Question

我正在尝试在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。

当我尝试在一个单独的概念验证应用程序上使用一个简单的窗口和一个按钮时 - 它工作正常。但是当我试图在我的真实应用程序中执行它时 - doWork子程序不会运行。而不是应用程序立即运行RunWorkerCompleted子并显示“上传完成”而不执行实际工作。

是否有关于MDI的内容阻止BackgroundWorker以与常规窗口应用程序相同的方式运行？

提前感谢您的帮助

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，因为它最有可能发生异常。正如@Zaggler提到的那样，您正在访问后台线程上的UI控件，这将导致这种情况。

MDI应用程序中的BackgroundWorker

1 个答案: