php与设计模式-观察者模式

观察者模式

在此种模式中，一个目标物件管理所有相依于它的观察者物件，并且在它本身的状态改变时主动发出通知。这通常透过呼叫各观察者所提供的方法来实现。此种模式通常被用来实现事件处理系统。

Demo：

//抽象通知者 
abstract class Subject 
{ 
    private $observers = array(); 

    public function  Attach(Observer $observer) 
    { 
        array_push($this->observers,$observer); 
    } 

    public function  Detach(Observer $observer) 
    { 
        foreach($this->observers as $k=>$v) 
        { 
            if($v==$observer) 
            { 
                unset($this->observers[$k]); 
            } 
        } 
    } 

    function  Notify() 
    { 
        foreach($this->observers as $v) 
        { 
            $v->Update(); 
        } 
    } 
} 
 
//具体通知者（Boss和Secretary） 
class ConcreteSubject extends Subject 
{ 
   public $subject_state; 
} 

//抽象观察者 
abstract class Observer 
{ 
    public abstract function Update(); 
} 

//具体观察者 
class ConcreteObserver extends Observer 
{ 
    private $name; 
    private $observerState; 
    public $subject; 

    public function __construct(ConcreteSubject $_sub,$_name) 
    { 
        $this->subject = $_sub; 
        $this->name = $_name; 
    } 

    public function  Update() 
    { 
        $this->observerState = $this->subject->subject_state; 
        echo "观察者".$this->name."的新状态是:".$this->observerState."<br/>"; 
    } 
} 
 
//-------------------------观察者模式----------------------- 
require_once "./Observe/Observe.php"; 
//前台 
$_s = new ConcreteSubject(); 
 
//宝银 
$baoyin = new ConcreteObserver($_s, "张三"); 
$jiangchao = new ConcreteObserver($_s,"李四"); 
 
//前台记下宝银姜超 
$_s->Attach($baoyin); 
$_s->Attach($jiangchao); 
 
//前台发现老板回来 
$_s->subject_state = "孙总回来了"; 
 
//前台发送通知 
$_s->Notify(); 

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