如何用PHP file_get_contents获取指定网页track标签的src属性值

Alright, let's walk through how to pull that captions track URL using PHP. First, we'll fetch the page content with file_get_contents, then parse the HTML to grab the specific attribute you need.

Method 1: Use DOMDocument (Recommended) #

This is the most reliable approach because HTML can be messy, and DOM parsers handle variations like extra whitespace, attribute order changes, etc., way better than regex.

// Fetch the HTML from your target website
$html = file_get_contents('https://your-target-site-url.com'); // Replace with your actual URL

// Set up DOMDocument to handle potentially imperfect HTML
$dom = new DOMDocument();
libxml_use_internal_errors(true); // Suppress parsing warnings for messy HTML
$dom->loadHTML($html);
libxml_clear_errors(); // Clear any stored warnings

// Use XPath to find the <track> tag with kind="captions"
$xpath = new DOMXPath($dom);
$captionsTrack = $xpath->query('//track[@kind="captions"]');

// Check if we found the track element and get the src attribute
if ($captionsTrack->length > 0) {
    $srcUrl = $captionsTrack->item(0)->getAttribute('src');
    echo $srcUrl; // Will output: https://rolled.oped.info/sub/jAghd9t8AB4/HfQZ32SovcY.vtt
} else {
    echo "Couldn't find a captions track on the page.";
}

Method 2: Quick Regex (Fragile, Not Recommended for Production) #

If you need a super quick solution and are confident the HTML structure won't change, you can use a regex. But be warned—this will break if the site modifies the HTML even slightly (like adding another attribute before src).

$html = file_get_contents('https://your-target-site-url.com');
$regexPattern = '/<track kind="captions" src="([^"]+)"/';

if (preg_match($regexPattern, $html, $matches)) {
    echo $matches[1]; // Outputs the captions URL
} else {
    echo "No captions track found.";
}

Pro Tip: Some sites block requests from file_get_contents by default. If you run into issues, add a user-agent header to mimic a real browser:

$context = stream_context_create([
    'http' => [
        'header' => 'User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/114.0.0.0 Safari/537.36'
    ]
]);
$html = file_get_contents('https://your-target-site-url.com', false, $context);

内容的提问来源于stack exchange，提问作者Jacob K.