java教程：线程锁之自旋锁

public class SimpleLock {

/**线程持有锁,null表示锁未被线程持有*/

     private AtomicReference<Thread> temp = new AtomicReference<>();

 static int num = 0;//被多个线程操作的同一个资源

      public void lock(){

          //获取当前正在执行的线程

          Thread currentThread = Thread.currentThread();

          while(!temp.compareAndSet(null, currentThread)){

              //当temp为null的时候compareAndSet返回true，反之为false

              //通过循环不断的自旋判断锁是否被其他线程持有

          }

      }

      public void unLock() {

            //获取当前正在执行的线程

            Thread currentThread = Thread.currentThread();

            if(temp.get() != currentThread){

                //exception ...

            }

            temp.set(null);

}

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

    //创建容量为100的线程池

    ExecutorService Service = Executors.newFixedThreadPool(100);

    //只能一个线程来操作的计数器，原子操作

    CountDownLatch countLatch = new CountDownLatch(100);

    SimpleLock lock = new SimpleLock();

    for (int i = 0; i < 100; i++) {

    Service.execute(new Runnable() {

    @Override

    public void run() {

    lock.lock();//开启锁

    ++num;

    lock.unLock();//释放锁

    countLatch.countDown();//计数下降

    }

    });

    }

    countLatch.await();

    System.out.println(num);

   }

}