【php设计模式】观察者模式

求助信当对象间存在一对多关系时，则使用观察者模式。比如，当一个对象被修改时，则会自动通知它的依赖对象。观察者模式属于行为型模式。

<?phpclass subject{    private $obrver_list;    private $num;    public function __construct(){        $this->obrver_list = new spldoublylinkedlist();    }    public function attach(obrver $obrver){        $this->obrver_list->push($obrver);    }    publ猪腰的做法ic function tnum($num){        $this->num = $num;        $this->notify();    }    public function getnum(){        return $this->num;    }    public function notify(){        foreach ($this->obrver_list as $obrver) {            $obrver->update();        }    }}abstract class obrver{    public $subj;    public function __construct(subject $subj){        $this->subj = $变焦subj;        $this->subj->attach($this);    }    abstract function update();}class binobrver extends obrver{    public function update(){        echo "二进制更新：".decbin($this->subj->getnum())."\n";    }}class octobrver extends obrver{    public function update(){        echo "八进制更新：".decoct($this->subj->getnum())."\n";    }}class hexobrver extends obrver{    public function update(){        echo "十六进制更新：".dechex($this->subj->getnum())."帅的网名\n";    }}$subject = new subject(食品安全培训内容);new binobrver($subject);new octobrver($subject);new hexobrver($subject);$subject->tnum(22);

运行结果：

二进制更新：10110八进制更新：26十六进制更新：16