public function loadMessages(/*# string */ $className)/*# : array */
    {
        $map = [];

        // reflect
        if (class_exists($className)) {
            $class = new \ReflectionClass($className);
            $file  = $class->getFileName();
            // language file 'Message.php' -> 'Message.zh_CN.php'
            $nfile = substr_replace($file, '.' . $this->language . '.php', -4);
            if (file_exists($nfile)) {
                $res = include $nfile;
                if (is_array($res)) {
                    $map = $res;
                }
            }
        }

        return $map;
    }