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线程同步辅助类的使用

news 来源：原创 2025/5/10 18:26:12

一、countDownLatch(减法)

public class CountDownLatchDemo {
    public static void main(String[] args) throws InterruptedException {


        CountDownLatch countDownLatch = new CountDownLatch(6);
        for (int i = 0; i < 6; i++) {
            new Thread(()->{
                System.out.println(Thread.currentThread().getName()+"OUT_OF");
                countDownLatch.countDown();
            }).start();
        }
        countDownLatch.await();
        System.out.println("Close Door");
    }
}

1、可以理解成countDown（）一次就减一直到0结束

2、countDownLatch.await();可以设置超时时间如：

countDownLatch.await(8, TimeUnit.SECONDS);

超时会抛出异常

二、CyclicBarrier（加法）

public class CyclicBarrierDemo {
    public static void main(String[] args) throws BrokenBarrierException, InterruptedException {
        //设置阻碍 达到数量 执行
        CyclicBarrier c = new CyclicBarrier(7, () -> {
            System.out.println("召唤神龙成功");
        });
        for (int i = 0; i < 3; i++) {
            final int temp=i;
            new Thread(()->{
                System.out.println(Thread.currentThread().getName()+"-----------------"+"收集第"+temp+"龙珠");
                try {
                    c.await(4, TimeUnit.SECONDS);
                } catch (InterruptedException e) {
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }
                ;
                System.out.println("第"+temp+"龙珠");
            }).start();
        }
    }
}

1、调用一次await() 就加1 到达指定数量结束

2、c.await();也可以设置超时时间

三、Semaphore

public class SemaphoreDemo {
    public static void main(String[] args) {
        //线程数量
        Semaphore semaphore = new Semaphore(3);
        for (int s = 0; s < 6; s++) {
            final int temp=s;
            new Thread(()->{
                try {
                    semaphore.acquire();
                    System.out.println(Thread.currentThread().getName()+"获取第"+temp+"停车位");
                    TimeUnit.SECONDS.sleep(3);
                    System.out.println(Thread.currentThread().getName()+"释放第"+temp+"停车位");
                } catch (InterruptedException e) {
                    throw new RuntimeException(e);
                } finally {
                    semaphore.release();
                }
            },String.valueOf(s)).start();
        }

    }
}