PHP面向接口编程

面向接口编程用于实现多态性，便于提高软件灵活性和可维护性。

<?php
/**
 *定义接口
 */
interface IDB{
        public function connect($host,$port,$user,$password,$db,$charset='GBK');
        public function getUserInfo($id);
        public function postNewFeed($feed);
}
/**
 *mysql实现
*/
class MySQL implements IDB{
        public function connect(){}
        public function getUserInfo($id){}
        public function postNewFeed($feed){}
}
/**
 *plsql实现
*/
class PLSQL implements IDB{
        public function connect(){}
        public function getUserInfo($id){}
        public function postNewFeed($feed){}
}

/**
 *工厂方法
 */
class DBFactory(){
        private $static $db = array();

        public function getInstance($type){
                switch (strtolower($type)){
                        case 'mysql':
                        if(!isset(self::$db['mysql']))
                                self::$db['mysql'] = new MySQL();
                        case 'plsql':
                        if(!isset(self::$db['plsql']))
                                self::$db['plsql'] = new PLSQL();
                        default:
                                throw new Exception('You must assign the db type!');
                }
        }
}

$db = DBFactory::getInstance('mysql');
$user_info = $db->getUserInfo($uid);
?>