在 WinForm 的进度条上显示 WinSCP .NET 程序集传输进度

Question

有一些主窗体，我在上面调用从 FTP 下载文件。提出此操作后，我希望看到新表单 ShowDialog 和它上面的进度条同时显示，然后显示进度并关闭新表单并返回主表单。然而，我的代码正在运行，当它开始处理时，我的主窗体冻结，然后新窗体出现然后关闭。我想更正的是在执行流程后立即显示此新表格。你能看一下并告诉我有什么问题吗？

这是我主窗体的下载过程调用：

Dim pro As New FrmProgressBarWinscp(WinScp, myremotePicturePath, ladujZdjeciaPath, True)

FrmProgressBarWinscp如下：

Public Class FrmProgressBarWinscp

    Property _winScp As WinScpOperation
    Property _remotePicture As String
    Property _ladujZdjecia As String
    Property _removesource As String

    Public Sub New()
        InitializeComponent()
    End Sub

    Sub New(winscp As WinScpOperation, remotePicture As String, ladujzdjecia As String, removesource As Boolean)
        ' This call is required by the designer.
        InitializeComponent()
        ' Add any initialization after the InitializeComponent() call.
        _winScp = winscp
        _remotePicture = remotePicture
        _ladujZdjecia = ladujzdjecia
        _removesource = removesource
        ShowDialog()
    End Sub

    Sub Run()

        Try
            Cursor = Cursors.WaitCursor
            _winScp.GetFile(_remotePicture, _ladujZdjecia, _removesource)
            ProgressBar1.Minimum = 0
            ProgressBar1.Maximum = 1
            ProgressBar1.Value = 0
            Do
                ProgressBar1.Value = WinScpOperation._lastProgress
                ProgressBar1.Refresh()
            Loop Until ProgressBar1.Value = 1
            Cursor = Cursors.Default
            'Close()

        Catch ex As Exception

        Finally
            If _winScp IsNot Nothing Then
                _winScp.SessionDispose()
            End If

            System.Threading.Thread.Sleep(10000)
            Close()
        End Try

    End Sub

    Private Sub FrmProgressBarWinscp_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Run()
    End Sub
End Class

我自己的Winscp class和使用的方法：

...
Function GetFile(source As String, destination As String, Optional removeSource As Boolean = False)
    Dim result As Boolean = True
    Try

        session.GetFiles(source, destination, removeSource).Check()

    Catch ex As Exception
        result = False
    End Try
    Return result
End Function

Private Shared Sub SessionFileTransferProgress(sender As Object, e As FileTransferProgressEventArgs)
    'Print transfer progress
    _lastProgress = e.FileProgress

End Sub

Public Shared _lastProgress As Integer

...

进一步讨论 3：

Main form:
 Dim tsk As Task(Of Boolean) = Task.Factory.StartNew(Of Boolean)(Function()
                                                                                                Return WinScp.GetFile(myremotePicturePath, ladujZdjeciaPath, True)

                                                                                            End Function)


                            Dim forma As New FrmProgressBar
                            forma.ShowDialog()

进度条形式：

Public Class FrmProgressBar

    Public Sub New()
        InitializeComponent()
    End Sub
    Sub Run()
        Try
            Do
                ProgressBar1.Value = WinScpOperation._lastProgress
                ProgressBar1.Refresh()
            Loop Until ProgressBar1.Value = 1
            Cursor = Cursors.Default

        Catch ex As Exception
        Finally
            MsgBox("before sleep")
            System.Threading.Thread.Sleep(10000)
            MsgBox("after sleep sleep")
            Close()
        End Try
    End Sub

    Private Sub FrmProgressBarWinscp_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Run()
    End Sub
End Class

点编号。 4:

  Dim tsk As Task(Of Boolean) = Task.Factory.StartNew(Of Boolean)(Function()
                                                                                                Return WinScp.GetFile(myremotePicturePath, ladujZdjeciaPath, True)

                                                                                            End Function)


                            Dim pic As New Waiting
                            pic.ShowDialog()

                            Task.WaitAll(tsk)
                            pic.Close()

第 5 点：

 Dim pic As New Waiting
                            pic.ShowDialog()
                            Dim tsk As Task = Task.Factory.StartNew(Sub() WinScp.GetFile(myremotePicturePath, ladujZdjeciaPath, pic, True))




                            Task.WaitAll(tsk)
                            'pic.Close()

在其他一些class中（可能之前没有提到这个方法放在不同的地方class - 我的自定义）

Public Function GetFile(source As String, destination As String, formclose As InvokeCloseForm, Optional removeSource As Boolean = False) As Boolean
        Dim result As Boolean = True
        Try
            session.GetFiles(source, destination, removeSource).Check()
        Catch ex As Exception
            result = False
        End Try
        formclose.RUn()
        Return result
    End Function

接口：

Public Interface InvokeCloseForm
    Sub RUn()
End Interface

等待表格：

Public Class Waiting
    Implements InvokeCloseForm

    Public Sub RUn() Implements InvokeCloseForm.RUn
        Me.Close()
    End Sub
End Class

Answer 1

阻塞中的Session.GetFiles method。

意思是returns传输完成后

解决方法是：

运行 WinSCP 传输（Session.GetFiles）在单独的线程中，不阻塞 GUI 线程。

请参阅 WinForm Application UI Hangs during Long-Running Operation
处理 Session.FileTransferProgress event.

不过请注意，事件处理程序将在后台线程上调用，因此您不能直接从处理程序更新进度条。您必须使用 Control.Invoke 来确保进度条在 GUI 线程上更新。

请参阅 How do I update the GUI from another thread?

下面是一个简单的实现。

更多版本的代码，参见WinSCP文章Displaying FTP/SFTP transfer progress on WinForms ProgressBar。

Public Class ProgressDialog1

    Private Sub ProgressDialog1_Load(
            sender As Object, e As EventArgs) Handles MyBase.Load
        ' Run download on a separate thread
        ThreadPool.QueueUserWorkItem(New WaitCallback(AddressOf Download))
    End Sub

    Private Sub Download(stateInfo As Object)
        ' Setup session options
        Dim mySessionOptions As New SessionOptions
        With mySessionOptions
            ... 
        End With

        Using mySession As Session = New Session
            AddHandler mySession.FileTransferProgress,
                AddressOf SessionFileTransferProgress

            ' Connect
            mySession.Open(mySessionOptions)

            mySession.GetFiles(<Source>, <Destination>).Check()
        End Using

        ' Close form (invoked on GUI thread)
        Invoke(New Action(Sub() Close()))
    End Sub

    Private Sub SessionFileTransferProgress(
            sender As Object, e As FileTransferProgressEventArgs)
        ' Update progress bar (on GUI thread)
        ProgressBar1.Invoke(
            New Action(Of Double)(AddressOf UpdateProgress), e.OverallProgress)
    End Sub

    Private Sub UpdateProgress(progress As Double)
        ProgressBar1.Value = progress * 100
    End Sub
End Class

如果您想阻止用户进行某些操作，您可能希望在操作过程中禁用进度表（或其部分）。

使用窗体或控件的 .Enabled 属性。

从您现有的 SessionFileTransferProgress 处理程序中调用 Application.DoEvents 方法是更简单但不可靠且通常不推荐的解决方案。

当然，您还必须从 SessionFileTransferProgress 更新进度条。

Private Shared Sub SessionFileTransferProgress(
        sender As Object, e As FileTransferProgressEventArgs)
    'Print transfer progress
    ProgressBar1.Value = e.FileProgress
    Application.DoEvents
End Sub

并且进度条的.Minimum和.Maximum必须设置在Session.GetFiles之前。

但是不要那样做！这是错误的做法。

而且，您仍然需要按照上述正确解决方案中的相同方式禁用 forms/controls。

在 WinForm 的进度条上显示 WinSCP .NET 程序集传输进度

Showing WinSCP .NET assembly transfer progress on WinForm's progress bar

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