/// <summary>
        /// 退出系统
        /// </summary>
        /// <returns></returns>
        public ActionResult Quit()
        {
            Session.Abandon();   //取消Session会话
            Session["UserId"] = null;
            Session["Role"] = null;

            return RedirectToAction("Login", "Auth", new { area = "" });  //回到指定界面
        }