php工厂模式

php工厂模式

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工厂模式：工厂类调用自身方法来生产对象实例。

示例：

interface DbFactory{
    public function new_db();
}


interface DbCls{
    public function connect_db();
    public function query();
    //...
}

//mysql数据库
class factory_mysql implements DbFactory{
    public function new_db(){
        return new db_mysql();
    } 
}

class db_mysql implements DbCls{
    public function connect_db(){
        echo 'mysql connect';
    }
    public function query(){
        echo 'mysql query';
    }
}

//sqlite数据库
class factory_sqlite implements DbFactory{
    public function new_db(){
        return new db_sqlite();
    } 
}

class db_sqlite implements DbCls{
    public function connect_db(){
        echo 'db_sqlite connect';
    }
    public function query(){
        echo 'db_sqlite query';
    }
}

//调用mysql
$obj = new factory_mysql();
$db = $obj->new_db();

$db->connect_db();
$db->query();

//调用sqlite
$obj = new factory_sqlite();
$db = $obj->new_db();
$db->connect_db();
$db->query();


//如果新增加一个数据库类
//只需要添加新的类，不用修改原有的类
//sqlite数据库
class factory_oracle implements DbFactory{
    public function new_db(){
        return new db_oracle();
    } 
}

class db_oracle implements DbCls{
    public function connect_db(){
        echo 'db_oracle connect';
    }
    public function query(){
        echo 'db_oracle query';
    }
}

$obj = new factory_oracle();
$db = $obj->new_db();
$db->connect_db();
$db->query();

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