/**
 * 工厂方法或者类生成对象,而不是在代码中直接new
 * 
 * 修改类名的时候,不需要每一个实例化语句都修改
 * 只需要修改对应的工厂方法
 * 
 * Class Factory
 * @package regina
 */
class Factory{
    static function createDatabase(){
        $db = Database::getInstance();
        return $db;
    }
}
/**
 * 单例模式,节省资源,一个类只能实例化一个对象
 * 
 * 使某个类的对象仅允许创建一个
 * 
 * 为了实现单例模式,要私有化构造函数和clone魔术方法
 * Class Database
 * @package regina
 */
class Database{
    
    protected static $db;
    private function __construct(){
    }
    private function __clone(){
    }
    static function getInstance(){
        if (self::$db){
            return self::$db;
        }
        self::$db = new Database();
        return self::$db;
    }
}
/**
 * 把new出来的对象保存在静态数值中,以便全局共享
 * 全局共享和交换对象
 * Class Register
 * @package regina
 */
class Register{
    protected static $array;
    static function set($name, $Obj){
        echo ‘Register set run....‘;
        self::$array[$name] = $Obj;
    }
    static function get($name){
        echo ‘Register get run....‘;
        return self::$array[$name];
    }
    function _unset($name){
        echo ‘Register unset run....‘;
        unset(self::$array[$name]);
    }
}
/**
 * 将各种截然不同的函数接口封装成统一的API
 * Interface IDatabase
 * @package regina
 */
interface IDatabase{
    function connect($host, $username, $password, $dbname);
    function query();
    function close();
}
class Mysqli implements Database{
    protected $conn;
    function connect($host, $username, $password, $dbname){
        echo ‘Mysqli connect run...‘;
    }
    function query(){
        echo ‘Mysqli query run...‘;
    }
    function close(){
        echo ‘Mysqli close run...‘;
    }
}
class Mysql implements Database{
    function connect($host, $username, $password, $dbname){
        echo ‘Mysql connect run...‘;
    }
    function query(){
        echo ‘Mysql query run...‘;
    }
    function close(){
        echo ‘Mysql close run...‘;
    }
}
将一组特定的行为和算法封装成类,以适应默写上下文的定义。
原文:http://www.cnblogs.com/alihenaixiao/p/6014424.html