@Component
public class OrderService {
    @Autowired
    private ApplicationEventPublisher eventPublisher;
 
    public void completeOrder(Order order) {
        // Business logic...
        eventPublisher.publishEvent(new OrderCompletedEvent(order));
    }
}
 
@Component
public class EmailListener {
    @EventListener
    public void handleOrderCompleted(OrderCompletedEvent event) {
        System.out.println("Sending email for order: " + event.getOrder().getId());
    }
}