使用VB.net读取和写入命令提示符控制台

Question

我在别处问过类似的问题,但也许我没有问过正确的方法,或者我不够清楚,所以我再问一次.

这是我想要的地方:

1. 打开Windows命令提示符
2. 通过dos命令运行DOS应用程序
3. 阅读dos框中显示的返回文本,并将其显示在Windows窗体的文本框中.这需要定期(例如,每秒)重复,并且不应关闭dos框.

我一直在试图使用Process和StartInfo命令,但它们只运行应用程序并立即关闭进程.我需要保持dos框打开并继续读取dos应用程序添加到其中的任何新文本.我也遇到了这个似乎可以解决我的问题的线程,但它是在C#中我无法转换它:

阅读Windows命令提示符STDOUT

我确实进入了打开命令提示符并启动应用程序的部分,但我不知道如何读取它不时地返回到dos框控制台的数据.我想不断检查变化,以便我可以对它们采取行动,也许使用定时器控件.

请帮忙.

谢谢!

我运行了由Stevedog友情提供的代码并使用它像这样:

  Private WithEvents _commandExecutor As New CommandExecutor()

  Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
    _commandExecutor.Execute("c:\progra~2\zbar\bin\zbarcam.exe", "")
  End Sub

  Private Sub _commandExecutor_OutputRead(ByVal output As String) Handles _commandExecutor.OutputRead
    txtResult.Text = output
  End Sub

但我得到的只是空白的dos盒子.zbarcam应用程序运行正常,因为我可以看到相机预览,我也可以看到它检测到QR码,但文本没有显示在dos框中,_commandExecutor_OutputRead除非我关闭DOS框,否则不会触发sub.

Answer 1

那个C#示例很糟糕,因为它没有显示如何实际读取标准输出流.创建一个这样的方法:

Public Function ExecuteCommand(ByVal filePath As String, ByVal arguments As String) As String
    Dim p As Process
    p = New Process()
    p.StartInfo.FileName = filePath
    p.StartInfo.UseShellExecute = False
    p.StartInfo.RedirectStandardInput = True
    p.StartInfo.RedirectStandardOutput = True
    p.Start()
    p.WaitForExit()
    Return p.StandardOutput.ReadToEnd()
End Function

然后你可以像这样调用它:

Dim output As String = ExecuteCommand("mycommand.exe", "")

当然这会进行同步通话.如果您希望它以异步方式调用命令行并在事件完成时引发事件,那么这也是可能的,但需要更多编码.

如果你想异步地做它并且只是定期检查固定间隔的更多输出,例如,这是一个简单的例子:

Public Class CommandExecutor
    Implements IDisposable

    Public Event OutputRead(ByVal output As String)

    Private WithEvents _process As Process

    Public Sub Execute(ByVal filePath As String, ByVal arguments As String)
        If _process IsNot Nothing Then
            Throw New Exception("Already watching process")
        End If
        _process = New Process()
        _process.StartInfo.FileName = filePath
        _process.StartInfo.UseShellExecute = False
        _process.StartInfo.RedirectStandardInput = True
        _process.StartInfo.RedirectStandardOutput = True
        _process.Start()
        _process.BeginOutputReadLine()
    End Sub

    Private Sub _process_OutputDataReceived(ByVal sender As Object, ByVal e As System.Diagnostics.DataReceivedEventArgs) Handles _process.OutputDataReceived
        If _process.HasExited Then
            _process.Dispose()
            _process = Nothing
        End If
        RaiseEvent OutputRead(e.Data)
    End Sub

    Private disposedValue As Boolean = False
    Protected Overridable Sub Dispose(ByVal disposing As Boolean)
        If Not Me.disposedValue Then
            If disposing Then
                If _process IsNot Nothing Then
                    _process.Kill()
                    _process.Dispose()
                    _process = Nothing
                End If
            End If
        End If
        Me.disposedValue = True
    End Sub

    Public Sub Dispose() Implements IDisposable.Dispose
        Dispose(True)
        GC.SuppressFinalize(Me)
    End Sub
End Class

然后你可以像这样使用它:

Public Class Form1
    Private WithEvents _commandExecutor As New CommandExecutor()

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        _commandExecutor.Execute("D:\Sandbox\SandboxSolution\ConsoleCs\bin\Debug\ConsoleCs.exe", "")
    End Sub

    Private Sub _commandExecutor_OutputRead(ByVal output As String) Handles _commandExecutor.OutputRead
        Me.Invoke(New processCommandOutputDelegate(AddressOf processCommandOutput), output)
    End Sub

    Private Delegate Sub processCommandOutputDelegate(ByVal output As String)
    Private Sub processCommandOutput(ByVal output As String)
        TextBox1.Text = output
    End Sub

    Private Sub Form1_FormClosed(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosedEventArgs) Handles Me.FormClosed
        _commandExecutor.Dispose()
    End Sub
End Class