Spring的Model 和 Map的原理源码解析

@GetMapping("/goto")
public String go(HttpServletRequest request,
                 Map<String,Object> map,
                 Model model){
    request.setAttribute("msg","传过来....");
    map.put("map","map hello word!!");
    model.addAttribute("model","model hello word!!");
    return "forward:success";
}
@ResponseBody
@GetMapping("/success")
public Map success(@RequestAttribute(value = "msg",required = false) String msg,
                   HttpServletRequest request){
    Map<String,Object> hashMap = new HashMap<>();
    Object msg1 = request.getAttribute("msg");
    Object map = request.getAttribute("map");
    Object model = request.getAttribute("model");
    hashMap.put("map1",map);
    hashMap.put("model",model);
    hashMap.put("msg1",msg1);
    return hashMap;
}

DispatchServlet类中的 
    doDispatch方法
        // Determine handler for the current request.
        mappedHandler = getHandler(processedRequest);//获取反射的方法处理器
        // Determine handler adapter for the current request.
		//获取参数处理器
        HandlerAdapter ha = getHandlerAdapter(mappedHandler.getHandler());
		// Actually invoke the handler.
		//反射执行方法和解析Model和Map
		mv = ha.handle(processedRequest, response, 	mappedHandler.getHandler());

MapMethodProcessor类中的
@Override
@Nullable
public Object resolveArgument(MethodParameter parameter, 
                              @Nullable ModelAndViewContainer mavContainer,
                              NativeWebRequest webRequest, 
                              @Nullable WebDataBinderFactory binderFactory) throws Exception {
    Assert.state(mavContainer != null, "ModelAndViewContainer is required for model exposure");
    
    return mavContainer.getModel();
}
 
然后进入ModelAndViewContainer类中的
    private final ModelMap defaultModel = new BindingAwareModelMap();
    public ModelMap getModel() {
    if (useDefaultModel()) {
        return this.defaultModel;//获取ModelMap
    }
    ......

ModelMethodProcessor类中的
@Override
@Nullable
 public Object resolveArgument(MethodParameter parameter,
                               @Nullable ModelAndViewContainer mavContainer,
                                  NativeWebRequest webRequest, 
                               @Nullable WebDataBinderFactory binderFactory) throws Exception {
    Assert.state(mavContainer != null, "ModelAndViewContainer is required for model exposure");
    return mavContainer.getModel();
}
然后进入ModelAndViewContainer类中的
    private final ModelMap defaultModel = new BindingAwareModelMap();
    public ModelMap getModel() {
    if (useDefaultModel()) {
        return this.defaultModel;//获取ModelMap   这个和那个Map获取的是同一个
    }
    ......

ServletInvocableHandlerMethod类中
    invokeAndHandle方法
    	//获取返回值的一个处理器
        try {
            this.returnValueHandlers.handleReturnValue(
                returnValue, getReturnValueType(returnValue), 
                mavContainer, webRequest);
        }
HandlerMethodReturnValueHandlerComposite类中的
    HandlerMethodReturnValueHandler方法 进行获取

RequestMappingHandlerAdapter类中 
    handleInternal方法
    		...
    		ModelAndView mav;
			...
			mav = invokeHandlerMethod(request, response, handlerMethod);
			...

DispatchServlet类中的 
    doDispatch方法
    	render(mv, request, response);
		view.render(mv.getModelInternal(), request, response);
 
AbstractView类中的
    render方法
    	//把BindingAwareModelMap的参数封装为Map
    	Map<String, Object> mergedModel = createMergedOutputModel(model, 
                                                              request, response);
		prepareResponse(request, response);
		//准备方法和放入参数到reques中
		renderMergedOutputModel(mergedModel, getRequestToExpose(request), 	
                                							response);
InternalResourceView类中的
    renderMergedOutputModel
    	// Expose the model object as request attributes.
		exposeModelAsRequestAttributes(model, request);//把参数放入到request中
AbstractView类中的
    //把参数放入到原生的request域中
    protected void exposeModelAsRequestAttributes(Map<String, Object> model,
                                                  HttpServletRequest request) 														throws Exception {
        model.forEach((name, value) -> {
            if (value != null) {
                request.setAttribute(name, value);
            }
            else {
                request.removeAttribute(name);
            }
        });
}