Download individual sequence

Hello!

I'm doing a small download manager, but I was stopped by a little problem xD
So I wanted to add all links to download in a listbox, and download them one at a time not all at once.

This is the code that has the problem NotSupportedException:

Code:

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    Private Sub down_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles down.Click
        download = New WebClient
        Dim save As String
        Dim ab As String
        save = urltxt.Text.Split("/"c)(urltxt.Text.Split("/"c).Length - 1)
        If urltxt.Text = "http://" Then
            MsgBox("Riempi l'url!!", MsgBoxStyle.Critical)
        Else
            For Each itm As String In ListBox1.Items
                download.DownloadFileAsync(New Uri(itm), brwtxt.Text + save)
            Next
        End If
    End Sub

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I said that does not support I / O operations simultaneously, but the problem is that I do not want to do any simultaneous action I just want you download the first link when finished proceed to the second, etc.

What's wrong? :sick:

That's not how that code will execute, it's going to just spawn a thread for each item and asynchronously download it. You need to handle when the file item finishes, then queue the next one. Right now you are queuing all of them at once.

Quote:

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Originally Posted by ForumAccount

That's not how that code will execute, it's going to just spawn a thread for each item and asynchronously download it. You need to handle when the file item finishes, then queue the next one. Right now you are queuing all of them at once.

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how should I do? I have to change everything?

I've attached a file called AsyncDownloadManager.vb that can handle this for you. The example code downloads some test/sample files to a directory at C:\test\downloads. The way you would use it is like so:

Code:

---

Imports System.ComponentModel

Public Class Form1

    '//fields
    Private WithEvents downloadManager As AsyncDownloadManager

    '//event handlers
    Private Sub Button1_Click(ByVal sender As System.Object, _
                              ByVal e As System.EventArgs) _
                              Handles Button1.Click

        Me.downloadManager = New AsyncDownloadManager()

        With Me.downloadManager

            '//queue an item, the order is the download order
            '//pass an uri or an address, and a file name
            .Queue("http://wordpress.org/extend/plugins/about/readme.txt", _
                  "C:\test\downloads\readme.txt")
            .Queue("http://www.catea.gatech.edu/grade/fs/10_CSS.pdf", _
                  "C:\test\downloads\10_CSS.pdf")
            .Queue("http://www.textfiles.com/hacking/homebank.txt", _
                  "C:\test\downloads\homebank.txt")
            .Queue("http://illiad.evms.edu/sample.pdf", _
                  "C:\test\downloads\sample.pdf")

            '//start async download
            .BeginDownload()
        End With

    End Sub

    Private Sub DownloadCompleted(ByVal sender As Object, _
                                  ByVal e As AsyncCompletedEventArgs) _
                                  Handles downloadManager.DownloadCompleted

        '//all files are done, clean up
        Me.downloadManager.Dispose()
        Me.downloadManager = Nothing
    End Sub

End Class

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This would be the extent of use. Everything else will be handled for you.

thanksssss :D