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安哥网络 发表于 2013-8-1 15:16:30

php设计模式 Observer(观察者模式)

<?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();

publicfunction registerObserver($observer)
    {
$this->_observers[] =$observer;
    }

publicfunction removeObserver($observer)
    {
$key=array_search($observer,$this->_observers);
if(!($key===false))
      {
unset($this->_observers[$key]);
      }
    }

publicfunction notifyObservers()
    {
foreach($this->_observers as$observer)
      {
if($observer instanceof Observer) $observer->update($this);
      }
    }
}

interface Observer
{
publicfunction update($observer);
}

interface DisplayElement
{
publicfunction display();
}

// -- 实例类定义
class NewsObserverable extends Observerable
{
private$_sports_news;
publicfunction setSportsNews($data)
    {
$this->_sports_news =$data;
$this->notifyObservers();
    }

publicfunction getSportsNews()
    {
return$this->_sports_news;
    }

private$_local_news;
publicfunction setLocalNews($data)
    {
$this->_local_news =$data;
$this->notifyObservers();
    }

publicfunction getLocalNews()
    {
return$this->_local_news;
    }
}

class SportsNews implements Observer,DisplayElement
{
private$_data=null;
publicfunction update($observer)
    {
if($this->_data !=$observer->getSportsNews())
      {
$this->_data =$observer->getSportsNews();
$this->display();
      }
    }

publicfunction display()
    {
echo$this->_data.date("Y-m-d H:i:s")."
";
    }
}

class LocalNews implements Observer,DisplayElement
{
private$_data=null;
publicfunction update($observer)
    {
if($this->_data !=$observer->getLocalNews())
      {
$this->_data =$observer->getLocalNews();
$this->display();
      }
    }

publicfunction display()
    {
echo$this->_data.date("Y-m-d H:i:s")."
";
    }
}

// -- 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 ");本文摘自：http://www.cnblogs.com/bluefrog/archive/2011/06/14/2080208.html

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