前言
大家应该都有所体会，很多时候在做网络爬虫的时候特别需要将爬虫搜索到的超链接进行处理，统一都改成绝对路径的，所以本文就写了一个正则表达式来对搜索到的链接进行处理。下面话不多说，来看看详细的介绍吧。
通常我们可能会搜索到如下的链接：
<!-- 空超链接 --><a href=""></a> <!-- 空白符 --><a href=" " rel="external nofollow" > </a><!-- a标签含有其它属性 --><a href="index.html" rel="external nofollow" rel="external nofollow" rel="external nofollow" alt="超链接"> index.html </a><a href="/" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" target="_blank"> / target="_blank" </a><a target="_blank" href="/" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" alt="超链接" > target="_blank" / alt="超链接" </a><a target="_blank" title="超链接" href="/" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" alt="超链接" > target="_blank" title="超链接" / alt="超链接" </a><!-- 根目录 --><a href="/" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" > / </a><a href="a" rel="external nofollow" > a </a><!-- 含参数 --><a href="/index.html?id=1" rel="external nofollow" > /index.html?id=1 </a><a href="?id=2" rel="external nofollow" > ?id=2 </a><!-- // --><a href="//index.html" rel="external nofollow" > //index.html </a><a href="//www.mafutian.net" rel="external nofollow" > //www.mafutian.net </a><!-- 站内链接 --><a href="http://www.hole_1.com/index.html" rel="external nofollow" > http://www.gaodaima.com/ </a><!-- 站外链接 --><a href="http://www.mafutian.net" rel="external nofollow" > http://www.gaodaima.com/ </a><a href="http://www.numberer.net" rel="external nofollow" > http://www.gaodaima.com/ </a><!-- 图片，文本文件格式的链接 --><a href="1.jpg" rel="external nofollow" > 1.jpg </a><a href="1.jpeg" rel="external nofollow" > 1.jpeg </a><a href="1.gif" rel="external nofollow" > 1.gif </a><a href="1.png" rel="external nofollow" > 1.png </a><a href="1.txt" rel="external nofollow" > 1.txt </a><!-- 普通链接 --><a href="index.html" rel="external nofollow" rel="external nofollow" rel="external nofollow" > index.html </a><a href="index.html" rel="external nofollow" rel="external nofollow" rel="external nofollow" > index.html </a><a href="./index.html" rel="external nofollow" > ./index.html </a><a href="../index.html" rel="external nofollow" > ../index.html </a><a href=".../" rel="external nofollow" > .../ </a><a href="..." rel="external nofollow" > ... </a><!-- 非链接，含有链接冒号 --> <a href="javascript:void(0)" rel="external nofollow" > javascript:void(0) </a><a href="a:b" rel="external nofollow" > a:b </a><a href="/a#a:b" rel=&qu<mark>（本文来）源gaodaimacom搞#^代%!码&网(</mark><pre>搞gaodaima代码
ot;external nofollow" > /a#a:b </a><a href="mailto:'[email protected]'" rel="external nofollow" > mailto:'[email protected]' </a><a href="/tencent://message/?uin=335134463" rel="external nofollow" > /tencent://message/?uin=335134463 </a> <!– 相对路径 –><a href="." rel="external nofollow" > . </a><a href=".." rel="external nofollow" > .. </a><a href="../" rel="external nofollow" > ../ </a><a href="/a/b/.." rel="external nofollow" > /a/b/.. </a><a href="/a" rel="external nofollow" > /a </a><a href="./b" rel="external nofollow" > ./b </a><a href="./././././././././b" rel="external nofollow" > ./././././././././b </a> <!– 其实就是 ./b –><a href="../c" rel="external nofollow" > ../c </a><a href="../../d" rel="external nofollow" > ../../d </a><a href="../a/../b/c/../d" rel="external nofollow" > ../a/../b/c/../d </a><a href="./../e" rel="external nofollow" > ./../e </a><a href="http://www.hole_1.org/./../e" rel="external nofollow" > http://www.gaodaima.com/ </a> <a href="./.././f" rel="external nofollow" > ./.././f </a><a href="http://www.hole_1.org/../a/…/../b/c/../d/.." rel="external nofollow" > http://www.gaodaima.com/ </a> <!– 带有端口号 –><a href=":8081/index.html" rel="external nofollow" > :8081/index.html </a><a href="http://www.mafutian.net:80/index.html" rel="external nofollow" > :80/index.html </a><a href="http://www.mafutian.net:8081/index.html" rel="external nofollow" > http://www.gaodaima.com/:8081/index.html </a><a href="http://www.mafutian.net:8082/index.html" rel="external nofollow" > http://www.gaodaima.com/:8082/index.html </a>
转载请注明原文链接：PHP利用正则表达式将相对路径转成绝对路径的方法
