Vb.net 无法取消BackgroundWorker进程

我有一个

BackgroundWorker

，它包含一个类

ExcelOutput

，用于将各种数据输出到工作簿，我应该马上提到设置了

bw.WorkerSupportsCancellation=True

在输出的每个阶段，我都会使用

Try/Catch

检查

ExcelOutput

中的错误，必要时还会显示错误（使用名为

ErroReport（）

的函数）

结合错误消息，我想取消

BackgroundWorker

以避免进一步的错误。为此，我已将

OutputWorker

属性添加到

ExcelOutput

类中，并将其设置为

bw_DoWork（）

方法中我的

BackgroundWorker

的副本

但是，在

ExcelOutput.ErrorReport（）

中执行的取消不起作用，我不知道为什么

请注意，我已经测试了

bw.CancellationPending

的值，并在出现错误后将其设置为

True

。我还测试了下面的

If

条件是否通过显示消息框起作用，并且也起作用。出于某种原因，似乎忽略了

Exit Sub

命令

有人能告诉我我做错了什么吗？谢谢

下面是如何设置

BackgroundWorker

类中的

bw\u DoWork（）

函数-

Private Sub bw_DoWork(ByVal sender As Object,
                      ByVal e As DoWorkEventArgs)

    Dim Excel As New ExcelOutput  ' Create a new instance of the ExcelOutput class
    Dim CurrentRow As Integer = 4    ' Set the first output row

    '** Include a copy of the OutputWorker in the ExcelOutput (so that the OutputWorker can be cancelled)
    Excel.OutputWorker = Me

    If bw.CancellationPending = True Then
        e.Cancel = True
        Exit Sub
    Else
        Excel.Prepare()
    End If

    If bw.CancellationPending = True Then
        e.Cancel = True
        Exit Sub
    Else
        CurrentRow = Excel.OutputGroup("General", Headers, Data, 4)
    End If

    ' More stuff here...

End Sub

Private Sub ErrorReport(ByVal Ex As Exception,
                        Optional ByVal CustomMessage As String = "")

    Call Me.ResetRange()    ' Destroy the 'Range' object
    Dim ErrorMessage As String = "Message: " & Ex.Message ' Set the default message
    If CustomMessage <> "" Then ErrorMessage = CustomMessage & vbCrLf & vbCrLf & Ex.Message
    Dim Result As Integer = MessageBox.Show(ErrorMessage,
                                            "An Error Has Occured",
                                            MessageBoxButtons.OK,
                                            MessageBoxIcon.Stop)

    '** Close the workbook (if it's open) and stop the OutputWorker *'
    Try
        Call Me.WB.Close(SaveChanges:=False)
        If Me.OutputWorker.WorkerSupportsCancellation = True Then
            Me.OutputWorker.CancelAsync()
        End If
    Catch
    End Try

End Sub

下面是如何设置

ExcelOutput

类中的

ErrorReport（）

函数-

Private Sub bw_DoWork(ByVal sender As Object,
                      ByVal e As DoWorkEventArgs)

    Dim Excel As New ExcelOutput  ' Create a new instance of the ExcelOutput class
    Dim CurrentRow As Integer = 4    ' Set the first output row

    '** Include a copy of the OutputWorker in the ExcelOutput (so that the OutputWorker can be cancelled)
    Excel.OutputWorker = Me

    If bw.CancellationPending = True Then
        e.Cancel = True
        Exit Sub
    Else
        Excel.Prepare()
    End If

    If bw.CancellationPending = True Then
        e.Cancel = True
        Exit Sub
    Else
        CurrentRow = Excel.OutputGroup("General", Headers, Data, 4)
    End If

    ' More stuff here...

End Sub

Private Sub ErrorReport(ByVal Ex As Exception,
                        Optional ByVal CustomMessage As String = "")

    Call Me.ResetRange()    ' Destroy the 'Range' object
    Dim ErrorMessage As String = "Message: " & Ex.Message ' Set the default message
    If CustomMessage <> "" Then ErrorMessage = CustomMessage & vbCrLf & vbCrLf & Ex.Message
    Dim Result As Integer = MessageBox.Show(ErrorMessage,
                                            "An Error Has Occured",
                                            MessageBoxButtons.OK,
                                            MessageBoxIcon.Stop)

    '** Close the workbook (if it's open) and stop the OutputWorker *'
    Try
        Call Me.WB.Close(SaveChanges:=False)
        If Me.OutputWorker.WorkerSupportsCancellation = True Then
            Me.OutputWorker.CancelAsync()
        End If
    Catch
    End Try

End Sub

Private子错误报告（ByVal Ex作为例外，
可选的ByVal CustomMessage（字符串=”）
调用我。ResetRange（）'销毁“Range”对象
Dim ErrorMessage As String=“Message:&Ex.Message”设置默认消息
如果是CustomMessage“”，则ErrorMessage=CustomMessage&vbCrLf&vbCrLf&Ex.Message
将结果调整为整数=MessageBox.Show（ErrorMessage，
“发生错误”，
MessageBoxButtons.OK，
MessageBoxIcon.Stop）
“**关闭工作簿（如果打开）并停止OutputWorker*”
尝试
Call Me.WB.Close（SaveChanges:=False）
如果Me.OutputWorker.workerSupportsScanCellation=True，则
Me.OutputWorker.CancelAsync（）
如果结束
抓住
结束尝试
端接头

您应该尝试将DoWorkEventsArgs作为参数添加到ErrorReport函数中

Private Sub ErrorReport(ByVal Ex As Exception,
                    Optional ByVal CustomMessage As String = "",
                    ByVal e As DoWorkEventsArgs)

Call Me.WB.Close(SaveChanges:=False)
    If e.WorkerSupportsCancellation = True Then
        e.CancelAsync()
    End If

---

您可以取消Backgroundworker。

谢谢，但这样我也能得到同样的结果。