Java并发编程之阻塞队列详解

import java.util.concurrent.ArrayBlockingQueue;

/** 
 * @author 作者：徐剑  E-mail:anxu_2013@163.com 
 * @version 创建时间：2016年3月20日 下午12:52:53 
 * 类说明 
 */
public class BlockingQueue
{
  public static void main(String[] args) throws InterruptedException
  {
    java.util.concurrent.BlockingQueue<String> blockingQueue = new ArrayBlockingQueue<>(5);
    for (int i = 0; i < 10; i++)
    {
      // 将指定元素添加到此队列中
      blockingQueue.put("加入元素" + i);
      System.out.println("向阻塞队列中添加了元素:" + i);
    }
    System.out.println("程序到此运行结束，即将退出----");
  }
}

public class BlockingQueue
{
  public static void main(String[] args) throws InterruptedException
  {
    java.util.concurrent.BlockingQueue<String> blockingQueue = new ArrayBlockingQueue<>(5);
    for (int i = 0; i < 10; i++)
    {
      // 将指定元素添加到此队列中
      blockingQueue.put("加入元素" + i);
      System.out.println("向阻塞队列中添加了元素:" + i);
      if(i>=4)
        System.out.println("移除队首元素"+blockingQueue.take());
    }
    System.out.println("程序到此运行结束，即将退出----");
  }

public class ArrayBlockingQueue<E> extends AbstractQueue<E>
    implements BlockingQueue<E>, java.io.Serializable {

  /** 底层存储结构-数组 */
  final Object[] items;

  /** 队首元素下标 */
  int takeIndex;

  /** 队尾元素下标 */
  int putIndex;

  /**队列元素总数 */
  int count;

  /** 重入锁 */
  final ReentrantLock lock;

  /** notEmpty等待条件 */
  private final Condition notEmpty;
  /** notFull等待条件 */
  private final Condition notFull;
  /**
   * Shared state for currently active iterators, or null if there
   * are known not to be any. Allows queue operations to update
   * iterator state.
   */
  transient Itrs itrs = null;

public void put(E e) throws InterruptedException
  {
    //先检查e是否为空
    checkNotNull(e);
    //获取锁
    final ReentrantLock lock = this.lock;
    lock.lockInterruptibly();
    try
    {
      //当队列已满，进入条件等待
      while (count == items.length)
        notFull.await();
      //队列不满，进行入队列操作
      enqueue(e);
    } 
    finally
    {
      //释放锁
      lock.unlock();
    }
  }

private void enqueue(E x)
  {
    final Object[] items = this.items;
    //队尾入队
    items[putIndex] = x;
    if (++putIndex == items.length)
      putIndex = 0;
    //队列总数+1
    count++;
    //notempty条件的等待集中随机选择一个线程，解除其阻塞状态
    notEmpty.signal();
  }

public E take() throws InterruptedException
  {
    //获取锁
    final ReentrantLock lock = this.lock;
    lock.lockInterruptibly();
    try
    {
      //队列为空
      while (count == 0)
        //线程加入notEmpty条件等待集
        notEmpty.await();
      //非空，出队列
      return dequeue();
    } finally
    {
      //释放锁
      lock.unlock();
    }
  }

/** 
 * @author 作者：徐剑  E-mail:anxu_2013@163.com 
 * @version 创建时间：2016年3月20日 下午2:21:55 
 * 类说明：阻塞队列实现的消费者-生产者模式
 */
public class Test
{
  private int queueSize = 10;
  private ArrayBlockingQueue<Integer> queue = new ArrayBlockingQueue<Integer>(queueSize);
  public static void main(String[] args)
  {
    Test test = new Test();
    Producer producer = test.new Producer();
    Consumer consumer = test.new Consumer();
    producer.start();
    consumer.start();
  }
  class Consumer extends Thread
  {
    @Override
    public void run()
    {
      consume();
    }

    private void consume()
    {
      while (true)
      {
        try
        {
          queue.take();
          System.out.println("从队列取走一个元素，队列剩余" + queue.size() + "个元素");
        } catch (InterruptedException e)
        {
          e.printStackTrace();
        }
      }
    }
  }
  class Producer extends Thread
  {
    @Override
    public void run()
    {
      produce();
    }
    private void produce()
    {
      while (true)
      {
        try
        {
          queue.put(1);
          System.out.println("向队列取中插入一个元素，队列剩余空间："+ (queueSize - queue.size()));
        } catch (InterruptedException e)
        {
          e.printStackTrace();
        }
      }
    }
  }
}