使用VB.net通过拖放上传多个文件到FTP服务器时出现问题

Question

我正在尝试通过拖放将多个文件添加到 FTP 服务器，我可以使用 try catch 块来做到这一点，如果我们正确地提供了 ftp 设置，则上传它们需要 1 秒，但是当我们提供错误的详细信息时挂断并且不给我任何错误消息，但如果我给出一个异常消息。

现在，我添加的每个文件都会收到错误消息和成功消息。我不希望这种情况发生。

谁能告诉我应该在哪里发送成功和失败的消息，以便上传需要​​几秒钟，如果没有应该立即给我一条消息。

我完全不知道我哪里出错了。

任何帮助将不胜感激！

这是我的代码：

Private Sub uploadFile(ByVal FTPAddress As String, ByVal filePath As String, ByVal username As String, ByVal password As String) 'Create FTP request

    Try
        Dim request As FtpWebRequest = DirectCast(FtpWebRequest.Create(FTPAddress & "/" & Path.GetFileName(filePath)), FtpWebRequest)

        request.Method = WebRequestMethods.Ftp.UploadFile
        request.Credentials = New NetworkCredential(username, password)
        request.UsePassive = True
        request.UseBinary = True
        request.KeepAlive = False

        Dim buffer As Byte() = Nothing
        'Load the file
        Using stream As FileStream = File.OpenRead(filePath)
            buffer = New Byte(CInt(stream.Length - 1)) {}
            stream.Read(buffer, 0, buffer.Length)
        End Using

        'Upload file
        Using reqStream As Stream = request.GetRequestStream()
            reqStream.Write(buffer, 0, buffer.Length)
        End Using

        MsgBox("Uploaded Successfully", MsgBoxStyle.Information)
    Catch
       MsgBox("Failed to upload.Please check the ftp settings", MsgBoxStyle.Critical)
    End Try
End Sub

这是拖放的代码

 Private Sub FlowLayoutPanel1_DragDrop(ByVal sender As Object, ByVal e As System.Windows.Forms.DragEventArgs) Handles FlowLayoutPanel1.DragDrop
    Try

        Dim Files As String() = CType(e.Data.GetData(DataFormats.FileDrop), String())

        For Each FileName As String In Files
                           Dim Extension As String = Path.GetExtension(FileName).ToLower
            If Array.IndexOf(SupportedExtensions, Extension) <> -1 Then
                uploadFile(txtFTPAddress.Text, FileName, txtUsername.Text, txtPassword.Text)

            End If

        Next
    Catch

    End Try

End Sub

Answer 1

由于每次加载文件时都会调用uploadFile，因此您可能希望将错误处理代码从该方法移至dragDrop 方法。这样，您将只收到一条消息，说明整个操作成功或失败。您还可以在 FtpWebRequest 上设置 Timeout 属性，以在上传时间超过几秒时取消上传。

那么uploadFile就变成了：

Private Sub uploadFile(ByVal FTPAddress As String, ByVal filePath As String, ByVal username As String, ByVal password As String) 'Create FTP request
    Dim request as FtpWebRequest = ...
    request.Timeout = 5000 ' Set timeout to 5 seconds
    '... several lines omitted
    'Upload file
    Using reqStream As Stream = request.GetRequestStream()
        reqStream.Write(buffer, 0, buffer.Length)
    End Using
End Sub

然后您可以将错误处理代码移动到处理拖放的方法中：

Private Sub FlowLayoutPanel1_DragDrop(ByVal sender As Object, ByVal e As  
    System.Windows.Forms.DragEventArgs) Handles FlowLayoutPanel1.DragDrop
    Try
       ' ... several lines omitted
       Next
       MsgBox("Uploaded Successfully", MsgBoxStyle.Information)
    Catch
       MsgBox("Failed to upload.Please check the ftp settings", MsgBoxStyle.Critical)
    End Try
End Sub