filter中获取controller上的注解

      
        @Order(value = Ordered.HIGHEST_PRECEDENCE)
        @Component
        @WebFilter(urlPatterns = "/*")
        public class xxxFilter extends OncePerRequestFilter {

            @Autowired(required = false)
            DispatcherServlet dispatcherServlet;

            @Autowired
            RequestMappingHandlerMapping requestMappingHandlerMapping;

            @SneakyThrows
            @Override
            protected void doFilterInternal(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, FilterChain filterChain) throws ServletException, IOException {
                // 这种方式是不行的，返回的是null
                Object handler = httpServletRequest.getAttribute(HandlerMapping.BEST_MATCHING_HANDLER_ATTRIBUTE);
                // 这种可以
                HandlerExecutionChain handlerMappingHandler = requestMappingHandlerMapping.getHandler(httpServletRequest);
                // 这种可以
                HandlerExecutionChain handler2 = getHandlerFromDispatcherServlet();
		            // doFilter ...
                filterChain.doFilter(httpServletRequest, httpServletResponse);
                // 这种可以
                handler = httpServletRequest.getAttribute(HandlerMapping.BEST_MATCHING_HANDLER_ATTRIBUTE);
                System.out.println(handler);
            }

            private HandlerExecutionChain getHandlerFromDispatcherServlet(HttpServletRequest request){
                List<HandlerMapping> handlerMappings = dispatcherServlet.getHandlerMappings();
                if (handlerMappings != null) {
                    for (HandlerMapping mapping : handlerMappings) {
                      HandlerExecutionChain handler = mapping.getHandler(request);
                      if (handler != null) {
                        return handler;
                      }
                    }
                }
                return null;
            }
        }