PHP正则表达式匹配URL，但不匹配图像

Question

I'm trying to use preg_match_all to extract all urls from a block of HTML code. I'm also trying to ignore all images.

Example HTML block:

$html = '<p>This is a test</p><br>http://www.facebook.com<br><img src="http://www.google.com/photo.jpg">www.yahoo.com https://www.aol.com<br>';

I'm using the following to try and build an array of URLS only. (not images)

if(preg_match_all('~(?:(?:https://)|(?:http://)|(?:www\.))(?![^" ]*(?:jpg|png|gif|"))[^" <>]+~', $html, $links))
{ 
 print_r($links); 
}

In the example above the $links array should contain:

http://www.facebook.com, www.yahoo.com, https://www.aol.com 

Google is left out because it contains the .jpg image extension. The problem occurs when I add an image like this one to $html:

<img src="http://www.google.com/image%201.jpg">

It seems as though the percent sign causes preg_match to break apart the URL and extract the following "link".

http://www.google.com/image 

Any idea how to grab ONLY url's that are not images? (even if they contain special characters that urls could commonly have)

Answer 1

Using DOM allows you to recognize the structure of an HTML document. In your case to recognize the parts you want to fetch the urls from.

1. Load the HTML using DOM
2. Fetch urls from link href attributes using Xpath (only if you want them, too)
3. Fetch text nodes from the DOM using Xpath
4. Use RegEx on text node value to match urls

Here is an example implementation:

$html = <<<'HTML'
  <p>This is a test</p>
  <br>
  http://www.facebook.com
  <br>
  <img src="http://www.google.com/photo.jpg">
  www.yahoo.com 
  https://www.aol.com
  <a href="http://www.google.com">Link</a>
  <!-- http://comment.ingored.url -->
  <br>
HTML;

$urls = array();

$dom = new DOMDocument();
$dom->loadHtml($html);
$xpath = new DOMXpath($dom);

// fetch urls from link href attributes
foreach ($xpath->evaluate('//a[@href]/@href') as $href) {
  $urls[] = $href->value;
}

// fetch urls inside text nodes
$pattern = '(
 (?:(?:https?://)|(?:www\.))
 (?:[^"\'\\s]+)
)xS';
foreach ($xpath->evaluate('/html/body//text()') as $text) {
  $matches = array();
  preg_match_all($pattern, $text->nodeValue, $matches);
  foreach ($matches[0] as $href) {
    $urls[] = $href;
  }
}

var_dump($urls);

Output:

array(4) {
  [0]=>
  string(21) "http://www.google.com"
  [1]=>
  string(23) "http://www.facebook.com"
  [2]=>
  string(13) "www.yahoo.com"
  [3]=>
  string(19) "https://www.aol.com"
}