曾经被面试过BlockingQueue吗？

final Lock lock = new ReentrantLock();
final Condition notFull = lock.newCondition();
final Condition notEmpty = lock.newCondition();

final Object[] items = new Object[100];
int putptr, takeptr, count;

public void put(Object x) throws InterruptedException {
    lock.lock();
    try {
        while (count == items.length) {
            notFull.await();
        }

        items[putptr] = x;
        if (++putptr == items.length)
            putptr = 0;
        ++count;
        notEmpty.signal();
    } finally {
        lock.unlock();
    }
}

public Object take() throws InterruptedException {
    lock.lock();
    try {
        while (count == 0) {
            notEmpty.await();
        }
        Object x = items[takeptr];
        if (++takeptr == items.length)
            takeptr = 0;
        --count;
        notFull.signal();
        return x;
    } finally {
        lock.unlock();
    }
}