vb.net - 在不卡住 UI 的情况下向 ListView 添加 150,000 条记录

Question

我有一个 ListView 循环，它向我的 ListView 添加 150,000 个项目。出于测试目的，我将此代码移至具有委托(delegate)的后台工作人员，但它仍然卡住了 UI。我正在尝试找到一个解决方案，以便它可以在我在应用程序中执行其他操作时在后台添加这些项目。你们推荐什么解决方案？

这就是我正在使用的

   Public Class Form1

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        ListView1.Clear()

        ListView1.BeginUpdate()

        bw.WorkerReportsProgress = True
        bw.RunWorkerAsync()
    End Sub

    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
        If bw.IsBusy Then bw.CancelAsync()
    End Sub

    Private Sub bw_DoWork(ByVal sender As Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles bw.DoWork
        For x = 1 To 125000
            Dim lvi As New ListViewItem("Item " & x)
            If bw.CancellationPending Then
                e.Cancel = True
                Exit For
            Else
                bw.ReportProgress(0, lvi)
            End If
        Next
    End Sub

    Private Sub bw_ProgressChanged(ByVal sender As Object, ByVal e As System.ComponentModel.ProgressChangedEventArgs) Handles bw.ProgressChanged
        Try
            Dim lvi As ListViewItem = DirectCast(e.UserState, ListViewItem)
            Me.ListView1.Items.Add(lvi)
        Catch ex As Exception
            Throw New Exception(ex.Message)
        End Try
    End Sub

    Private Sub bw_RunWorkerCompleted(ByVal sender As Object, ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles bw.RunWorkerCompleted
        ListView1.EndUpdate()
        If Not e.Cancelled Then
            Debug.Print("Done")
        Else
            Debug.Print("Cancelled")
        End If
    End Sub
End Class

Answer 1

尝试一下，这是您需要的一个很好的示例...我还有一个进度条，显示进度等，请参阅随附的示例图像。另外，我没有看到您需要执行此类操作的任何代表，我的有一个需要的代表。原因是您要向 UI 线程上的控件添加项目，为了添加项目，我们需要知道是否需要 Invoke，如果需要，我们调用，否则我们将项目添加到控件。 ..我还让线程休眠，这样它就可以休息一下；这也防止 UI 想要在这里或那里锁定，现在它可以响应NO FREEZING。

 Option Strict On
 Option Explicit On

Public Class Form1

Delegate Sub SetListItem(ByVal lstItem As ListViewItem) 'Your delegate..

'Start the process...
Private Sub btnStartProcess_Click(sender As Object, e As EventArgs) Handles btnStartProcess.Click
    lvItems.Clear()
    bwList.RunWorkerAsync()
End Sub

Private Sub AddListItem(ByVal lstItem As ListViewItem)
    If Me.lvItems.InvokeRequired Then 'Invoke if required...
        Dim d As New SetListItem(AddressOf AddListItem) 'Your delegate...
        Me.Invoke(d, New Object() {lstItem})
    Else 'Otherwise, no invoke required...
        Me.lvItems.Items.Add(lstItem)
    End If
End Sub

Private Sub bwList_DoWork(sender As Object, e As System.ComponentModel.DoWorkEventArgs) Handles bwList.DoWork
    Dim intCount As Integer = CInt(txtCount.Text)
    Dim dblPercent As Integer = 100
    Dim intComplete As Integer = 0
    Dim li As ListViewItem = Nothing

    For i As Integer = 1 To CInt(txtCount.Text)
        If Not (bwList.CancellationPending) Then
            li = New ListViewItem
            li.Text = "Item " & i.ToString
            AddListItem(li)
            Threading.Thread.Sleep(1) 'Give the thread a very..very short break...
        ElseIf (bwList.CancellationPending) Then
            e.Cancel = True
            Exit For
        End If

        intComplete = CInt(CSng(i) / CSng(intCount) * 100)
        If intComplete < dblPercent Then
            bwList.ReportProgress(intComplete)
        End If

        If li IsNot Nothing Then
            li = Nothing
        End If
    Next

End Sub

Private Sub bwList_ProgressChanged(sender As Object, e As System.ComponentModel.ProgressChangedEventArgs) Handles bwList.ProgressChanged
    pbList.Value = e.ProgressPercentage
End Sub

Private Sub bwList_RunWorkerCompleted(sender As Object, e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles bwList.RunWorkerCompleted
    If pbList.Value < 100 Then pbList.Value = 100
    MessageBox.Show(lvItems.Items.Count.ToString & " items were added!")
End Sub

Private Sub btnStopWork_Click(sender As Object, e As EventArgs) Handles btnStopWork.Click
    bwList.CancelAsync()
End Sub

Private Sub btnRestart_Click(sender As Object, e As EventArgs) Handles btnRestart.Click
    pbList.Value = 0
    lvItems.Items.Clear()
    txtCount.Text = String.Empty
End Sub
End Class

实际截图...