Page_Load基类，重写OnLoad

        protected override void OnLoad(EventArgs e)
        {
            userid = PublicFun.GetSessionValue(HttpContext.Current.Session, "member_id", 0);//前台用户
            if (userid == 0)
            {
                userid = PublicFun.GetCookieValue("UserID", 0);
                if (userid > 0)
                {
                    usertype = 1; //后台用户
                }
                else
                {
                    Response.Write("很抱歉，请您先登录再进行访问！");
                    Response.End();
                }
            }

            base.OnLoad(e);
        }