别怕,手把手带你撕、拉、扯下SpringMVC的外衣

    protected HttpServletRequest checkMultipart(HttpServletRequest request) throws MultipartException {
        //multipartResolver这是个视图解析器,所以这里是判断一下有没有视图解析器,以及request是不是一个二进制请求
        if (this.multipartResolver != null && this.multipartResolver.isMultipart(request)) {
            if (WebUtils.getNativeRequest(request, MultipartHttpServletRequest.class) != null) {
                logger.debug("Request is already a MultipartHttpServletRequest - if not in a forward, " +
                        "this typically results from an additional MultipartFilter in web.xml");
            }
            else if (request.getAttribute(WebUtils.ERROR_EXCEPTION_ATTRIBUTE) instanceof MultipartException) {
                logger.debug("Multipart resolution failed for current request before - " +
                        "skipping re-resolution for undisturbed error rendering");
            }
            else {
                // 如果是二进制的话,把request包装一层,返回MultipartHttpServletRequest
                return this.multipartResolver.resolveMultipart(request);
            }
        }
        // If not returned before: return original request.
        return request;
    }

<bean name="/hello" class="权限定名"></bean>

HandlerExecutionChain handler = hm.getHandler(request);

if (ha.supports(handler)) {
    return ha;
}

String method = request.getMethod();

if (!mappedHandler.applyPreHandle(processedRequest, response)) {
    return;
}

public class MyInterceptor implements HandlerInterceptor {

    //表示控制器方法执行之前调用的方法,返回结果为boolean,如果为true,表示放行,如果为false,表示拦截
    public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception {
        System.out.println("MyInterceptor.preHandle");
        return true;
    }

    //控制器执行完方法之后,视图结合之前
    public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {
        System.out.println("MyInterceptor.postHandle");
    }

    //视图结合完成之后调用的方法
    public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {
        System.out.println("MyInterceptor.afterCompletion");
    }
}

// Actually invoke the handler.
mv = ha.handle(processedRequest, response,mappedHandler.getHandler());

@RequestMapping("/test")
public String test(Model model) {
    model.addAttribute("msg", "Hello Toby");
    return "hello";
}

//默认视图名称
applyDefaultViewName(request, mv);

@RequestMapping("/value2")
public User value2() {
    //报错:Circular view path [value2]: would dispatch back to the current handler URL [/value2] again
    //此时该方法只有模型,没有视图,SpringMVC会默认给你视图,默认的视图名为:请求的名字(/value2)
    //相当于又去重新请求/value2
    return new User("toby","24");
}

processDispatchResult(processedRequest, response, mappedHandler, mv, dispatchException);

//这里决定究竟是转发还是重定向,或者说变成其他视图
view.render(mv.getModelInternal(), request, response);

protected RequestDispatcher getRequestDispatcher(HttpServletRequest request, String path) {
    return request.getRequestDispatcher(path);
}

rd.forward(request, response);

mappedHandler.triggerAfterCompletion(request, response, null);