php -删除特定的标签或img标签，如果href或src不以http, https或www开头 - PHP-Remove specific a tag or img tag if href or src does not start with http, https, or www

我想从$string_1中删除特定的a和img标签，如果<src>或<href>不以<a>或<img>标签内的www, http或https开始。

例如，通过删除:

将$string_1转换为$string_2

<img src="/wp-content/uploads/2014/06/photography-business-2.jpg" alt="photography business growth 1 650x430 6 Simple Ways To Help Grow Your Photography Business" width="650" height="430" class="alignnone size-large wp-image-609513" title="6 Simple Ways To Help Grow Your Photography Business"/>

和

<a href="/photography-business-growth/" rel="nofollow">Read more about Photography Business Growth &gt;</a>

因为src和href标签不以http, https或www开头。

$string_1 = '
<div class="mainpost"><p><img src="/wp-content/uploads/2014/06/photography-business-2.jpg" alt="photography business growth 1 650x430 6 Simple Ways To Help Grow Your Photography Business" width="650" height="430" class="alignnone size-large wp-image-609513" title="6 Simple Ways To Help Grow Your Photography Business"/></p>
<div class="mainpost"><p><img src="http://www.domain.com/wp-content/uploads/2014/06/photography-business-2.jpg" alt="photography business growth 1 650x430 6 Simple Ways To Help Grow Your Photography Business" width="650" height="430" class="alignnone size-large wp-image-609513" title="6 Simple Ways To Help Grow Your Photography Business"/></p>
<p><a href="http://domain.com/photography-business-growth/" rel="nofollow">Read more about Photography Business Growth &gt;</a></p>
<p>Photography Business Growth | With a world wide recession, photographers and small business owners are forced, more than ever, to think creatively, to think differently and outside of the box. With very little or no money to invest in your business, can you move forward? How can you build your brand and make sure to get happier, paying clients through your door?<br/><span id="more-609494"/></p>
<p>If you take good shots it doesn’t mean you’ll gain success and popularity among customers. For those of you who have survived start=up and built successful brands, you may be wondering which step to take next to grow your business beyond its current status. There are numerous possibilities, some of which we’ll outline here. You need to know how to sell yourself well! Everything is quite simple and you can do it yourself.</p>
<p><a href="/photography-business-growth/" rel="nofollow">Read more about Photography Business Growth &gt;</a></p>
';
$string_2= '
<div class="mainpost"><p></p>
<div class="mainpost"><p><img src="http://www.domain.com/wp-content/uploads/2014/06/photography-business-2.jpg" alt="photography business growth 1 650x430 6 Simple Ways To Help Grow Your Photography Business" width="650" height="430" class="alignnone size-large wp-image-609513" title="6 Simple Ways To Help Grow Your Photography Business"/></p>
<p><a href="http://domain.com/photography-business-growth/" rel="nofollow">Read more about Photography Business Growth &gt;</a></p>
<p>Photography Business Growth | With a world wide recession, photographers and small business owners are forced, more than ever, to think creatively, to think differently and outside of the box. With very little or no money to invest in your business, can you move forward? How can you build your brand and make sure to get happier, paying clients through your door?<br/><span id="more-609494"/></p>
<p>If you take good shots it doesn’t mean you’ll gain success and popularity among customers. For those of you who have survived start=up and built successful brands, you may be wondering which step to take next to grow your business beyond its current status. There are numerous possibilities, some of which we’ll outline here. You need to know how to sell yourself well! Everything is quite simple and you can do it yourself.</p>
';

你能帮我解决这个问题吗?由于

这是PHP中的第一种方法。它适用于您的示例数据。$string_2中缺少尾字符"

"吗?

$string_3 = $string_1;
$pattern = "([^wh]|w[^w]|ww[^w]|h[^t]|ht[^t]|htt[^p])";
$string_3 = preg_replace("/<img src='"".$pattern."[^>]*>/","",$string_3);
$string_3 = preg_replace("/<a href='"".$pattern."[^>]*>[^<]*<'/a>/","",$string_3);

我将使用DOM解析器。有了DOM文档，您可以使用XPath来选择所需的元素。

# Parse the HTML snippet into a DOM document
$doc = new DOMDocument();
$doc->loadHTML($string_1);
# Create an XPath selector
$selector = new DOMXPath($doc);
# Define the XPath query
# The syntax highlighter messed this up. Take it as it is!
$query = <<<EOF
  //a[not(starts-with(@href, "http"))
  and not(starts-with(@href, "www"))]
| //img[not(starts-with(@src, "http"))
  and not(starts-with(@src, "www"))]
EOF;
# Issue the XPath query and remove every resulting node
foreach($selector->query($query) as $node) {
    $node->parentNode->removeChild($node);
}
# Write back the modified `<div>` element into a string
echo $doc->saveHTML(
    $selector->query('//div[@class="mainpost"]')->item(0)
);

一种解决方案是在前端使用Javascript完成此操作。如果没有这个选项，您可以查看PHP库来解析和遍历DOM，例如http://simplehtmldom.sourceforge.net