ApplicationListener的简单使用

ApplicationListener在Spring框架中的作用是监听并处理应用程序中的事件。
ApplicationListener接口定义了一个onApplicationEvent方法，当监听器监听到事件发布后，会执行这个方法。这使得开发者能够灵活地响应应用程序中的各种事件，实现发布-订阅模式的功能。通过这种方式，Spring框架实现了应用程序内部不同组件之间的松耦合通信，提高了系统的可扩展性和可维护性。
代码结构：

1、定义监听实体

根据发布和订阅的实体不同，进行区分不同的监听。
People

package com.dyaqi.domain;import lombok.Getter;
import lombok.Setter;
import lombok.ToString;
import org.springframework.context.ApplicationEvent;/*** @author: dongyq* @date: 2023/4/17 17:34* @since:* @功能描述:*/
@Getter
@Setter
@ToString
public class People extends ApplicationEvent {public String name;public Integer age;public People(Object source, String name, Integer age) {super(source);this.name = name;this.age = age;}
}

User

package com.dyaqi.domain;import lombok.Getter;
import lombok.Setter;
import lombok.ToString;
import org.springframework.context.ApplicationEvent;/*** @author: dongyq* @date: 2023/4/17 17:34* @since:* @功能描述:*/
@Getter
@Setter
@ToString
public class User extends ApplicationEvent {public String name;public Integer age;public User(Object source, String name, Integer age) {super(source);this.name = name;this.age = age;}
}

2、定义发布者

package com.dyaqi.publisher;import com.dyaqi.domain.People;
import com.dyaqi.domain.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationEventPublisher;
import org.springframework.stereotype.Component;/*** @author: dongyq* @date: 2023/4/17 17:40* @since:* @功能描述:*/
@Component
public class Publisher {@Autowiredprivate ApplicationEventPublisher applicationEventPublisher;public void publis() {System.out.println("发布事件");applicationEventPublisher.publishEvent(new People(this,"张三", 29));applicationEventPublisher.publishEvent(new User(this,"李四", 18));}
}

3、定义订阅者

Listener1 监听 People

package com.dyaqi.listener;import com.dyaqi.domain.People;
import org.springframework.context.ApplicationListener;
import org.springframework.stereotype.Component;/*** @author: dongyq* @date: 2023/4/17 17:37* @since:* @功能描述:*/
@Component
public class Listener1 implements ApplicationListener<People> {@Overridepublic void onApplicationEvent(People people) {System.out.println("Listener1 监听到事件");System.out.println(people.toString());}
}

Listener2监听 User

package com.dyaqi.listener;import com.dyaqi.domain.People;
import com.dyaqi.domain.User;
import org.springframework.context.ApplicationListener;
import org.springframework.stereotype.Component;/*** @author: dongyq* @date: 2023/4/17 17:37* @since:* @功能描述:*/
@Component
public class Listener2 implements ApplicationListener<User> {@Overridepublic void onApplicationEvent(User user) {System.out.println("Listener2 监听到事件");System.out.println(user.toString());}
}

使用注解监听

package com.dyaqi.listener;import com.dyaqi.domain.User;
import org.springframework.context.ApplicationListener;
import org.springframework.context.event.EventListener;
import org.springframework.stereotype.Component;/*** @author: dongyq* @date: 2023/4/17 17:37* @since:* @功能描述:*/
@Component
public class Listener3 {@EventListenerpublic void onApplicationEvent(User user) {System.out.println("Listener3 监听到事件");System.out.println(user.toString());}
}

4、日志