PHP教程：浅谈PHP解析URL函数parse_url和parse_str

<?php
$url = 'http://username:password@hostname/path?arg=value#anchor';
print_r(parse_url($url));
echo parse_url($url, PHP_URL_PATH);
?>

Array
(
    [scheme] => http
    [host] => hostname
    [user] => username
    [pass] => password
    [path] => /path
    [query] => arg=value
    [fragment] => anchor
)
/path

<?php
$str = "first=value&arr[]=foo+bar&arr[]=baz";
parse_str($str);
echo $first;  // value
echo $arr[0]; // foo bar
echo $arr[1]; // baz
parse_str($str, $output);
echo $output['first'];  // value
echo $output['arr'][0]; // foo bar
echo $output['arr'][1]; // baz
?>

    /**
     * Parse a DSN string, which can have one of the following formats:
     *
     * - host:port
     * - redis://user:pass@host:port/db?option1=val1&option2=val2
     * - tcp://user:pass@host:port/db?option1=val1&option2=val2
     *
     * Note: the 'user' part of the DSN is not used.
     *
     * @param string $dsn A DSN string
     * @return array An array of DSN compotnents, with 'false' values for any unknown components. e.g.
     *               [host, port, db, user, pass, options]
     */
    public static function parseDsn($dsn)
    {
        if ($dsn == '') {
            // Use a sensible default for an empty DNS string
            $dsn = 'redis://' . self::DEFAULT_HOST;
        }
        $parts = parse_url($dsn);
        // Check the URI scheme
        $validSchemes = array('redis', 'tcp');
        if (isset($parts['scheme']) && ! in_array($parts['scheme'], $validSchemes)) {
            throw new \InvalidArgumentException("Invalid DSN. Supported schemes are " . implode(', ', $validSchemes));
        }
        // Allow simple 'hostname' format, which `parse_url` treats as a path, not host.
        if ( ! isset($parts['host']) && isset($parts['path'])) {
            $parts['host'] = $parts['path'];
            unset($parts['path']);
        }
        // Extract the port number as an integer
        $port = isset($parts['port']) ? intval($parts['port']) : self::DEFAULT_PORT;
        // Get the database from the 'path' part of the URI
        $database = false;
        if (isset($parts['path'])) {
            // Strip non-digit chars from path
            $database = intval(preg_replace('/[^0-9]/', '', $parts['path']));
        }
        // Extract any 'user' and 'pass' values
        $user = isset($parts['user']) ? $parts['user'] : false;
        $pass = isset($parts['pass']) ? $parts['pass'] : false;
        // Convert the query string into an associative array
        $options = array();
        if (isset($parts['query'])) {
            // Parse the query string into an array
            parse_str($parts['query'], $options);
        }
        return array(
            $parts['host'],
            $port,
            $database,
            $user,
            $pass,
            $options,
        );
    }