public function addFile($sFile)
    {
        if (empty($sFile)) {
            throw new Exception('Parameter $sFile is empty!');
        }

        if (empty($this->_sBaseDirectory)) {
            throw new Exception('Base directory is not set, please use setter setBaseDirectory!');
        }

        if (is_file($this->_sBaseDirectory . $sFile)) {
            $this->_aFiles[] = $sFile;

            return true;
        }

        return false;
    }