通过classname获取DOM元素 [英] Getting DOM elements by classname

问题描述

我正在使用 PHP DOM ，我正在尝试获取具有给定类名称的DOM节点内的元素。获取该子元素的最佳方式是什么？

I'm using PHP DOM and I'm trying to get an element within a DOM node that have a given class name. What's the best way to get that sub-element?

更新：我最终使用 Mechanize for PHP更容易使用。

Update: I ended up using Mechanize for PHP which was much easier to work with.

推荐答案

更新：Xpath版本的 * [@ class〜='my-class'] css selector

Update: Xpath version of *[@class~='my-class'] css selector

所以在我的评论下面回应hakre的评论我很好奇，并研究了 Zend_Dom_Query 之后的代码。看起来上面的选择器被编译到以下xpath（未经测试）：

So after my comment below in response to hakre's comment i got curious and looked into the code behind Zend_Dom_Query. It looks like the above selector is compiled to the following xpath (untested):

[contains（concat（''，normalize-space class），''），'my-class'）]

所以php将是：

$dom = new DomDocument();
$dom->load($filePath);
$finder = new DomXPath($dom);
$classname="my-class";
$nodes = $finder->query("//*[contains(concat(' ', normalize-space(@class), ' '), ' $classname ')]");

基本上我们在这里做的就是将 class 属性，使得即使单个类也被空格限定，并且完整的类列表在空格中被界定。然后追加我们正在寻找一个空格的类。这样我们才有效地寻找并找到只有 my-class 的实例。

Basically all we do here is normalize the class attribute so that even a single class is bounded by spaces, and the complete class list is bounded in spaces. Then append class we are searching for with a space. This way we are effectively looking for and find only instances of my-class.

使用xpath选择器？

Use an xpath selector?

$dom = new DomDocument();
$dom->load($filePath);
$finder = new DomXPath($dom);
$classname="my-class";
$nodes = $finder->query("//*[contains(@class, '$classname')]");

如果只有一种类型的元素，您可以替换 * 与特定的标记名。

If it is only ever one type of element you can replace the * with the particular tagname.

如果您需要使用非常复杂的选择器做很多，我会推荐 Zend_Dom_Query ，它支持CSS选择器语法jQuery）：

If you need to do alot of this with very complex selector i would recommend Zend_Dom_Query which supports CSS selector syntax (a la jQuery):

$finder = new Zend_Dom_Query($html);
$classname = 'my-class';
$nodes = $finder->query("*[class~=\"$classname\"]");

这篇关于通过classname获取DOM元素的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！