首先這個對象返回的數據中主要包含模型數據和邏輯視圖名检访，整個流程圖如下所示：
image.png
在之前講到的doDispatch()方法中，獲取到相關的HandlerExcutionChain和handlerAdapter對象医清，然后調用handlerAdapter的方法handler()卖氨，傳入request,response,handler三個參數，之后調用handleInternal方法
protected ModelAndView handleInternal(HttpServletRequest request, HttpServletResponse response, HandlerMethod handlerMethod) throws Exception {
this.checkRequest(request);
ModelAndView mav;
if (this.synchronizeOnSession) {
HttpSession session = request.getSession(false);
if (session != null) {
Object mutex = WebUtils.getSessionMutex(session);
synchronized(mutex) {
mav = this.invokeHandlerMethod(request, response, handlerMethod);
}
} else {
mav = this.invokeHandlerMethod(request, response, handlerMethod);
}
} else {
mav = this.invokeHandlerMethod(request, response, handlerMethod);
}
if (!response.containsHeader("Cache-Control")) {
if (this.getSessionAttributesHandler(handlerMethod).hasSessionAttributes()) {
this.applyCacheSeconds(response, this.cacheSecondsForSessionAttributeHandlers);
} else {
this.prepareResponse(response);
}
}
return mav;
}
這個方法會先檢查一下request是否符合要求，然后再檢測是否同步開啟session系吭，默認是false，然后這個方法中會調用invokeHandlerMethod()方法獲取mav
rotected ModelAndView invokeHandlerMethod(HttpServletRequest request, HttpServletResponse response, HandlerMethod handlerMethod) hrows Exception {
ServletWebRequest webRequest = new ServletWebRequest(request, response);
Object result;
try {
WebDataBinderFactory binderFactory = this.getDataBinderFactory(handlerMethod);
ModelFactory modelFactory = this.getModelFactory(handlerMethod, binderFactory);
ServletInvocableHandlerMethod invocableMethod = this.createInvocableHandlerMethod(handlerMethod);
invocableMethod.setHandlerMethodArgumentResolvers(this.argumentResolvers);
invocableMethod.setHandlerMethodReturnValueHandlers(this.returnValueHandlers);
invocableMethod.setDataBinderFactory(binderFactory);
invocableMethod.setParameterNameDiscoverer(this.parameterNameDiscoverer);
ModelAndViewContainer mavContainer = new ModelAndViewContainer();
mavContainer.addAllAttributes(RequestContextUtils.getInputFlashMap(request));
modelFactory.initModel(webRequest, mavContainer, invocableMethod);
mavContainer.setIgnoreDefaultModelOnRedirect(this.ignoreDefaultModelOnRedirect);
AsyncWebRequest asyncWebRequest = WebAsyncUtils.createAsyncWebRequest(request, response);
asyncWebRequest.setTimeout(this.asyncRequestTimeout);
WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request);
asyncManager.setTaskExecutor(this.taskExecutor);
asyncManager.setAsyncWebRequest(asyncWebRequest);
asyncManager.registerCallableInterceptors(this.callableInterceptors);
asyncManager.registerDeferredResultInterceptors(this.deferredResultInterceptors);
if (asyncManager.hasConcurrentResult()) {
result = asyncManager.getConcurrentResult();
mavContainer = (ModelAndViewContainer)asyncManager.getConcurrentResultContext()[0];
asyncManager.clearConcurrentResult();
if (this.logger.isDebugEnabled()) {
this.logger.debug("Found concurrent result value [" + result + "]");
}
invocableMethod = invocableMethod.wrapConcurrentResult(result);
}
invocableMethod.invokeAndHandle(webRequest, mavContainer, new Object[0]);
if (!asyncManager.isConcurrentHandlingStarted()) {
ModelAndView var15 = this.getModelAndView(mavContainer, modelFactory, webRequest);
return var15;
}
result = null;
} finally {
webRequest.requestCompleted();
}
return (ModelAndView)result;
}
首先先創(chuàng)建web容器的request請求，然后進行一系列參數設置和相關的方法槐臀，到一個重要的方法氓仲，invokeAndHandler(webRequest,mavContainer,new Object[0])，該方法是用于獲取view的
public void invokeAndHandle(ServletWebRequest webRequest, ModelAndViewContainer mavContainer, Object... providedArgs) throws Exception {
Object returnValue = this.invokeForRequest(webRequest, mavContainer, providedArgs);
this.setResponseStatus(webRequest);
if (returnValue == null) {
if (this.isRequestNotModified(webRequest) || this.getResponseStatus() != null || mavContainer.isRequestHandled()) {
mavContainer.setRequestHandled(true);
return;
}
} else if (StringUtils.hasText(this.getResponseStatusReason())) {
mavContainer.setRequestHandled(true);
return;
}
mavContainer.setRequestHandled(false);
try {
this.returnValueHandlers.handleReturnValue(returnValue, this.getReturnValueType(returnValue), mavContainer, webRequest);
} catch (Exception var6) {
if (this.logger.isTraceEnabled()) {
this.logger.trace(this.getReturnValueHandlingErrorMessage("Error handling return value", returnValue), var6);
}
throw var6;
}
}
invokeAndHandler方法中調用了invokeForRequest()方法獲取執(zhí)行請求方法的返回值
public Object invokeForRequest(NativeWebRequest request, ModelAndViewContainer mavContainer, Object... providedArgs) throws Exception {
Object[] args = this.getMethodArgumentValues(request, mavContainer, providedArgs);
if (this.logger.isTraceEnabled()) {
this.logger.trace("Invoking '" + ClassUtils.getQualifiedMethodName(this.getMethod(), this.getBeanType()) + "' with arguments " + Arrays.toString(args));
}
Object returnValue = this.doInvoke(args);
if (this.logger.isTraceEnabled()) {
this.logger.trace("Method [" + ClassUtils.getQualifiedMethodName(this.getMethod(), this.getBeanType()) + "] returned [" + returnValue + "]");
}
return returnValue;
}
首先先獲取request請求的參數，輸出成object數組欢顷，然后向doInvoke()方法傳入該數組作為參數
protected Object doInvoke(Object... args) throws Exception {
ReflectionUtils.makeAccessible(this.getBridgedMethod());
try {
return this.getBridgedMethod().invoke(this.getBean(), args);
} catch (IllegalArgumentException var5) {
this.assertTargetBean(this.getBridgedMethod(), this.getBean(), args);
String text = var5.getMessage() != null ? var5.getMessage() : "Illegal argument";
throw new IllegalStateException(this.getInvocationErrorMessage(text, args), var5);
} catch (InvocationTargetException var6) {
Throwable targetException = var6.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 {
String text = this.getInvocationErrorMessage("Failed to invoke handler method", args);
throw new IllegalStateException(text, targetException);
}
}
}
doInvoke()方法中重要的是getBridgeMethod().invoke(getBean(),args)方法的調用
getBridgeMethod()是獲取Controller的執(zhí)行請求的方法抬驴，然后通過反射機制缆巧，獲取執(zhí)行請求的返回值
這邊可以思考下，為什么使用getBridgeMethod()陕悬，而不直接使用getMethod()，兩個方法的返回值也是一樣的
獲取到方法的返回值胧卤，即view="index"后拼岳，一路返回到上一層，到invokeHandlerMethod()方法,執(zhí)行該方法中的下一個方法getModelAndView(mavContainer,modelFactory,webRequest)
private ModelAndView getModelAndView(ModelAndViewContainer mavContainer, ModelFactory modelFactory, NativeWebRequest webRequest) throws Exception {
modelFactory.updateModel(webRequest, mavContainer);
if (mavContainer.isRequestHandled()) {
return null;
} else {
ModelMap model = mavContainer.getModel();
ModelAndView mav = new ModelAndView(mavContainer.getViewName(), model, mavContainer.getStatus());
if (!mavContainer.isViewReference()) {
mav.setView((View)mavContainer.getView());
}
if (model instanceof RedirectAttributes) {
Map<String, ?> flashAttributes = ((RedirectAttributes)model).getFlashAttributes();
HttpServletRequest request = (HttpServletRequest)webRequest.getNativeRequest(HttpServletRequest.class);
RequestContextUtils.getOutputFlashMap(request).putAll(flashAttributes);
}
return mav;
}
}
在這段代碼里邊叶撒，我們能看見耐版，每個modelAndView都是通過代碼自己new出來的，傳入了三個參數,viewName,model和status,這三個參數都是通過mavContainer來獲取的
第一個參數古瓤，viewName
mavContainer.getViewName()方法返回viewName,如果view是String類型的實例腺阳，那么返回view,否則返回null
第二個參數,model
mavContainer.getModel(), 得到defaultModel或者是redirectModel，之前在invokeHandlerMethod創(chuàng)建modelFactory的時候就設置了兩個參數的值
第三個參數status
mavContainer.getStatus(),該方法返回的值的類型是HttpStatus叽奥，也就是狀態(tài)碼
最后返回modelAndView對象
參考鏈接：
https://blog.csdn.net/qq924862077/article/details/53944721
https://blog.csdn.net/u010233323/article/details/52515773
