function get_http_code($url="localhost", $port=80, $fsock_timeout=10){
    set_time_limit(0);
    ignore_user_abort(true);

    // 記錄開始時間
    list($usec, $sec) = explode(" ", microtime(true));
    $timer['start'] = (float)$usec + (float)$sec;

    // 校驗URL
    if(!preg_match("/^https?:＼/＼//i", $url)){
        $url = "http://".$url;
    }
    // 支持HTTPS
    if(preg_match("/^https:＼/＼//i", $url)){
        $port = 443;
    }

    // 解析URL
    $urlinfo = parse_url($url);
    if(empty($urlinfo['path'])){
        $urlinfo['path'] = '/';
    }
    $host = $urlinfo['host'];
    $uri = $urlinfo['path'] . (empty($urlinfo['query'])?'':$urlinfo['query']);

    // 通過fsock打開連接
    if(!$fp = fsockopen($host, $port, $errno, $error, $fsock_timeout)){
        list($usec, $sec) = explode(" ", microtime(true));
        $timer['end'] = (float)$usec + (float)$sec;
        $usetime = (float)$timer['end'] - (float)$timer['start'];

        return array('code'=>-1, 'usetime'=>$usetime);
    }

    // 提交請求
    $status = socket_get_status($fp);
    $out = "GET {$uri} HTTP/1.1＼r＼n";
    $out .= "Host: {$host}＼r＼n";
    $out .= "Connection: Close＼r＼n＼r＼n";
    $write = fwrite($fp, $out);
    if(!$write){
        list($usec, $sec) = explode(" ", microtime(true));
        $timer['end'] = (float)$usec + (float)$sec;
        $usetime = (float)$timer['end'] - (float)$timer['start'];

        return array('code'=>-2, 'usetime'=>$usetime);
    }

    $ret = fgets($fp, 1024);
    preg_match("/http＼/＼d＼.＼d＼s(＼d+)/i", $ret, $m);
    $code = $m[1];
    fclose($fp);

    list($usec, $sec) = explode(" ", microtime(true));
    $timer['end'] = (float)$usec + (float)$sec;
    $usetime = (float)$timer['end'] - (float)$timer['start'];

    return array('code'=>$code, 'usetime'=>$usetime);
}

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, 'http://www.dhdzp.com/');
curl_setopt($ch, CURLOPT_RANGE, '0-500');
curl_setopt($ch, CURLOPT_BINARYTRANSFER, 1);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$result = curl_exec($ch);
curl_close($ch);
echo $result;

$writefn = function($ch, $chunk) {
  static $data='';
  static $limit = 500; // 500 bytes, it's only a test
  $len = strlen($data) + strlen($chunk);
  if ($len >= $limit ) {
    $data .= substr($chunk, 0, $limit-strlen($data));
    echo strlen($data) , ' ', $data;
    return -1;
  }
  $data .= $chunk;
  return strlen($chunk);
};
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, 'http://www.dhdzp.com/');
curl_setopt($ch, CURLOPT_RANGE, '0-500');
curl_setopt($ch, CURLOPT_BINARYTRANSFER, 1);
curl_setopt($ch, CURLOPT_WRITEFUNCTION, $writefn);
$result = curl_exec($ch);
curl_close($ch);