springMVC

1.Springmvc的 【核心组件】
1.DispatcherServlet 中央调度器
2.ViewResolver 视图解析器
3.HandlerMapping 映射器处理器
4.Handler 处理器
5.HandlerAdaptor 处理器适配器
6.View 视图

2.处理器：这个处理器是个虚指的概念 宏观
体现形态：Servlet Servlet
Controller Springmvc
Action Struts2

3.请求流程
解析器：Interceptor 拦截器 Handler 反向Interceptor 拦截器 可以增强我们的请求和响应功能。

4.Spring MVC HandlerMapping 代码层面的执行流程

1.找到DispatcherServlet

2.找到doDispatch()方法

asynchronous:异步的
synchronous：同步的

//入参进来一个request
protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception {

HttpServletRequest processedRequest = request;
处理器执行链
HandlerExecutionChain mappedHandler = null;
多部分请求 解析器 （文件上传）
boolean multipartRequestParsed = false;

WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request);

try {
try {
模型（数据）和视图
ModelAndView err = null;
异常
Exception dispatchException = null;

try {
//指的是 DispatcherServlet 的实例 看看请求是不是多部分请求

<form enctype="multipart/form-data"> 表单有文件域 上传文件了

processedRequest = this.checkMultipart(request);

multipartRequestParsed = processedRequest != request;

mappedHandler = this.getHandler(processedRequest);

3. protected HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {

handlerMappings单列集合 。Set List
Iterator var2 = this.handlerMappings.iterator();
HandlerExecutionChain handler;
if(!var2.hasNext()) return null;
每next()拿到一个HandlerMapping实例
HandlerMapping hm = (HandlerMapping)var2.next();
handler = hm.getHandler(request);
return handler;
}

4.我们知道，HandlerMapping是一个接口 ，找实现类 Ctrl+H
public final HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {

Object handler = this.getHandlerInternal(request);
if(handler == null) {
handler = this.getDefaultHandler();
}

if(handler == null) {
return null;
} else {
if(handler instanceof String) {
String handlerName = (String)handler; // /hello
handler = this.getApplicationContext().getBean(handlerName);
}

return this.getHandlerExecutionChain(handler, request);
}
}

5. protected HandlerExecutionChain getHandlerExecutionChain(Object handler, HttpServletRequest request) {

HandlerExecutionChain chain = handler instanceof HandlerExecutionChain?
(HandlerExecutionChain)handler:new HandlerExecutionChain(handler);

 

chain.addInterceptors(this.getAdaptedInterceptors());

String lookupPath = this.urlPathHelper.getLookupPathForRequest(request);

Iterator var5 = this.mappedInterceptors.iterator();

while(var5.hasNext()) {
MappedInterceptor mappedInterceptor = (MappedInterceptor)var5.next();
if(mappedInterceptor.matches(lookupPath, this.pathMatcher)) {
chain.addInterceptor(mappedInterceptor.getInterceptor());
}
}

return chain;
}