php查看请求头信息获取远程图片大小的方法分享

$fp = fsockopen(".baidu.", 80, $errno, $errstr, 30);
if ($fp) {
    //这里请求设置为HEAD就行了
    $out = "HEAD /img/baidu_sylogo1.gif HTTP/1.1\r\n";
    $out .= "Host: .baidu.\r\n";
    $out .= "Connection: Close\r\n\r\n";
    fwrite($fp, $out);
    while (!feof($fp)) {
        $header = fgets($fp);
        if (stripos($header, 'Content-Length') !== false) {
            $size = trim(substr($header, strpos($header, ':') + 1));
            echo $size;
        }
    }
    fclose($fp);
} else {
    echo "$errstr ($errno)";
}