备忘录模式及php实现

<?phpheader("Content-type:text/html;Charset=utf-8");//备忘录class Memento{    public $id;    public $name;    public $liveLevel;    function __construct($id,$name,$liveLevel){        $this->id = $id;        $this->name = $name;        $this->liveLevel = $liveLevel;    }}//备忘录管理器class Originator{     public static $mementos = array();     private static $instance = null;     //单例模式确保只有一个管理器     private function __construct(){     }     //返回单例对象     static function getInstance(){         if(!(self::$instance instanceOf slef)){              self::$instance = new self();         }         return self::$instance;     }     //存备忘录     function setMemento($id,Memento $memento){         self::$mementos[$id] = $memento;     }     //取备忘录     function getMemento($id){         return self::$mementos[$id];     }}//创建者，玩家，可存取自身状态class Player{    private static $i = 0;  //静态变量累加用于给$id赋值    public $id; //每个对象独一无二，用于保存状态备忘录到管理器    private $name; //姓名    private $liveLevel;  //生命值    function __construct($name){        $this->name = $name;        $this->id = self::$i;        self::$i++;    }    //初始化    function init(){       $this->liveLevel = 100;    }    //生命值减少10    function damage(){        $this->liveLevel -=10;    }       //显示现有状态    function displayState(){        echo "姓  名：".$this->name."<br/>";        echo "生命值：".$this->liveLevel."<br/>";    }    //保存状态到一个备忘录中，该备忘录将被放置到管理器中    function saveState(){        $originator = Originator::getInstance();        $originator->setMemento($this->id,new Memento($this->id,$this->name,$this->liveLevel));    }    //恢复备忘录    function getState(){        $originator = Originator::getInstance();        $memento = $originator->getMemento($this->id);        $this->id = $memento->id;        $this->name = $memento->name;        $this->liveLevel = $memento->liveLevel;    }}//测试//创建、初始化角色并显示状态$player = new Player("张三");$player->init();$player->displayState(); //生命值100//开始游戏前存档$player->saveState();//开始游戏,收到伤害生命值减少，显示状态$player->damage();$player->damage();$player->displayState(); //生命值80//回档恢复原来状态，显示状态$player->getState();$player->displayState();  //生命值100 ?>