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ASP.NET实现抓取网页中的链接

[ 来源:www.it55.com | 作者: | 时间:2007-07-14 | 收藏 | 推荐 ] 【大中小】

    输入一个地址，就可以把那个网页中的链接提取出来，下面这段代码可以轻松实现，主要的是用到了正则表达式。

  GetUrl.ASPx代码如下：

  <%@ Page Language="<a href="http://dev.21tx.com/language/vb/" target="_blank">VB</a>" CodeBehind="GetUrl.aspx.vb" AutoEventWireup="false" Inherits="aspx<a href="http://dev.21tx.com/web/" target="_blank">Web</a>.GetUrl" %>
  <html>
  <head>
  <META http-equiv="content-type" content="text/html; charset=gb2312">
  </head>
  <body>
  <form id="Form1" method="post" runat="server">
   <P>
   <asp:Label id="Label1" runat="server"></asp:Label>
   <asp:TextBox id="urlTextBox" runat="server" Width="336px">
   http://lucky_elove.www1.dotnetplayground.com/

http://www.it55.com/

   </asp:TextBox>
   <asp:Button OnClick="scrapeButton_Click" id="scrapeButton" runat="server"></asp:Button>
   </P>
   <HR width="100%" SIZE="1">
   <P>
   <asp:Label id="TipResult" runat="server"></asp:Label>
   <asp:TextBox id="resultLabel" runat="server" TextMode="MultiLine"
   Width="100%" Height="400"></asp:TextBox>
   </P>
  </form>
  </body>
  </html>
  后代码GetUrl.aspx.vb如下：

  Imports System.IO
  Imports System.Net
  Imports System.Text
  Imports System.Text.RegularExpressions
  Imports System

  Public Class GetUrl
   Inherits System.Web.UI.Page
   Protected WithEvents Label1 As System.Web.UI.WebControls.Label

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   Protected WithEvents urlTextBox As System.Web.UI.WebControls.TextBox
   Protected WithEvents scrapeButton As System.Web.UI.WebControls.Button
   Protected WithEvents TipResult As System.Web.UI.WebControls.Label
   Protected WithEvents resultLabel As System.Web.UI.WebControls.TextBox

  #Region " Web 窗体设计器生成的代码 "

   '该调用是 Web 窗体设计器所必需的。
   <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()

   End Sub

   Private Sub Page_Init(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Init IT资讯之家 www.it55.com
   'CODEGEN: 此方法调用是 Web 窗体设计器所必需的
   '不要使用代码编辑器修改它。
   InitializeComponent()
   End Sub

  #End Region

   Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
   '在此处放置初始化页的用户代码
   Label1.Text = "请输入一个URL地址："
   scrapeButton.Text = "分离Href链接"
   End Sub
   Private report As New StringBuilder()
   Private webPage As String
   Private countOfMatches As Int32

   Public Sub scrapeButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) http://www.it55.com/
   webPage = GrabUrl()
   Dim myDelegate As New MatchEvaluator(AddressOf MatchHandler)

   Dim linksExpression As New Regex( _
   "\<a.+?href=http://edu.iecool.com/show/['""](?!http\:\/\/)(?!mailto\:)(?>foundAnchor>[^'"">]+?)[^>]*?\>", _
   RegexOptions.Multiline Or RegexOptions.IgnoreCase Or RegexOptions.IgnorePatternWhitespace)

   Dim newWebPage As String = linksExpression.Replace(webPage, myDelegate)

   TipResult.Text = "<h2>从 " & urlTextBox.Text & "分离出的Href链接</h2>" & _
   "<b>找到并整理" & countOfMatches.ToString() & " 个链接</b><br><br>" & _
   report.ToString().Replace(Environment.NewLine, "<br>")

sflj www.it55.com kg^&fgd

   TipResult.Text &= "<h2>整理过的页面</h2><script>window.document.title='抓取网页中的链接'</script>"
   resultLabel.Text = newWebPage
   End Sub

   Public Function MatchHandler(ByVal m As Match) As String
   Dim link As String = m.Groups("foundAnchor").Value
   Dim rToL As New Regex("^", RegexOptions.Multiline Or RegexOptions.RightToLeft)
   Dim col, row As Int32
   Dim lineBegin As Int32 = rToL.Match(webPage, m.Index).Index

   row = rToL.Matches(webPage, m.Index).Count

（编辑：IT资讯之家 www.it55.com）