PHP regular expressions in action: matching audio links

With the development of the audio industry, more and more websites and applications need to support automatic identification and embedding of audio links. In the implementation process of developers, it is a common method to use regular expressions to match audio links. This article will introduce how to match audio links and extract key information in PHP regular expressions.

1. Analyze the structure of the audio link

Before matching the audio link, we need to understand the structure of the audio link. Generally, the audio link includes the following parts:

• Protocol: such as http, https, ftp, etc.
• Domain name or IP address: refers to the domain name or IP address of the server where the audio resource is located.
• Port number: refers to the port number used to access audio resources.
• Path: refers to the path of the audio resource on the server.
• File name: refers to the name of the audio file.
• Extension: refers to the extension of the audio file, common ones include mp3, wav, ogg, etc.

For example, the following is a typical audio link:

http://www.example.com:8080/music/album01/song01.mp3

2. Use regular expressions to match audio links

With the audio link Knowing the structure, we can use regular expressions to match audio links. Suppose we want to extract all audio links from an HTML page, we can write the following regular expression:

$pattern = '/<a[^>]+href=["|']?([^"'s]+.mp3)["|']?[^>]*>(.*)</a>/iU';

This regular expression first matches the characters ending with .mp3 in the href attribute value string. Note that non-greedy mode (U) is used here to avoid matching part of multiple links.

3. Extract key information of the audio link

After using regular expressions to match the audio link, we also need to extract key information from it, such as protocol, domain name, path, File name, etc. You can use PHP's built-in functions to achieve this step.

For example, we can use the parse_url() function to extract the protocol, domain name, path and file name in the link:

$url = 'http://www.example.com:8080/music/album01/song01.mp3';
$parse = parse_url($url);
$scheme = $parse['scheme']; // 返回"http"
$host = $parse['host']; // 返回"www.example.com"
$port = $parse['port']; // 返回"8080"
$path = $parse['path']; // 返回"/music/album01/song01.mp3"
$filename = basename($path); // 返回"song01.mp3"

It should be noted that the parse_url() function cannot directly extract the file Name needs to be extracted using the basename() function.

4. Decoding URI encoding

In some cases, paths and file names in links may be URL encoded. You can use the urldecode() function in PHP to decode.

For example, we can use the following code to decode the path and file name in the link:

$path = urldecode($path);
$filename = urldecode($filename);

5. Full code example

Finally, let’s Take a look at a complete code example that extracts and outputs the key information of all audio links from an HTML page:

$html = '......';
$pattern = '/<a[^>]+href=["|']?([^"'s]+.mp3)["|']?[^>]*>(.*)</a>/iU';
preg_match_all($pattern, $html, $matches);
$urls = $matches[1];
foreach ($urls as $url) {
    $parse = parse_url($url);
    $scheme = $parse['scheme'];
    $host = $parse['host'];
    $port = $parse['port'];
    $path = $parse['path'];
    $filename = basename($path);
    $path = urldecode($path);
    $filename = urldecode($filename);
    echo "协议：$scheme
";
    echo "域名：$host
";
    echo "端口号：$port
";
    echo "路径：$path
";
    echo "文件名：$filename

";
}

As you can see from the above code example, regular expressions are used to match audio links and extract key information. It is not difficult. Developers only need to combine regular expressions and PHP built-in functions to achieve this function.

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