TWPUG問答 - 如何偵測URL資源是否存在

<?php
function checkUrl($url) {
    preg_match('/^(?P<protocol>[a-z]+):\/\/(?P<hostname>[\w\._-]+)(?P<resource>\/.*)/',
        $url, $uriSet);
    $portMap = array('http' => 80, 'https' => 443);
    if (!isset($portMap[$uriSet['protocol']]))
        return false;
    else
        $port = $portMap[$uriSet['protocol']];
    $fh = fsockopen('tcp://'.$uriSet['hostname'], $port, $errno, $errstr, 30);
    if (!$fh) {
        //echo "$errstr ($errno)<br />\n";

        $rc = false;
    } else {
        $cmd = "HEAD {$uriSet['resource']} HTTP/1.1\r\n";
        $cmd .= "Host: www.example.com\r\n";
        $cmd .= "Connection: Close\r\n\r\n";

        fputs($fh, $cmd);
        $response = fgets($fh);
        list($h, $rc) = explode(' ', $response);
        while(!feof($fh))
            fgets($fh);
        fclose($fh);
        
    }
    return $rc;
}

echo checkUrl('http://www.google.com.tw/intl/en_com/images/logo_plain.png'), "\n";

echo checkUrl('http://www.google.com.tw/intl/en_com/images/logo_plain.xxx'), "\n";

?>