DispatcherServlet.getHandler

protected HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {
        if (this.handlerMappings != null) {
            for (HandlerMapping mapping : this.handlerMappings) {
                HandlerExecutionChain handler = mapping.getHandler(request);
                if (handler != null) {
                    return handler;
                }
            }
        }
        return null;
    }

DispatcherServlet.getHandler方法真正調(diào)用的其實(shí)就是RequestMappingHandlerMapping.getHadler方法，返回的HandlerExecutionChain中有真正的handler和3個攔截器，分別是LongTaskTimingHandlerInterceptor，ConversionServiceExposingInterceptor，ResourceUrlProviderExposingInterceptor。

1. RequestMappingHandlerMapping是怎么通過request定位到對應(yīng)的handler的
2. RequestMappingHandlerMapping怎么獲取到攔截器的，如果我要寫個攔截器，應(yīng)該怎么配置，有什么注意事項(xiàng)

//todo