设计模式-观察者模式

package com.example.kafka.notify;

import java.util.ArrayList;
import java.util.List;


public abstract class Subject {

    private List list = new ArrayList<>();

    
    public void addObserver(Observer obj){
        list.add(obj);
    }

    
    public void deleteObserver(Observer obj){
        list.remove(obj);
    }

    
    public void notifyAllObserver(){
        for (Observer obj:list) {
            obj.update(this);
        }
    }
    
}

具体主题角色

package com.example.kafka.notify;


public class GameSubject extends  Subject{
    private String name;
    private String content;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }

    public GameSubject(String name, String content) {
        super();
        this.name = name;
        this.content = content;
    }
    public void sendSubject(GameSubject sub){
        sub.notifyAllObserver();
    }
}

抽象观察者

package com.example.kafka.notify;


public interface Observer {

    public void update(Subject sub);
}

 具体观察者角色

package com.example.kafka.notify;

import ch.qos.logback.core.net.SyslogOutputStream;


public class GamePlay implements Observer{
    @Override
    public void update(Subject sub) {
        GameSubject subject = (GameSubject) sub;
        String content = subject.getContent();
        if (content != null){
            content = content.toLowerCase();
        }
        if(content.contains("pc")){
            System.out.println("PC玩家： 我这个主题非常感兴趣！");
        } else {
            System.out.println("我对这个主题不感兴趣！");
        }
        System.out.println("本次游行主题发布者："+subject.getName());


    }
}

测试

public static void main(String[] args) {
        String name = "jack";
        String content="英雄联盟手游版+PC版";
        GameSubject gameSubject = new GameSubject(name, content);
        Observer observer = new GamePlay();
        gameSubject.addObserver(observer);
        gameSubject.sendSubject(gameSubject);
}

执行结果

PC玩家： 我这个主题非常感兴趣！
本次游行主题发布者：jack

学无止境~~