#region 判断远程文件是否存在        /// 
        /// 判断远程文件是否存在        /// 
        ///         /// 
            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