观察者模式

观察者模式有时也被称作发布/订阅模式，该模式用于为对象实现发布/订阅功能：一旦主体对象状态发生改变，与之关联的观察者对象会收到通知，并进行相应操作。

<?php

/**
 * 观察者接口
 */
interface ObserverInterface
{
    public function update($params);
}

/**
 * 被观察者接口
 */
interface BeenObservedInterface
{
    public function attach(ObserverInterface $observer);
    public function detach(ObserverInterface $observer);
    public function notify();
}



class Observer implements ObserverInterface
{
    public function update($params)
    {
        $reflection = new ReflectionClass($params);
        echo "<br/>The Button(BeenObserved) ".$reflection->getName()." has been clicked!";
    }
}


class BeenObserved implements BeenObservedInterface
{
    private $_observers;

    public function attach(ObserverInterface $observer)
    {
        $this->_observers[spl_object_hash($observer)] = $observer;
    }

    public function detach(ObserverInterface $observer)
    {
        unset($this->_observers[spl_object_hash($observer)]);
    }

    public function notify()
    {
        foreach ($this->_observers as $observer) {
            $observer->update($observer);
        }
    }

    public function test()
    {
        $this->notify();
    }
}



$observer = new Observer();
$observer2 = new Observer();
$beenObserved = new BeenObserved();

$beenObserved->attach($observer);
$beenObserved->attach($observer2);

$beenObserved->test();