);

if (isGet || "HEAD".equals(method)) \{

long lastModified = ha.getLastModified(request, mappedHandler.getHandler());

if (logger.isDebugEnabled()) \{

String requestUri = urlPathHelper.getRequestUri(request);

logger.debug("Last-Modified value for \[" + requestUri + "\] is: " + lastModified);

if (new ServletWebRequest(request, response).checkNotModified(lastModified) && isGet) \{

return;

// 执行前置通知

if (!mappedHandler.applyPreHandle(processedRequest, response)) \{

return;

try \{

// 解析方法参数，注入方法参数，并且执行Handler；最后返回ModelAndView；

mv = ha.handle(processedRequest, response, mappedHandler.getHandler());

finally \{

if (asyncManager.isConcurrentHandlingStar ted()) \{

return;

// 设置默认视图

applyDefaultViewName(request, mv);

// 执行后置通知

mappedHandler.applyPostHandle(processedRequest, response, mv);

catch (Exception ex) \{

dispatchException = ex;

// 处理返回结果：根据视图名匹配视图解析器，返回视图；最后将视图输出；

processDispatchResult(processedRequest, response, mappedHandler, mv, dispatchException);

catch (Exception ex) \{

// 执行完成通知

triggerAfterCompletion(processedRequest, response, mappedHandler, ex);

catch (Error err) \{

// 执行完成通知

triggerAfterCompletionWi thError(processedRequest, response, mappedHandler, err);

finally \{

// 处理异步通知

if (asyncManager.isConcurrentHandlingStar ted()) \{

// Instead of postHandle and afterCompletion

mappedHandler.applyAfterConcurrentHand lingStarted(processedRequest, response);

return;

// 清除multipart/form-data资源

if (multipartRequestParsed) \{

cleanupMultipart(processedRequest);

[sg_trans.gif]: /images/20220529/f7af75c1543c452ea5fcd5e9c5314f97.png
[SpringMVC]: http://s13.sinaimg.cn/mw690/001Sm5PUzy6IS9XxIPq2c&690
[SpringMVC_SpringMVC]: /images/20220529/4066b62786294e8bac67baeba9bc6ce9.png
[SpringMVC 1]: http://s11.sinaimg.cn/mw690/001Sm5PUzy6IS9Xj88Oba&690
[SpringMVC_SpringMVC 1]: /images/20220529/135f3812f51844b7a17abe9ca000370c.png
[SpringMVC 2]: http://s8.sinaimg.cn/mw690/001Sm5PUzy6IS9XjJjxe7&690
[SpringMVC_SpringMVC 2]: /images/20220529/07d71fd9c50f46cb85bdbd0083de225f.png
[SpringMVC 3]: http://s15.sinaimg.cn/mw690/001Sm5PUzy6IS9Xlo5g0e&690
[SpringMVC_SpringMVC 3]: /images/20220529/e91fae45f4da460bb2904b763dbf7e3f.png
[SpringMVC 4]: http://s10.sinaimg.cn/mw690/001Sm5PUzy6IS9XkN8529&690
[SpringMVC_SpringMVC 4]: /images/20220529/55d63f67013748e0b00d91347035996e.png
[SpringMVC 5]: http://s2.sinaimg.cn/mw690/001Sm5PUzy6IS9Xf3Tr11&690
[SpringMVC_SpringMVC 5]: /images/20220529/9afb3fc8374940de8570b853d214a16b.png
[SpringMVC 6]: http://s16.sinaimg.cn/mw690/001Sm5PUzy6IS9XwFoXbf&690
[SpringMVC_SpringMVC 6]: /images/20220529/f0ebc7ada9e742cf9135b760ae42405b.png
[SpringMVC 7]: http://s14.sinaimg.cn/mw690/001Sm5PUzy6IS9XzGsR9d&690
[SpringMVC_SpringMVC 7]: /images/20220529/320c65141621420285cfa927ec96dba0.png