防止ajax非正常访问

http://www.cnblogs.com/yagzh2000/archive/2013/06/09/3128042.html

 http://www.cnblogs.com/henw/archive/2012/01/31/2333783.html

if ("http://" + Request.UrlReferrer.Host + ":" + Request.UrlReferrer.Port == ConfigStore.CommonSettings.App_Site_Url)
            {
                Random randnum = new Random();
                string telcode = randnum.Next(1000, 9999).ToString();
                return Json(new { flag = true });
            }