How to download multiple URLs at the same time? - vb.net

Question

Public Class Form1
For i As Integer = 0 To RichTextBox1.Lines.Length - 1
wreq=System.Net.WebRequest.Create("i th Internet address")
wreq.AutomaticDecompression = Net.DecompressionMethods.GZip
wres = wreq.GetResponse
Dim s As System.IO.Stream = wres.GetResponseStream
Dim sr As New System.IO.StreamReader(s)
html = sr.ReadToEnd
s = html.Split(";")
'here is other codes
Next
End Class
this is part of my program.
When I use this, it takes a long time for everyone to download. How can I download all the addresses at the same time?
I found the following code on the internet enter code here to do this, but I do not know how to use it in the my program. Please help. Thank you.
Imports System.Threading.Tasks
Imports System.Net
Imports System.IO
Public Class Form1
Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
'Start a background task so as not to freeze up the UI.
Me.BackgroundWorker1.RunWorkerAsync()
End Sub
Private Sub BackgroundWorker1_DoWork(sender As System.Object, e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
Dim files As String() 'Get file paths.
'Download multiple files simultaneously.
Parallel.ForEach(files,
Sub(f) Call New WebClient().DownloadFile(f,
Path.Combine("local folder here",
Path.GetFileName(f))))
End Sub
Private Sub BackgroundWorker1_RunWorkerCompleted(sender As Object, e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles BackgroundWorker1.RunWorkerCompleted
MessageBox.Show("All files downloaded")
End Sub
End Class

Answer 1

Take a look on this. Might be a good start (part of your code implemented on each method).
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim urls() As String = RichTextBox1.Lines.Select(Function(url) Trim(url))
Parallel.ForEach(urls, Sub(f)
If Not String.IsNullOrEmpty(f) Then
DownloadAsync(f)
End If
End Sub)
End Sub
Function DownloadAsync(URL As String) As Task(Of Boolean)
Try
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12
Dim html As String = ""
Dim result As Boolean
Dim request As HttpWebRequest = HttpWebRequest.Create(URL)
request.AutomaticDecompression = DecompressionMethods.GZip
request.Timeout = 500
request.Method = "GET"
request.UserAgent = "Mozilla/5.0 (Macintosh; Intel Mac OS X x.y; rv:42.0) Gecko/20100101 Firefox/42.0"
Using response As Task(Of WebResponse) = request.GetResponseAsync
If response.Result IsNot Nothing Then
Using ioStream As IO.Stream = response.Result.GetResponseStream
Using sr As New System.IO.StreamReader(ioStream)
html = sr.ReadToEnd
Dim s() As String = html.Split(";"c)
For Each sl In s
Debug.WriteLine(sl)
Next
End Using
result = True
End Using
End If
End Using
Return Task.FromResult(result)
Catch ex As Exception
Debug.WriteLine(ex.Message)
End Try
Return Task.FromResult(False)
End Function