ajaxSetup全局配置，发送前和接收响应后

        $.ajaxSetup({
            //在请求发送之前执行，将token发送过去
            beforeSend(xhr,setting){
                let token = localStorage.getItem("token");
                xhr.setRequestHeader("x-access-token",token);
            },
            //在请求完成响应返回时执行
            complete(xhr, setting) {
                if (xhr.responseJSON.code === 401) {
                    alert(xhr.responseJSON.message);
                    router.go('/index');
                }
            }
        })