使用PHP DOM文档，按类选择HTML元素并获取其文本 - Using PHP DOM document, to select HTML element by its class and get its text

Using PHP DOM document, to select HTML element by its class and get its text

我试图通过使用带有以下HTML（相同结构）和以下代码的PHP的DOM元素，从div中获取文本，其中class='review-text'。

但是这似乎不起作用

HTML

$html = '
    <div class="page-wrapper">
        <section class="page single-review" itemtype="http://schema.org/Review" itemscope="" itemprop="review">
            <article class="review clearfix">
                <div class="review-content">
                    <div class="review-text" itemprop="reviewBody">
                    Outstanding ... 
                    </div>
                </div>
            </article>
        </section>
    </div>
';

PHP代码

    $classname = 'review-text';
    $dom = new DOMDocument;
    $dom->loadHTML($html);
    $xpath     = new DOMXPath($dom);
    $results = $xpath->query("//*[@class and contains(concat(' ', normalize-space(@class), ' '), ' $classname ')]");
    if ($results->length > 0) {
        echo $review = $results->item(0)->nodeValue;
    }

按类选择元素的XPATH语法在本博客中提供

我尝试过许多来自StackOverflow的在线教程示例，但似乎都不起作用。我是不是错过了什么？

下面的XPath查询可以满足您的需要。只需将提供给$xpath->query的参数替换为以下内容：

//div[@class="review-text"]

编辑：为了便于开发，您可以在线测试自己的XPath查询，网址为http://www.xpathtester.com/test.

第2版：对该代码进行了测试；它运行得很好。

<?php
$html = '
    <div class="page-wrapper">
        <section class="page single-review" itemtype="http://schema.org/Review" itemscope="" itemprop="review">
            <article class="review clearfix">
                <div class="review-content">
                    <div class="review-text" itemprop="reviewBody">
                    Outstanding ... 
                    </div>
                </div>
            </article>
        </section>
    </div>
';
$classname = 'review-text';
$dom = new DOMDocument;
$dom->loadHTML($html);
$xpath = new DOMXPath($dom);
$results = $xpath->query("//*[@class='" . $classname . "']");
if ($results->length > 0) {
    echo $review = $results->item(0)->nodeValue;
}
?>

扩展Frak Houweling答案，也可以使用DomXpath在特定的DomNode中搜索。这可以通过将contextNode作为第二个参数传递给DomXpath->query方法来实现：

$dom = new DOMDocument;
$dom->loadHTML ($html);
$xpath = new DOMXPath ($dom);
foreach ($xpath->query ("//section[@class='page single-review']") as $section)
{
    // search for sub nodes inside each element
    foreach ($xpath->query (".//div[@class='review-text']", $section) as $review)
    {
        echo $review->nodeValue;
    }
}

请注意，在节点内部搜索时，您需要通过在表达式开头添加一个点.来使用相对路径：

"//div[@class='review-text']" // absolute path, search starts from the root element
".//div[@class='review-text']" // relative path, search starts from the provided contextNode