<?php

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

/**

* db接口

* 实现连接数据库函数conn

*/

 interface db

{

    function conn();

}

/**

 * 工厂接口

 * 实现创建连接函数createDb

 */

 interface factory

{

    function createDb();

}

/**

* mysql类

*/

class DbMysql implements db

{

    public function conn()

    {

        echo "连接上了mysql<br>";

    }

}

/**

* sqlite类

*/

class DbSqlite implements db

{

    public function conn()

    {

        echo "连接上了sqlite<br>";

    }

}

/**

* MysqlFactory

*/

class MysqlFactory implements factory

{

    public function createDb()

    {

        return new DbMysql();

    }

}

/**

* SqliteFactory

*/

class SqliteFactory implements factory

{

    public function createDb()

    {

        return new DbSqlite();

    }

}

//不修改源代码，扩展oracle数据库

/**

* oracle

*/

class DbOracle implements db

{

    public function conn()

    {

        echo "连上了oracle数据库<br>";

    }

}

/**

* oracle工厂类

*/

class OracleFactory implements factory

{

    public function createDb()

    {

        return new DbOracle();

    }

}

// 客户端调用

$factory = new MysqlFactory();

$db = $factory->createDb();

$db->conn();

$factory = new SqliteFactory();

$db = $factory->createDb();

$db->conn();

$factory = new OracleFactory();

$db = $factory->createDb();

$db->conn();