Membuat Download Manager Di VBNET - Seperti Internet Download Manager

by viandwi 10.03 1 komentar VB.NET

 

Pernah berfikir untuk membuat sebuah Download Manager Seperti IDM atau lainya? Dan disini lah tempat anda beljar membuat aplikasi seperti itu. Di artikel kali ini aku akan share tentang bagaimana cara membuat sebuah Download Manager menggunakan VB.NET . Kecepat download filenya pun saya coba sudah lumayan bagus dan hampir sama dengan download manager di firefox atau di crome. untuk membuatnya ikuti langkah berikut :

1] Buat Sebuah Project Baru
Buat project di Visual Studio mu dengan cara  menekan menu File > New Project. atau anda bisa meneruskan project mu yang lain dengan cara File > Open Project lalu ke Project > New Windows Form.

2] Tata Letak Form

Gunakan tata letak diatas sebagai tata letak desain form mu, list toolbox yang digunakan adalah :
*Label1 sampai Label6
*1 Textbox
* 1 Progress bar
*SaveFile Dialog
*Background Worker
* 2 Button
semua componet dengan properti : Name => Default


3] Masukan Code
klik 2 kali pada area form atau klik kanan lalu "View Code". masukan code berikut :

Imports System.Net

Public Class Form1

    Dim wheretosave As String ''Where the program save the file

    Delegate Sub DownloadComplateSafe(ByVal cancelled As Boolean)

    Delegate Sub ChangeTextSafe(ByVal lenght As Long, ByVal position As Integer, ByVal percent As Integer, ByVal speed As Double)

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load

        Label6.Text = ""

    End Sub

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

        If Me.TextBox1.Text <> "" AndAlso Me.TextBox1.Text.StartsWith("http://") Then

            'we will create the save file dialog here

            Me.SaveFileDialog1.FileName = Me.TextBox1.Text.Split("/"c)(Me.TextBox1.Text.Split("/"c).Length - 1)

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

                Me.wheretosave = Me.SaveFileDialog1.FileName

                Me.SaveFileDialog1.FileName = ""

                Label3.Text = "Save to : " & Me.wheretosave

                Me.TextBox1.Enabled = False

                Me.Button1.Enabled = False

                Me.Button2.Enabled = True

                Me.BackgroundWorker1.RunWorkerAsync() ' start our download

            End If

        Else

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

        End If

    End Sub

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

        ' creating the request and getting the response

        Dim theResponse As HttpWebResponse

        Dim theRequest As HttpWebRequest

        Try 'check if the file is exist

            theRequest = WebRequest.Create(Me.TextBox1.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.Warning)

            'we will create the delegate here

            ' just wait fo a moment

            Dim cancelDelegate As New DownloadComplateSafe(AddressOf DownloadComplate)

            Me.Invoke(cancelDelegate, True)

            Exit Sub

        End Try

        Dim lenght As Long = theResponse.ContentLength 'Size of the response (in bytes)

        ' we will create the functions for update the informations

        ' just wait for a moment

        Dim safedelegate As New ChangeTextSafe(AddressOf ChangeText)

        Me.Invoke(safedelegate, lenght, 0, 0, 0)

        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) / lenght

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

            ' sorry for it, just replace the variable speed to double

            ' lets try it again

            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 DownloadComplateSafe(AddressOf DownloadComplate)

            Me.Invoke(canceldelegate, True)

            Exit Sub

        End If

        Dim complatedelegate As New DownloadComplateSafe(AddressOf DownloadComplate)

        Me.Invoke(complatedelegate, False)

    End Sub

    Public Sub ChangeText(ByVal lenght As Long, ByVal position As Integer, ByVal percent As Integer, ByVal speed As Double)

        Me.Label4.Text = "File Size: " & Math.Round((lenght / 1024), 2) & " KB"

        Me.Label2.Text = "Downloading: " & Me.TextBox1.Text

        Me.Label6.Text = "Downloaded " & Math.Round((position / 1024), 2) & " KB OF " & Math.Round((lenght / 1024), 2) & " KB (" & ProgressBar1.Value & " %) "

        If speed = -1 Then

            Me.Label5.Text = "Speed : Calculating ..."

        Else

            Me.Label5.Text = "Speed : " & Math.Round((speed / 1024), 2) & " KB/s"

        End If

        Me.ProgressBar1.Value = percent

    End Sub

    Public Sub DownloadComplate(ByVal cancelled As Boolean)

        Me.TextBox1.Enabled = True

        Me.Button1.Enabled = True

        Me.Button2.Enabled = False

        If cancelled Then

            Label6.Text = "Cancelled"

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

        Else

            Label6.Text = "Download Successfully"

            MessageBox.Show("Donload Complated", "All Ok", MessageBoxButtons.OK, MessageBoxIcon.Information)

        End If

        Me.ProgressBar1.Value = 0

        Me.Label2.Text = "Downloading :"

        Me.Label3.Text = "Safe to :"

        Me.Label4.Text = "File Size :"

        Me.Label5.Text = "Download Speed :"

        Me.Label6.Text = ""

    End Sub

    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click

        Me.BackgroundWorker1.CancelAsync() ' its for send cancel request

        ' lets try it

    End Sub

End Class

4] Lakukan uji coba

tekan F5 utun melakukan Start Debug.

Jika ada yang ditanyaka silahkan di komentar atau kontak saya.

viandwicyber@gmail.com

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