Question

我该如何做一个检查，首先下载东西，然后才启动 program.exe ？我已经尝试做这样的事情，但是当下载未完成时，它会执行文件操作，并且会引发一些错误。我的代码：

Dim client As WebClient = New WebClient
Dim SourcePath As String = "C:\ProgramData\KDetector\UserAssistView.exe"
Dim SaveDirectory As String = "C:\ProgramData\KDetector"
Dim FileName As String = System.IO.Path.GetFileName(SourcePath)
Dim SavePath As String = System.IO.Path.Combine(SaveDirectory, FileName)
If System.IO.File.Exists(SavePath) Then
    Process.Start("C:\ProgramData\KDetector\UserAssistView.exe")
Else
    client.DownloadFileAsync(New Uri("http://ge.tt/70n8YPr2"), "C:\ProgramData\KDetector\")
    Process.Start("C:\ProgramData\KDetector\UserAssistView.exe")
End If

Answer 1

您正在调用异步DownloadFile方法。异步方法不会阻塞调用线程。

为了避免出现此问题，您的代码必须像这样：

    Dim downloadLink As String = "http://www.nirsoft.net/utils/userassistview.zip"
    Dim saveFilePath As String = "C:\ProgramData\KDetector\userassistvkew.zip"
    Dim fileName As String = Path.GetFileNameWithoutExtension(saveFilePath)
    Dim client As WebClient = New WebClient
    Try
        CheckExsist(saveFilePath, fileName)
        'Before was client.DownloadFileAsync(New Uri("http://ge.tt/70n8YPr2"))
        client.DownloadFile(downloadLink, saveFilePath)
        MsgBox("Download file completed. File saved in: " & saveFilePath)
        'Zip extraction stuff
    Catch ex As Exception
        MsgBox(ex.Message)
    End Try

这是CheckExsist子：

Private Sub CheckExsist(ByRef sourcePath As String, ByVal fileName As String, Optional ByVal counter As Integer = 1)
    If System.IO.File.Exists(sourcePath) Then
        sourcePath = sourcePath.Replace(Path.GetFileName(sourcePath), "") & fileName & "(" & counter & ")" & Path.GetExtension(sourcePath)
        counter += 1
        CheckExsist(sourcePath, fileName, counter)
    End If
End Sub

我设法从官方网站下载了该软件，并将其另存为.zip。如果遇到任何问题或错误，请对最后几行进行编码，以编程方式提取.zip，如果您有其他问题，请随时提出。无论如何，vb.net上有很多关于zip提取的帖子

Vb.net问题下载

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