BackgroundWorker 不想停止工作

Question

我创建了一个简单的文件下载程序，下载第一组然后开始下载另一组并从列表中下载文件。但有时会停在 3 个文件并下载。我查了一下之前下载到100%还没有下载完成的问题。

Private Sub Download(ByVal Down As Integer)
    On Error Resume Next
    Dim req As System.Net.WebRequest
    Dim resp As System.Net.WebResponse
    TextBox1.Text = Convert.ToString("http://example.com/files/" + Convert.ToString(Down) + ".zip")
    TextBox2.Text = Convert.ToString(Down)
    req = Net.WebRequest.Create(TextBox1.Text)
    resp = req.GetResponse
    req.Method = Net.WebRequestMethods.Http.Get
    download_size = resp.ContentLength
    ProgressBar1.Maximum = download_size
    Console.WriteLine(BackgroundWorker1.IsBusy)
    BackgroundWorker1.RunWorkerAsync()
    Timer1.Start()
End Sub

Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
    On Error Resume Next
    downloaded_size = My.Computer.FileSystem.GetFileInfo(FlatTextBox1.Text + "\" + TextBox2.Text + ".zip").Length
    ProgressBar1.Value = downloaded_size
    If ProgressBar1.Value = ProgressBar1.Maximum Then
        Timer1.Stop()
        BackgroundWorker1.CancelAsync()
        If Timer2.Enabled = False Then
            Timer2.Start()'Timer 5sec to to start function Download(x) and ProgressBar set to 0
        End If
    End If
End Sub

Private Sub BackgroundWorker1_DoWork(sender As Object, e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
    On Error Resume Next
    Console.WriteLine(TextBox1.Text + " | " + FlatTextBox1.Text + "\" + TextBox2.Text + ".zip")
    My.Computer.Network.DownloadFile(TextBox1.Text, FlatTextBox1.Text + "\" + TextBox2.Text + ".zip", "", "", False, 360000, True)

End Sub

Answer 1

下载文件比使用 BackgroundWorker 更好的方法是 WebClient 和函数 DownloadFileAsync。但需要在工具箱中启用WebClient。

Private Sub Download(ByVal Down As Integer)
    TextBox2.Text = Convert.ToString(Down)
    Dim Adresa As String = "http://example.com/files/" + Convert.ToString(Down) + ".zip"
    WebClient1.DownloadFileAsync(New Uri(Adresa), FlatTextBox1.Text + "\" + TextBox2.Text + ".zip")
End Sub

Private Sub WebClient1_DownloadProgressChanged(sender As Object, e As Net.DownloadProgressChangedEventArgs) Handles WebClient1.DownloadProgressChanged
    ProgressBar1.Value = e.ProgressPercentage
End Sub

Private Sub WebClient1_DownloadFileCompleted(sender As Object, e As System.ComponentModel.AsyncCompletedEventArgs) Handles WebClient1.DownloadFileCompleted
    ProgressBar1.Value = 0
    'Here place script to download next file..
End Sub

BackgroundWorker 不想停止工作

BackgroundWorker does not want to stop working

.net

vb.net

visual-studio-2015

backgroundworker