多线程设计模式 -- ProducerConsumer

放蛋糕的桌子

public class Table {
    private final String[] buffer;
    private int tail;  /下一个放put的地方 
    private int head;  //下一个放的take地方 
    private int count; // buffer内的蛋糕数
    public Table(int count) {
        this.buffer = new String[count];
        this.head = 0;
        this.tail = 0;
        this.count = 0;
    }
    // 放置蛋糕
    public synchronized void put(String cake) throws InterruptedException {
        System.out.println(Thread.currentThread().getName() + " puts " + cake);
        while (count >= buffer.length) {
            wait();//当蛋糕数大于容器大小是等待
        }
        buffer[tail] = cake;
        tail = (tail + 1) % buffer.length;
        count++;
        notifyAll();//唤醒等待线程
    }
    
   
    // 取得蛋糕
    public synchronized String take() throws InterruptedException {
        while (count <= 0) {
            wait();//当蛋糕数为0时,等待
        }
        String cake = buffer[head];
        head = (head + 1) % buffer.length;
        count--;
        notifyAll();//唤醒等待线程
        System.out.println(Thread.currentThread().getName() + " takes " + cake);
        return cake;
    }
}

吃线程

public class EaterThread extends Thread {
    private final Random random;
    private final Table table;
    public EaterThread(String name, Table table, long seed) {
        super(name);
        this.table = table;
        this.random = new Random(seed);
    }
    public void run() {
        try {
            while (true) {
                String cake = table.take();
                Thread.sleep(random.nextInt(1000));
            }
        } catch (InterruptedException e) {
        }
    }
}

做线程

public class MakerThread extends Thread {
    private final Random random;
    private final Table table;
    private static int id = 0; //  蛋糕的流水号(所有厨师共通)
    public MakerThread(String name, Table table, long seed) {
        super(name);
        this.table = table;
        this.random = new Random(seed);
    }
    public void run() {
        try {
            while (true) {
                Thread.sleep(random.nextInt(1000));
                String cake = "[ Cake No." + nextId() + " by " + getName() + " ]";
                table.put(cake);
            }
        } catch (InterruptedException e) {
        }
    }
    private static synchronized int nextId() {
        return id++;
    }
}

测试线程

public class Main {
    public static void main(String[] args) {
        Table table = new Table(3);     // 建立可以放置3個蛋糕的桌子
        new MakerThread("MakerThread-1", table, 31415).start();
        new MakerThread("MakerThread-2", table, 92653).start();
        new MakerThread("MakerThread-3", table, 58979).start();
        new EaterThread("EaterThread-1", table, 32384).start();
        new EaterThread("EaterThread-2", table, 62643).start();
        new EaterThread("EaterThread-3", table, 38327).start();
    }
}