+ ---- SPRINGMVC execution flow underlying analytical

SpringMVC flowchart as shown above, according to the figure, at the bottom of the source in series:

　　1. Locate doDisPatch in the DispatcherServlet

　　2. Observe the method body, then find getHandler method

　　3. point into the method, also found that calls another method getHandler

　　4. The click-through method, an interface is found, then we enter the abstract class AbstractHandlerMappingof getHandler Method:

　　5. Check getHandlerExecutionChain method　

protected HandlerExecutionChain getHandlerExecutionChain(Object handler, HttpServletRequest request) {
    //如果不是chain类型，将handler作为构造函数创建一个chain实例
    HandlerExecutionChain chain = (handler instanceof HandlerExecutionChain ?
                                   (HandlerExecutionChain) handler : new HandlerExecutionChain(handler));
 
    //获得有效url路径，用于匹配拦截器规则
    String lookupPath = this.urlPathHelper.getLookupPathForRequest(request);
    //获取所有拦截器
    for (HandlerInterceptor interceptor : this.adaptedInterceptors) {
        //如果是MappedInterceptor类型的，按照规则看看当前拦截器是否需要加入拦截
        if (interceptor instanceof MappedInterceptor) {
            MappedInterceptor mappedInterceptor = (MappedInterceptor) interceptor;
            //如果拦截器规则设置/*，表示拦截所有，也就是说url是什么都会加入
            if (mappedInterceptor.matches(lookupPath, this.pathMatcher)) {
                chain.addInterceptor(mappedInterceptor.getInterceptor());
            }
        }
        else {
            //该拦截器直接加入拦截器链
            chain.addInterceptor(interceptor);
        }
    }
    return chain;

　　6.返回到DispatcherServlet，这样我们知道getHandler方法就是通过HandlerMapping（处理映射器）返回一个处理链，处理链中包含了n个拦截（上面代码详解）

　　7.进入getHandlerAdapter方法

　　这里回忆一下默认的Adapter实现有哪些：

org.springframework.web.servlet.HandlerAdapter=org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter,\
    org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter,\
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter

　　其中前两个Adapter都跟我们当前的例子没关系，怎么看出来的呢？回到getHandlerAdapter方法中，接下来会遍历Adapter列表，依此调用supports方法查询与当前handler是否支持。其上两个Adapter一个是处理HttpRequestHandler，一个是处理Controller类的，只有最后一个RequestMappingHandlerAdapter的supports方法才是我们要的

　　8.进入RequestMappingHandlerAdapter

　　此时看到上面两个方法，便一切都能说通了，如下图：

　　9.这一步，我们知道中央调度器将处理链交给处理器适配器进行处理器Handler的匹配，从而调用Controller的方法，返回ModelAndView，交给中央调度器，然后进行下面的视图解析，渲染视图等

+ ---- SPRINGMVC execution flow underlying analytical

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