我们如何使用 FtpWebRequest 显示上传进度条

Question

我正在使用FtpWebRequest 将文件上传到 ftp。我需要显示完成了多少的状态。

到目前为止，我的代码是：

public void Upload(string filename, string url)
{
    FileInfo fileInf = new FileInfo(filename);
    string uri = "ftp://" + url + "/" + fileInf.Name;
    FtpWebRequest reqFTP;
    //string uri = "ftp://" + Host + "/public_html/testing/blogtest/" + fileInf.Name;

    // Create FtpWebRequest object from the Uri provided
    reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri(uri));

    // Provide the WebPermission Credintials
    reqFTP.Credentials = new NetworkCredential(Username, Password);

    // By default KeepAlive is true, where the control connection is not closed
    // after a command is executed.
    reqFTP.KeepAlive = false;
    //reqFTP.UsePassive = true;
    // Specify the command to be executed.
    reqFTP.Method = WebRequestMethods.Ftp.UploadFile;

    // Specify the data transfer type.
    reqFTP.UseBinary = true;

    // Notify the server about the size of the uploaded file
    reqFTP.ContentLength = fileInf.Length;

    // The buffer size is set to 2kb
    int buffLength = 2048;
    byte[] buff = new byte[buffLength];
    int contentLen;

    // Opens a file stream (System.IO.FileStream) to read the file to be uploaded
    FileStream fs = fileInf.OpenRead();

    // Stream to which the file to be upload is written
    Stream strm = reqFTP.GetRequestStream();

    // Read from the file stream 2kb at a time
    contentLen = fs.Read(buff, 0, buffLength);

    // Till Stream content ends
    while (contentLen != 0)
    {
        // Write Content from the file stream to the FTP Upload Stream
        strm.Write(buff, 0, contentLen);
        contentLen = fs.Read(buff, 0, buffLength);
    }

    // Close the file stream and the Request Stream
    strm.Close();
    fs.Close();
}

Answer 1

一个简单的使用FtpWebRequest 的FTP 上传示例和使用Task class 的WinForms 进度条：

private void button1_Click(object sender, EventArgs e)
{
    // Run Upload on background thread
    Task.Run(() => Upload());
}

private void Upload()
{
    string url = "ftp://ftp.example.com/remote/path/file.zip";
    FtpWebRequest request = (FtpWebRequest)WebRequest.Create(url);
    request.Credentials = new NetworkCredential("username", "password");
    request.Method = WebRequestMethods.Ftp.UploadFile;

    using (Stream fileStream = File.OpenRead(@"C:\local\path\file.zip"))
    using (Stream ftpStream = request.GetRequestStream())
    {
        progressBar1.Invoke(
            (MethodInvoker)delegate { 
                progressBar1.Maximum = (int)fileStream.Length; });

        byte[] buffer = new byte[10240];
        int read;
        while ((read = fileStream.Read(buffer, 0, buffer.Length)) > 0)
        {
            ftpStream.Write(buffer, 0, read);
            progressBar1.Invoke(
                (MethodInvoker)delegate {
                    progressBar1.Value = (int)fileStream.Position; });
        }
    }
}

核心上传代码基于：
Upload and download a file to/from FTP server in C#/.NET

Answer 2

使用 async/await 模式的 IProgress 接口的可取消方法，利用 overlapped I/O（如果可用）。请参阅KB156932 以确定您的方案是否符合条件。在打开流之前检查取消令牌，否则会在文件传输时卸载到流的异步方法。

我做的基准测试很少，但怀疑这仅在发送大文件时才实用。使用重叠 I/O 的性能可能会随着较小的文件，尤其是较小的缓冲区大小而降低。

public async Task FtpAsync(string sourceFile, Uri destinationUri, string user, SecureString password, IProgress<decimal> progress, CancellationToken token)
{
  const int bufferSize = 128 * 1024;  // 128kb buffer
  progress.Report(0m);

  var request = (FtpWebRequest)WebRequest.Create(destinationUri);
  request.Method = WebRequestMethods.Ftp.UploadFile;
  request.Credentials = new NetworkCredential(user, password);

  token.ThrowIfCancellationRequested();

  using (var fileStream = new FileStream(sourceFile, FileMode.Open, FileAccess.Read, FileShare.Read, bufferSize, true))
  {
    using (var ftpStream = await request.GetRequestStreamAsync())
    {
      var buffer = new byte[bufferSize];
      int read;

      while ((read = await fileStream.ReadAsync(buffer, 0, buffer.Length, token)) > 0)
      {
        await ftpStream.WriteAsync(buffer, 0, read, token);
        var percent = 100m * ((decimal)fileStream.Position / fileStream.Length);
        progress.Report(percent);
      }
    }
  }

  var response = (FtpWebResponse)await request.GetResponseAsync();
  var success = (int)response.StatusCode >= 200 && (int)response.StatusCode < 300;
  response.Close();
  if (!success)
    throw new Exception(response.StatusDescription);
}

Answer 3

最简单的方法是使用BackgroundWorker 并将您的代码放入DoWork 事件处理程序。并通过BackgroundWorker.ReportProgress 报告进度。

基本思路：

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    var ftpWebRequest = (FtpWebRequest)WebRequest.Create("ftp://example.com");
    ftpWebRequest.Method = WebRequestMethods.Ftp.UploadFile;
    using (var inputStream = File.OpenRead(fileName))
    using (var outputStream = ftpWebRequest.GetRequestStream())
    {
        var buffer = new byte[1024 * 1024];
        int totalReadBytesCount = 0;
        int readBytesCount;
        while ((readBytesCount = inputStream.Read(buffer, 0, buffer.Length)) > 0)
        {
            outputStream.Write(buffer, 0, readBytesCount);
            totalReadBytesCount += readBytesCount;
            var progress = totalReadBytesCount * 100.0 / inputStream.Length;
            backgroundWorker1.ReportProgress((int)progress);
        }
    }
}

private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
    progressBar.Value = e.ProgressPercentage;
}

确保WorkerReportsProgress 已启用

backgroundWorker2.WorkerReportsProgress = true;

使用BackgroundWorker，您还可以轻松实现上传取消。

Answer 4

请参阅BackgroundWorker，它允许您在 GUI 仍然响应的同时运行耗时的任务，并且还提供进度/取消。