加深对AQS原理的理解示例一：实现一个独占锁

/**
 *@Desc
 * 这个自定义的独占锁 只是一个简单的版本，非常粗糙，只为了加深对AQS原理理解。但还有一些列问题有待解决，比如锁的重入，锁不允许被其他线程中断等！
 *@Author zhangfengshi
 *@Date 2021/4/1 7:24 下午
 *@Version 1.0
 */
public class MutiLock implements Lock {

    public  class Sync extends AbstractQueuedSynchronizer{

        //是否处于独占状态
        @Override
        public boolean isHeldExclusively(){
            return getState()==1;//访问或修改同步状态
        }
        //获取锁
        @Override
        public boolean tryAcquire(int arg){
            if(compareAndSetState(0,1)){
                //设置当前线程拥有独占访问权
                setExclusiveOwnerThread(Thread.currentThread());
                return true;
            }
            return false;
        }
        //释放锁
        @Override
        public boolean tryRelease(int arg){
            //已经释放就抛异常
            if(getState()==0){
                throw  new IllegalMonitorStateException();
            }
            setExclusiveOwnerThread(null);
            setState(0);
            return true;
        }

        public Condition newCondition(){
            return new ConditionObject();
        }
    }

    public Sync sync=new Sync();
    @Override
    public void lock() {
        sync.acquire(1);
    }

    @Override
    public void lockInterruptibly() throws InterruptedException {
        sync.acquireInterruptibly(1);
    }

    @Override
    public boolean tryLock() {
        return sync.tryAcquire(1);
    }

    @Override
    public boolean tryLock(long time, TimeUnit unit) throws InterruptedException {
        return sync.tryAcquireNanos(1, unit.toNanos(time));
    }

    @Override
    public void unlock() {
        sync.tryRelease(1);
    }

    @Override
    public Condition newCondition() {
        return sync.newCondition();
    }

    public boolean isLock(){
        return sync.isHeldExclusively();
    }
}