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：
<![CDATA[<%@ page language="vb" codebehind="geturl.<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>x.vb” autoeventwireup=”false” inherits=”<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>xweb.geturl” %><br />
<html><br />
<head><br />
<meta http-equiv="content-type" content="text/html; charset=gb2312"><br />
</head><br />
<body></p>
<form id="form1" method="post" runat="server">
<p>
<<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:label id=”label1″ runat=”server”></<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:label><br />
<<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:textbox id=”urltextbox” runat=”server” width=”336px”><br />
http://lucky_elove.www1.dotnetplayground.com/<br />
</<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:textbox><br />
<<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:button onclick=”scrapebutton_click” id=”scrapebutton” runat=”server”></<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:button>
</p>
<hr width="100%" size="1">
<p>
<<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:label id=”tipresult” runat=”server”></<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:label><br />
<<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:textbox id=”resultlabel” runat=”server” textmode=”multiline”<br />
width=”100%” height=”400″></<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:textbox>
</p>
</form>
<p></body><br />
</html> ]]>
后代码geturl.aspx.vb如下：
<(?!mailto\:)(?>foundanchor>[^””>]+?)[^>]*?\>”, _<br />
regexoptions.multiline or regexoptions.ignorecase or regexoptions.ignorepatternwhitespace)</p>
<p> dim newwebpage as string = linksexpression.replace(webpage, mydelegate)</p>
<p> tipresult.text = “</p>
<h2>从 ” & urltextbox.text & “分离出的href链接</h2>
<p>” & _<br />
“<b>找到并整理” & countofmatches.tostring() & ” 个链接</b></p>
<p>” & _<br />
report.tostring().replace(environment.newline, “<br />“)<br />
tipresult.text &= “</p>
<h2>整理过的页面</h2>
<p><script>window.document.title=抓取网页中的链接</script>”<br />
resultlabel.text = newwebpage<br />
end sub</p>
<p> public function matchhandler(byval m as match) as string<br />
dim link as string = m.groups(“foundanchor”).value<br />
dim rtol as new regex(“^”, regexoptions.multiline or regexoptions.righttoleft)<br />
dim col, row as int32<br />
dim linebegin as int32 = rtol.match(webpage, m.index).index</p>
<p> row = rtol.matches(webpage, m.index).count<br />
col = m.index – linebegin</p>
<p> report.appendformat( _<br />
“link <b>{0}</b>, fixed at row: {1}, col: {2}{3}”, _<br />
server.htmlencode(m.groups(0).value), _<br />
row, _<br />
col, _<br />
environment.newline _<br />
)<br />
dim newlink as string<br />
if link.startswith(“/”) then<br />
newlink = link.substring(1)<br />
else<br />
newlink = link<br />
end if</p>
<p> countofmatches += 1<br />
return m.groups(0).value.replace(link, newlink)<br />
end function</p>
<p> private function graburl() as string<br />
dim wc as new webclient()<br />
dim s as stream = wc.openread(urltextbox.text)<br />
dim sr as streamreader = new streamreader(s, system.text.encoding.default)<br />
graburl = sr.readtoend<br />
s.close()<br />
wc.dispose()<br />
end function</p>
<p>end class<br />
]]>
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抓取网页中的链接-.NET教程,Asp.Net开发
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