Java多线程之Condition接口的实现

import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;import java.util.concurrent.locks.Condition;import java.util.concurrent.locks.Lock;import java.util.concurrent.locks.ReentrantLock;/** * 有时候线程取得lock后需要在一定条件下才能做某些工作，比如说经典的Producer和Consumer问题。 * 在Java 5.0以前，这种功能是由Object类的wait(), notify()和notifyAll()等方法实现的， * 在5.0里面，这些功能集中到了Condition这个接口来实现。 */public class ConditionTest {/** * 篮子程序，这里为了简化问题，篮子中最多只能有一个苹果。 * Consumer必须在篮子里有苹果的时候才能吃苹果，否则它必须暂时放弃对篮子的锁定， * 等到Producer往篮子里放了苹果后再去拿来吃。而Producer必须等到篮子空了才能往里放苹果， * 否则它也需要暂时解锁等Consumer把苹果吃了才能往篮子里放苹果。 */public static class Basket {// 锁Lock lock = new ReentrantLock();//根据锁产生Condition对象Condition produced = lock.newCondition();Condition consumed = lock.newCondition();// 篮子中的苹果数，最多为1int num = 0;/** * 生产苹果，往篮子里放 * @throws InterruptedException */public void produce() throws InterruptedException {// 获得锁lock.lock();System.out.println("Producer get a lock...");try {// 判断是否满足生产条件while (num == 1) {// 如果有苹果，则不生产，放弃锁，进入睡眠// 等待消费者消费System.out.println("Producer sleep...");consumed.await(); System.out.println("Producer awaked...");}/*生产苹果*/Thread.sleep(500);System.out.println("Producer produced an Apple.");num = 1;// 通知等待produced Condition的线程produced.signal();} finally {lock.unlock();}}/** * 消费苹果，从篮子中取 * @throws InterruptedException */public void consume() throws InterruptedException {// 获得锁lock.lock();System.out.println("Consumer get a lock...");try {// 判断是否满足消费条件while (num == 0) {// 如果没有苹果，无法消费，则放弃锁，进入睡眠// 等待生产者生产苹果System.out.println("Consumer sleep...");produced.await();  System.out.println("Consumer awaked...");}/*吃苹果*/Thread.sleep(500);System.out.println("Consumer consumed an Apple.");num = 0;// 发信号唤醒某个等待consumed Condition的线程consumed.signal();} finally {lock.unlock();}}}/** * 测试Basket程序 */public static void testBasket() throws Exception {final Basket basket = new Basket();//定义一个producerRunnable producer = new Runnable() {public void run() {try {basket.produce();} catch (InterruptedException ex) {ex.printStackTrace();}}};// 定义一个consumerRunnable consumer = new Runnable() {public void run() {try {basket.consume();} catch (InterruptedException ex) {ex.printStackTrace();}}};//各产生3个consumer和producerExecutorService service = Executors.newCachedThreadPool();for (int i = 0; i < 3; i++){service.submit(producer);}for (int i = 0; i < 3; i++){service.submit(consumer);}service.shutdown();}      public static void main(String[] args) throws Exception {ConditionTest.testBasket();}}