2.2 Dispatcher请求过程-获取HandlerAdapter

接着 【2.1】第二点

getHandlerAdapter

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

这里就用到了上一节中的mapperHandler

protected HandlerAdapter getHandlerAdapter(Object handler) throws ServletException {
        if (this.handlerAdapters != null) {
            Iterator var2 = this.handlerAdapters.iterator();

            while(var2.hasNext()) {
                HandlerAdapter adapter = (HandlerAdapter)var2.next();
                if (adapter.supports(handler)) {
                    return adapter;
                }
            }
        }

        throw new ServletException("No adapter for handler [" + handler + "]: The DispatcherServlet configuration needs to include a HandlerAdapter that supports this handler");
    }

看看HandlerAdapter是什么

HandlerAdapter

public interface HandlerAdapter {
    boolean supports(Object var1);
	//执行处理方法
    @Nullable
    ModelAndView handle(HttpServletRequest var1, HttpServletResponse var2, Object var3) throws Exception;

    long getLastModified(HttpServletRequest var1, Object var2);
}

重要的方法就是那个handle
传入request,response,和handler

AbstractHandlerMethodAdapter

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

RequestMappingHandlerAdapter

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;
    }
	
	@Nullable
    protected ModelAndView invokeHandlerMethod(HttpServletRequest request, HttpServletResponse response, HandlerMethod handlerMethod) throws 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);
            if (this.argumentResolvers != null) {
                invocableMethod.setHandlerMethodArgumentResolvers(this.argumentResolvers);
            }

            if (this.returnValueHandlers != null) {
                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();
                LogFormatUtils.traceDebug(this.logger, (traceOn) -> {
                    String formatted = LogFormatUtils.formatValue(result, !traceOn);
                    return "Resume with async result [" + formatted + "]";
                });
                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;
    }