前往顾页
以后地位: 主页 > 收集编程 > .Net实例教程 >

实现抓取网页中的链接法度代码

时候:2011-05-31 20:01来源:知行网www.zhixing123.cn 编辑:麦田守望者

输入一个地点,便可以把阿谁网页中的链接提取出来,下面这段代码可以轻松实现,首要的是用到了正则表达式。

GetUrl.aspx代码以下:
<%@ Page Language="vb" CodeBehind="GetUrl.aspx.vb" AutoEventWireup="false" Inherits="aspxWeb.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/
</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以下:
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
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 窗体设想器天生的代码 "

'该调用是 Web 窗体设想器所必须的。
<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
'CODEGEN: 此体例调用是 Web 窗体设想器所必须的
'不要利用代码编辑器点窜它。
InitializeComponent()
End Sub

#End Region

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
'在此处安排初始化页的用户代码
Label1.Text = "请输入一个URL地点:"
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)
webPage = GrabUrl()
Dim myDelegate As New MatchEvaluator(AddressOf MatchHandler)

Dim linksExpression As New Regex( _
"\<a.+?href=['""](?!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>找到并清算" & countOfMatches.ToString() & " 个链接</b><br><br>" & _
report.ToString().Replace(Environment.NewLine, "<br>")
TipResult.Text &= "<h2>清算过的页面</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
col = m.Index - lineBegin

report.AppendFormat( _
"Link <b>{0}</b>, fixed at row: {1}, col: {2}{3}", _
Server.HtmlEncode(m.Groups(0).Value), _
row, _
col, _
Environment.NewLine _
)
Dim newLink As String
If link.StartsWith("/") Then
newLink = link.Substring(1)
Else
newLink = link
End If

countOfMatches += 1
Return m.Groups(0).Value.Replace(link, newLink)
End Function

Private Function GrabUrl() As String
Dim wc As New WebClient()
Dim s As Stream = wc.OpenRead(urlTextBox.Text)
Dim sr As StreamReader = New StreamReader(s, System.Text.Encoding.Default)
GrabUrl = sr.ReadToEnd
s.Close()
wc.Dispose()
End Function

End Class
 

------分开线----------------------------
标签(Tag):C# C#实例教程 c#根本教程 C#源代码
------分开线----------------------------
保举内容
猜你感兴趣