2021-10-29

juc工具类

CyclicBarrier：
栅栏循环，定义一个数的最终数值，可以使得线程的调度有序的执行，先将循环当中的数输出完成然后再进行判断如果为0，则结束最后进行lambda表达式当中的方法，有序的进行。

public class CycDemo {
    private static final int NUMBER=7;
    public static void main(String[] args) {
        //栅栏循环
        CyclicBarrier cc = new CyclicBarrier(NUMBER,()->{
            System.out.println("集齐七颗龙珠召唤神龙");
        });
        for (int i = 0; i <=6 ; i++) {
            new Thread(()->{
                System.out.println(Thread.curren`在这里插入代码片`tThread().getName()+"颗龙珠");
                try {
                    cc.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } catch (BrokenBarrierException e) {
                    e.printStackTrace();
                }
            },String.valueOf(i)).start();
        }

    }
}

栅栏的实现：

/**
     * Returns the number of parties currently waiting at the barrier.
     * This method is primarily useful for debugging and assertions.
     *
     * @return the number of parties currently blocked in {@link #await}
     */
    public int getNumberWaiting() {
        final ReentrantLock lock = this.lock;//可重入锁  非公平锁
        lock.lock();//上锁
        try {
            return parties - count;
        } finally {
            lock.unlock();//进行解锁
        }
    }

Semaphore信号灯：

//六个车位三辆车抢车位
public class SemaphoreDemo {
    public static void main(String[] args) throws InterruptedException {
        Semaphore ss = new Semaphore(3);

        for (int i = 0; i <=5 ; i++) {
            ss.acquire();
            new Thread(()->{

                try {
                    System.out.println(Thread.currentThread().getName()+"辆车抢到了车位");
                    TimeUnit.SECONDS.sleep(new Random().nextInt(5));//休眠的秒数
                    System.out.println(Thread.currentThread().getName()+"辆车释放了车位");
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }finally {
                    ss.release();
                }
            },String.valueOf(i)).start();
        }
    }
}```
acquire
release