/// <summary>

        /// 在调用视图之前拦截非法用户

        /// </summary>

        /// <param name="filterContext"></param>

        protected override void OnActionExecuting(ActionExecutingContext filterContext)

        {

            if (Session["userid"] == null) //判断session是否为空

            {

                filterContext.Result = new RedirectResult(Url.Action("LoginShow", "Login"));//方法名，控制器名

                return;

            }

            base.OnActionExecuting(filterContext);

        }