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  DelayQueue
  
  
  ：一个使用优先级队列实现的无界阻塞队列。

支持延时获取的元素的阻塞队列，元素必须要实现Delayed接口。

适用场景：实现自己的缓存系统，订单到期，限时支付等等。

• 将订单放入队列

public class PutOrder implements Runnable {
    private DelayQueue<ItemVo<Order>> queue;

    public PutOrder(DelayQueue<ItemVo<Order>> queue) {
        this.queue = queue;
    }
    @Override
    public void run() {
        //5秒到期
        Order ordeTb = new Order("Tb12345",366);
        ItemVo<Order> itemTb = new ItemVo<Order>(5000,ordeTb);
        queue.offer(itemTb);
        System.out.println("订单5秒后到期："+ordeTb.getOrdernum());

        //8秒到期
        Order ordeJd = new Order("Jd54321",753);
        ItemVo<Order> itemJd = new ItemVo<Order>(8000,ordeJd);
        queue.offer(itemJd);
        System.out.println("订单8秒后到期："+ordeJd.getOrdernum());

    }
}

• 取出到期订单

public class FetchOrder implements Runnable {
    private DelayQueue<ItemVo<Order>> queue;

    public FetchOrder(DelayQueue<ItemVo<Order>> queue) {
        this.queue = queue;
    }

    @Override
    public void run() {
        while (true){
            try {
                ItemVo<Order> vo = queue.take();
                System.out.println("get from queue....."+vo.getData().toString());
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

• 测试
  public class DelayQueueTest {
      public static void main(String[] args) throws InterruptedException {
  
          DelayQueue<ItemVo<Order>> queue = new DelayQueue<>();
          new Thread(new PutOrder(queue)).start();
          new Thread(new FetchOrder(queue)).start();
          for (int i = 1; i < 20; i++) {
              //TimeUnit.MILLISECONDS.sleep(500);
              Thread.sleep(500);
              System.out.println(i * 500);
          }
  
  
      }
  }

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