java.util.concurrent.CountDownLatch

 

import java.util.concurrent.CountDownLatch;

/**
 * 案例：一台机器启动后，有5个人的工人同时在这台机器上进行操作，5个工人有的效率高有的效率低，
 * 当这5个工人操作完毕时，关闭机器。
 * 
 * @author Administrator
 * 
 */
public class TestCountDownLatchDriverWorker {

	/**
	 * @param args
	 * @throws InterruptedException
	 */
	public static void main(String[] args) throws InterruptedException {
		// 创建1个驱动器的倒数计数器
		CountDownLatch driverStartLatch = new CountDownLatch(1);
		// 创建5个工人倒数计数器
		CountDownLatch workerDoneLath = new CountDownLatch(5);
		for (int i = 1; i <= 5; i++) {
			Thread worker = new Thread(new Worker(driverStartLatch,
					workerDoneLath, i));
			worker.start();
		}
		driverStartup();
		// 使驱动器倒数计数为0，让worker线程继续执行其他代码。
		driverStartLatch.countDown();
		workerDoneLath.await();// 等待工人做完事情。
		driverShoutDown();

	}

	public static void driverStartup() {
		System.out.println("Driver start up and running.");
	}

	public static void driverShoutDown() {
		System.out.println("Driver shout down.");
	}

	static class Worker implements Runnable {

		// 驱动启动时开关
		private CountDownLatch driverStartLatch;
		// 工人做完事的开关
		private CountDownLatch workerDoneLath;

		private int id;

		public Worker(CountDownLatch driverStartLatch,
				CountDownLatch workerDoneLath, int id) {
			this.driverStartLatch = driverStartLatch;
			this.id = id;
			this.workerDoneLath = workerDoneLath;
		}

		@Override
		public void run() {
			try {
				// 等待驱动启动。
				driverStartLatch.await();
				// 驱动器启动后继续执行以下语句
				Thread.sleep((long) (Math.max(1000, Math.random() * 5000)));
				System.out.println("Worker " + id + " has done his work.");
				// 工人完事情计数，
				workerDoneLath.countDown();
			} catch (InterruptedException e) {
				e.printStackTrace();
			}

		}

	}

}

 

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