Question

我正在通过肥皂电话阅读DataTable，需要很长时间才能完成。为了使GUI保持活动状态并更新选取框，我可以在后台工作程序上执行soapcall并等待它在Runworkercompleted子中设置全局变量标志。该表填充得很好，并且dowork返回，但是完成的runworker永远不会被调用。

如果我重新编码这个以将标志设置为DOWORK中的最后一个东西，那么下次我调用TableGetterThread.RunWorkerAsync它会告诉我它不能同时运行任务（附加信息：此BackgroundWorker当前正忙，无法同时运行多个任务。）

对我所做错事的任何帮助都非常感激。

    waiting = True
    TableGetterThread.RunWorkerAsync(New tableInfo(tablename, filter))
    While waiting
        Me.Refresh()
        Threading.Thread.Sleep(100)
    End While

Private Sub TableGetterThread_DoWork(sender As Object, e As System.ComponentModel.DoWorkEventArgs) Handles TableGetterThread.DoWork
    Dim user As String = "username"
    Dim pass As String = "password"
    getTable_Table = Nothing
    getTable_Table = bromcomReader.getEntityData(e.Argument.tablename, e.Argument.Filter, user, pass).Tables(0)
    getTable_Table.TableName = e.Argument.tablename
    Console.WriteLine("FinishedDoWork")
End Sub

Private Sub TableGetterThread_RunWorkerCompleted(sender As Object, e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles TableGetterThread.RunWorkerCompleted
    Console.WriteLine("Completed")
    waiting = False
End Sub

Answer 1

缺陷在于逻辑本身。主线程和RunWorkerCompleted必须在同一个线程上运行。因此，当您等待Waiting设置为false时，您处于主线程中，因此永远不会调用RunWorkerCompleted。将waiting = False设为BackgroundWorker_Dowork的最后一步。我建议您使用AutoReset Event代替While loop等待。

您可以使用此代码作为参考。

Public Class Form1

    Private Property waiting As Boolean

    Private Sub BackgroundWorker1_DoWork(sender As System.Object, e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
        Console.WriteLine("Hey")
        waiting = False
    End Sub

    Private Sub BackgroundWorker1_RunWorkerCompleted(sender As System.Object, e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles BackgroundWorker1.RunWorkerCompleted

    End Sub

    Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
        waiting = True
        BackgroundWorker1.RunWorkerAsync()
        While waiting
            Me.Refresh()
            Threading.Thread.Sleep(100)
        End While
    End Sub
End Class

vb.net Backgroundworker DoWork没有结束

1 个答案: