php 通过类名获取DOM元素
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Getting DOM elements by classname
提问by bgcode
I'm using PHP DOMand 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?
我正在使用PHP DOM并且我试图在具有给定类名的 DOM 节点中获取一个元素。获取该子元素的最佳方法是什么？
Update:I ended up using Mechanizefor PHP which was much easier to work with.
更新：我最终使用Mechanize了 PHP，它更容易使用。
回答by prodigitalson
Update: Xpath version of *[@class~='my-class']css selector
更新：*[@class~='my-class']CSS 选择器的Xpath 版本
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):
因此，在我对 hakre 的评论做出以下评论之后，我很好奇并查看了Zend_Dom_Query. 看起来上面的选择器被编译为以下 xpath（未经测试）：
[contains(concat(' ', normalize-space(@class), ' '), ' my-class ')]
[contains(concat(' ', normalize-space(@class), ' '), ' my-class ')]
so the php would be:
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 ')]");
Basically, all we do here is normalize the classattribute so that even a single class is bounded by spaces, and the complete class list is bounded in spaces. Then append the class we are searching for with a space. This way we are effectively looking for and find only instances of my-class.
基本上，我们在这里所做的只是对class属性进行规范化，这样即使是单个类也以空格为界，而完整的类列表也以空格为界。然后用空格附加我们正在搜索的类。这样我们就可以有效地寻找并只找到my-class.
Use an xpath selector?
使用 xpath 选择器？
$dom = new DomDocument();
$dom->load($filePath);
$finder = new DomXPath($dom);
$classname="my-class";
$nodes = $finder->query("//*[contains(@class, '$classname')]");
If it is only ever one type of element you can replace the *with the particular tagname.
如果它只是一种类型的元素，您可以用*特定的标记名替换。
If you need to do alot of this with very complex selector i would recommend Zend_Dom_Querywhich supports CSS selector syntax (a la jQuery):
如果你需要用非常复杂的选择器做很多这样的事情，我会推荐Zend_Dom_Query它支持 CSS 选择器语法（a la jQuery）：
$finder = new Zend_Dom_Query($html);
$classname = 'my-class';
$nodes = $finder->query("*[class~=\"$classname\"]");
回答by Tschallacka
If you wish to get the innerhtml of the class without the zend you could use this:
如果你想在没有 zend 的情况下获得类的innerhtml，你可以使用这个：
$dom = new DomDocument();
$dom->load($filePath);
$classname = 'main-article';
$finder = new DomXPath($dom);
$nodes = $finder->query("//*[contains(concat(' ', normalize-space(@class), ' '), ' $classname ')]");
$tmp_dom = new DOMDocument();
foreach ($nodes as $node)
{
$tmp_dom->appendChild($tmp_dom->importNode($node,true));
}
$innerHTML.=trim($tmp_dom->saveHTML());
echo $innerHTML;
回答by dav
I think the accepted way is better, but I guess this might work as well
我认为公认的方式更好，但我想这也可能有效
function getElementByClass(&$parentNode, $tagName, $className, $offset = 0) {
$response = false;
$childNodeList = $parentNode->getElementsByTagName($tagName);
$tagCount = 0;
for ($i = 0; $i < $childNodeList->length; $i++) {
$temp = $childNodeList->item($i);
if (stripos($temp->getAttribute('class'), $className) !== false) {
if ($tagCount == $offset) {
$response = $temp;
break;
}
$tagCount++;
}
}
return $response;
}
回答by oabarca
There is also another approach without the use of DomXPathor Zend_Dom_Query.
还有另一种不使用DomXPathor 的方法Zend_Dom_Query。
Based on dav's original function, I wrote the following function that returns all the children of the parent node whose tag and class match the parameters.
基于 dav 的原始函数，我编写了以下函数，该函数返回标签和类与参数匹配的父节点的所有子节点。
function getElementsByClass(&$parentNode, $tagName, $className) {
$nodes=array();
$childNodeList = $parentNode->getElementsByTagName($tagName);
for ($i = 0; $i < $childNodeList->length; $i++) {
$temp = $childNodeList->item($i);
if (stripos($temp->getAttribute('class'), $className) !== false) {
$nodes[]=$temp;
}
}
return $nodes;
}
suppose you have a variable $htmlthe following HTML:
假设您有一个$html以下 HTML的变量：
<html>
<body>
<div id="content_node">
<p class="a">I am in the content node.</p>
<p class="a">I am in the content node.</p>
<p class="a">I am in the content node.</p>
</div>
<div id="footer_node">
<p class="a">I am in the footer node.</p>
</div>
</body>
</html>
use of getElementsByClassis as simple as:
使用getElementsByClass很简单：
$dom = new DOMDocument('1.0', 'utf-8');
$dom->loadHTML($html);
$content_node=$dom->getElementById("content_node");
$div_a_class_nodes=getElementsByClass($content_node, 'div', 'a');//will contain the three nodes under "content_node".
回答by iautomation
DOMDocumentis slow to type and phpQueryhas bad memory leak issues. I ended up using:
DOMDocument打字很慢，而且phpQuery有严重的内存泄漏问题。我最终使用了：
https://github.com/wasinger/htmlpagedom
https://github.com/wasinger/htmlpagedom
To select a class:
要选择一个班级：
include 'includes/simple_html_dom.php';
$doc = str_get_html($html);
$href = $doc->find('.lastPage')[0]->href;
I hope this helps someone else as well
我希望这对其他人也有帮助
