首先这个对象返回的数据中主要包含模型数据和逻辑视图名，整个流程图如下所示：
image.png
在之前讲到的doDispatch()方法中，获取到相关的HandlerExcutionChain和handlerAdapter对象，然后调用handlerAdapter的方法handler()，传入request,response,handler三个参数，之后调用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;
}
这个方法会先检查一下request是否符合要求，然后再检测是否同步开启session，默认是false，然后这个方法中会调用invokeHandlerMethod()方法获取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;
}
首先先创建web容器的request请求，然后进行一系列参数设置和相关的方法，到一个重要的方法，invokeAndHandler(webRequest,mavContainer,new Object[0])，该方法是用于获取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方法中调用了invokeForRequest()方法获取执行请求方法的返回值
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;
}
首先先获取request请求的参数，输出成object数组，然后向doInvoke()方法传入该数组作为参数
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)方法的调用
getBridgeMethod()是获取Controller的执行请求的方法，然后通过反射机制，获取执行请求的返回值
这边可以思考下，为什么使用getBridgeMethod()，而不直接使用getMethod()，两个方法的返回值也是一样的
获取到方法的返回值，即view="index"后，一路返回到上一层，到invokeHandlerMethod()方法,执行该方法中的下一个方法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;
}
}
在这段代码里边，我们能看见，每个modelAndView都是通过代码自己new出来的，传入了三个参数,viewName,model和status,这三个参数都是通过mavContainer来获取的
第一个参数，viewName
mavContainer.getViewName()方法返回viewName,如果view是String类型的实例，那么返回view,否则返回null
第二个参数,model
mavContainer.getModel(), 得到defaultModel或者是redirectModel，之前在invokeHandlerMethod创建modelFactory的时候就设置了两个参数的值
第三个参数status
mavContainer.getStatus(),该方法返回的值的类型是HttpStatus，也就是状态码
最后返回modelAndView对象
参考链接：
https://blog.csdn.net/qq924862077/article/details/53944721
https://blog.csdn.net/u010233323/article/details/52515773
