wait notify 实例，生产消费者模式（转）

今天发现了一段很标准的多线程代码，记得以前也写过，但是没有这个这么小巧和标准。

import java.util.LinkedList;
import java.util.Queue;
import java.util.Random;

/**
 * Simple Java program to demonstrate How to use wait, notify and notifyAll()
 * method in Java by solving producer consumer problem.
 *
 * @author Javin Paul
 */
public class ProducerConsumerInJava {
    public static void main(String args[]) {
        System.out.println("How to use wait and notify method in Java");
        System.out.println("Solving Producer Consumper Problem");
        Queue<Integer>  buffer = new LinkedList<>();
        int maxSize = 10;
        Thread producer = new Producer(buffer, maxSize, "PRODUCER");
        Thread consumer = new Consumer(buffer, maxSize, "CONSUMER");
        producer.start();
        consumer.start();
    }

    /**
     * Producer Thread will keep producing values for Consumer
     * to consumer. It will use wait() method when Queue is full
     * and use notify() method to send notification to Consumer
     * Thread.
     *
     * @author WINDOWS 8
     */
    static class Producer extends Thread {
        private Queue<Integer> queue;
        private int maxSize;

        public Producer(Queue<Integer> queue, int maxSize, String name) {
            super(name);
            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, " + "Producer thread waiting for " + "consumer to take something from queue");
                            queue.wait();
                        } catch (Exception ex) {
                            ex.printStackTrace();
                        }
                    }
                    Random random = new Random();
                    int i = random.nextInt();
                    System.out.println("Producing value : " + i);
                    queue.add(i);
                    queue.notifyAll();
                }
            }
        }
    }


    /**
     * Consumer Thread will consumer values form shared queue.
     * It will also use wait() method to wait if queue is
     * empty. It will also use notify method to send
     * notification to producer thread after consuming values
     * from queue.
     *
     * @author WINDOWS 8
     *
     */
    static class Consumer extends Thread {
        private Queue<Integer> queue;
        private int maxSize;

        public Consumer(Queue<Integer> queue, int maxSize, String name) {
            super(name);
            this.queue = queue;
            this.maxSize = maxSize;
        }

        @Override
        public void run() {
            while (true) {
                synchronized (queue) {
                    while (queue.isEmpty()) {
                        System.out.println("Queue is empty," + "Consumer thread is waiting" + " for producer thread to put something in queue");
                        try {
                            queue.wait();
                        } catch (Exception ex) {
                            ex.printStackTrace();
                        }
                    }
                    System.out.println("Consuming value : " + queue.remove());
                    queue.notifyAll();
                }
            }
        }

    }
}

　　这一段代码有意思的是千锤百炼