Java中CyclicBarrier 循環屏障

 // parties表示屏障攔截的線程數量，每個線程調用 await 方法告訴 CyclicBarrier 我已經到達瞭屏障，然後當前線程被阻塞。
 public CyclicBarrier(int parties)
 // 用於在線程到達屏障時，優先執行 barrierAction，方便處理更復雜的業務場景(該線程的執行時機是在到達屏障之後再執行)

//屏障 指定數量的線程全部調用await()方法時，這些線程不再阻塞
// BrokenBarrierException 表示柵欄已經被破壞，破壞的原因可能是其中一個線程 await() 時被中斷或者超時
public int await() throws InterruptedException, BrokenBarrierException
public int await(long timeout, TimeUnit unit) throws InterruptedException, BrokenBarrierException, TimeoutException
//循環  通過reset()方法可以進行重置

public class CyclicBarrierTest2 {
    //保存每個學生的平均成績
    private Conc urrentHashMap<String, Integer> map=new ConcurrentHashMap<String,Integer>();
    private ExecutorService threadPool= Executors.newFixedThreadPool(3);
    private CyclicBarrier cb=new CyclicBarrier(3,()->{
        int result=0;
        Set<String> set = map.keySet();
        for(String s:set){
            result+=map.get(s);
        }
        System.out.println("三人平均成績為:"+(result/3)+"分");
    });
    public void count(){
        for(int i=0;i<3;i++){
            threadPool.execute(new Runnable(){

                @Override
                public void run() {
                    //獲取學生平均成績
                    int score=(int)(Math.random()*40+60);
                    map.put(Thread.currentThread().getName(), score);
                    System.out.println(Thread.currentThread().getName()
                            +"同學的平均成績為："+score);
                    try {
                        //執行完運行await(),等待所有學生平均成績都計算完畢
                        cb.await();
                    } catch (InterruptedException | BrokenBarrierException e) {
                        e.printStackTrace();
                    }
                }

            });
        }
    }
    public static void main(String[] args) {
        CyclicBarrierTest2 cb=new CyclicBarrierTest2();
        cb.count();
    }
}

public class CyclicBarrierTest3 {
    public static void main(String[] args) {
        AtomicInteger counter = new AtomicInteger();
        ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(
                5, 5, 1000, TimeUnit.SECONDS,
                new ArrayBlockingQueue<>(100),
                (r) -> new Thread(r, counter.addAndGet(1) + " 號 "),
                new ThreadPoolExecutor.AbortPolicy());

        CyclicBarrier cyclicBarrier = new CyclicBarrier(5,
                () -> System.out.println("裁判：比賽開始~~"));

        for (int i = 0; i < 10; i++) {
            threadPoolExecutor.submit(new Runner(cyclicBarrier));
        }

    }
    static class Runner extends Thread{
        private CyclicBarrier cyclicBarrier;
        public Runner (CyclicBarrier cyclicBarrier) {
            this.cyclicBarrier = cyclicBarrier;
        }
        @Override
        public void run() {
            try {
                int sleepMills = ThreadLocalRandom.current().nextInt(1000);
                Thread.sleep(sleepMills);
                System.out.println(Thread.currentThread().getName() + " 選手已就位, 準備共用時： " + sleepMills + "ms" + cyclicBarrier.getNumberWaiting());
                cyclicBarrier.await();

            } catch (InterruptedException e) {
                e.printStackTrace();
            }catch(BrokenBarrierException e){
                e.printStackTrace();
            }
        }
    }

}