在多线程场景中使用生产者消费者模式较为流行，一般主要的实现方式有以下几种

1.最古老的等待通知方式 wait/notify/notifyAll，这3个方法需要跟synchronized配套

/***
 * 生产者消费者模式之wait/notify/notifyAll
 */
public class ProducerConsumer1 {
    private LinkedList<String> products = new LinkedList<>();
    private static final int MAX_SIZE = 10; // 最大库存
    private Object lock = new Object();
    /**
     * 生产商品，添加到库存
     */
    public void produce(String e) {
        synchronized (lock) {
            try {
                while (products.size() >= MAX_SIZE) {
                    lock.wait();
                }
                products.add(e);
                System.out.println(" 放入一个商品: " + e + "，总库存为：" + products.size());
                lock.notifyAll();
            } catch (Exception ex) {
                ex.printStackTrace();
            }
        }

    }

    /**
     * 消费商品,从库存中移除
     */
    public void consume() {
        synchronized (lock) {
            try {
                while (products.size() == 0) {
                    lock.wait();
                }
                String product = products.removeFirst();
                System.out.println(" 消费一个商品: " + product + ", 总库存为: " + products.size());
                lock.notifyAll();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    /***
     * 生产者线程
     */
    private class Producer implements Runnable {
        public void run() {
            for (int i = 0; i < 20; i++) {
                produce(" 商品 " + i);
            }
        }
    }

    /***
     * 消费者线程
     */
    private class Customer implements Runnable {
        public void run() {
            for (int i = 0; i < 20; i++) {
                consume();
            }
        }
    }

    public static void main(String[] args) {
        ProducerConsumer1 lc = new ProducerConsumer1();
        new Thread(lc.new Producer()).start();
        new Thread(lc.new Customer()).start();

    }
}

2.lock condition的await/signall/signalAll，这3个方法需要跟lock/unlock配套
await/signal/signalAll是在JAVA进程中实现的，无需切换到内核态
wait/notify/notifyAll 是通过monitor管程来实现的，有可能会切换到内核态
一般不推荐使用wait/notify/notifyAll

/***
 * 生产者消费者模式之await/signal/signalAll
 */
public class ProducerConsumer2 {

    private LinkedList<String> products = new LinkedList<>();

    private static final int MAX_SIZE = 10; // 最大库存

    private Lock lock = new ReentrantLock();// 资源锁

    private Condition condition = lock.newCondition();// 库存非满和非空条件

    /**
     * 生产商品，添加到库存
     */
    public void produce(String e) {
        lock.lock();
        try {
            while (products.size() >= MAX_SIZE) {
                condition.await();
            }

            products.add(e);
            System.out.println(" 放入一个商品: " + e + "，总库存为：" + products.size());
            condition.signalAll();

        } catch (Exception ex) {
            ex.printStackTrace();
        } finally {
            lock.unlock();
        }
    }

    /**
     * 消费商品,从库存中移除
     */
    public void consume() {
        lock.lock();
        try {
            while (products.size() == 0) {
                condition.await();
            }

            String product = products.removeFirst();
            System.out.println(" 消费一个商品: " + product + ", 总库存为: " + products.size());
            condition.signalAll();

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }

    }

    /***
     * 生产者线程
     */
    private class Producer implements Runnable {
        public void run() {
            for (int i = 0; i < 20; i++) {
                produce(" 商品 " + i);
            }
        }

    }

    /***
     * 消费者线程
     */
    private class Customer implements Runnable {

        public void run() {
            for (int i = 0; i < 20; i++) {
                consume();
            }
        }
    }

    public static void main(String[] args) {
        ProducerConsumer2 lc = new ProducerConsumer2();
        new Thread(lc.new Producer()).start();
        new Thread(lc.new Customer()).start();

    }
}

3.通过BlockingQueue的实现方式最简单直接，也是最常用的方式

/***
 * 生产者消费者模式之BlockingQueue
 */
public class ProducerConsumer3 {

    private LinkedBlockingQueue<String> queue = new LinkedBlockingQueue<>(10);

    /**
     * 生产商品，添加到库存
     */
    public void produce(String e) {
        try {
            queue.put(e);
            System.out.println(" 放入一个商品: " + e + "，总库存为：" + queue.size());
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

    /**
     * 消费商品,从库存中移除
     */
    public void consume() {
        String product = null;
        try {
            product = queue.take();
            System.out.println(" 消费一个商品: " + product + ", 总库存为: " + queue.size());
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    /***
     * 生产者线程
     */
    private class Producer implements Runnable {
        public void run() {
            for (int i = 0; i < 20; i++) {
                produce(" 商品 " + i);
            }
        }
    }

    /***
     * 消费者线程
     */
    private class Customer implements Runnable {
        public void run() {
            for (int i = 0; i < 20; i++) {
                consume();
            }
        }
    }

    public static void main(String[] args) {
        ProducerConsumer3 lc = new ProducerConsumer3();
        new Thread(lc.new Producer()).start();
        new Thread(lc.new Customer()).start();

    }
}