十一、信号量控制Semaphore

import java.util.concurrent.Semaphore;

public class SemaphoreDemo {
    /**
     * 设置信号量为1
     */
    private static Semaphore semaphore = new Semaphore(1);

    public static void main(String[] args) throws InterruptedException {
        // 当前信号量为1
        System.out.println(semaphore.availablePermits());
        // 信号量 -1
        semaphore.acquire();
        // 当前信号量为0
        System.out.println(semaphore.availablePermits());
        // 尝试获取信号量失败
        System.out.println(semaphore.tryAcquire());
        // 信号量不变，为0
        System.out.println(semaphore.availablePermits());
        // 释放信号量 +1
        semaphore.release();
        // 信号量为1
        System.out.println(semaphore);
        // 获取信号量成功
        System.out.println(semaphore.tryAcquire());
    }

}