.net - vb net update UI控件来自单独的线程事件

Question

这个问题在这里已经有了答案:





Updating GUI items upon an event raised by a thread of another class VB.nET

(1 个回答)


3个月前关闭。




我有一个名为 SFTPConnectorManager.vb 的类，它负责管理与服务器的 FTP 连接。我有 Form1.vb 类，它是主要的 GUI。我想更新 Form1 上的 ProgressBar 以显示文件传输的进度。负责与 FTP 服务器建立连接的函数在一个新线程上启动，这允许 form1 不会被卡住，这很好，但是对我来说挑战是能够更新进度条，这对我来说是行不通的我。

我尝试过/做过的事情:

使用委托(delegate)从单独的线程

更新 UI

使用后台工作人员并使用它的进度更改事件，我想我可能会在这里做一些事情，但后来我记得 UI 的更新需要在文件传输事件期间发生，特别是 SessionFileTransferProgress，而不是当我引发进度更改事件时.

阅读了超过 20 页有关多线程和事件处理的文档，我猜还是不明白...

我需要发生的事情:

更新进度条 UI 控件，在文件传输正在进行时更新，并且它不需要卡住 UI，因此它需要在单独的线程上运行(我相信到目前为止我已经实现了)

我正在使用的代码:

https://winscp.net/eng/docs/library_session

https://winscp.net/eng/docs/library_session_filetransferprogress

Form1.vb

 Public Sub sub1(ByVal x As Integer, y As Integer)
    StatusLabel2.Text = "Connected"
    ProgressBar1.Maximum = ProgressBar1.Maximum + x
    ProgressBar1.Value = ProgressBar1.Value + y

End Sub

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles StartBtn.Click
    '    If (BackgroundWorker1.IsBusy) <> True Then
    '        BackgroundWorker1.RunWorkerAsync()
    '    End If

    'Call Xml reader To Get respective values And store them into Class Property

    Dim oConnect = New SFTPConnectorManager
    Dim oXmlRead As XmlReader = XmlReader.Create("D:\dale_documents\projects\programming\vbnet\remote_data_backup\sftp_backup\settings.xml")

    While (oXmlRead.Read())

        Dim eType = oXmlRead.NodeType

        If (eType = XmlNodeType.Element) Then

            If (oXmlRead.Name = "HostName") Then
                oConnect.HostName = oXmlRead.ReadInnerXml.ToString
            End If

            If (oXmlRead.Name = "UserName") Then
                oConnect.UserName = oXmlRead.ReadInnerXml.ToString
            End If

            If (oXmlRead.Name = "Password") Then
                oConnect.Password = oXmlRead.ReadInnerXml.ToString
            End If

            If (oXmlRead.Name = "Port") Then
                oConnect.Port = oXmlRead.ReadInnerXml.ToString
            End If

            If (oXmlRead.Name = "Protocol") Then
                oConnect.ProtocolSelection = oXmlRead.ReadInnerXml.ToString
            End If

            If (oXmlRead.Name = "FTPMode") Then
                oConnect.FtpModeSelection = oXmlRead.ReadInnerXml.ToString
            End If

            If (oXmlRead.Name = "SSHFingerPrint") Then
                oConnect.SSHKey = oXmlRead.ReadInnerXml.ToString
            End If

            If (oXmlRead.Name = "Remotepath") Then
                oConnect.RemotePath = oXmlRead.ReadInnerXml.ToString
            End If

            If (oXmlRead.Name = "Localpath") Then
                oConnect.LocalPath = oXmlRead.ReadInnerXml.ToString
            End If
        End If

    End While

    Dim eProtocolOptions = oConnect.ProtocolSelection
    Dim sUserName = oConnect.UserName
    Dim sHostName = oConnect.HostName
    Dim sPassword = oConnect.Password
    Dim sSSHKey = oConnect.SSHKey
    Dim iPort = oConnect.Port
    Dim sRemotePath = oConnect.RemotePath
    Dim sLocalPath = oConnect.LocalPath
    Dim bFlag = oConnect.bFlag


    Dim asOptions = New String() {eProtocolOptions, sHostName, sUserName, iPort, sPassword, sSSHKey, sRemotePath, sLocalPath}

    oConnect.TestThread(asOptions)

SFTPConnectorManager.vb

Function StartConnectionThread(asOptions)

    Try
        Dim oSessionOptions As New SessionOptions
        With oSessionOptions
            .Protocol = ProtocolSelection
            .HostName = HostName
            .UserName = UserName
            .PortNumber = Port
            .Password = Password
            .SshHostKeyFingerprint = SSHKey
        End With

        Using oSession As New Session
            AddHandler oSession.FileTransferProgress, AddressOf SessionFileTransferProgress
            oSession.Open(oSessionOptions)

            Dim oTransferOptions As New TransferOptions
            oTransferOptions.TransferMode = TransferMode.Binary

            oSession.GetFiles(RemotePath, LocalPath, False, oTransferOptions)

            oSession.Close()

            bFlag = False
        End Using

        MessageBox.Show("File Transfer Compelete")

        Return 0
    Catch ex As Exception
        MessageBox.Show(ex.ToString())
        Return 1
    End Try

End Function

 Public Delegate Sub SetbarValues(maximum As Integer, value As Integer)
Private Sub SessionFileTransferProgress(ByVal sender As Object, ByVal e As FileTransferProgressEventArgs)


    Dim oForm1 = Form1
    Dim msd As SetbarValues = AddressOf oForm1.sub1

    If oForm1.InvokeRequired Then
        msd.Invoke(1, 1)
    Else
        oForm1.sub1(1, 1)
    End If

    'oForm1.ProgressUpdate()

    'If (Form1.CheckForIllegalCrossThreadCalls) Then
    '    MsgBox("Illegal cross-thread operation deteced.")
    'End If


End Sub

Public Sub TestThread(asOption())
    Dim oSFTPConnectionManager = New SFTPConnectorManager
    Dim Thread As New Thread(AddressOf oSFTPConnectionManager.StartConnectionThread)

    oSFTPConnectionManager.ProtocolSelection = asOption(0)
    oSFTPConnectionManager.HostName = asOption(1)
    oSFTPConnectionManager.UserName = asOption(2)
    oSFTPConnectionManager.Port = asOption(3)
    oSFTPConnectionManager.Password = asOption(4)
    oSFTPConnectionManager.SSHKey = asOption(5)
    oSFTPConnectionManager.RemotePath = asOption(6)
    oSFTPConnectionManager.LocalPath = asOption(7)

    Thread.Start()

End Sub

所以你可能会看到我尝试使用委托(delegate)，我对它进行了相当多的阅读，我相信这是我需要从单独的线程更新 UI 元素，但我显然误解了它，因为我无法实现我自己的项目中的概念。 UI 更改需要在 SessionFileTransferProgress 事件期间发生。

伙计们，女孩们，我对此束手无策，这是我最后的救命之恩，如果我不能理解和实现这些概念，我认为我将无法继续学习编程。

Answer 1

这是一个显示概念的简单示例。它有一个类，它有一些长时间运行的(原文如此)事件，想要向 UI 报告进度。您需要一个带有两个按钮、一个进度条和一个文本框的表单。希望这在概念上有所帮助。

Public Class Form1

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        ProgressBar1.Value = 0
        Dim foo As New SomeClass(New Action(AddressOf showProg))
        foo.SimulateActivity() 'long running
        Button2.Select()
    End Sub

    Public Sub showProg()
        If Me.InvokeRequired Then ' on the UI?
            Me.Invoke(Sub() showProg()) ' no, run this on the UI
        Else
            ProgressBar1.Increment(1) ' yes, on the UI
        End If
    End Sub

    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
        'test if UI available while long running
        'press button 2 while long running to confirm UI
        TextBox1.Text = ProgressBar1.Value.ToString
    End Sub
End Class

Public Class SomeClass

    Private _action As Action
    Public Sub New(progress As Action)
        Me._action = progress
    End Sub

    Public Sub SimulateActivity()
        'runs on thread
        Dim t As Task
        t = Task.Run(Sub()
                         For x As Integer = 1 To 100
                             Me._action()
                             Threading.Thread.Sleep(50)
                         Next
                     End Sub)
    End Sub
End Class