在上传数据时显示进度

Question

我正在使用以下代码 这里 上传文件

Public Function UploadFile(ByVal oFile As FileInfo) As Boolean
Dim ftpRequest As FtpWebRequest
Dim ftpResponse As FtpWebResponse
Try
ftpRequest = CType(FtpWebRequest.Create(FTPSite + CurrentDirectory + oFile.Name), _
    FtpWebRequest)
ftpRequest.Method = WebRequestMethods.Ftp.UploadFile
ftpRequest.Proxy = Nothing
ftpRequest.UseBinary = True
ftpRequest.Credentials = New NetworkCredential(UserName, Password)
ftpRequest.KeepAlive = KeepAlive
ftpRequest.EnableSsl = UseSSL
If UseSSL Then ServicePointManager.ServerCertificateValidationCallback = _
    New RemoteCertificateValidationCallback(AddressOf ValidateServerCertificate)
Dim fileContents(oFile.Length) As Byte
Using fr As FileStream = oFile.OpenRead
fr.Read(fileContents, 0, Convert.ToInt32(oFile.Length))
End Using
Using writer As Stream = ftpRequest.GetRequestStream
writer.Write(fileContents, 0, fileContents.Length)
End Using
ftpResponse = CType(ftpRequest.GetResponse, FtpWebResponse)
ftpResponse.Close()
ftpRequest = Nothing
Return True
Catch ex As WebException
Return False
End Try
End Function

我想扩展它，因此我也可以上传进度。问题是我不知道从哪里开始。显示上传进度的“逻辑”是什么？

在预定义的零件中“拆分文件”并上传它们？

Answer 1

您需要在背景线程上执行上传请求，以避免阻止UI线程。最简单的方法是使用背景工作者类。它是专门为这种情况设计的。

    Dim backgroundWorker As New System.ComponentModel.BackgroundWorker()
    backgroundWorker.WorkerReportsProgress = True
    backgroundWorker.WorkerSupportsCancellation = True
    AddHandler backgroundWorker.DoWork, AddressOf Me.BackgroundFileDownload
    AddHandler backgroundWorker.ProgressChanged, AddressOf Me.ProgressChanged
    AddHandler backgroundWorker.RunWorkerCompleted, AddressOf Me.JobCompleted

事件进行了变化和RunWorkerComplet的内容在UI线程上运行，并允许您使用当前下载的状态相应地更新进度栏。他们看起来像这样：

Protected Sub ProgressChanged(ByVal sender As Object, ByVal e As ProgressChangedEventArgs)
        progressBar.Value = e.ProgressPercentage
End Sub

Dowork在背景线程上被调用，并且是您要实际调用您编写的uploadfile（）函数的地方。对于ftpwebrequest，您将要首先获取文件的大小，然后当您上传数据块时，将您在迄今为止上传的内容除以文件的完整大小以使一个百分比完成。就像是

Worker.ReportProgress(Math.Round((_bytesUploaded / _fileSize) * 100))

希望这可以帮助。

Answer 2

我不确定此代码是否在Windows表单或网页上运行，这会改变您实际显示进度的方式。但是无论哪种方式，您首先希望此方法报告有关它的进度的进度。

为此，最好的选择是使用事件。这是您需要添加到此类和功能的内容：

首先是持有百分比的班级：

Public Class ProgressEventArgs
    Inherits System.EventArgs

    Public Sub New(ByVal pPercentage As Decimal)
        _Percentage = pPercentage
    End Sub

    Private _Percentage As Decimal
    Public ReadOnly Property Percentage() As Decimal
        Get
            Return _Percentage
        End Get
    End Property

End Class

接下来，您需要在上载文件所属的类中添加一个事件：

Public Event Progress(ByVal sender As Object, ByRef e As ProgressEventArgs)

最终，UploadFile，您需要提出此活动：

....
writer.Write(fileContents, 0, blockread) 
    RaiseEvent Progress(Me, new ProgressEventArgs(100 * block / blocks))
Next
....

无论您从哪里打电话，您都可以收听活动：

Private Sub HandleProgress(ByVal sender As Object, ByRef e As ProgressEventArgs)
    '.... Update screen
End Sub

....
AddHandler YourUploadClass.Progress AddressOf HandleProgress