生產者消費者模式

原理

生產者在倉庫沒有滿的時候進行生產，滿了後等待

消費者在倉庫有存貨事新型消費，沒貨是等待

示例

#Phone

public class Phone {
    private int id;
    public Phone() {
        id = new Random().nextInt();
    }

    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
}

#Storage

public class Storage {
    int index;
    private final int MAX;
    Queue<Phone> phoneQueue;

    public Storage(int max) {
        index = 0;
        MAX = max;
        phoneQueue = new ArrayDeque<>(MAX);
    }

    public synchronized Phone consume() {
        while (index <= 0) {
            try {
                System.out.println("倉庫空了，等待中。。。。。");
                wait();
                System.out.println("倉庫不空了，繼續消費。。。。。");
            }catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        Phone phone = phoneQueue.poll();
        System.out.println("consume Phone:" + phone.getId());
        index--;
        notify();
        return phone;
    }

    public synchronized void produce(Phone phone) {
        while (index >= MAX) {
            try {
                System.out.println("倉庫滿了，等待中。。。");
                wait();
                System.out.println("倉庫不滿了，繼續生產。。。");
            }catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        System.out.println("produce Phone:" + phone.getId());
        index++;
        phoneQueue.add(phone);
        notify();
    }
}

說明：

synchonized保證對象只能被一個線程佔用

執行wat()後，當前線程處於等待狀態，釋放鎖，讓別的線程能夠繼續執行

執行notify()後，喚醒其餘處於wait()狀態的線程繼續執行

#Producer

public class Producer implements Runnable{
    Storage storage;
    public Producer(Storage storage) {
        this.storage = storage;
    }

    @Override
    public void run() {
        Phone phone = new Phone();
        storage.produce(phone);
    }
}

#Consumer

public class Consumer implements Runnable{
    Storage storage;
    public Consumer(Storage storage) {
        this.storage = storage;
    }

    @Override
    public void run() {
        try {
            Thread.sleep(5000);
        }catch (InterruptedException e) {
            e.printStackTrace();
        }
        Phone phone = storage.consume();
    }
}

#Main

public class Main {
    public static void main(String[] args) {
        Storage storage = new Storage(35);
        for (int i = 0; i < 40; i++) {
            new Thread(new Producer(storage)).start();
        }

        for (int i = 0; i < 40; i++) {
            new Thread(new Consumer(storage)).start();
        }

    }
}