Design-patterns/observer.php at master · LaughingMeMe/Design-patterns · GitHub

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<?php

//观察者模式

//行为型模式：能够便利的查看目标对象状态的对象，并且提供与核心对象非耦合的指定功能性

//可观察类,一个CD站点首页CD的最近出售情况，在CD被出售的情况下去发出指令去更新CD最近出售情况

class CD{

public $title = '';

public $band = '';

private $_observers = array();

public function __construct($title,$band){

$this->title = $title;

$this->band = $band;

}

public function addObserver($type,$observer){

array_push($this->_observers[$type],$observer);

}

public function notifyObserver($type){

if(isset($this->_observers[$type])){

if(is_array($this->_observers) && !empty($this->_observers)){

foreach ($this->_observers as $key => $value) {

$value->update($this);

}

public function buy(){

$this->notifyObserver('purchased');

}

class buyCDNotifyStreamObserver{

public function update(CD $cd){

echo $this->title.'_'.$this->band.'_'.'is_already_purchased'.'剩余xxx张';

}

//当CD被购买的时候，通知用户已买还剩余多少张

//当一个类的核心属性创建时候，如果存在可观察状态的变化，最佳的做法是基于观察者模式创建与目标对象交互的其他类

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