Java阻塞队列中的BlockingQueue接口详解

    //存储的数据 存放在数组中
    final Object[] items;
    //读数据位置
    int takeIndex;
    //写入数据位置
    int putIndex;
    //数据数量
    int count;
    //队列同步相关属性
    final ReentrantLock lock;
    private final Condition notEmpty;
    private final Condition notFull;

 public ArrayBlockingQueue(int capacity) {
        this(capacity, false);
    }
   //通过初始容量和是否公平性抢锁标志来进行实例化
    public ArrayBlockingQueue(int capacity, boolean fair) {
        if (capacity <= 0)
            throw new IllegalArgumentException();
        this.items = new Object[capacity];
        lock = new ReentrantLock(fair);
        notEmpty = lock.newCondition();
        notFull =  lock.newCondition();
    }
    //通过初始容量capacity、公平性标志fair和集合c
    public ArrayBlockingQueue(int capacity, boolean fair,Collection<? extends E> c) {
        this(capacity, fair);
        final ReentrantLock lock = this.lock;
        lock.lock(); // Lock only for visibility, not mutual exclusion
        try {
            int i = 0;
            try {
                for (E e : c) {
                    //数据是不能为null
                    checkNotNull(e);
                    items[i++] = e;
                }
            } catch (ArrayIndexOutOfBoundsException ex) {
                throw new IllegalArgumentException();
            }
            count = i;
            putIndex = (i == capacity) ? 0 : i;
        } finally {
            lock.unlock();
        }
    }

 public void put(E e) throws InterruptedException {
        //检测插入数据不能为null
        checkNotNull(e);
        //添加可中断的锁
        final ReentrantLock lock = this.lock;
        lock.lockInterruptibly();
        try {
            while (count == items.length) //容量满了需要阻塞
                notFull.await();
            //当前集合未满，执行插入操作
            insert(e);
        } finally {
            //释放锁
            lock.unlock();
        }
    }
    private void insert(E x) {
        items[putIndex] = x;
        putIndex = inc(putIndex);
        ++count;
        //通知take操作已经有数据吗，如果有take方法阻塞，此时可被唤醒来执行take操作
        notEmpty.signal();
    }
  //循环数组的特殊标志处理 ，如果是到最大值则重定向到0号索引
    final int inc(int i) {
        return (++i == items.length) ? 0 : i;
    }

    public E take() throws InterruptedException {
        //添加可中断的锁
        final ReentrantLock lock = this.lock;
        lock.lockInterruptibly();
        try {
            while (count == 0) //队列中没有数据时，需要阻塞，直到有数据put进入队列通知该操作可以继续执行
                notEmpty.await();
            //有数据时
            return extract();
        } finally {
            //释放锁
            lock.unlock();
        }
    }
    private E extract() {
        final Object[] items = this.items;
        E x = this.<E>cast(items[takeIndex]);
        items[takeIndex] = null;
        takeIndex = inc(takeIndex);
        --count;
        //发出通知 通知put方法，唤醒put操作
        notFull.signal();
        return x;
    }