在 PHP 中从字符串中提取 DOM 元素
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Extract DOM-elements from string, in PHP
提问by user635443
Possible Duplicates:
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Best methods to parse HTML
I have one string-variable in my php-script, that contains html-page. How i can extract DOM-elements from this string?
我的 php 脚本中有一个字符串变量，它包含 html 页面。我如何从这个字符串中提取 DOM 元素？
For example, in this string '<div class="someclass">text</div>', i wish get variable 'text'. How i can do this?
例如，在这个字符串中'<div class="someclass">text</div>'，我希望得到变量“文本”。我怎么能做到这一点？
回答by Pascal MARTIN
You need to use the DOMDocumentclass, and, more specifically, its loadHTMLmethod, to load your HTML string to a DOM object.
您需要使用DOMDocument该类，更具体地说，使用它的loadHTML方法将 HTML 字符串加载到 DOM 对象。
For example :
例如 ：
$string = <<<HTML
<p>test</p>
<div class="someclass">text</div>
<p>another</p>
HTML;
$dom = new DOMDocument();
$dom->loadHTML($string);
After that, you'll be able to manipulate the DOM, using for instance the DOMXPathclass to do XPath queries on it.
之后，您将能够操作 DOM，例如使用DOMXPath该类对其进行 XPath 查询。
For example, in your case, you could use something based on this portion of code :
例如，在您的情况下，您可以使用基于这部分代码的内容：
$xpath = new DOMXpath($dom);
$result = $xpath->query('//div[@class="someclass"]');
if ($result->length > 0) {
var_dump($result->item(0)->nodeValue);
}
Which, here, would get you the following output :
在这里，您会得到以下输出：
string 'text' (length=4)
As an alternative, instead of DOMDocument, you could also use simplexml_load_stringand SimpleXMLElement::xpath-- but for complex manipulations, I generally prefer using DOMDocument.
作为替代方案，DOMDocument您也可以使用simplexml_load_stringand来代替，SimpleXMLElement::xpath但对于复杂的操作，我通常更喜欢使用DOMDocument.
回答by Tim Cooper
Have a look at DOMDocumentand DOMXPath.
$DOM = new DOMDocument();
$DOM->loadHTML($str);
$xpath = new DOMXPath($DOM);
$someclass_elements = $xpath->query('//[@class = "someclass"]');
// ...
