Visual Basic e.TotalBytesToReceive始终给出-1

问题描述

您好，我已经制作了一个可以工作的FTP下载器，但是我想在下载文件之前先获取文件大小.我使用e.TotalBytesToReceive，但它始终为我提供-1的值，而e.bytesrecived的效果很好. (我将使用这两个值来制作进度条).这是我的代码:

Hi I have made a working FTP downloader, but I want to get file size before downloading the file. I use e.TotalBytesToReceive but it always gives me the value of -1, while e.bytesrecived works very good . (I will use these 2 values to make a progressbar). Here is my code:

Imports System.Net

Public Class Download

    WithEvents WebIllyria As New Net.WebClient 'WithEvents WebClient As New Net.WebClient

    Private Sub Download_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim Uri As New Uri("ftp://[email protected]/illyria.exe")
        Try

            WebIllyria.Credentials = New Net.NetworkCredential("username", "password")
            WebIllyria.DownloadFileAsync(Uri, "c:\illyria.exe")

        Catch ex As Exception

            MsgBox(ex.ToString)
        End Try
    End Sub

    Private Sub WebIllyria_DownloadProgressChanged(ByVal sender As Object, ByVal e As System.Net.DownloadProgressChangedEventArgs) Handles WebIllyria.DownloadProgressChanged
        ProgressDownload.Value = e.ProgressPercentage
        Label4.Text = e.TotalBytesToReceive
        Label3.Text = e.BytesReceived
        Label2.Text = e.ProgressPercentage & "%"
        If ProgressDownload.Value = 100 Then
            MessageBox.Show("Download Completed!!")
            Label2.Text = "..."
        End If
    End Sub
End Class

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