private void ValidCookies()
        {
            int count =Request.Cookies.Count;
            if (count > 5) {
                HttpCookieCollection cookies = Request.Cookies;
                for (int i = 0; i < cookies.Count; i++)
                {
                    Response.Write("<br/>Cookie键：" + cookies[i].Name + "，值：" + cookies[i].Value + "，Domain：" + cookies[i].Domain + "，Path：" + cookies[i].Path + "Expire：" + cookies[i].Expires.ToString("yyyy-MM-dd HH:mm:ss"));
                }
                return;
            }
           
            if (!string.IsNullOrEmpty(Request.Cookies["xfk_sid"].Value))
            {
                HttpCookie cookie = HttpContext.Current.Request.Cookies["xfk_sid"];
                if (cookie != null)
                {
                    cookie.Expires = DateTime.Now.AddYears(-3);
                    HttpContext.Current.Response.Cookies.Add(cookie);
                }
                ValidCookies();
            }
        }