<?php
/**
 * 【观察者模式】
 * PHP5中提供了 观察者(observer) 和 被观察者(subject) 的接口
 * 在手册搜索：SplSubject (PHP 5 >= 5.1.0)
 *
 * SplSubject  {
 *         abstract public void attach ( SplObserver $observer )
 *         abstract public void detach ( SplObserver $observer )
 *         abstract public void notify ( void )
 * }
 *
 */

header("Content-type: text/html; charset=utf-8");

/*根据登录次数和爱好，进行观察.定义user类，实现SplSubject接口 */
class User implements SplSubject{
    public $lognum; //登录次数
    public $hobby; //爱好
    protected $observers; //用来储存对象

    public function __construct($hobby){
        $this->lognum = rand(1,10); //登录次数：随机数
        $this->hobby = $hobby; //爱好：参数传递
        $this->observers = new SplObjectStorage();
    }

    //登录操作
    public function login(){
        //操作session... 代码忽略
        //登录后，触发notify
        $this->notify();
    }

    //观察
    public function attach(SPLObserver $observer){
        $this->observers->attach($observer);
    }

    //取消观察
    public function detach(SPLObserver $observer){
        $this->observers->detach($observer);
    }

    //通知
    public function notify(){
        $this->observers->rewind();
        //不断循环获取储存的对象
        while($this->observers->valid()){
            $observer = $this->observers->current();
            $observer->update($this);
            $this->observers->next();
        }
    }

}

/*假如现在有个“安全模块” security 要来观察 */
class security implements SPLObserver{
    public function update(SplSubject $subject){
        if($subject->lognum < 3){
            echo '这是第'.$subject->lognum.'次安全登录<br>';
        }else{
            echo '这是第'.$subject->lognum.'次登录，出现异常。<br>';
        }
    }
}

/*再假如现在有个“广告模块” ad 要来观察 */
class ad implements SPLObserver{
    public function update(SplSubject $subject){
        if($subject->hobby == 'sports'){
            echo '开运动会<br>';
        }else{
            echo '哈哈哈哈哈哈<br>';
        }
    }
}

/*实施观察*/
//实例化User
$user = new User('sports');
//实施“安全模块”的观察
$user->attach(new security());
//实施“广告模块”的观察
$user->attach(new ad());
//执行登录操作
$user->login();