[심화] 10. 푸쉬

Customer.java

package ex08.push.sub;

public interface Customer {
    void update(String msg);
}

Cu1.java

package ex08.push.sub;

public class Cus1 implements Customer {
    @Override
    public void update(String msg) {
        System.out.println("손님1이 받은 알림 : " + msg);
    }
}

Cus2.java

package ex08.push.sub;

public class Cus2 implements Customer {
    @Override
    public void update(String msg) {
        System.out.println("손님2이 받은 알림 : " + msg);
    }
}

Mart.java

package ex08.push.pub;

import ex08.push.sub.Customer;

public interface Mart { // Publisher
    // 1. 구독
    void add(Customer customer);

    // 2. 구독 취소
    void remove(Customer customer);

    // 3. 출판
    void received();

    // 4. 알림
    void notify(String msg);
}

LotteMart.java

package ex08.push.pub;

import ex08.push.sub.Customer;

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

public class LotteMart implements Mart {

    // 구독자 리스트
    private List<Customer> customerList = new ArrayList<>();

    // 구독 등록
    @Override
    public void add(Customer customer) {
        customerList.add(customer);
    }

    // 구독 취소
    @Override
    public void remove(Customer customer) {
        customerList.remove(customer);
    }

    // 출판
    @Override
    public void received() {
        for (int i = 0; i < 5; i++) {
            System.out.println(".");
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
        }
        notify("LotteMart : 바나나"); // 콜백 메서드
    }

    @Override
    public void notify(String msg) {
        for (Customer customer : customerList) {
            customer.update(msg);
        }
    }
}

EMart.java

package ex08.push.pub;

import ex08.push.sub.Customer;

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

public class EMart implements Mart {

    // 구독자 리스트
    private List<Customer> customerList = new ArrayList<>();

    // 구독 등록
    @Override
    public void add(Customer customer) {
        customerList.add(customer);
    }

    // 구독 취소
    @Override
    public void remove(Customer customer) {
        customerList.remove(customer);
    }

    // 출판
    @Override
    public void received() {
        for (int i = 0; i < 5; i++) {
            System.out.println(".");
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
        }
        notify("EMart : 딸기"); // 콜백 메서드
    }

    @Override
    public void notify(String msg) {
        for (Customer customer : customerList) {
            customer.update(msg);
        }
    }
}

App.java

package ex08.push;

import ex08.push.pub.EMart;
import ex08.push.pub.LotteMart;
import ex08.push.sub.Cus1;
import ex08.push.sub.Cus2;

public class App {
    public static void main(String[] args) {
        // 1. 객체 초기화
        LotteMart lotteMart = new LotteMart();
        EMart emart = new EMart();
        Cus1 cus1 = new Cus1();
        Cus2 cus2 = new Cus2();

        // 2. 구독
        lotteMart.add(cus1);
        lotteMart.add(cus2);

        emart.add(cus1);
        emart.add(cus2);

        // 3. 구독 취소
        lotteMart.remove(cus2);

        // 4. 출판 (누가 할 지는 나중에 정하면 됨)
        new Thread(() -> {
            lotteMart.received();
        }).start();
        new Thread(() -> {
            emart.received();
        }).start();
    }
}

Thread를 2개 만든 이유