PHP面向对象进阶设计模式：观察者模式使用实例

<?php  
interface Observable{  
    function attach( Observer $observer );  
    function detach( Observer $observer );  
    function notify();  
}  
  
  
class login implements Observable{  
    const LOGIN_USER_UNKNOW = 1;  
    const LOGIN_WRONG_PASS = 2;  
    const LOGIN_ACCESS = 3;  
    private $status = array();  
    private $observers = array();  
  
    public function setStatus( $status, $user, $ip ) {  
        $this->status = array( $status, $user, $ip );  
    }  
    public function getStatus() {  
        return $this->status;  
    }  
    public function handleLogin( $user, $pass, $ip ) {  
        switch ( mt_rand( 1, 3 ) ) {  
        case 1:  
            $this->setStatus( self::LOGIN_USER_UNKNOW, $user, $ip );  
            $ret = false;  
            break;  
        case 2:  
            $this->setStatus( self::LOGIN_WRONG_PASS, $user, $ip );  
            $ret = false;  
            break;  
        case 3:  
            $this->setStatus( self::LOGIN_ACCESS, $user, $ip );  
            $ret = true;  
            break;  
        }  
        $this->notify();  
        return $ret;  
    }  
  
  
    public function attach( Observer $observer ) {  
        $this->observers[] = $observer;  
    }  
  
    public function detach( Observer $observer ) {  
        $newObservers = array();  
        foreach ( $this->observers as $obs ) {  
            if ( $obs !== $observer )  
                $newObservers[] = $obs;  
        }  
        $this->observers = $newObservers;  
    }  
  
    public function notify() {  
        foreach ( $this->observers as $obs ) {  
            $obs->update( $this );  
        }  
    }  
}  
  
interface Observer{  
    function update( Observable $observable );  
}  
  
class SecurityMonitor implements Observer{  
    function update( Observable $observable ) {  
        $status = $observable->getStatus();  
        if($status[0] == Login::LOGIN_WRONG_PASS){  
            echo __CLASS__.":".$status[1]."于".$status[2]."登录失败";  
        }  
    }  
}  
  
$login = new Login();  
$login->attach(new SecurityMonitor());  
$login->handleLogin(&#39;XXX&#39;,&#39;XXX&#39;,&#39;127.0.0.1&#39;);  
?>  
出错时的运行结果：  
SecurityMonitor:XXX于127.0.0.1登录失败[Finished in 0.1s]