Snippet

Příklad jednoduchého stahovacího programu

Přidáno: 29.10.2008 Kategorie: VB.NET - Sítě Autor: Petr Mánek

Prvky:
- ProgressBar1 - klasický progressbar ukazující postup procesu
- TextBox1 - textbox obsahující URL stahovaného souboru
- Button1 - tlačítko Stáhnout
- Label2 - ukazuje rychlost stahování
- Label4 - ukazuje zbývající čas
- Timer1 - interval 1 sekunda - disabled

    Dim WithEvents webcl As New WebClient()
    Dim minule As Long
    Dim stazeno As Long
    Dim celkem As Long

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Try
            Timer1.Start()
            If Not IO.Directory.Exists(Application.StartupPath + "\Staženo") Then IO.Directory.CreateDirectory(Application.StartupPath + "\Staženo")
            webcl.DownloadFileAsync(New Uri(TextBox1.Text), Application.StartupPath + "\Staženo\" + IO.Path.GetFileName(TextBox1.Text))
        Catch ex As Exception : MsgBox("Nelze stáhnout soubor" + ControlChars.NewLine + ex.ToString, MsgBoxStyle.Exclamation, "Chyba")
        End Try
    End Sub

    Private Sub webcl_DownloadFileCompleted(ByVal sender As Object, ByVal e As System.ComponentModel.AsyncCompletedEventArgs) Handles webcl.DownloadFileCompleted
        Timer1.Stop()
        ProgressBar1.Value = 0
        Label2.Text = ""
        Label4.Text = ""
        MsgBox("Stahování dokončeno", MsgBoxStyle.Information, "Informace")
    End Sub

    Private Sub webcl_DownloadProgressChanged(ByVal sender As Object, ByVal e As System.Net.DownloadProgressChangedEventArgs) Handles webcl.DownloadProgressChanged
        stazeno = e.BytesReceived
        celkem = e.TotalBytesToReceive
        ProgressBar1.Value = e.ProgressPercentage
    End Sub

    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        Dim navic As Long = (stazeno / 1024) - (minule / 1024)
        Dim zbyva As Long = (celkem / 1024) - (stazeno / 1024)
        Dim tspan As TimeSpan = TimeSpan.FromSeconds(zbyva / navic)

        Label2.Text = navic.ToString + " kB/s"
        Label4.Text = Math.Floor(tspan.TotalHours).ToString + ":" + Microsoft.VisualBasic.Right("00" + tspan.Minutes.ToString, 2) + ":" + Microsoft.VisualBasic.Right("00" + tspan.Seconds.ToString, 2)
        minule = stazeno
    End Sub