public static function getAbsoluteUrl($url = null)
    {
        if (is_null($url)) {
            return '';
        }
        if (self::isUrl($url)) {
            return $url;
        }
        $url            = '/'.self::resolvePath($url);
        $current_url    = self::getRequestUrl(true, true);
        $curr           = substr($current_url, 0, strrpos($current_url, '/') );
        return $curr.$url;
    }