} class json { /** * @param $returnData * @return string */ public function get($returnData) { return json_encode($returnData); } } class xml { /** * @param $returnData * @return string */ public function get($returnData) { $xml = '<?xml version="1.0" encoding="utf-8"?>'; $xml .= '<return>'; $xml .= '<data>' . serialize($returnData) . '</data>'; $xml .= '</return>'; return $xml; } } $cd = new CD('cd1', 'zhu a zhu'); echo $cd->getCd(new json()); echo "<hr>"; echo $cd->getCd(new xml());