blocks|key|267983|text|css更新:+Xpath版本的+*[@class~='my-class']+选择器|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|CODE|entityRanges|data|267984|因此，在我对hakre的评论进行了下面的评论之后，我变得很好奇，并研究了Zend_Dom_Query背后的代码。上面的选择器看起来被编译成了下面的xpath+(未经测试)：|267985|[contains(concat('+',+normalize-space(@class),+'+'),+'+my-class+')]|267986|所以PHP应该是：|267987|$dom+=+new+DomDocument();
$dom->load($filePath);
$finder+=+new+DomXPath($dom);
$classname="my-class";
$nodes+=+$finder->query("//*[contains(concat('+',+normalize-space(@class),+'+'),+'+$classname+')]");|code-block|syntax|javascript|267988|基本上，我们在这里所做的就是规范化class属性，这样即使是单个类也是以空格为边界的，而完整的类列表也是以空格为边界的。然后在我们要搜索的类后面加上一个空格。通过这种方式，我们可以有效地查找并找到my-class的实例。|267989|267990|使用xpath选择器？|267991|$dom+=+new+DomDocument();
$dom->load($filePath);
$finder+=+new+DomXPath($dom);
$classname="my-class";
$nodes+=+$finder->query("//*[contains(@class,+'$classname')]");|267992|如果只有一种类型的元素，您可以用特定的标记名替换*。|267993|如果你需要用非常复杂的选择器做很多这样的事情，我推荐Zend_Dom_Query，它支持CSS选择器语法(就像jQuery一样)：|267994|$finder+=+new+Zend_Dom_Query($html);
$classname+=+'my-class';
$nodes+=+$finder->query("*[class~=\"$classname\"]");|267995|entityMap|0|LINK|mutability|MUTABLE|url|http://framework.zend.com/manual/en/zend.dom.query.html^0|G|L|12|3|G|L|0|0|2E|10|E|0|0|1V|0|1V|0|0|9|0|0|0|32|H|5|2Q|8|0|0|0|B|0|0|0|Q|O|1|0|0|1T|Q|E|Q|E|0|0|0^^$0|@$1|2|3|4|5|6|7|1C|8|@$9|1D|A|1E|B|C]|$9|1F|A|1G|B|C]|$9|1H|A|1I|B|D]]|E|@]|F|$]]|$1|G|3|H|5|6|7|1J|8|@$9|1K|A|1L|B|C]|$9|1M|A|1N|B|D]]|E|@]|F|$]]|$1|I|3|J|5|6|7|1O|8|@$9|1P|A|1Q|B|C]|$9|1R|A|1S|B|D]]|E|@]|F|$]]|$1|K|3|L|5|6|7|1T|8|@$9|1U|A|1V|B|C]]|E|@]|F|$]]|$1|M|3|N|5|O|7|1W|8|@]|E|@]|F|$P|Q]]|$1|R|3|S|5|6|7|1X|8|@$9|1Y|A|1Z|B|C]|$9|20|A|21|B|D]|$9|22|A|23|B|D]]|E|@]|F|$]]|$1|T|3|-4|5|6|7|24|8|@]|E|@]|F|$]]|$1|U|3|V|5|6|7|25|8|@$9|26|A|27|B|C]]|E|@]|F|$]]|$1|W|3|X|5|O|7|28|8|@]|E|@]|F|$P|Q]]|$1|Y|3|Z|5|6|7|29|8|@$9|2A|A|2B|B|C]|$9|2C|A|2D|B|D]]|E|@]|F|$]]|$1|10|3|11|5|6|7|2E|8|@$9|2F|A|2G|B|C]|$9|2H|A|2I|B|D]]|E|@$9|2J|A|2K|1|2L]]|F|$]]|$1|12|3|13|5|O|7|2M|8|@]|E|@]|F|$P|Q]]|$1|14|3|-4|5|6|7|2N|8|@]|E|@]|F|$]]]|15|$16|$5|17|18|19|F|$1A|1B]]]]

Update: Xpath version of <code>*[@class~='my-class']</code> css selector
So after my comment below in response to hakre's comment, I got curious and looked into the code behind <code>Zend_Dom_Query</code>. It looks like the above selector is compiled to the following xpath (untested):
<code>[contains(concat(' ', normalize-space(@class), ' '), ' my-class ')]</code>
So the PHP would be:
<pre><code>$dom = new DomDocument();
$dom-&gt;load($filePath);
$finder = new DomXPath($dom);
$classname=&quot;my-class&quot;;
$nodes = $finder-&gt;query(&quot;//*[contains(concat(' ', normalize-space(@class), ' '), ' $classname ')]&quot;);
</code></pre>
Basically, all we do here is normalize the <code>class</code> attribute so that even a single class is bounded by spaces, and the complete class list is bounded in spaces. Then append the class we are searching for with a space. This way we are effectively looking for and find only instances of <code>my-class </code>.
<hr />
Use an xpath selector?
<pre><code>$dom = new DomDocument();
$dom-&gt;load($filePath);
$finder = new DomXPath($dom);
$classname=&quot;my-class&quot;;
$nodes = $finder-&gt;query(&quot;//*[contains(@class, '$classname')]&quot;);
</code></pre>
If it is only ever one type of element you can replace the <code>*</code> with the particular tagname.
If you need to do a lot of this with very complex selector I would recommend <a href="http://framework.zend.com/manual/en/zend.dom.query.html" rel="noreferrer"><code>Zend_Dom_Query</code></a> which supports CSS selector syntax (a la jQuery):
<pre><code>$finder = new Zend_Dom_Query($html);
$classname = 'my-class';
$nodes = $finder-&gt;query(&quot;*[class~=\&quot;$classname\&quot;]&quot;);
</code></pre>

blocks|key|2958766|text|如果您希望获得不带zend的类的innerhtml，您可以使用以下命令：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2958767|$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;|code-block|syntax|javascript|2958768|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

If you wish to get the innerhtml of the class without the zend you could use this:

<pre><code>$dom = new DomDocument();
$dom-&gt;load($filePath);
$classname = 'main-article';
$finder = new DomXPath($dom);
$nodes = $finder-&gt;query("//*[contains(concat(' ', normalize-space(@class), ' '), ' $classname ')]");
$tmp_dom = new DOMDocument(); 
foreach ($nodes as $node) 
 {
 $tmp_dom-&gt;appendChild($tmp_dom-&gt;importNode($node,true));
 }
$innerHTML.=trim($tmp_dom-&gt;saveHTML()); 
echo $innerHTML;
</code></pre>

blocks|key|262643|text|我认为公认的方法更好，但我想这也可能行得通|type|unstyled|depth|inlineStyleRanges|entityRanges|data|262644|function+getElementByClass(&$parentNode,+$tagName,+$className,+$offset+=+0)+{
++++$response+=+false;

++++$childNodeList+=+$parentNode->getElementsByTagName($tagName);
++++$tagCount+=+0;
++++for+($i+=+0;+$i+<+$childNodeList->length;+$i%2B%2B)+{
++++++++$temp+=+$childNodeList->item($i);
++++++++if+(stripos($temp->getAttribute('class'),+$className)+!==+false)+{
++++++++++++if+($tagCount+==+$offset)+{
++++++++++++++++$response+=+$temp;
++++++++++++++++break;
++++++++++++}

++++++++++++$tagCount%2B%2B;
++++++++}

++++}

++++return+$response;
}|code-block|syntax|javascript|262645|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I think the accepted way is better, but I guess this might work as well

<pre><code>function getElementByClass(&amp;$parentNode, $tagName, $className, $offset = 0) {
 $response = false;

 $childNodeList = $parentNode-&gt;getElementsByTagName($tagName);
 $tagCount = 0;
 for ($i = 0; $i &lt; $childNodeList-&gt;length; $i++) {
 $temp = $childNodeList-&gt;item($i);
 if (stripos($temp-&gt;getAttribute('class'), $className) !== false) {
 if ($tagCount == $offset) {
 $response = $temp;
 break;
 }

 $tagCount++;
 }

 }

 return $response;
}
</code></pre>

blocks|key|2958844|text|还有另一种不使用DomXPath或Zend_Dom_Query的方法。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2958845|基于dav的原始函数，我编写了以下函数，该函数返回其标记和类与参数匹配的父节点的所有子节点。|2958846|function+getElementsByClass(&$parentNode,+$tagName,+$className)+{
++++$nodes=array();

++++$childNodeList+=+$parentNode->getElementsByTagName($tagName);
++++for+($i+=+0;+$i+<+$childNodeList->length;+$i%2B%2B)+{
++++++++$temp+=+$childNodeList->item($i);
++++++++if+(stripos($temp->getAttribute('class'),+$className)+!==+false)+{
++++++++++++$nodes[]=$temp;
++++++++}
++++}

++++return+$nodes;
}|code-block|syntax|javascript|2958847|假设你有一个变量$html如下：|2958848|<html>
+<body>
++<div+id="content_node">
++++<p+class="a">I+am+in+the+content+node.
++++<p+class="a">I+am+in+the+content+node.
++++<p+class="a">I+am+in+the+content+node.++++
++</div>
++<div+id="footer_node">
++++<p+class="a">I+am+in+the+footer+node.
++</div>
+</body>
</html>|2958849|getElementsByClass的使用非常简单，如下所示：|2958850|$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".|2958851|entityMap^0|8|8|H|E|0|0|0|8|5|0|0|0|I|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|11|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|12|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|13|8|@$9|14|A|15|B|C]]|D|@]|E|$]]|$1|O|3|P|5|J|7|16|8|@]|D|@]|E|$K|L]]|$1|Q|3|R|5|6|7|17|8|@$9|18|A|19|B|C]]|D|@]|E|$]]|$1|S|3|T|5|J|7|1A|8|@]|D|@]|E|$K|L]]|$1|U|3|-4|5|6|7|1B|8|@]|D|@]|E|$]]]|V|$]]

There is also another approach without the use of <code>DomXPath</code> or <code>Zend_Dom_Query</code>.

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.

<pre><code>function getElementsByClass(&amp;$parentNode, $tagName, $className) {
 $nodes=array();

 $childNodeList = $parentNode-&gt;getElementsByTagName($tagName);
 for ($i = 0; $i &lt; $childNodeList-&gt;length; $i++) {
 $temp = $childNodeList-&gt;item($i);
 if (stripos($temp-&gt;getAttribute('class'), $className) !== false) {
 $nodes[]=$temp;
 }
 }

 return $nodes;
}
</code></pre>

suppose you have a variable <code>$html</code> the following HTML:

<pre><code>&lt;html&gt;
 &lt;body&gt;
 &lt;div id="content_node"&gt;
 &lt;p class="a"&gt;I am in the content node.&lt;/p&gt;
 &lt;p class="a"&gt;I am in the content node.&lt;/p&gt;
 &lt;p class="a"&gt;I am in the content node.&lt;/p&gt; 
 &lt;/div&gt;
 &lt;div id="footer_node"&gt;
 &lt;p class="a"&gt;I am in the footer node.&lt;/p&gt;
 &lt;/div&gt;
 &lt;/body&gt;
&lt;/html&gt;
</code></pre>

use of <code>getElementsByClass</code> is as simple as:

<pre><code>$dom = new DOMDocument('1.0', 'utf-8');
$dom-&gt;loadHTML($html);
$content_node=$dom-&gt;getElementById("content_node");

$div_a_class_nodes=getElementsByClass($content_node, 'div', 'a');//will contain the three nodes under "content_node".
</code></pre>

blocks|key|262659|text|DOMDocument键入速度很慢，并且phpQuery存在严重的内存泄漏问题。我最终使用了：|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|262660|https://github.com/wasinger/htmlpagedom|262661|要选择一个类：|262662|include+'includes/simple_html_dom.php';

$doc+=+str_get_html($html);
$href+=+$doc->find('.lastPage')[0]->href;|code-block|syntax|javascript|262663|我希望这对其他人也有帮助。|262664|entityMap|0|LINK|mutability|MUTABLE|url^0|0|B|K|8|0|0|13|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|X|8|@$9|Y|A|Z|B|C]|$9|10|A|11|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|12|8|@]|D|@$9|13|A|14|1|15]]|E|$]]|$1|H|3|I|5|6|7|16|8|@]|D|@]|E|$]]|$1|J|3|K|5|L|7|17|8|@]|D|@]|E|$M|N]]|$1|O|3|P|5|6|7|18|8|@]|D|@]|E|$]]|$1|Q|3|-4|5|6|7|19|8|@]|D|@]|E|$]]]|R|$S|$5|T|U|V|E|$W|G]]]]

DOMDocument is slow to type and phpQuery has bad memory leak issues. I ended up using:

<a href="https://github.com/wasinger/htmlpagedom" rel="noreferrer">https://github.com/wasinger/htmlpagedom</a>

To select a class:

<pre><code>include 'includes/simple_html_dom.php';

$doc = str_get_html($html);
$href = $doc-&gt;find('.lastPage')[0]-&gt;href;
</code></pre>

I hope this helps someone else as well

blocks|key|264867|text|为此，我更喜欢使用Symfony。他们的库非常好。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|264868|使用The+DomCrawler+Component|offset|length|264869|示例：|style|BOLD|264870|$browser+=+new+HttpBrowser(HttpClient::create());
$crawler+=+$browser->request('GET',+'example.com');
$class+=+$crawler->filter('.class')->first();|code-block|syntax|javascript|264871|entityMap|0|LINK|mutability|MUTABLE|url|https://symfony.com/doc/current/components/dom_crawler.html#resolving-a-uri^0|0|2|O|0|0|0|3|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|X|8|@]|9|@$D|Y|E|Z|1|10]]|A|$]]|$1|F|3|G|5|6|7|11|8|@$D|12|E|13|H|I]]|9|@]|A|$]]|$1|J|3|K|5|L|7|14|8|@]|9|@]|A|$M|N]]|$1|O|3|-4|5|6|7|15|8|@]|9|@]|A|$]]]|P|$Q|$5|R|S|T|A|$U|V]]]]

I prefer using Symfony for this. Their libraries are pretty nice.
Use the <a href="https://symfony.com/doc/current/components/dom_crawler.html#resolving-a-uri" rel="nofollow noreferrer">The DomCrawler Component</a>
Example:
<pre><code>$browser = new HttpBrowser(HttpClient::create());
$crawler = $browser-&gt;request('GET', 'example.com');
$class = $crawler-&gt;filter('.class')-&gt;first();
</code></pre>

blocks|key|268065|text|PHP的原生DOM处理非常糟糕，帮您自己一个忙，使用这个或任何其他现代HTML解析包，它可以在几行代码中处理这个问题：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|268066|使用安装paquettg/php-html-parser|offset|length|268067|composer+require+paquettg/php-html-parser|code-block|syntax|javascript|268068|然后在包含此内容的同一文件夹中创建一个.php文件|268069|<?php

//+load+dependencies+via+Composer
require+__DIR__+.+'/vendor/autoload.php';

use+PHPHtmlParser\Dom;

$dom+=+new+Dom;
$dom->loadFromUrl("https://example.com");
$links+=+$dom->find('.classname+a');

foreach+($links+as+$link)+{
++++echo+$link->getAttribute('href');
}|268070|附言:你可以找到关于如何在Composer's+homepage上安装Composer的信息。|268071|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/paquettg/php-html-parser|1|https://getcomposer.org/^0|0|4|O|0|0|0|0|0|D|J|1|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|11|8|@]|9|@$D|12|E|13|1|14]]|A|$]]|$1|F|3|G|5|H|7|15|8|@]|9|@]|A|$I|J]]|$1|K|3|L|5|6|7|16|8|@]|9|@]|A|$]]|$1|M|3|N|5|H|7|17|8|@]|9|@]|A|$I|J]]|$1|O|3|P|5|6|7|18|8|@]|9|@$D|19|E|1A|1|1B]]|A|$]]|$1|Q|3|-4|5|6|7|1C|8|@]|9|@]|A|$]]]|R|$S|$5|T|U|V|A|$W|X]]|Y|$5|T|U|V|A|$W|Z]]]]

PHP's native DOM handling is so absurdly bad, do yourself a favour and use this or any other modern HTML parsing package which can handle this within in few lines:
Install <a href="https://github.com/paquettg/php-html-parser" rel="nofollow noreferrer">paquettg/php-html-parser</a> with
<pre class="lang-sh prettyprint-override"><code>composer require paquettg/php-html-parser
</code></pre>
Then create a .php file in the same folder with this content
<pre class="lang-php prettyprint-override"><code>&lt;?php

// load dependencies via Composer
require __DIR__ . '/vendor/autoload.php';

use PHPHtmlParser\Dom;

$dom = new Dom;
$dom-&gt;loadFromUrl(&quot;https://example.com&quot;);
$links = $dom-&gt;find('.classname a');

foreach ($links as $link) {
 echo $link-&gt;getAttribute('href');
}
</code></pre>
P.S. You'll find information on how to install Composer on <a href="https://getcomposer.org/" rel="nofollow noreferrer">Composer's homepage</a>.

I'm using <a href="http://www.php.net/manual/en/book.dom.php" rel="noreferrer">PHP DOM</a> 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?

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

Getting DOM elements by classname

jQuery

我正在使用，并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？PHP：我最终使用的是Mechanize，它更容易使用。

问通过类名获取DOM元素
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