/// <summary>        /// FTP下载文件（带进度条）        /// </summary>        /// <param name="filename"></param>        public void DownloadFile(string filename)        {            float percent = 0;            string filePathName = string.Empty;            string url = string.Empty;            filePathName = Path.Combine(Application.StartupPath, filename);            string dirPath = GetDirPath(filePathName);            if (!Directory.Exists(dirPath))                Directory.CreateDirectory(dirPath);            //=>替换文件目录中的路径为网络路径            filename = filename.Replace("\\", "/");            url = "ftp://" + clientUpdateInfo.UpdateFTPIP + "/" + clientUpdateInfo.UpdatePath + "/" + filename;            var reqFtp = (FtpWebRequest)FtpWebRequest.Create(new Uri(url));            reqFtp.Method = WebRequestMethods.Ftp.DownloadFile;            reqFtp.UseBinary = true;            reqFtp.KeepAlive = false;//一定要设置此属性，否则一次性下载多个文件的时候，会出现异常。            reqFtp.Credentials = new NetworkCredential(clientUpdateInfo.FtpUserName, clientUpdateInfo.FtpUserPwd);            var response = (FtpWebResponse)reqFtp.GetResponse();            long totalBytes = response.ContentLength;            if (prog != null)            {                this.BeginInvoke(new MethodInvoker(delegate()                {                    prog.Maximum = (int)totalBytes;                }));            }            Stream st = response.GetResponseStream();            var so = new FileStream(filePathName, FileMode.Create);            long totalDownloadedByte = 0;            byte[] by = new byte[1024];            int osize = st.Read(by, 0, (int)by.Length);            while (osize > 0)            {                totalDownloadedByte = osize + totalDownloadedByte;                so.Write(by, 0, osize);                if (prog != null)                {                    this.BeginInvoke(new MethodInvoker(delegate()                    {                        prog.Value = (int)totalDownloadedByte;                    }));                }                osize = st.Read(by, 0, (int)by.Length);                percent = (float)totalDownloadedByte * 1.0f / (float)totalBytes * 100;                Application.DoEvents();                this.BeginInvoke(new MethodInvoker(delegate()                {                    lbDownInfo.Text = "正在下载" + filename + ",下载进度为:" + Math.Round(percent, 2) + "%";                    lbDownInfo.Refresh();                }));                Application.DoEvents();            }            so.Close();            st.Close();            response.Close();        }        private void FtpDownload(string filename)        {            string filePathName = string.Empty;            string url = string.Empty;            filePathName = Path.Combine(Application.StartupPath, filename);            string dirPath = GetDirPath(filePathName);            if (!Directory.Exists(dirPath))                Directory.CreateDirectory(dirPath);            //=>替换文件目录中的路径为网络路径            filename = filename.Replace("\\", "/");            url = "ftp://" + clientUpdateInfo.UpdateFTPIP + "/" + clientUpdateInfo.UpdatePath + "/" + filename;            FtpWebRequest reqFTP;            this.BeginInvoke(new MethodInvoker(delegate()            {                this.lbDownInfo.Text = "开始下载中...";            }));            FileStream outputStream = new FileStream(filePathName, FileMode.Create);            reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri(url));            reqFTP.Credentials = new NetworkCredential(clientUpdateInfo.FtpUserName, clientUpdateInfo.FtpUserPwd);            reqFTP.Method = WebRequestMethods.Ftp.DownloadFile;            reqFTP.UseBinary = true;            reqFTP.KeepAlive = false;            FtpWebResponse response = (FtpWebResponse)reqFTP.GetResponse();            Stream ftpStream = response.GetResponseStream();            int bufferSize = 1024;            int readCount;            byte[] buffer = new byte[bufferSize];            readCount = ftpStream.Read(buffer, 0, bufferSize);            //FTP上文件的大小            int allbye = GetFtpFileSize(filename);// (int)response.ContentLength;            int startbye = 0;            this.BeginInvoke(new MethodInvoker(delegate()              {                  this.prog.Maximum = allbye;                  this.prog.Minimum = 0;                  this.prog.Visible = true;                  this.lbDownInfo.Visible = true;              }));            while (readCount > 0)            {                outputStream.Write(buffer, 0, readCount);                readCount = ftpStream.Read(buffer, 0, bufferSize);                startbye += readCount;                this.BeginInvoke(new MethodInvoker(delegate()                  {                      this.lbDownInfo.Text = "已下载:" + (int)(startbye / 1024) + "KB/" + "总长度:"                                            + (int)(allbye / 1024) + "KB" + " " + " 文件名:" + filename;                      prog.Value = startbye;                      this.lbDownInfo.Refresh();                  }));                Application.DoEvents();                Thread.Sleep(5);            }            this.BeginInvoke(new MethodInvoker(delegate()            {                this.prog.Visible = false;                this.lbDownInfo.Text = "下载成功!";            }));            ftpStream.Close();            outputStream.Close();            response.Close();        }