';    }}class dbsqlite implements db{    public function conn(){        echo '04-连接上了sqlite 
';    }}//定义多个工厂类，分别实现上面的工厂接口class mysqlFactory implements Factory{    public function createDB(){        $db = new dbmysql();        return $db->conn();    }}class sqliteFactory implements Factory{    public function createDB(){        $db = new dbsqlite();        return $db->conn();    }}/* 客户端开发 */$fact = new mysqlFactory(); $fact->createDB();$fact = new sqliteFactory(); $fact->createDB();////==== 假如现在新增 oracle的相关数据(前面的代码不用改)：class dboracle implements db{    public function conn(){        echo '04-连接上了oracle';    }}class oracleFactory implements Factory{    public function createDB(){        $db = new dboracle();        return $db->conn();    }}//客户端调用$fact = new oracleFactory();$fact->createDB(); //输出“04-连接上了oracle”