php设计模式 Observer (观察者模式)
25种php设计模式，你全都知道吗？下面用代码介绍观察者模式(Observer模式)
<?php
/**
* 观察者模式
*
* 定义对象间的一种一对多的依赖关系,以便当一个对象的状态发生改变时,所有依赖于它的对象都得到通知并自动刷新
* 能够便利地创建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
* 插件系统
*/
class Observerable {
private $_observers = array();
public function registerObserver($observer) {
$this->_observers[] = $observer;
}
public function removeObserver($observer) {
$key = array_search($observer, $this->_observers);
if (!($key === false)) {
unset($this->_observers[$key]);
}
}
public function notifyObservers() {
foreach ($this->_observers as $observer) {
if ($observer instanceof Observer) $observer->update($this);
}
}
}
interface Observer {
public function update($observer);
}
interface DisplayElement {
public function display();
}
// -- 实例类定义
class NewsObserverable extends Observerable {
private $_sports_news;
public function setSportsNews($data) {
$this->_sports_news = $data;
$this->notifyObservers();
}
public function getSportsNews() {
return $this->_sports_news;
}
private $_local_news;
public function setLocalNews($data) {
$this->_local_news = $data;
$this->notifyObservers();
}
public function getLocalNews() {
return $this->_local_news;
}
}
class SportsNews implements Observer, DisplayElement {
private $_data = null;
public function update($observer) {
if ($this->_data != $observer->getSportsNews()) {
$this->_data = $observer->getSportsNews();
$this->display();
}
}
public function display() {
echo $this->_data . date("Y-m-d H:i:s") . "<br/>";
}
}
class LocalNews implements Observer, DisplayElement {
private $_data = null;
public function update($observer) {
if ($this->_data != $observer->getLocalNews()) {
$this->_data = $observer->getLocalNews();
$this->display();
}
}
public function display() {
echo $this->_data . date("Y-m-d H:i:s") . "<br/>";
}
}
// -- 实例化 ---
$objObserver = new NewsObserverable();
$local = new LocalNews();
$sports = new SportsNews();
$objObserver->registerObserver($local);
$objObserver->registerObserver($sports);
$objObserver->setSportsNews("sports news 1 ");
$objObserver->setLocalNews("local news 1 ");
$objObserver->removeObserver($sports);
$objObserver->setLocalNews("local news 2 ");
$objObserver->setSportsNews("sports news 2 ");
$objObserver->removeObserver($local);
$objObserver->setLocalNews("local news 3 ");其他相关设计模式：
http://www.phprm.com/develop/memento.html 备忘录模式(Memento模式)
http://www.phprm.com/develop/observer.html 观察者模式(Observer模式)
http://www.phprm.com/develop/template.html 模板方法模式(Template Method模式)
http://www.phprm.com/develop/command.html 命令模式(command模式)
http://www.phprm.com/develop/composite.html 组合模式(composite模式)
http://www.phprm.com/develop/flyweight.html 享元模式(flyweight模式)
http://www.phprm.com/develop/strategy.html 策略模式(strategy模式)
http://www.phprm.com/develop/state.html 状态模式(state模式)
http://www.phprm.com/develop/adapter.html 适配器模式(adapter模式)
http://www.phprm.com/develop/factory.html 工厂模式(factory模式)
http://www.phprm.com/develop/prototype.html 原型模式(prototype模式)
http://www.phprm.com/develop/facade.html 外观模式(facade模式)
http://www.phprm.com/develop/singleton.html 单例模式(singleton模式)
http://www.phprm.com/develop/bridge.html 桥梁模式(bridge模式)
http://www.phprm.com/develop/decorator.html 装饰模式(decorator模式)
http://www.phprm.com/develop/abstract.html 抽象工厂模式(abstract factory模式)
http://www.phprm.com/develop/builder.html 建造者模式(Builder模式)
http://www.phprm.com/develop/visitor.html 访问者模式(Visitor模式)
http://www.phprm.com/develop/interpreter.html 解释器模式(Interpreter模式)
http://www.phprm.com/develop/mediator.html 中介者模式(Mediator模式)
http://www.phprm.com/develop/chain.html 职责链模式(Chain Of Responsibility模式)
http://www.phprm.com/develop/proxy.html 代理模式(Proxy模式)
http://www.phprm.com/develop/interator.html 迭代器模式(Interator模式)
http://www.phprm.com/develop/dao.html 数据访问对象模式(DAO模式)
http://www.phprm.com/develop/delegation.html 委托模式(Delegation模式)
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