https://www.cnblogs.com/Andrew520/p/11116516.html

 1 package com.sunny.core.sunnycore.ssm.publish;
 2 
 3 import com.sunny.core.sunnycore.ssm.subscriber.Subscriber;
 4 import org.springframework.stereotype.Service;
 5 
 6 /**
 7  * @Description: TODO
 8  * @Author Lg
 9  * @Date 2022/4/2
10  */
11 @Service
12 public
 
 interface PublishService {
13     //註冊
14     void register(Subscriber subscriber);
15     //刪除
16     void remove(Subscriber subscriber);
17     //通知
18     void notifyObserver();
19 }

 1 package com.sunny.core.sunnycore.ssm.publish;
 2 
 3 import com.sunny.core.sunnycore.ssm.subscriber.Subscriber;
 4
 
 import org.springframework.util.ObjectUtils;
 5 
 6 import java.util.ArrayList;
 7 import java.util.List;
 8 import java.util.Observer;
 9 
10 /**
11  * @Description: TODO
12  * @Author Lg
13  * @Date 2022/4/2
14  */
15 public class PublishServiceImpl implements PublishService{
16 
17     //訂閱者集合
18     private
 
 List<Subscriber> userList = new ArrayList<>();
19     //訊息
20     private String message;
21     @Override
22     public void register(Subscriber subscriber) {
23         userList.add(subscriber);
24     }
25 
26     @Override
27     public void remove(Subscriber subscriber) {
28         if(!ObjectUtils.isEmpty(subscriber)&&userList.size()>0){
29             userList.remove(subscriber);
30         }
31     }
32 
33     @Override
34     public void notifyObserver() {
35         userList.forEach(e->{
36             e.getMessage(message);
37         });
38     }
39 
40     public void setMessage(String message){
41         this.message = message;
42         notifyObserver();
43     }
44 }

 1 package com.sunny.core.sunnycore.ssm.subscriber;
 2 
 3 import org.springframework.stereotype.Service;
 4 
 5 /**
 6  * @Description: TODO
 7  * @Author Lg
 8  * @Date 2022/4/2
 9  */
10 @Service
11 public interface Subscriber {
12     //得到訊息
13     void getMessage(String message);
14 }

 1 package com.sunny.core.sunnycore.ssm.subscriber;
 2 
 3 /**
 4  * @Description: TODO
 5  * @Author Lg
 6  * @Date 2022/4/2
 7  */
 8 public class SubscriberImpl implements Subscriber{
 9 
10     //訂閱者名稱
11     private String name;
12     //訊息
13     private String message;
14 
15     public SubscriberImpl(String name) {
16         this.name = name;
17     }
18     @Override
19     public void getMessage(String message) {
20         this.message = message;
21         read();
22     }
23 
24     private void read() {
25         System.out.println(name + ":" + "收到訊息內為：" + message);
26     }
27 }