public class SpinLockDemo {
    AtomicReference<Thread> atomicReference = new AtomicReference<>();
    public void lock() {
        Thread thread = Thread.currentThread();
        System.out.println(Thread.currentThread().getName()+"\t"+"----come in");
        // 因為atomicReference沒有set,所以是null,compareAndSet方法比較如果是null,就修改為當前線程,如果不是null,就循環(huán)判斷
        while (!atomicReference.compareAndSet(null, thread)) {
        }
    }
    public void unLock() {
        Thread thread = Thread.currentThread();
        // 如果atomicReference存儲的是當前線程,就修改為null
        atomicReference.compareAndSet(thread,null);
        System.out.println(Thread.currentThread().getName()+"\t"+"----task over,unLock...");
    }
    public static void main(String[] args) {
        SpinLockDemo spinLockDemo = new SpinLockDemo();
        new Thread(() -> {
            spinLockDemo.lock();
            // 業(yè)務邏輯
            try { TimeUnit.SECONDS.sleep(5); } catch (InterruptedException e) { e.printStackTrace(); }
            spinLockDemo.unLock();
        },"A").start();
        // 暫停500毫秒,線程A先于B啟動
        try { TimeUnit.MILLISECONDS.sleep(500); } catch (InterruptedException e) { e.printStackTrace(); }
        new Thread(() -> {
            spinLockDemo.lock();
            spinLockDemo.unLock();
        },"B").start();
    }
}