用PHP代替JS玩转DOM
事情的起源比较简单,我需要把一个导航页的数据整理好写入数据库。一个比较直观的方法是对html文件进行分析,通用的方法是用php的正则表达式来匹配。但是这样做开发和维护都很困难,代码可读性非常差。
导航页的数据都是规则的排列在DOM树当中的,用JS可以用几个循环轻松的对其进行操作,而且JS需要依赖浏览器,操作数据库很困难。其实PHP就有现成的类库对DOM树种的节点进行增删改查操作,在此做一些笔记。
这里涉及到2个类 DOMDocument 和 DOMXPath。
其实思路比较明确,就是通过DOMDocument将一个html file转换成DOM树的数据结构,再用DOMXPath的实例去搜索这个DOM树,拿到想要特定节点,接下来就可以对当前节点的子树进行遍历,得到想要的结果。
写一个最简单的demo
在当前目录下有一个这样一个导航的html文件 "./hao.html"
现在需要得到所有标签的中文内容,php代码如下:
<?php //将html/xml文件转换成DOM树$dom = new DOMDocument();$dom->loadHTMLFile("hao.html");//得到所有class为fix的dl标签// example 1: for everything with an id//$elements = $xpath->query("//*[@id]");// example 2: for node data in a selected id//$elements = $xpath->query("/html/body/div[@id='yourTagIdHere']");// example 3: same as above with wildcard//$elements = $xpath->query("*/div[@id='yourTagIdHere']");$xpath = new DOMXPath($dom);$dls = $xpath->query('//dl[@class="fix"]');foreach ($dls as $dl) { $spans = $dl->childNodes; foreach ($spans as $span) { echo trim($span->textContent)."\t"; } echo "\n";} ?>
输出结果如下:
注意:值得注意的一点是DOMDocument的默认编码方式是Latin,所以在处理utf编码的中文的时候,需要在
后面紧跟着填入
<meta http-equiv="content-type" content="text/html; charset=utf-8">
在其他位置,或者是只写上都是不识别的哦

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