<?php

header("Content-type:text/html;charset=utf-8");

/**

* 共同接口

*/

 interface db

{

    function conn();

}

/**

* mysql类

*/

class DbMysql implements db

{

    public function conn()

    {

        echo "连接上了mysql";

    }

}

/**

* sqlite类

*/

class DbSqlite implements db

{

    public function conn()

    {

        echo "连接上了sqlite";

    }

}

$db = new DbMysql();

$db->conn();

$db = new DbSqlite();

$db->conn();