本文主要介绍java中生产者/消费者模式的实现，对java线程锁机制的一次深入理解。

生产者/消费者模型

生产者/消费者模型要保证，同一个资源在同一时间节点下只能被最多一个线程访问，这个在java中用锁就很容易实现。

下面的例子就是模拟多个生产者生产，多个消费者消费的demo

//抽象生产者
public abstract class AbstractProducer implements Runnable {abstract void produce() throws InterruptedException;@Overridepublic void run() {try {while (true) {produce();}} catch (InterruptedException e) {e.printStackTrace();}}
}//抽象消费者
public abstract class AbstractConsumer implements Runnable {abstract void consume() throws InterruptedException;@Overridepublic void run() {try {while (true) {consume();}} catch (InterruptedException e) {e.printStackTrace();}}
}public class ConsumerAndProducerDemo {private static final AtomicInteger ATOMIC_INTEGER = new AtomicInteger();private static final ReentrantLock LOCK = new ReentrantLock();private static final Condition CONDITION = LOCK.newCondition();private static final Queue<Product> PRODUCTS = new LinkedList<>();private static final int SIZE = 4;public static class Product {int id;Product(int id) {this.id = id;}}//实现消费者private static class Consumer extends AbstractConsumer {@Overridevoid consume() throws InterruptedException {try {LOCK.lock();while (PRODUCTS.isEmpty()) {CONDITION.await();}Product product = PRODUCTS.poll();Thread.sleep((long) (500 + Math.random() * 1000));System.out.println(" consume product " + product.id);CONDITION.signalAll();} finally {LOCK.unlock();}}}//实现生产者private static class Producer extends AbstractProducer {@Overridevoid produce() throws InterruptedException {try {LOCK.lock();while (PRODUCTS.size() >= SIZE) {CONDITION.await();}Thread.sleep(1000);Product product = new Product(ATOMIC_INTEGER.incrementAndGet());PRODUCTS.add(product);System.out.println("produce product " + product.id);CONDITION.signalAll();} finally {LOCK.unlock();}}}public static void main(String[] args) {for (int index = 0; index < 2; index++) {new Thread(new Producer()).start();}for (int index = 0; index < 3; index++) {new Thread(new Consumer()).start();}}
}
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上面的demo这么实现

1. 启动多个线程模拟多个生产者和多个消费者
2. 同时使用了queue用来缓存产品
3. 当缓存区没满时生产者生产
4. 当缓冲区满时消费者开始消费

线程之间的同步，这里使用了ReentrantLock，ReentrantLock在之前的博客中有介绍过，当然也可以使用Object自带的wait()等方法，实现同步这里就不在修改demo另行实现了。