vb.net - 异步控制事件的更新表单

Question

几周前，我为 ServiceController 控件编写了一个包装器，以增强和简化基本 ServiceController。我所做的更改之一是使用 System.Threading.Timer 添加一个监控组件。对象。在任何状态更改时，都会向父类引发一个事件。实际监控工作正常，但是当在主窗体中处理事件时，我的程序突然结束 - 没有异常，没有警告，它只是退出。这是控件的骨架版本:

Public Class EnhancedServiceController
    Inherits ServiceController

    Public Event Stopped(ByVal sender As Object, ByVal e As System.EventArgs)
    Public Event Started(ByVal sender As Object, ByVal e As System.EventArgs)

    Private _LastStatus As System.ServiceProcess.ServiceControllerStatus

    Private serviceCheckTimer as System.Threading.Timer
    Private serviceCheckTimerDelegate as System.Threading.TimerCallback

    ...

    Private Sub StartMonitor()
        MyBase.Refresh()
        _LastStatus = MyBase.Status
        serviceCheckTimerDelegate = New System.Threading.TimerCallback(AddressOf CheckStatus)
        serviceCheckTimer = New System.Threading.Timer(serviceCheckTimerDelegate, Nothing, 0, 60*1000)
    End Sub

    Private Sub CheckStatus()
        MyBase.Refresh()
        Dim s As Integer = MyBase.Status
        Select Case s
            Case ServiceControllerStatus.Stopped
                If Not s = _LastStatus Then
                    RaiseEvent Stopped(Me, New System.EventArgs)
                End If
            Case ServiceControllerStatus.Running
                If Not s = _LastStatus Then
                    RaiseEvent Started(Me, New System.EventArgs)
                End If
        End Select
        _LastStatus = s
    End Sub

End Class

和形式:

Public Class Form1
    Private Sub ServiceStarted(ByVal sender As Object, ByVal e As System.EventArgs) Handles ESC.Started
        Me.TextBox1.Text = "STARTED"
    End Sub

    Private Sub ServiceStopped(ByVal sender As Object, ByVal e As System.EventArgs) Handles ESC.Stopped
        Me.TextBox1.Text = "STOPPED"
    End Sub
End Class

如果我不得不猜测，我会说存在某种线程问题，但我不确定如何在表单中处理它。有什么想法吗？

Answer 1

如果是线程问题，那么您可能正在尝试从非 UI 线程更新 UI。

所以这样的事情应该可以解决这个问题......

Private Delegate Sub UpdateTextBoxDelegate(byval tText as String)

Private Sub UpdateTextBox(byval tText As String)
    If Me.InvokeRequired Then
        Me.Invoke(New UpdateTextBoxDelegate(AddressOf UpdateTextBox), tText)
        Exit Sub
    End If

    TextBox1.Text = tText
End Sub

Private Sub ServiceStarted(ByVal sender As Object, ByVal e As System.EventArgs) Handles ESC.Started 
    UpdateTextBox ("STARTED")
End Sub 

Private Sub ServiceStopped(ByVal sender As Object, ByVal e As System.EventArgs) Handles ESC.Stopped
    UpdateTextBox("STOPPED")
End Sub