Question

我正在尝试使用4个网络客户端同时下载4个文件。它同时下载所有4个文件，但前两个进度条工作正常，第三个进度条与第一个进度条完全一致，第四个进度条与第二个进度条完全一致。这是我的代码与此问题相关。

Public WithEvents downloadFile1 As WebClient
Public WithEvents downloadFile2 As WebClient
Public WithEvents downloadFile3 As WebClient
Public WithEvents downloadFile4 As WebClient

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    System.Net.ServicePointManager.DefaultConnectionLimit = 10
End Sub


Private Sub startDownloadFile1()

    downloadFile1 = New WebClient
    Dim targetURL As String = lstURLs.Items.Item(0)
    Dim destinationPath As String = "e:\Downloads\0.jpg"
    downloadFile1.DownloadFileAsync(New Uri(targetURL), destinationPath)

End Sub

Private Sub startDownloadFile2()

    downloadFile2 = New WebClient
    Dim targetURL As String = lstURLs.Items.Item(1)
    Dim destinationPath As String = "e:\Downloads\1.jpg"
    downloadFile2.DownloadFileAsync(New Uri(targetURL), destinationPath)

End Sub

和similler for startDownloadFile3（）和startDownloadFile（）

Private Sub btnDownload_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDownload.Click
    startDownloadFile1()
    startDownloadFile2()
    startDownloadFile3()
    startDownloadFile4()
End Sub

Private Sub downloadFile1_DownloadProgressChanged(ByVal sender As Object, ByVal e As System.Net.DownloadProgressChangedEventArgs) Handles downloadFile1.DownloadProgressChanged

    pb1.Value = e.ProgressPercentage

End Sub

Private Sub downloadFile2_DownloadProgressChanged(ByVal sender As Object, ByVal e As System.Net.DownloadProgressChangedEventArgs) Handles downloadFile2.DownloadProgressChanged

    pb2.Value = e.ProgressPercentage

End Sub

Private Sub downloadFile3_DownloadProgressChanged(ByVal sender As Object, ByVal e As System.Net.DownloadProgressChangedEventArgs) Handles downloadFile1.DownloadProgressChanged

    pb3.Value = e.ProgressPercentage

End Sub

Private Sub downloadFile4_DownloadProgressChanged(ByVal sender As Object, ByVal e As System.Net.DownloadProgressChangedEventArgs) Handles downloadFile2.DownloadProgressChanged

    pb4.Value = e.ProgressPercentage

End Sub

Answer 1

Private Sub downloadFile3_DownloadProgressChanged(ByVal sender As Object, ByVal e As System.Net.DownloadProgressChangedEventArgs) Handles **downloadFile1.**DownloadProgressChanged

   pb3.Value = e.ProgressPercentage

End Sub

Private Sub downloadFile4_DownloadProgressChanged(ByVal sender As Object, ByVal e As System.Net.DownloadProgressChangedEventArgs) Handles **downloadFile2.**DownloadProgressChanged

    pb4.Value = e.ProgressPercentage

更改为：简单错误

Private Sub downloadFile3_DownloadProgressChanged(ByVal sender As Object, ByVal e As System.Net.DownloadProgressChangedEventArgs) Handles **downloadFile3.**DownloadProgressChanged

   pb3.Value = e.ProgressPercentage

End Sub

Private Sub downloadFile4_DownloadProgressChanged(ByVal sender As Object, ByVal e As System.Net.DownloadProgressChangedEventArgs) Handles **downloadFile4.**DownloadProgressChanged

    pb4.Value = e.ProgressPercentage

进度条不适用于VB.NET中的第三次下载

1 个答案: