c# - 我如何修复 backgroundworker 忙 c# 代码

Question

当我运行我的代码时，我总是得到后台工作人员很忙。有帮助吗？

       struct FtpSetting
    {
        public string Server { get; set; }
        public string Username { get; set; }
        public string Password { get; set; }
        public string FileName { get; set; }
        public string FullName { get; set; }
    }

    FtpSetting _inputParameter;

    private void backgroundWorker_DoWork(object sender, DoWorkEventArgs e)
    {
        string fileName = ((FtpSetting)e.Argument).FileName;
        string fullName = ((FtpSetting)e.Argument).FullName;
        string userName = ((FtpSetting)e.Argument).Username;
        string password = ((FtpSetting)e.Argument).Password;
        string server = ((FtpSetting)e.Argument).Server;
        FtpWebRequest request = (FtpWebRequest)WebRequest.Create(new Uri(string.Format("{0}/{1}", server, fileName)));
        request.Method = WebRequestMethods.Ftp.UploadFile;
        request.Credentials = new NetworkCredential(userName, password);
        Stream ftpStream = request.GetRequestStream();
        FileStream fs = File.OpenRead(fullName);
        byte[] buffer = new byte[1024];
        double total = (double)fs.Length;
        int byteRead = 0;
        double read = 0;
        do
        {
            if (!backgroundWorker.CancellationPending)
            {
                //Upload file & update process bar
                byteRead = fs.Read(buffer, 0, 1024);
                ftpStream.Write(buffer, 0, byteRead);
                read += (double)byteRead;
                double percentage = read / total * 100;
                backgroundWorker.ReportProgress((int)percentage);
            }
        }
        while (byteRead != 0);
        fs.Close();
        ftpStream.Close();
    }

    private void backgroundWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)
    {
        lblStatus.Text = $"Uploaded {e.ProgressPercentage} %";
        progressBar.Value = e.ProgressPercentage;
        progressBar.Update();
    }

    private void backgroundWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {
        lblStatus.Text = "Upload complete !";
    }

    private void btnUpload_Click(object sender, EventArgs e)
    {
        string dir = "C:\\Users\\bluevels\\Pictures\\";
        string[] files = Directory.GetFiles(dir);
        foreach (string file in files)
        {

            string FileName = Path.GetFileName(file);

            FileInfo fi = new FileInfo(FileName);
            _inputParameter.Username = txtUserName.Text;
            _inputParameter.Password = txtPassword.Text;
            _inputParameter.Server = txtServer.Text;
            _inputParameter.FileName = fi.Name;
            _inputParameter.FullName = fi.FullName;
            backgroundWorker.RunWorkerAsync(_inputParameter);

        }
    }

    private void Form1_Load(object sender, EventArgs e)
    {

    }

我不断收到这一行的错误

backgroundWorker.RunWorkerAsync(_inputParameter);

Answer 1

通过将 RunWorkerAsync() 放置在 foreach 中，您试图在 worker 已经运行时使用同一个实例启动多个副本。

考虑将循环移动到 worker 本身:

class FtpSetting
{
    public string Server { get; set; }
    public string Username { get; set; }
    public string Password { get; set; }
    public string[] Files { get; set; }
}

private void btnUpload_Click(object sender, EventArgs e)
{
    if (backgroundWorker.IsBusy)
       return;

      string dir = "C:\\Users\\bluevels\\Pictures\\";
      string[] files = Directory.GetFiles(dir);

     _inputParameter.Username = txtUserName.Text;
     _inputParameter.Password = txtPassword.Text;
     _inputParameter.Server = txtServer.Text;
     _inputParameter.Files = files;
     backgroundWorker.RunWorkerAsync(_inputParameter);
}

自然地，worker 的主体将需要更改，因为 e 现在是一个文件列表。其余属性可以直接从实例字段中读取。

private void backgroundWorker_DoWork(object sender, DoWorkEventArgs e)
{
    var setting = (FtpSetting)e.Argument;
    ...
    for (int fileNum = 0; fileNum < setting.Files.Length; fileNum++)
    {
         if (backgroundWorker.CancellationPending)
             break;

         do
             ...
             // use setings.Files[fileNum]
             // also divide percentage done by setting.Files.Length e.g.
             double percentage = (100/setting.Files.Length)+fileNum + (read / total * 100);
             ...
    }

  }

这样一来，如果您决定从多个站点进行真正的并发下载(您将需要多个工作人员或可能考虑TPL DataFlow)，代码更改将最少。