MDI 应用程序中的 BackgroundWorker

Question

我正在尝试在我的 MDI 应用程序中使用 BackgroundWorker 来处理将文件上传到 FTP 服务器并在进度条上显示进度的过程。

当我尝试使用一个简单的 window 和一个按钮在单独的概念验证应用程序上执行此操作时 - 它工作正常。但是当我尝试在我的真实应用程序中执行此操作时 - doWork sub 不会运行。取而代之的是应用程序立即运行s RunWorkerCompleted sub 并向我显示 "Upload complete" 而没有执行实际工作。

关于 MDI 是否有什么东西阻止 BackgroundWorker 运行与常规 window 应用程序相同的方式？

在此先感谢您的帮助

代码：

 Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click

    bWorker.RunWorkerAsync()

End Sub

Private Sub bWorker_DoWork(sender As Object, e As System.ComponentModel.DoWorkEventArgs) Handles bWorker.DoWork

    Dim source = Application.StartupPath + "\Db\test.mdb"
    Dim NameToUpload As String = Path.GetFileName(source)

    NameToUpload = NameToUpload.Replace(".", DateTime.Now.ToShortTimeString() + ".")

    Dim request As FtpWebRequest = DirectCast(WebRequest.Create(Host + "/" + txtLogin.Text + "/" + NameToUpload), FtpWebRequest)
    request.Method = WebRequestMethods.Ftp.UploadFile
    request.Credentials = New NetworkCredential(txtLogin.Text, txtPassword.Text)
    Dim FileStream() As Byte = File.ReadAllBytes(source)
    Dim requestStream As System.IO.Stream = request.GetRequestStream()

    For offset As Integer = 0 To FileStream.Length Step 1024
        bWorker.ReportProgress(CType(offset * ProgressBar1.Maximum / FileStream.Length, Integer))
        Dim chSize As Integer = FileStream.Length - offset
        If chSize > 1024 Then chSize = 1024
        requestStream.Write(FileStream, offset, chSize)
    Next
    requestStream.Close()
    requestStream.Dispose()
End Sub

Private Sub bWorker_ProgressChanged(sender As Object, e As System.ComponentModel.ProgressChangedEventArgs)
    ProgressBar1.Value = e.ProgressPercentage

End Sub

Private Sub bWorker_RunWorkerCompleted(sender As Object, e As System.ComponentModel.RunWorkerCompletedEventArgs)
    MsgBox("Upload complete")
End Sub

Answer 1

您需要检查 RunWorkerCompleted 事件中的 e.Error，因为它很可能有异常。正如@Zaggler 提到的，您正在后台线程上访问 UI 控件，这将导致此问题。

MDI 应用程序中的 BackgroundWorker

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