Spring事件发布

Posted 2022-11-12 root_zhb

事件发布

• 1、基础
• 2、开发流程

1、基础

1. ApplicationContext 中的事件处理是通过 ApplicationEvent 类和 ApplicationListener 接口提供的。

2. 如果将实现 ApplicationListener 接口的bean部署到上下文中（@Component），则每次将 ApplicationEvent 发布到 ApplicationContext 时，该bean都会得到通知。

3. spring事件监听，是以异步方式来操作的，而AOP是同步的。

public abstract class ApplicationEvent extends EventObject 

    // 事件源
    public ApplicationEvent(Object source) 
        super(source);
        this.timestamp = System.currentTimeMillis();
    

    public final long getTimestamp() 
        return this.timestamp;
    

@FunctionalInterface
public interface ApplicationListener<E extends ApplicationEvent> extends EventListener 

    // 处理事件
    void onApplicationEvent(E event);

2、开发流程

实际开发中，分为三个类：Event、Publisher、Listener。

/**
 * 事件类
 * 1、继承ApplicationEvent
 * 2、重写构造方法
 * 3、参数set、get
 *
  */
public class PaymentDistributionEvent extends ApplicationEvent 

    private Payment payment;

    public PaymentDistributionEvent(Object source,Payment payment) 
        super(source);
        this.payment=payment;
    

    public Payment getPayment() 
        return payment;
    

    public void setPayment(Payment payment) 
        this.payment = payment;
    

/**
 * 发布类
 * 1、声明bean
 * 2、实现接口ApplicationEventPublisherAware
 * 3、重写方法setApplicationEventPublisher
 * 4、实现自己的方法，并在方法内调用Spring发布事件
 */
@Component
public class PaymentDistributionPublisher implements ApplicationEventPublisherAware 

    private ApplicationEventPublisher applicationEventPublisher;

    @Override
    public void setApplicationEventPublisher(ApplicationEventPublisher applicationEventPublisher) 
        this.applicationEventPublisher=applicationEventPublisher;
    

    public void publish(PaymentDistributionEvent paymentDistributionEvent) 
        //业务代码忽略
        applicationEventPublisher.publishEvent(paymentDistributionEvent);
    

---

/**
 * 监听类
 * 1、声明bean
 * 2、实现接口ApplicationListener<E>
 * 3、重写方法onApplicationEvent，方法内部做事
 */
@Component
public class PaymentDistributionListener implements ApplicationListener<PaymentDistributionEvent> 

    @Override
    public void onApplicationEvent(PaymentDistributionEvent paymentDistributionEvent) 
        Payment payment = paymentDistributionEvent.getPayment();
        System.out.println("============"+payment.getId()+"==="+payment.getSerial()+"===============");
    

使用注解实现监听，可监听多个

@Component
public class PaymentDistributionListener 

    @EventListener(PaymentDistributionEvent.class)
    public void onApplicationEvent(PaymentDistributionEvent paymentDistributionEvent) 
        Payment payment = paymentDistributionEvent.getPayment();
        System.out.println("============"+payment.getId()+"==="+payment.getSerial()+"===============");