php unicode中国語変換

class Helper_Tool
{
    static function unicodeDecode($data)
    {
        function replace_unicode_escape_sequence($match)
        {
            return mb_convert_encoding(pack('H*', $match[1]), 'UTF-8', 'UCS-2BE');
        }

        $rs = preg_replace_callback('/\\\\u([0-9a-f]{4})/i', 'replace_unicode_escape_sequence', $data);
        return $rs;
    }
}