1、定义事件继承ApplicationEvent

/**
 * 订单完成事件
 */
@Getter
public class OrderFinishedEvent extends ApplicationEvent {

    private final Order order;

    public OrderFinishedEvent(Object source, Order order) {
        super(source);
        this.order = order;
    }
}

2、发布事件

@Resource
private ApplicationContext applicationContext;

applicationContext.publishEvent(new OrderFinishedEvent(this, order));

3、监听事件

（1）实现ApplicationListener

@Component
public class FirstOrderFinishedListener implements ApplicationListener<OrderFinishedEvent> {
    @Override
    public void onApplicationEvent(OrderFinishedEvent event) {
        Order order = event.getOrder();
        ...
    }
}

（2）注解@EventListener

// ({可监听多个事件，逗号分隔})
@EventListener(OrderFinishedEvent.class)
// 参数0或1个，返回类型任意（异步@Async时不能返回原生类型如boolean）
public void onApplicationEvent(OrderFinishedEvent event) {
    logger.info("订单完成：{}", JSON.toJSONString(event));
    Order order = event.getOrder();
}

备注：监听事件通常会异步处理，方法加上注解 @Async("threadPoolTaskExecutor")，使用指定线程池异步处理。