使用单独的线程将多个网页下载到一个公共的richtextbox [英] download multiple webpages using separate threads to a common richtextbox

问题描述

我想要的是使用多线程下载多个URL网页，并将每个页面的内容添加到类似的richtextbox.但是iam最后只将单线程内容多次添加到richtextbox中.我的代码是:

What i want is to download multiple url webpages using multi-threading and also add the content from each page to a similar richtextbox. But iam ending up with only single thread content being added multiple times into the richtextbox. My code is :

For i As Integer = 0 To ListBox1.Items.Count - 1
           dim t as new thread(addressof dwnld)
glblcnt = i
       Next

Public Sub dwnld()

        Dim result As String = String.Empty
      
        Dim txt As String = ""

        Dim request As HttpWebRequest = DirectCast(WebRequest.Create(ListBox1.Items(glblcnt).tostring, HttpWebRequest)

        request.Method = "GET"

        Using stream = request.GetResponse().GetResponseStream()
            Using reader = New StreamReader(stream, Encoding.UTF8)
                result = reader.ReadToEnd()
            End Using
        End Using

        Dim doc As New HtmlAgilityPack.HtmlDocument()

        doc.Load(New StringReader(result))

        Dim root As HtmlNode = doc.DocumentNode

        For Each link As HtmlNode In root.SelectNodes("//a")
            Dim att As String = link.InnerText.Trim
            txt = txt & att
        Next

        Me.settext(txt)

    End Sub

问题是我需要一种方法，将列表框中的不同url传递给每个线程，以下载不同的网页.然后，每个网页将经过相同的处理，然后将链接添加到Richtextbox.

信息:

settext方法是一个委托，其中线程将文本添加到richtextbox中-没问题

如果有人可以，请让我知道如何解决该问题，我将非常感激.

谢谢

the problem is that i need a way to pass different url from a listbox to each thread to download a different web page. Then each webpage will undergo same processing and then the links to be added to a richtextbox.

info :

settext method is a delegate where thread adds the text to the richtextbox - no problem with that

If anyone could please let me know how to correct the problem i would be very thankful.

Thanks

推荐答案

要将数据传递到线程中，您需要执行类似的操作

To pass data into the thread you need to do something similar

for Counter as integer = 0 to 100
 dim t as new thread(addressof FooBar)
 t.start(counter)
next

private sub FooBar(byval Value as integer)
 debug.print(value.tostring)
end sub

使用本文进一步阅读 ParameterizedThreadStart委托 [ ^ ]

use this article for further reading ParameterizedThreadStart Delegate[^]

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