如果我在symfony2中创建自定义事件,我如何访问实体管理器

namespace AppBundle\Event;

use Symfony\Component\EventDispatcher\Event;

class MyCustomEvent extends Event
{
    const NAME = 'my_custom_event';

    private $entityManager;

    public function __construct($entityManager)
    {
        $this->entityManager = $entityManager;
    }

    public function getEntityManager()
    {
        return $this->entityManager;
    }
}

services:
    app.event_listener.my_custom_event_listener:
        class: AppBundle\EventListener\MyCustomEventListener
        arguments: ['@event_dispatcher']
        tags:
            - { name: kernel.event_listener, event: my_custom_event, method: onMyCustomEvent }

namespace AppBundle\EventListener;

use AppBundle\Event\MyCustomEvent;

class MyCustomEventListener
{
    private $dispatcher;

    public function __construct($dispatcher)
    {
        $this->dispatcher = $dispatcher;
    }

    public function onMyCustomEvent(MyCustomEvent $event)
    {
        $entityManager = $event->getEntityManager();

        // 在这里访问实体管理器并执行您需要的操作
    }
}

$event = new MyCustomEvent($entityManager);
$this->get('event_dispatcher')->dispatch(MyCustomEvent::NAME, $event);