Visual Basic 2010 Downloading a file With Progress Bar

Question

Is there any way in Visual Basic 2010 that I can download a file to a specific location, with a progress bar showing how much of the file has downloaded.

Answer 1

Hi,

yes it's possible. The question is in which way do you want download a file. Through http or ftp.

You can get the filsize before the download start. The maximum value of progressbar would be the filesize in kb / mb or gb. To show the progress you can check every second how much mb are downloaded and add it as value to the value property.

 

With this method you can show a download progress.

Regards

martinwy

Answer 2

I would like to download the file through HTTP. Currently, I use the System.Net.WebClient method to download data (strings, small bits of info etc.). What method can I use that will download the file in a way that I can detect how much has been downloaded?

Answer 3

here is an example from codeproject.  i haven't tried it yet

Imports System.Net
Public Class mainForm

  Dim whereToSave As String 'Where the program save the file

  Delegate Sub ChangeTextsSafe(ByVal length As Long, ByVal position As Integer, ByVal percent As Integer, ByVal speed As Double)
  Delegate Sub DownloadCompleteSafe(ByVal cancelled As Boolean)

  Public Sub DownloadComplete(ByVal cancelled As Boolean)
    Me.txtFileName.Enabled = True
    Me.btnDownload.Enabled = True
    Me.btnCancel.Enabled = False

    If cancelled Then

      Me.Label4.Text = "Cancelled"

      MessageBox.Show("Download aborted", "Aborted", MessageBoxButtons.OK, MessageBoxIcon.Information)


    Else
      Me.Label4.Text = "Successfully downloaded"

      MessageBox.Show("Successfully downloaded!", "All OK", MessageBoxButtons.OK, MessageBoxIcon.Information)


    End If

    Me.ProgressBar1.Value = 0
    Me.Label5.Text = "Downloading: "
    Me.Label6.Text = "Save to: "
    Me.Label3.Text = "File size: "
    Me.Label2.Text = "Download speed: "
    Me.Label4.Text = ""

  End Sub

  Public Sub ChangeTexts(ByVal length As Long, ByVal position As Integer, ByVal percent As Integer, ByVal speed As Double)

    Me.Label3.Text = "File Size: " & Math.Round((length / 1024), 2) & " KB"

    Me.Label5.Text = "Downloading: " & Me.txtFileName.Text

    Me.Label4.Text = "Downloaded " & Math.Round((position / 1024), 2) & " KB of " & Math.Round((length / 1024), 2) & "KB (" & Me.ProgressBar1.Value & "%)"

    If speed = -1 Then
      Me.Label2.Text = "Speed: calculating..."
    Else
      Me.Label2.Text = "Speed: " & Math.Round((speed / 1024), 2) & " KB/s"
    End If

    Me.ProgressBar1.Value = percent


  End Sub

  Private Sub btnDownload_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDownload.Click

    If Me.txtFileName.Text <> "" AndAlso Me.txtFileName.Text.StartsWith("http://") Then


      Me.SaveFileDialog1.FileName = Me.txtFileName.Text.Split("/"c)(Me.txtFileName.Text.Split("/"c).Length - 1)

      If Me.SaveFileDialog1.ShowDialog = Windows.Forms.DialogResult.OK Then

        Me.whereToSave = Me.SaveFileDialog1.FileName

        Me.SaveFileDialog1.FileName = ""

        Me.Label6.Text = "Save to: " & Me.whereToSave

        Me.txtFileName.Enabled = False
        Me.btnDownload.Enabled = False
        Me.btnCancel.Enabled = True

        Me.BackgroundWorker1.RunWorkerAsync() 'Start download

      End If

    Else

      MessageBox.Show("Please insert valid URL for download", "Warning", MessageBoxButtons.OK, MessageBoxIcon.Warning)

    End If

  End Sub

  Private Sub BackgroundWorker1_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork

    'Creating the request and getting the response
    Dim theResponse As HttpWebResponse
    Dim theRequest As HttpWebRequest
    Try 'Checks if the file exist

      theRequest = WebRequest.Create(Me.txtFileName.Text)
      theResponse = theRequest.GetResponse
    Catch ex As Exception

      MessageBox.Show("An error occurred while downloading file. Possibe causes:" & ControlChars.CrLf & _
              "1) File doesn't exist" & ControlChars.CrLf & _
              "2) Remote server error", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)

      Dim cancelDelegate As New DownloadCompleteSafe(AddressOf DownloadComplete)

      Me.Invoke(cancelDelegate, True)

      Exit Sub
    End Try
    Dim length As Long = theResponse.ContentLength 'Size of the response (in bytes)

    Dim safedelegate As New ChangeTextsSafe(AddressOf ChangeTexts)
    Me.Invoke(safedelegate, length, 0, 0, 0) 'Invoke the TreadsafeDelegate

    Dim writeStream As New IO.FileStream(Me.whereToSave, IO.FileMode.Create)

    'Replacement for Stream.Position (webResponse stream doesn't support seek)
    Dim nRead As Integer

    'To calculate the download speed
    Dim speedtimer As New Stopwatch
    Dim currentspeed As Double = -1
    Dim readings As Integer = 0

    Do

      If BackgroundWorker1.CancellationPending Then 'If user abort download
        Exit Do
      End If

      speedtimer.Start()

      Dim readBytes(4095) As Byte
      Dim bytesread As Integer = theResponse.GetResponseStream.Read(readBytes, 0, 4096)

      nRead += bytesread
      Dim percent As Short = (nRead * 100) / length

      Me.Invoke(safedelegate, length, nRead, percent, currentspeed)

      If bytesread = 0 Then Exit Do

      writeStream.Write(readBytes, 0, bytesread)

      speedtimer.Stop()

      readings += 1
      If readings >= 5 Then 'For increase precision, the speed it's calculated only every five cicles
        currentspeed = 20480 / (speedtimer.ElapsedMilliseconds / 1000)
        speedtimer.Reset()
        readings = 0
      End If
    Loop

    'Close the streams
    theResponse.GetResponseStream.Close()
    writeStream.Close()

    If Me.BackgroundWorker1.CancellationPending Then

      IO.File.Delete(Me.whereToSave)

      Dim cancelDelegate As New DownloadCompleteSafe(AddressOf DownloadComplete)

      Me.Invoke(cancelDelegate, True)

      Exit Sub

    End If

    Dim completeDelegate As New DownloadCompleteSafe(AddressOf DownloadComplete)

    Me.Invoke(completeDelegate, False)

  End Sub

  Private Sub mainForm_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    Me.Label4.Text = ""
  End Sub

  Private Sub btnCancel_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCancel.Click
    Me.BackgroundWorker1.CancelAsync() 'Send cancel request
  End Sub

  Private Sub LinkLabel1_LinkClicked(ByVal sender As System.Object, ByVal e As System.Windows.Forms.LinkLabelLinkClickedEventArgs) Handles LinkLabel1.LinkClicked
    MessageBox.Show("Created by Carmine_XX (www.thetotalsite.it)" & ControlChars.CrLf & "To report bugs/suggestions/comments please contact me by email: [e-mail] or in the project page on CodeProject.com", "About", MessageBoxButtons.OK, MessageBoxIcon.Information)
  End Sub
End Class

 

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Answer 4

Hi,

okay.I have some code for you. With it you can get the headerinformation of a file. 

  Public Function getHttpHeaderfromFile(ByVal server As String, ByVal _
   filepath As String) As String
 
    Dim tcpClient As New Sockets.TcpClient
    Dim ipAddress As Net.IPAddress = Dns.GetHostEntry(server).AddressList(0)
 
    Dim ascii As Encoding = Encoding.ASCII
 
    Dim request As String = "HEAD " + filepath + " HTTP/1.1" + _
     ControlChars.Cr + ControlChars.Lf + _
                "Host: " + server + ControlChars.Cr + _
                ControlChars.Lf + _
                "Accept: */*" + ControlChars.Cr + _
                ControlChars.Lf + _
                "Connection: close" + ControlChars.Cr + _
                ControlChars.Lf + ControlChars.Cr + _
                ControlChars.Lf
 
    Dim bytesSent As [Byte]() = ascii.GetBytes(request)
 
    tcpClient.Connect(ipAddress, 80)
 
    tcpClient.Client.Send(bytesSent, bytesSent.Length, 0)
 
    Dim bytes As Int32
    Dim bytesReceived(255) As [Byte]
    Dim receivedString As [String] = ""
 
    Do
      bytes = tcpClient.Client.Receive(bytesReceived, _
       bytesReceived.Length, 0)
      receivedString = receivedString + Encoding.ASCII.GetString( _
      bytesReceived, 0, bytes)
    Loop While bytes > 0
 
    Return receivedString.ToString
 
  End Function

There you can check any information and look at the filesize.

Regards

martinwy

Answer 5

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

    downloadFile("http://www.website.com/file.dat", "C:\downloads\file.dat")

  End Sub

  Private Sub downloadFile(ByVal srcPath As String, ByVal destPath As String)

    Dim wClient As New System.Net.WebClient()
    AddHandler wClient.DownloadProgressChanged, AddressOf downloadFile_ProgressChanged

    wClient.DownloadFileAsync(New System.Uri(srcPath), destPath)

  End Sub

  Private Sub downloadFile_ProgressChanged(ByVal sender As Object, ByVal e As System.Net.DownloadProgressChangedEventArgs)
    ProgressBar1.Maximum = e.TotalBytesToReceive
    ProgressBar1.Value = e.BytesReceived
    Application.DoEvents()
    If e.ProgressPercentage = 100 Then
      'download completed
    End If
  End Sub

---

Thanks

"Feel the Force !"  | My blog

Answer 6

Imports System.Net
Public Class Form1
  Dim WithEvents WC As New WebClient
  Private Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button1.Click
    WC.DownloadFileAsync(New Uri("http://johnweinhold.com/Documents/DSVideoEditor.zip"), "DownloadedFile.zip")
  End Sub
  Private Sub WC_DownloadProgressChanged(ByVal sender As Object, ByVal e As DownloadProgressChangedEventArgs) Handles WC.DownloadProgressChanged
    ProgressBar1.Value = e.ProgressPercentage
  End Sub
End Class

Answer 7

This gave me a Error that

"An unhandled exception of type 'System.NullReferenceException' occurred in <project-name>.exe"

Why is that

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0xeddie21847nc2012ol11i

I'm using VS2012

Answer 8

Really thx sir , it worked 100% fine :)

Answer 9

Try this

Imports System.Net

Private Sub cmdsave_Click(sender As Object, e As EventArgs) Handles cmdsave.Click        SaveFileDialog1.Filter=".jpg|*.jpg|.exe|*.exe|.zip|*.zip|.rar|*.rar|.png|*.png|.gif|*.gif|.mp4|*.mp4|.iso|*.iso|.mp3|*.mp3|.dotx|*.dotx"
        SaveFileDialog1.ShowDialog()
        TextBox2.Text = SaveFileDialog1.FileName
    End Sub
    Public WithEvents download As WebClient
    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
        download = New WebClient
        download.DownloadFileAsync(New Uri(TextBox1.Text), TextBox2.Text)
    End Sub

    Private Sub download_downloadProgressChanged(sender As Object, e As DownloadProgressChangedEventArgs) Handles download.DownloadProgressChanged
        ProgressBar1.Value = e.ProgressPercentage

    End Sub                    'Hope This helps