#region 判断远程文件是否存在           /// <summary>           /// 判断远程文件是否存在           /// </summary>           /// <param name="fileUrl"></param>           /// <returns></returns>           public static bool RemoteFileExists(string fileUrl)           {               HttpWebRequest re = null;               HttpWebResponse res = null;               try               {                   re = (HttpWebRequest)WebRequest.Create(fileUrl);                   res = (HttpWebResponse)re.GetResponse();                   if (res.ContentLength != 0)                   {                       //MessageBox.Show("文件存在");                       return true;                   }               }               catch (Exception)               {                   //MessageBox.Show("无此文件");                   return false;               }               finally               {                   if (re != null)                   {                       re.Abort();//销毁关闭连接                   }                   if (res != null)                   {                       res.Close();//销毁关闭响应                   }               }               return false;           }           #endregion