C# 如何在winforms中使用服务器Url、用户名和密码在FTP服务器中存储多个文件

给出以下代码中的任何修改

private void Upload144_Click(object sender, EventArgs e)
    {
        OpenFileDialog fileobj = new OpenFileDialog();
        fileobj.InitialDirectory = "C:\\";
        //fileobj.Filter = "Video files (*.mp4)";
        //fileobj.ShowDialog();

        if (fileobj.ShowDialog() == DialogResult.OK)
        {
            if (fileobj.CheckFileExists)
            {
                string test = Properties.Settings.Default.Connection;
                SqlConnection con = new SqlConnection(test);
                con.Open();
                string correctfilename = System.IO.Path.GetFileName(fileobj.FileName);
                SqlCommand cmd = new SqlCommand("Insert into Path(ID,Path5) VALUES   ((select isnull(MAX(id),0) + 1 from Path),'\\Videos\\" + correctfilename + "')", con);

                cmd.ExecuteNonQuery();

                string path = Application.StartupPath.Substring(0, Application.StartupPath.Length - 10);
                con.Close();

                //For Progressbar
                DataTable dt = new DataTable();
           //   SqlDataAdapter da = new SqlDataAdapter(cmd);
           //   da.Fill(dt);

                timer5.Enabled = true;

                // FOR FtpServer File Upload::
                string uploadfile = fileobj.FileName;
                string uploadFileName = new FileInfo(uploadfile).Name;

                string uploadUrl = "ftp://ftp.infotech.com/";
                FileStream fs = new FileStream(uploadfile, FileMode.Open, FileAccess.Read);
                try
                {
                    long FileSize = new FileInfo(uploadfile).Length; // File size of file being uploaded.
                    Byte[] buffer = new Byte[FileSize];

                    fs.Read(buffer, 0, buffer.Length);

                    fs.Close();
                    fs = null;
                    string ftpUrl = string.Format("{0}/{1}", uploadUrl, uploadFileName);
                    FtpWebRequest requestObj = FtpWebRequest.Create(ftpUrl) as FtpWebRequest;
                    requestObj.Method = WebRequestMethods.Ftp.UploadFile;
                    requestObj.Credentials = new NetworkCredential("test@sample.com", "test@123");
                    Stream requestStream = requestObj.GetRequestStream();
                    requestStream.Write(buffer, 0, buffer.Length);

                    requestStream.Flush();
                    requestObj = null;
                }
                catch (Exception ex)
                {
                    //MessageBox.Show("File upload/transfer Failed.\r\nError Message:\r\n" + ex.Message, "Succeeded", MessageBoxButtons.OK, MessageBoxIcon.Information);
                }
            }
        }
    }

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对于使用上述代码，我在ftp服务器中存储了单个文件，但我无法在ftp服务器中存储超过2个文件。建议更改代码。每次请求文件上载后，连接将自动关闭。