生产者消费者问题

实例代码用 Object 的 wait()和notify() 实现，也可用 ReentrantLock 和 Condition 来完成。或者直接使用阻塞队列。

public class ProducerConsumer {
    public static void main(String[] args) {
        ProducerConsumer main = new ProducerConsumer();
        Queue buffer = new LinkedList<>();
        int maxSize = 5;
        new Thread(main.new Producer(buffer, maxSize), "Producer1").start();
        new Thread(main.new Consumer(buffer, maxSize), "Comsumer1").start();
        new Thread(main.new Consumer(buffer, maxSize), "Comsumer2").start();
    }

    class Producer implements Runnable {
        private Queue queue;
        private int maxSize;

        Producer(Queue queue, int maxSize) {
            this.queue = queue;
            this.maxSize = maxSize;
        }

        @Override
        public void run() {
            while (true) {
                synchronized (queue) {
                    while (queue.size() == maxSize) {
                        try {
                            System.out.println("Queue is full");
                            queue.wait();
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                    try {
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    Random random = new Random();
                    int i = random.nextInt();
                    System.out.println(Thread.currentThread().getName() + " Producing value : " + i);
                    queue.add(i);
                    queue.notifyAll();
                }
            }
        }
    }

    class Consumer implements Runnable {
        private Queue queue;
        private int maxSize;

        public Consumer(Queue queue, int maxSize) {
            super();
            this.queue = queue;
            this.maxSize = maxSize;
        }

        @Override
        public void run() {
            while (true) {
                synchronized (queue) {
                    while (queue.isEmpty()) {
                        try {
                            System.out.println("Queue is empty");
                            queue.wait();
                        } catch (Exception ex) {
                            ex.printStackTrace();
                        }
                    }
                    try {
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    System.out.println(Thread.currentThread().getName() + " Consuming value : " + queue.remove());
                    queue.notifyAll();
                }
            }
        }
    }
}