【SpringBoot教程 事件】3.SpringBoot自定义事件和发布订阅机制

前面讲到了SpringBoot 七个生命周期回调事件函数，SpringBoot底层是在jdk中的java.util.EventObject类和java.util.EventListener之上封装实现的发布订阅机制。同时也提供了自定义事件定义，该种方式是一种设计模式–观察者设计模式，优势在于解耦，模块和模块耦合度降低方便扩展。

如下实现一个需求：注册用户，然后插入到数据库，另外还需要给用户发邮件和短信。

1.创建用户注册事件基类

import org.springframework.context.ApplicationEvent;


public class UserRegisterEvent extends ApplicationEvent {

    
    private String name;

    public UserRegisterEvent(Object source) {
        super(source);
    }


    public UserRegisterEvent(Object source, String name) {
        super(source);
        this.name = name;
    }

    public String getUserName() {
        return name;
    }
}

2.用户注册，发布事件例子。

import lombok.extern.java.Log;
import org.springframework.context.ApplicationEventPublisher;
import org.springframework.context.ApplicationEventPublisherAware;
import org.springframework.stereotype.Service;

@Service
@Log
public class UserService implements ApplicationEventPublisherAware {

    private ApplicationEventPublisher applicationEventPublisher;

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

    public void register(String userName) {
        log.info("用户注册" + userName + ", 数据插入到数据库！");

        // 发布用户注册事件
        applicationEventPublisher.publishEvent(new UserRegisterEvent(this, userName));
    }
}

3.发送短信，订阅事件例子。

import lombok.extern.java.Log;
import org.springframework.context.ApplicationListener;
import org.springframework.stereotype.Service;


@Service
@Log
public class SmsService implements ApplicationListener {

    @Override
    public void onApplicationEvent(UserRegisterEvent event) {
        log.info("发送短信给用户：" + event.getUserName());
    }
}

4.发送邮件，订阅事件例子。

import lombok.extern.java.Log;
import org.springframework.context.ApplicationListener;
import org.springframework.stereotype.Service;


@Service
@Log
public class EmailService implements ApplicationListener {

    @Override
    public void onApplicationEvent(UserRegisterEvent event) {
        log.info("发送邮件给用户：" + event.getUserName());
    }
}

5.测试类，模拟用户注册。

import org.springframework.context.ApplicationEvent;


public class UserRegisterEvent  extends ApplicationEvent {

    
    private String name;

    public UserRegisterEvent(Object source) {
        super(source);
    }


    public UserRegisterEvent(Object source, String name) {
        super(source);
        this.name = name;
    }

    public String getUserName() {
        return name;
    }
}

打印如下：

2022-06-08 15:49:48.196  INFO 27560 --- [           main] com.terry.event.event.UserService        : 用户注册terry, 数据插入到数据库！
2022-06-08 15:49:48.197  INFO 27560 --- [           main] com.terry.event.event.EmailService       : 发送邮件给用户：terry
2022-06-08 15:49:48.198  INFO 27560 --- [           main] com.terry.event.event.SmsService         : 发送短信给用户：terry