C# .net判断访问来源是否是智能手机

 ///<summary>
     /// 根据 Agent 判断是否是智能手机
     ///summary>
     ///<returns>returns>
     public static bool CheckAgent()
     {
         bool flag = false;

         string agent = 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;
     }