无法更新文本框 vb.net -crossthreading

debugcn 发表于 Dev

法比奥·拉梅罗

我正在尝试使应用程序运行多个（特别是 adb）命令并获取输出并显示在标签中。

首先，我需要启动进程来执行命令。感谢 stackoverflow 和 @pasty 我发现了这个（第二个回复）：如何在 Visual Basic 中逐行获取命令提示符窗口的输出？

好吧，我认为因为它输出到控制台，所以将它写入标签很简单。大错！它给了我一个交叉线程错误！一点点谷歌搜索和堆栈溢出我发现了这个：vb.net 从一个线程访问，而不是在它创建的线程上

好吧，我试图实现它，但程序只是崩溃冻结。

这是代码：

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    ' store error output lines

    Dim executable As String() = {"adb", "adb"}
    Dim arguments As String() = {"help", "reboot"}
    For i As Integer = 0 To 0
        Dim process = New Process()
        process.StartInfo = createStartInfo(executable(i), arguments(i))
        process.EnableRaisingEvents = True
        AddHandler process.Exited, Sub(ByVal sendera As Object, ByVal ea As System.EventArgs)
                                       Console.WriteLine(process.ExitTime)
                                       Console.WriteLine(". Processing done.")
                                       'UpdateTextBox(ea)

                                   End Sub
        ' catch standard output
        AddHandler process.OutputDataReceived, Sub(ByVal senderb As Object, ByVal eb As DataReceivedEventArgs)
                                                   If (Not String.IsNullOrEmpty(eb.Data)) Then
                                                       Console.WriteLine(String.Format("{0}> {1}", DateTime.Now.ToString("dd.MM.yyyy HH:mm:ss"), eb.Data))
                                                       'UpdateTextBox(eb.Data)

                                                   End If
                                               End Sub
        ' catch errors
        AddHandler process.ErrorDataReceived, Sub(ByVal senderc As Object, ByVal ec As DataReceivedEventArgs)
                                                  Console.WriteLine(String.Format("! {0}", ec.Data))
                                                  Dim a As String = String.Format("! {0}", ec.Data)
                                                  'UpdateTextBox(a)
                                              End Sub
        ' start process
        Dim result = process.Start()
        ' and wait for output
        process.BeginOutputReadLine()
        ' and wait for errors :-)
        process.BeginErrorReadLine()
        process.WaitForExit()

    Next

End Sub

Private Sub UpdateTextBox(ByVal a As String)
    If Me.InvokeRequired Then
        Dim args() As String = {a}
        Me.Invoke(New Action(Of String)(AddressOf UpdateTextBox), args)
        Return
    End If
    Label1.Text += "a"
End Sub

Private Function createStartInfo(ByVal executable As String, ByVal arguments As String) As ProcessStartInfo
    Dim processStartInfo = New ProcessStartInfo(executable, arguments)
    processStartInfo.WorkingDirectory = Path.GetDirectoryName(executable)
    ' we want to read standard output
    processStartInfo.RedirectStandardOutput = True
    ' we want to read the standard error
    processStartInfo.RedirectStandardError = True
    processStartInfo.UseShellExecute = False
    processStartInfo.ErrorDialog = False
    processStartInfo.CreateNoWindow = True
    Return processStartInfo

End Function

和源代码：https : //github.com/iAmAOpenSource/SyncfusionWindowsFormsApplication3

标记

调用process.WaitForExit()将阻塞 UI 线程，直到产生的进程退出，但在处理输出时process.OutputDataReceived您正在调用的事件Me.Invoke试图在 UI 线程上运行代码，该线程被阻塞，因此程序冻结。您可以将逻辑Button1_Click移到另一个线程上，例如

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    Task.Run(
        Sub()
            ... current logic
        End Sub
    )
End Sub

这样 UI 线程就不会被阻塞，Me.Invoke调用也不会导致死锁。

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