public static bool CheckIsMobile()

        {

            bool flag = false;

            string agent = SystemWeb.HttpContext.Current.Request.UserAgent;

            string[] keywords = { "Android", "iPhone", "iPod", "iPad", "Windows Phone", "MQQBrowser" };

            //排除 Windows 桌面系统

            if (!agent.Contains("Windows NT") || (agent.Contains("Windows NT") && agent.Contains("compatible; MSIE 9.0;")))

            {

                //排除 苹果桌面系统

                if (!agent.Contains("Windows NT") && !agent.Contains("Macintosh"))

                {

                    foreach (string item in keywords)

                    {

                        if (agent.Contains(item))

                        {

                            flag = true;

                            break;

                        }

                    }

                }

            }

            return flag;

        }

 public ActionResult Login(string url)

        {

            if (CheckIsMobile())

            {

                return RedirectToAction("PhoneLogin");

            }

}