CountDownLatch、CyclicBarrier和Semaphore使用

// 构造方法，count决定等待多少个线程
public CountDownLatch(int count)
// 等待线程完成数减1
public void countDown()
// 调用await本线程会挂起，当等待线程未完成数为0，即countDown调用次数等于构造方法参数值时会被唤醒
public void await()
public boolean await(long timeout, TimeUnit unit)

public class CountDownLatchTest {
    public static void main(String[] args) {
        final CountDownLatch countDownLatch = new CountDownLatch(2);
        for (int i = 0; i < 2; i++) {
            new Thread(() -> {
                try {
                    String name = Thread.currentThread().getName();
                    System.out.println("子线程" + name + "正在运行中......");
                    TimeUnit.SECONDS.sleep(5);
                    System.out.println("子线程" + name + "执行完毕");
                    countDownLatch.countDown();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }).start();
        }

        try {
            System.out.println("======等待两个子线程执行完毕");
            // 只有子线程执行完毕个数等于CountDownLatch初始化个数才会继续执行await后面代码
            countDownLatch.await();
            System.out.println("两个子线程都执行完毕！！！！！！");
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        System.out.println("主线程继续执行中。。。。。。。。");
    }
}

子线程Thread-0正在运行中......
======等待两个子线程执行完毕
子线程Thread-1正在运行中......
子线程Thread-1执行完毕
子线程Thread-0执行完毕
两个子线程都执行完毕！！！！！！
主线程继续执行中。。。。。。。。

// 构造方法设置同组线程数
public CyclicBarrier(int parties)
// 构造方法设置同组线程数；全部达到障碍物时执行barrierAction函数
public CyclicBarrier(int parties, Runnable barrierAction)
// 某个线程调用await时挂起，需要等同组所有线程到达才能唤醒
public int await() throws InterruptedException, BrokenBarrierException

/**
 * Created on 18/3/15 14:40.
 *
 * @author wolf
 */
public class CyclicBarrierTest {
    public static void main(String[] args) {
        int n = 3;
        CyclicBarrier barrier = new CyclicBarrier(n);
        for (int i = 0; i < 3; i++) {
            new Worker(barrier).start();
        }

        try {
            TimeUnit.SECONDS.sleep(6);
            System.out.println("--------讨厌的循环利用分割线------------");
        } catch (Exception e) {
            e.printStackTrace();
        }

        for (int i = 0; i < n; i++) {
            new Worker(barrier).start();
        }
    }

    static class Worker extends Thread {
        private CyclicBarrier barrier;
        public Worker(CyclicBarrier barrier) {
            this.barrier = barrier;
        }
        @Override
        public void run() {
            long startTime = System.currentTimeMillis();
            String name = Thread.currentThread().getName();
            System.out.println("线程 " + name + " 正在执行任务.......");
            try {
                int time = RandomUtils.nextInt(1, 5);
                TimeUnit.SECONDS.sleep(time);
                System.out.println("线程 " + name + " 执行任务完毕！！！用时：" + time);
                barrier.await();
            } catch (Exception e) {
                e.printStackTrace();
            }
            System.out.println("线程 " + name + " 全部耗时:"+(System.currentTimeMillis()-startTime));
        }
    }
}

// 构造方法设置可用资源的数量，即许可证的数量
public Semaphore(int permits)
// 构造方法设置可用资源的数量，即许可证的数量,fair 是否公平获得许可证，默认是先来后到公平的
public Semaphore(int permits, boolean fair)
// 同步获取许可证，
public void acquire() throws InterruptedException
// 尝试获取许可证，结果直接返回
public boolean tryAcquire()
// 尝试获取许可证，结果等待时间超时直接返回
public boolean tryAcquire(long timeout, TimeUnit unit)
// 释放许可证，可给其它等待线程使用
public void release()

public class SemaphoreTest {
    public static void main(String[] args) {
        int no = 5;
        Semaphore semaphore = new Semaphore(2);
        for (int i = 0; i < no; i++) {
            new Worker(i, semaphore).start();
        }
    }
    static class Worker extends Thread {
        private int no;
        private Semaphore semaphore;
        public Worker(int no, Semaphore semaphore) {
            this.no = no;
            this.semaphore = semaphore;
        }
        @Override
        public void run() {
            try {
                long startTime = System.currentTimeMillis();
                semaphore.acquire();
                System.out.println("worker " + this.no + " 获取许可证，开始工作....");
                int time = RandomUtils.nextInt(1, 5);
                TimeUnit.SECONDS.sleep(time);
                semaphore.release();
                System.out.println("worker " + this.no + " 完成工作，释放许可证！耗时：" + (System.currentTimeMillis() - startTime));
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
}