Hello
I need to write a small application to download web pages. I only need basic features, so I guess the WebClient object is good enough.
To avoid freezing the UI, I was thinking of using WebClient.DownloadStringAsync(), but dowloading must occur in the right order, while DownloadStringAsync() apparently will download pages in any order:
Do you know of a way to 1) download web pages in a specific order 2) in a way that won't freeze the UI?
Thank you.
I need to write a small application to download web pages. I only need basic features, so I guess the WebClient object is good enough.
To avoid freezing the UI, I was thinking of using WebClient.DownloadStringAsync(), but dowloading must occur in the right order, while DownloadStringAsync() apparently will download pages in any order:
Code:
Public Class Form1
Private Sub AlertStringDownloaded(ByVal sender As Object, ByVal e As DownloadStringCompletedEventArgs)
If e.Cancelled = False AndAlso e.Error Is Nothing Then
'Download web page, extract bit using regex, and write it to file
End If
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim theaters As New Dictionary(Of String, String)
theaters.Add("Theater1", "http://www.acme.com/1")
theaters.Add("Theater2", "http://www.acme.com/2")
'Must use async mode, or UI freezes
For Each kvp As KeyValuePair(Of String, String) In theaters
Dim webClient As New WebClient
AddHandler webClient.DownloadStringCompleted, AddressOf AlertStringDownloaded
webClient.Encoding = Encoding.UTF8
'IMPORTANT: How to make sure async download occurs in the expected order?
webClient.DownloadStringAsync(New Uri(kvp.Value))
Next
End Sub
End ClassThank you.