PHP中如何实现事件驱动？

class Event {
    private $name;
    private $data;

    public function __construct($name, $data = null) {
        $this->name = $name;
        $this->data = $data;
    }

    public function getName() {
        return $this->name;
    }

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

class EventDispatcher {
    private $listeners = [];

    public function addListener($eventName, callable $listener) {
        if (!isset($this->listeners[$eventName])) {
            $this->listeners[$eventName] = [];
        }
        $this->listeners[$eventName][] = $listener;
    }

    public function dispatch(Event $event) {
        $eventName = $event->getName();
        if (isset($this->listeners[$eventName])) {
            foreach ($this->listeners[$eventName] as $listener) {
                $listener($event);
            }
        }
    }
}

// 使用示例
$dispatcher = new EventDispatcher();

$dispatcher->addListener('user.registered', function(Event $event) {
    $userData = $event->getData();
    echo "User {$userData['username']} has been registered.\n";
});

$userRegisteredEvent = new Event('user.registered', ['username' => 'john_doe']);
$dispatcher->dispatch($userRegisteredEvent);