fix http server handler (#1456)

transport/http/server.go

@@ -139,12 +139,12 @@ func NewServer(opts ...ServerOption) *Server {
 	for _, o := range opts {
 		o(srv)
 	}
+	srv.router = mux.NewRouter()
+	srv.router.Use(srv.filter())
 	srv.Server = &http.Server{
-		Handler:   FilterChain(srv.filters...)(srv),
+		Handler:   FilterChain(srv.filters...)(srv.router),
 		TLSConfig: srv.tlsConf,
 	}
-	srv.router = mux.NewRouter()
-	srv.router.Use(srv.filter())
 	return srv
 }
 
@@ -170,7 +170,7 @@ func (s *Server) HandleFunc(path string, h http.HandlerFunc) {
 
 // ServeHTTP should write reply headers and data to the ResponseWriter and then return.
 func (s *Server) ServeHTTP(res http.ResponseWriter, req *http.Request) {
-	s.router.ServeHTTP(res, req)
+	s.Handler.ServeHTTP(res, req)
 }
 
 func (s *Server) filter() mux.MiddlewareFunc {