这个输出结果就是我根据你写的代码输出的。其中线程3为什么在线程1、2读的时候也能进行写呢？

public class CinemaReadWriteLock {

    private static final ReentrantReadWriteLock reentrantReadWriteLock = new ReentrantReadWriteLock();
    /**
     * 读锁
     */
    private static final ReentrantReadWriteLock.ReadLock readLock = reentrantReadWriteLock.readLock();
    /**
     * 写锁
     */
    private static final ReentrantReadWriteLock.WriteLock writeLock = reentrantReadWriteLock.writeLock();

    /**
     * 读锁：只能多读
     */
    public static void read() {
        readLock.lock();
        try {
            System.out.println(Thread.currentThread().getName() + "：获取到了读锁");
            TimeUnit.SECONDS.sleep(2);
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            readLock.unlock();
            System.out.println(Thread.currentThread().getName() + "：释放了读锁");
        }
    }

    /**
     * 写锁：只能一写
     */
    public static void write() {
        writeLock.lock();
        try {
            System.out.println(Thread.currentThread().getName() + "：获取到了写锁");
            TimeUnit.SECONDS.sleep(3);
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            System.out.println(Thread.currentThread().getName() + "：释放了写锁");
            writeLock.unlock();
        }
    }

    public static void main(String[] args) {
        new Thread(CinemaReadWriteLock::read,"1").start();

        new Thread(CinemaReadWriteLock::read,"2").start();

        new Thread(CinemaReadWriteLock::write,"3").start();

        new Thread(CinemaReadWriteLock::write,"4").start();
    }
}

我用的是JDK 11，发现这个现象与JDK 8不一样。