进度条，等待表单

Question

在我的主窗体中，我有一个按钮可以跨多个数据库加载大量存储过程。我想在加载时创建一个进度/等待表单。当我按下按钮时，它会显示等待表单。
我有一个调用workerDoWork 的后台工作进程。 在该方法中，我想调用具有所有代码的主窗体来进行加载。当我公开它时，我可以调用它。但是主窗体内有很多引用，全局变量，被调用的不同方法都不起作用。我怎样才能让它工作而不必将所有代码移动到等待表单中。？

等待表单中的代码。

Protected Overrides Sub OnLoad(ByVal e As System.EventArgs)
    MyBase.OnLoad(e)

    _worker = New BackgroundWorker()
    AddHandler _worker.DoWork, AddressOf WorkerDoWork
    AddHandler _worker.RunWorkerCompleted, AddressOf WorkerCompleted

    _worker.RunWorkerAsync()
End Sub

' This is executed on a worker thread and will not make the dialog unresponsive.  If you want
' to interact with the dialog (like changing a progress bar or label), you need to use the
' worker's ReportProgress() method (see documentation for details)
Private Sub WorkerDoWork(ByVal sender As Object, ByVal e As DoWorkEventArgs)
    'Dim main As New frmMain()
    frmMain.LoadARData()
    ' MsgBox("hi there ")

End Sub




' This is executed on the UI thread after the work is complete.  It's a good place to either
' close the dialog or indicate that the initialization is complete.  It's safe to work with
' controls from this event.
Private Sub WorkerCompleted(ByVal sender As Object, ByVal e As RunWorkerCompletedEventArgs)
    Me.DialogResult = Windows.Forms.DialogResult.OK
    Me.Close()
End Sub

Answer 1

你有：

frmMain.LoadARData()

正在使用 frmMain 的 默认实例，很可能与您在屏幕上显示的不同（导致错误和意外行为）。

您需要引用正确的 frmMain 实例才能使其正常工作。解决此问题的一种方法是将 frmMain 的引用传递给 Show()/ShowDialog() 调用：

' ... running from within frmMain ...
Dim progress As New frmProgress()
progress.ShowDialog(Me) ' <-- passing in "Me" (the reference to frmMain)

现在，在您的进度表单中，您可以将 Owner 属性转换为 frmMain 类型并调用您想要的方法：

Private Sub WorkerDoWork(ByVal sender As Object, ByVal e As DoWorkEventArgs)
    Dim main As frmMain = DirectCast(Me.Owner, frmMain)
    main.LoadARData()
End Sub