观察者模式

1.观察者模式

PHP内置的类提供了对SPL的原生支持，实现如下。

class ConcreteSubject implements SplSubject
{
    private $observers;
    private $data;

    public function __construct()
    {
        $this->observers = new SplObjectStorage();
    }
    
    public function attach(SplObserver $observer)
    {
        $this->observers->attach($observer);
    }

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

    public function detach(SplObserver $observer)
    {
        $this->observers->detach($observer);
    }

    public function setData($dataNow){
        $this->data = $dataNow;
    }

    public function getData(){
        return $this->data;
    }
}

class ConcreteObserver implements SplObserver {

    public function update(SplSubject $subject)
    {
        echo $subject->getData();
    }
}

class Client
{
    public function __construct()
    {
        echo "create three new concrete observers,a new concrete subject:";
        $ob1 = new ConcreteObserver();
        $ob2 = new ConcreteObserver();
        $ob3 = new ConcreteObserver();
        $subject = new ConcreteSubject();
        $subject->setObservers();
        $subject->setData("here is your data\n");
        $subject->attach($ob1);
        $subject->attach($ob2);
        $subject->attach($ob3);
        $subject->notify();
        $subject->detach($ob3);
        $subject->notify();
    }
}
$worker = new Client();