//被察者抽象類
class Observed implements SplSubject{
    protected $_name;
    protected $_observers;

    //實例化,生成一個觀察者對象
    public function __construct(){
        $this->_observers = new SplObjectStorage();
    }

    // 添加觀察者對象
    public function attach(SplObserver $observer){
        $this->_observers->attach($observer);
    }

    //刪除觀者對象
    public function detach(SplObserver $observer){
        $this->_observers->detach($observer);
    }

    //通知消息
    public function notify(){
        foreach($this->_observers as $observer){
            $observer->showMessage($this);
        }
    }

    //普通方法: 設置值
    public function setName($name){
        $this->_name = $name;
        $this->notify();
    }

    //普通方法: 獲取值
    public function getName(){
        return $this->_name;
    }

    //普通方法:設置年齡
    public function setAge($age){
        $this->age = $age;
        foreach($this->_observers as $observer){
            $observer->showAge($this->_name,$this->age);
        }
    }

}

// 觀察者抽象類
class Observer implements SplObserver{

    //顯示消息提示
    public function showMessage(SplSubject $obj){
        $user = $obj->getName();
        if($user==='admin'){
            echo '您好, ',$user,'歡迎您進入管理后臺<br/>';
        }else{
            echo "你好, '$user' 你已經被添加到了用戶列表<br/>";
        }
    }
    //這是繼承父類的抽象方法
    public function update(SplSubject $subject) {}

    //顯示個人年齡
    public function showAge($name,$age){
        echo "<script>alert('$name 的年齡是: $age')</script>";
    }
}

$subject = new Observed();  //生成一個被觀察者對象
$observer = new Observer(); //生成一個觀察者對象
$subject->attach($observer);//把觀察者傳入到被觀察中去
$subject->setName('張三'); //調用 setName 方法
/*
 * 通過面的 setName 就會調用  $this->notify();
* 通過調用  $this->notify()就會調用 $observer->showMessage($this)方法,
* 即每個觀察者對象的 showMessage($obj)方法;
*/
$subject->setName('admin');
$subject->setAge(24);