spring源码_spring源码分析MVC

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在spring Boot之前&＃xff0c;我们再创建spring web工程的时候&＃xff0c;都会创建非常多的配置&＃xff0c;下面我们来看一下web.xml中配置的一段代码

dispatcherServletorg.springframework.web.servlet.DispatcherServletcontextConfigLocationclasspath*:spring-mvc.xml1dispatcherServlet/*

这个是我们启动spring web的一段关键代码&＃xff0c;以前&＃xff0c;web项目都是基于servlet规范的&＃xff0c;而servlet在初始化的会调用init方法&＃xff0c;这个servlet就是启动web项目的入口&＃xff0c;下面我们来看一下DispatcherServlet类.在DispatcherServlet类中&＃xff0c;我们找不到init方法&＃xff0c;因此&＃xff0c;寻找其父类。

在HttpServletBean类中&＃xff0c;我们找到了init方法

public final void init() throws ServletException { // Set bean properties from init parameters. PropertyValues pvs &＃61; new ServletConfigPropertyValues(getServletConfig(), this.requiredProperties); if (!pvs.isEmpty()) { try { BeanWrapper bw &＃61; PropertyAccessorFactory.forBeanPropertyAccess(this); ResourceLoader resourceLoader &＃61; new ServletContextResourceLoader(getServletContext()); bw.registerCustomEditor(Resource.class, new ResourceEditor(resourceLoader, getEnvironment())); initBeanWrapper(bw); bw.setPropertyValues(pvs, true); } catch (BeansException ex) { if (logger.isErrorEnabled()) { logger.error("Failed to set bean properties on servlet &＃39;" &＃43; getServletName() &＃43; "&＃39;", ex); } throw ex; } } // Let subclasses do whatever initialization they like. initServletBean();}

在这段代码这&＃xff0c;我们看到了一个关键的方法initServletBean,调用这个方法开始初始化servlet,我们来分析一下这个方法

protected final void initServletBean() throws ServletException { getServletContext().log("Initializing Spring " &＃43; getClass().getSimpleName() &＃43; " &＃39;" &＃43; getServletName() &＃43; "&＃39;"); if (logger.isInfoEnabled()) { logger.info("Initializing Servlet &＃39;" &＃43; getServletName() &＃43; "&＃39;"); } long startTime &＃61; System.currentTimeMillis(); try { this.webApplicationContext &＃61; initWebApplicationContext(); initFrameworkServlet(); } catch (ServletException | RuntimeException ex) { logger.error("Context initialization failed", ex); throw ex; } if (logger.isDebugEnabled()) { String value &＃61; this.enableLoggingRequestDetails ? "shown which may lead to unsafe logging of potentially sensitive data" : "masked to prevent unsafe logging of potentially sensitive data"; logger.debug("enableLoggingRequestDetails&＃61;&＃39;" &＃43; this.enableLoggingRequestDetails &＃43; "&＃39;: request parameters and headers will be " &＃43; value); } if (logger.isInfoEnabled()) { logger.info("Completed initialization in " &＃43; (System.currentTimeMillis() - startTime) &＃43; " ms"); }}

看到这里&＃xff0c;我们看见了一个关键的方法&＃xff0c;初始化web上下文容器initWebApplicationContext

protected WebApplicationContext initWebApplicationContext() { WebApplicationContext rootContext &＃61; WebApplicationContextUtils.getWebApplicationContext(getServletContext()); WebApplicationContext wac &＃61; null; if (this.webApplicationContext !&＃61; null) { // A context instance was injected at construction time -> use it wac &＃61; this.webApplicationContext; if (wac instanceof ConfigurableWebApplicationContext) { ConfigurableWebApplicationContext cwac &＃61; (ConfigurableWebApplicationContext) wac; if (!cwac.isActive()) { // The context has not yet been refreshed -> provide services such as // setting the parent context, setting the application context id, etc if (cwac.getParent() &＃61;&＃61; null) { // The context instance was injected without an explicit parent -> set // the root application context (if any; may be null) as the parent cwac.setParent(rootContext); } configureAndRefreshWebApplicationContext(cwac); } } } if (wac &＃61;&＃61; null) { // No context instance was injected at construction time -> see if one // has been registered in the servlet context. If one exists, it is assumed // that the parent context (if any) has already been set and that the // user has performed any initialization such as setting the context id wac &＃61; findWebApplicationContext(); } if (wac &＃61;&＃61; null) { // No context instance is defined for this servlet -> create a local one wac &＃61; createWebApplicationContext(rootContext); } if (!this.refreshEventReceived) { // Either the context is not a ConfigurableApplicationContext with refresh // support or the context injected at construction time had already been // refreshed -> trigger initial onRefresh manually here. synchronized (this.onRefreshMonitor) { onRefresh(wac); } } if (this.publishContext) { // Publish the context as a servlet context attribute. String attrName &＃61; getServletContextAttributeName(); getServletContext().setAttribute(attrName, wac); } return wac;}

configureAndRefreshWebApplicationContext方法帮助我们配置和刷新上下文容器&＃xff0c;他帮助我们完成了配置文件中bean的加载&＃xff0c;通过这个方法&＃xff0c;就可以跟我们之前启动的spring的方式关联上了

protected void configureAndRefreshWebApplicationContext(ConfigurableWebApplicationContext wac) { if (ObjectUtils.identityToString(wac).equals(wac.getId())) { // The application context id is still set to its original default value // -> assign a more useful id based on available information if (this.contextId !&＃61; null) { wac.setId(this.contextId); } else { // Generate default id... wac.setId(ConfigurableWebApplicationContext.APPLICATION_CONTEXT_ID_PREFIX &＃43; ObjectUtils.getDisplayString(getServletContext().getContextPath()) &＃43; &＃39;/&＃39; &＃43; getServletName()); } } wac.setServletContext(getServletContext()); wac.setServletConfig(getServletConfig()); wac.setNamespace(getNamespace()); wac.addApplicationListener(new SourceFilteringListener(wac, new ContextRefreshListener())); // The wac environment&＃39;s #initPropertySources will be called in any case when the context // is refreshed; do it eagerly here to ensure servlet property sources are in place for // use in any post-processing or initialization that occurs below prior to #refresh ConfigurableEnvironment env &＃61; wac.getEnvironment(); if (env instanceof ConfigurableWebEnvironment) { ((ConfigurableWebEnvironment) env).initPropertySources(getServletContext(), getServletConfig()); } postProcessWebApplicationContext(wac); applyInitializers(wac); wac.refresh();}

在这里我们看到了一个令人惊喜的方法&＃xff0c;refresh&＃xff0c;这个就是spring上下文容器容器启动的方法 &＃xff0c;他最终会调用AbstractApplicationContext的refresh方法&＃xff0c;这个方法终于将spring&＃xff0c;spring mvc的启动关联起来了

我们再接着来分析mvc的启动过程,在启动完spring容器后&＃xff0c;它会调用onRefresh方法来启动spring的九大组件

protected void onRefresh(ApplicationContext context) { initStrategies(context);}/** * Initialize the strategy objects that this servlet uses. *

May be overridden in subclasses in order to initialize further strategy objects. */protected void initStrategies(ApplicationContext context) { initMultipartResolver(context); initLocaleResolver(context); initThemeResolver(context); initHandlerMappings(context); initHandlerAdapters(context); initHandlerExceptionResolvers(context); initRequestToViewNameTranslator(context); initViewResolvers(context); initFlashMapManager(context);}

看到这里&＃xff0c;我们看到了平时非常熟悉的几大组件MultipartResolver(多文件上传)、HandlerMappings、HandlerAdapters(将 controller返回的方法适配成一个ModelAndView)、HandlerExceptionResolvers(异常处理),RequestToViewNameTranslator,ViewResolvers(将结果处理成一个view),FlashMapManager(进行redirect参数传输)

下面&＃xff0c;我们来看一下这些组件是如何进行初始化的

private void initMultipartResolver(ApplicationContext context) { try { this.multipartResolver &＃61; context.getBean(MULTIPART_RESOLVER_BEAN_NAME, MultipartResolver.class); if (logger.isTraceEnabled()) { logger.trace("Detected " &＃43; this.multipartResolver); } else if (logger.isDebugEnabled()) { logger.debug("Detected " &＃43; this.multipartResolver.getClass().getSimpleName()); } } catch (NoSuchBeanDefinitionException ex) { // Default is no multipart resolver. this.multipartResolver &＃61; null; if (logger.isTraceEnabled()) { logger.trace("No MultipartResolver &＃39;" &＃43; MULTIPART_RESOLVER_BEAN_NAME &＃43; "&＃39; declared"); } }}

通过这段代码&＃xff0c;我们可以看到&＃xff0c;组件的初始化比较简单this.multipartResolver &＃61; context.getBean(MULTIPART_RESOLVER_BEAN_NAME, MultipartResolver.class);,就是取出容器中的bean赋值给这些组件,这些组件的初始化大致相同&＃xff0c;我就不一一分析了&＃xff0c;有兴趣的可以自己看看

下面我们来分析一下调用过程是怎样的

熟悉servlet规范的都知道&＃xff0c;在调用servlet时&＃xff0c;会调用servlet的service方法,在寻找方法时&＃xff0c;我们优先在当前类中进行查找&＃xff0c;即先查找DispatcherServlet,然后再在其父类中依次寻找&＃xff0c;通过这种方式&＃xff0c;我们在FrameworkServlet类中找到了service方法

protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { HttpMethod httpMethod &＃61; HttpMethod.resolve(request.getMethod()); // 当请求方式为PATCH或者为空时&＃xff0c;调用&＃96;processRequest&＃96; if (httpMethod &＃61;&＃61; HttpMethod.PATCH || httpMethod &＃61;&＃61; null) { processRequest(request, response); } else { // 调用父类的service方法 super.service(request, response); }}

一般我们的请求方式为GET或者POST&＃xff0c;因此调用super.service(request, response);,已GET请求为例

protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { String method &＃61; req.getMethod(); long lastModified; if (method.equals("GET")) { lastModified &＃61; this.getLastModified(req); if (lastModified &＃61;&＃61; -1L) { this.doGet(req, resp); } else { long ifModifiedSince; try { ifModifiedSince &＃61; req.getDateHeader("If-Modified-Since"); } catch (IllegalArgumentException var9) { ifModifiedSince &＃61; -1L; } if (ifModifiedSince

由于doGet方法被子类覆盖(Override)了&＃xff0c;因此&＃xff0c;这里会调用子类的doGet方法&＃xff0c;因此&＃xff0c;有回到了FrameworkServlet类中

protected final void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { processRequest(request, response);}

在这里有调用了processRequest&＃xff0c;到这里&＃xff0c;又和上面其他的请求类型殊途同归了

protected final void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { long startTime &＃61; System.currentTimeMillis(); Throwable failureCause &＃61; null; LocaleContext previousLocaleContext &＃61; LocaleContextHolder.getLocaleContext(); LocaleContext localeContext &＃61; buildLocaleContext(request); RequestAttributes previousAttributes &＃61; RequestContextHolder.getRequestAttributes(); ServletRequestAttributes requestAttributes &＃61; buildRequestAttributes(request, response, previousAttributes); WebAsyncManager asyncManager &＃61; WebAsyncUtils.getAsyncManager(request); asyncManager.registerCallableInterceptor(FrameworkServlet.class.getName(), new RequestBindingInterceptor()); initContextHolders(request, localeContext, requestAttributes); try { doService(request, response); } catch (ServletException | IOException ex) { failureCause &＃61; ex; throw ex; } catch (Throwable ex) { failureCause &＃61; ex; throw new NestedServletException("Request processing failed", ex); } finally { resetContextHolders(request, previousLocaleContext, previousAttributes); if (requestAttributes !&＃61; null) { requestAttributes.requestCompleted(); } logResult(request, response, failureCause, asyncManager); publishRequestHandledEvent(request, response, startTime, failureCause); }}

到这里&＃xff0c;我们又看到了一个关键的方法,doService,我们来看一下这个方法具体做了什么&＃xff0c;这个方法被DispatcherServlet重写了&＃xff0c;因此&＃xff0c;我们直接看DispatcherServlet类中的doService方法

protected void doService(HttpServletRequest request, HttpServletResponse response) throws Exception { logRequest(request); // Keep a snapshot of the request attributes in case of an include, // to be able to restore the original attributes after the include. Map attributesSnapshot &＃61; null; if (WebUtils.isIncludeRequest(request)) { attributesSnapshot &＃61; new HashMap<>(); Enumeration> attrNames &＃61; request.getAttributeNames(); while (attrNames.hasMoreElements()) { String attrName &＃61; (String) attrNames.nextElement(); if (this.cleanupAfterInclude || attrName.startsWith(DEFAULT_STRATEGIES_PREFIX)) { attributesSnapshot.put(attrName, request.getAttribute(attrName)); } } } // Make framework objects available to handlers and view objects. request.setAttribute(WEB_APPLICATION_CONTEXT_ATTRIBUTE, getWebApplicationContext()); request.setAttribute(LOCALE_RESOLVER_ATTRIBUTE, this.localeResolver); request.setAttribute(THEME_RESOLVER_ATTRIBUTE, this.themeResolver); request.setAttribute(THEME_SOURCE_ATTRIBUTE, getThemeSource()); if (this.flashMapManager !&＃61; null) { // 获取redirect传输的参数 FlashMap inputFlashMap &＃61; this.flashMapManager.retrieveAndUpdate(request, response); if (inputFlashMap !&＃61; null) { request.setAttribute(INPUT_FLASH_MAP_ATTRIBUTE, Collections.unmodifiableMap(inputFlashMap)); } request.setAttribute(OUTPUT_FLASH_MAP_ATTRIBUTE, new FlashMap()); request.setAttribute(FLASH_MAP_MANAGER_ATTRIBUTE, this.flashMapManager); } try { // 请求分发 doDispatch(request, response); } finally { if (!WebAsyncUtils.getAsyncManager(request).isConcurrentHandlingStarted()) { // Restore the original attribute snapshot, in case of an include. if (attributesSnapshot !&＃61; null) { restoreAttributesAfterInclude(request, attributesSnapshot); } } }}

我们又看到了一个干活的方法doDispatch(request, response);

protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception { HttpServletRequest processedRequest &＃61; request; HandlerExecutionChain mappedHandler &＃61; null; boolean multipartRequestParsed &＃61; false; WebAsyncManager asyncManager &＃61; WebAsyncUtils.getAsyncManager(request); try { ModelAndView mv &＃61; null; Exception dispatchException &＃61; null; try { // 多文件上传 processedRequest &＃61; checkMultipart(request); multipartRequestParsed &＃61; (processedRequest !&＃61; request); // Determine handler for the current request. // 获取handler mappedHandler &＃61; getHandler(processedRequest); if (mappedHandler &＃61;&＃61; null) { // 找不到handler&＃xff0c;返回404 noHandlerFound(processedRequest, response); return; } // Determine handler adapter for the current request. // 获取HandlerAdapter HandlerAdapter ha &＃61; getHandlerAdapter(mappedHandler.getHandler()); // Process last-modified header, if supported by the handler. String method &＃61; request.getMethod(); boolean isGet &＃61; "GET".equals(method); if (isGet || "HEAD".equals(method)) { long lastModified &＃61; ha.getLastModified(request, mappedHandler.getHandler()); if (new ServletWebRequest(request, response).checkNotModified(lastModified) && isGet) { return; } } // 调用拦截器的PreHandle方法 if (!mappedHandler.applyPreHandle(processedRequest, response)) { return; } // Actually invoke the handler. // 通过HandlerAdapter将请求转成ModelAndView mv &＃61; ha.handle(processedRequest, response, mappedHandler.getHandler()); if (asyncManager.isConcurrentHandlingStarted()) { return; } applyDefaultViewName(processedRequest, mv); // 调用拦截器的PostHandle方法 mappedHandler.applyPostHandle(processedRequest, response, mv); } catch (Exception ex) { dispatchException &＃61; ex; } catch (Throwable err) { // As of 4.3, we&＃39;re processing Errors thrown from handler methods as well, // making them available for &＃64;ExceptionHandler methods and other scenarios. dispatchException &＃61; new NestedServletException("Handler dispatch failed", err); } processDispatchResult(processedRequest, response, mappedHandler, mv, dispatchException); } catch (Exception ex) { // 调用拦截器的AfterCompletion方法 triggerAfterCompletion(processedRequest, response, mappedHandler, ex); } catch (Throwable err) { // 调用拦截器的AfterCompletion方法 triggerAfterCompletion(processedRequest, response, mappedHandler, new NestedServletException("Handler processing failed", err)); } finally { if (asyncManager.isConcurrentHandlingStarted()) { // Instead of postHandle and afterCompletion if (mappedHandler !&＃61; null) { mappedHandler.applyAfterConcurrentHandlingStarted(processedRequest, response); } } else { // Clean up any resources used by a multipart request. if (multipartRequestParsed) { cleanupMultipart(processedRequest); } } }}

通过这个方法&＃xff0c;我们找到了在web中我们常用的HandlerInterceptor是如何触发的&＃xff0c;也算是不虚此行,接下来&＃xff0c;我们来分析一下HandlerAdapter如何将请求转化成ModelAndView的&＃xff0c;即分析handle方法

在这里我们有看到了多个实现&＃xff0c;有时候&＃xff0c;我们无法知道具体调用的是那个类&＃xff0c;这个时候&＃xff0c;我们就可以采用调试的方式来判断具体调用的是那个类&＃xff0c;AbstractHandlerMethodAdapter

public final ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { return handleInternal(request, response, (HandlerMethod) handler);}

protected ModelAndView handleInternal(HttpServletRequest request, HttpServletResponse response, HandlerMethod handlerMethod) throws Exception { ModelAndView mav; checkRequest(request); // Execute invokeHandlerMethod in synchronized block if required. if (this.synchronizeOnSession) { HttpSession session &＃61; request.getSession(false); if (session !&＃61; null) { Object mutex &＃61; WebUtils.getSessionMutex(session); synchronized (mutex) { mav &＃61; invokeHandlerMethod(request, response, handlerMethod); } } else { // No HttpSession available -> no mutex necessary mav &＃61; invokeHandlerMethod(request, response, handlerMethod); } } else { // No synchronization on session demanded at all... mav &＃61; invokeHandlerMethod(request, response, handlerMethod); } if (!response.containsHeader(HEADER_CACHE_CONTROL)) { if (getSessionAttributesHandler(handlerMethod).hasSessionAttributes()) { applyCacheSeconds(response, this.cacheSecondsForSessionAttributeHandlers); } else { prepareResponse(response); } } return mav;}

在这里有调用了invokeHandlerMethod&＃xff0c;这个就是去通过反射调用controller中的方法,我们来具体看一下是怎么调用的

protected ModelAndView invokeHandlerMethod(HttpServletRequest request, HttpServletResponse response, HandlerMethod handlerMethod) throws Exception { ServletWebRequest webRequest &＃61; new ServletWebRequest(request, response); try { // 省略。。。 invocableMethod.invokeAndHandle(webRequest, mavContainer); if (asyncManager.isConcurrentHandlingStarted()) { return null; } return getModelAndView(mavContainer, modelFactory, webRequest); } finally { webRequest.requestCompleted(); }}

我们接着看invokeAndHandle方法

public void invokeAndHandle(ServletWebRequest webRequest, ModelAndViewContainer mavContainer, Object... providedArgs) throws Exception {// 执行请求 Object returnValue &＃61; invokeForRequest(webRequest, mavContainer, providedArgs); setResponseStatus(webRequest); if (returnValue &＃61;&＃61; null) { if (isRequestNotModified(webRequest) || getResponseStatus() !&＃61; null || mavContainer.isRequestHandled()) { disableContentCachingIfNecessary(webRequest); mavContainer.setRequestHandled(true); return; } } else if (StringUtils.hasText(getResponseStatusReason())) { mavContainer.setRequestHandled(true); return; } mavContainer.setRequestHandled(false); Assert.state(this.returnValueHandlers !&＃61; null, "No return value handlers"); try { this.returnValueHandlers.handleReturnValue( returnValue, getReturnValueType(returnValue), mavContainer, webRequest); } catch (Exception ex) { if (logger.isTraceEnabled()) { logger.trace(formatErrorForReturnValue(returnValue), ex); } throw ex; }}

在这里有调用了invokeForRequest方法来获取returnValue

public Object invokeForRequest(NativeWebRequest request, &＃64;Nullable ModelAndViewContainer mavContainer, Object... providedArgs) throws Exception { Object[] args &＃61; this.getMethodArgumentValues(request, mavContainer, providedArgs); if (this.logger.isTraceEnabled()) { this.logger.trace("Arguments: " &＃43; Arrays.toString(args)); } return this.doInvoke(args);}

我们又看到了以do开头的方法,

protected Object doInvoke(Object... args) throws Exception { ReflectionUtils.makeAccessible(this.getBridgedMethod()); try { // 通过反射调用方法 return this.getBridgedMethod().invoke(this.getBean(), args); } catch (IllegalArgumentException var4) { this.assertTargetBean(this.getBridgedMethod(), this.getBean(), args); String text &＃61; var4.getMessage() !&＃61; null ? var4.getMessage() : "Illegal argument"; throw new IllegalStateException(this.formatInvokeError(text, args), var4); } catch (InvocationTargetException var5) { Throwable targetException &＃61; var5.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(this.formatInvokeError("Invocation failure", args), targetException); } }}

我们终于看到了反射调用method的方法

接下来&＃xff0c;我们接着分析spring如何将返回值处理成ModelAndView&＃xff0c;这个也十分的简单,就是调用了getModelAndView,方法&＃xff0c;然后通过new来创建一个ModelAndView

private ModelAndView getModelAndView(ModelAndViewContainer mavContainer, ModelFactory modelFactory, NativeWebRequest webRequest) throws Exception { modelFactory.updateModel(webRequest, mavContainer); if (mavContainer.isRequestHandled()) { return null; } ModelMap model &＃61; mavContainer.getModel(); ModelAndView mav &＃61; new ModelAndView(mavContainer.getViewName(), model, mavContainer.getStatus()); if (!mavContainer.isViewReference()) { mav.setView((View) mavContainer.getView()); } if (model instanceof RedirectAttributes) { Map flashAttributes &＃61; ((RedirectAttributes) model).getFlashAttributes(); HttpServletRequest request &＃61; webRequest.getNativeRequest(HttpServletRequest.class); if (request !&＃61; null) { RequestContextUtils.getOutputFlashMap(request).putAll(flashAttributes); } } return mav;}

我们接着来看spring如何处理ModelAndView&＃xff0c;这个方法就是processDispatchResult

private void processDispatchResult(HttpServletRequest request, HttpServletResponse response, &＃64;Nullable HandlerExecutionChain mappedHandler, &＃64;Nullable ModelAndView mv, &＃64;Nullable Exception exception) throws Exception { boolean errorView &＃61; false; if (exception !&＃61; null) { if (exception instanceof ModelAndViewDefiningException) { logger.debug("ModelAndViewDefiningException encountered", exception); mv &＃61; ((ModelAndViewDefiningException) exception).getModelAndView(); } else { Object handler &＃61; (mappedHandler !&＃61; null ? mappedHandler.getHandler() : null); mv &＃61; processHandlerException(request, response, handler, exception); errorView &＃61; (mv !&＃61; null); } } // Did the handler return a view to render? if (mv !&＃61; null && !mv.wasCleared()) { render(mv, request, response); if (errorView) { WebUtils.clearErrorRequestAttributes(request); } } else { if (logger.isTraceEnabled()) { logger.trace("No view rendering, null ModelAndView returned."); } } if (WebAsyncUtils.getAsyncManager(request).isConcurrentHandlingStarted()) { // Concurrent handling started during a forward return; } if (mappedHandler !&＃61; null) { // Exception (if any) is already handled.. mappedHandler.triggerAfterCompletion(request, response, null); }}

在这里&＃xff0c;我们看到了两个关键的方法&＃xff0c;一个是render(渲染页面&＃xff0c;将ModelAndView转成view)&＃xff0c;triggerAfterCompletion,调用拦截器的AfterCompletion方法,我们来分析一下render方法

protected void render(ModelAndView mv, HttpServletRequest request, HttpServletResponse response) throws Exception { // Determine locale for request and apply it to the response. Locale locale &＃61; (this.localeResolver !&＃61; null ? this.localeResolver.resolveLocale(request) : request.getLocale()); response.setLocale(locale); View view; String viewName &＃61; mv.getViewName(); if (viewName !&＃61; null) { // We need to resolve the view name. view &＃61; resolveViewName(viewName, mv.getModelInternal(), locale, request); if (view &＃61;&＃61; null) { throw new ServletException("Could not resolve view with name &＃39;" &＃43; mv.getViewName() &＃43; "&＃39; in servlet with name &＃39;" &＃43; getServletName() &＃43; "&＃39;"); } } else { // No need to lookup: the ModelAndView object contains the actual View object. view &＃61; mv.getView(); if (view &＃61;&＃61; null) { throw new ServletException("ModelAndView [" &＃43; mv &＃43; "] neither contains a view name nor a " &＃43; "View object in servlet with name &＃39;" &＃43; getServletName() &＃43; "&＃39;"); } } // Delegate to the View object for rendering. if (logger.isTraceEnabled()) { logger.trace("Rendering view [" &＃43; view &＃43; "] "); } try { if (mv.getStatus() !&＃61; null) { response.setStatus(mv.getStatus().value()); } // 将view转成相应的页面 view.render(mv.getModelInternal(), request, response); } catch (Exception ex) { if (logger.isDebugEnabled()) { logger.debug("Error rendering view [" &＃43; view &＃43; "]", ex); } throw ex; }}

我们接着来看view.render方法&＃xff0c;这个有进入了AbstractView类中

public void render(&＃64;Nullable Map model, HttpServletRequest request, HttpServletResponse response) throws Exception { if (logger.isDebugEnabled()) { logger.debug("View " &＃43; formatViewName() &＃43; ", model " &＃43; (model !&＃61; null ? model : Collections.emptyMap()) &＃43; (this.staticAttributes.isEmpty() ? "" : ", static attributes " &＃43; this.staticAttributes)); } // 返回页面的参数 Map mergedModel &＃61; createMergedOutputModel(model, request, response); prepareResponse(request, response); renderMergedOutputModel(mergedModel, getRequestToExpose(request), response);}

我们接着来看InternalResourceView的renderMergedOutputModel方法

protected void renderMergedOutputModel( Map model, HttpServletRequest request, HttpServletResponse response) throws Exception { // Expose the model object as request attributes. exposeModelAsRequestAttributes(model, request); // Expose helpers as request attributes, if any. exposeHelpers(request); // Determine the path for the request dispatcher. String dispatcherPath &＃61; prepareForRendering(request, response); // Obtain a RequestDispatcher for the target resource (typically a JSP). RequestDispatcher rd &＃61; getRequestDispatcher(request, dispatcherPath); if (rd &＃61;&＃61; null) { throw new ServletException("Could not get RequestDispatcher for [" &＃43; getUrl() &＃43; "]: Check that the corresponding file exists within your web application archive!"); } // If already included or response already committed, perform include, else forward. if (useInclude(request, response)) { response.setContentType(getContentType()); if (logger.isDebugEnabled()) { logger.debug("Including [" &＃43; getUrl() &＃43; "]"); } rd.include(request, response); } else { // Note: The forwarded resource is supposed to determine the content type itself. if (logger.isDebugEnabled()) { logger.debug("Forwarding to [" &＃43; getUrl() &＃43; "]"); } rd.forward(request, response); }}

下面附上spring MVC初始化、调用的时序图