利用DelayQueue实现延时消息队列（简易版MQ）

1.上文

关于阻塞队列的介绍：http://blog.csdn.net/caicongyang/article/details/50649897

2.需求

 延迟消息队列：

1)2个小时后给用户发送短信。
2)15分钟后关闭网络连接。
3)2分钟后再次尝试回调。

3.案例demo

Message.Java

 package com.ccy.concurrent;

 import java.util.concurrent.Delayed;
 import java.util.concurrent.TimeUnit;

 /**
  * <p>
  * Title: Message.java
  * Package com.ccy.concurrent
  * </p>
  * <p>
  * Description: 延迟执行的消息
  * <p>
  * @author Tom.Cai
  * @created 2016-2-10 下午7:39:48
  * @version V1.0
  *
  */
 public class Message implements Delayed{
         private String id;
         private String name;
         private long activeTime;//执行时间

         public Message(){

         }

         public Message(String id, String name,long activeTime) {
             super();
             this.id = id;
             this.name = name;
             this.activeTime = TimeUnit.NANOSECONDS.convert(activeTime, TimeUnit.MILLISECONDS) + System.nanoTime();
         }
         public String getId() {
             return id;
         }
         public void setId(String id) {
             this.id = id;
         }
         public String getName() {
             return name;
         }
         public void setName(String name) {
             this.name = name;
         }

         @Override
         public int compareTo(Delayed delayed) {
             Message msg = (Message)delayed;
             return Integer.valueOf(this.id)>Integer.valueOf(msg.id)?1:( Integer.valueOf(this.id)<Integer.valueOf(msg.id)?-1:0);
         }

         @Override
         public long getDelay(TimeUnit unit) {
              return unit.convert(this.activeTime - System.nanoTime(), TimeUnit.NANOSECONDS);
         }



 }

Producer.javaProducer

 package com.ccy.concurrent;

 import java.util.concurrent.DelayQueue;

 public class Producer implements Runnable{
     private DelayQueue<Message> queue;

     public Producer(DelayQueue<Message> queue){
         this.queue = queue;
     }

     @Override
     public void run() {
         //5秒后发送消息
         Message m2 = new Message("2","Tom",5000);
         queue.offer(m2);
         System.out.println("消息生产者往消息队列放置消息："+m2.getId()+":"+m2.getName());
         //3秒后发送消息
         Message m1 = new Message("1","Tom",3000);
         queue.offer(m1);
         System.out.println("消息生产者往消息队列放置消息："+m1.getId()+":"+m1.getName());

     }


 }

Consumer.java

 package com.ccy.concurrent;

 import java.util.concurrent.DelayQueue;

 public class Consumer implements Runnable{
     private DelayQueue<Message> queue;

     public Consumer(DelayQueue<Message> queue){
         this.queue = queue;
     }

     @Override
     public void run() {
         while(true){
             try {
                 Message take = queue.take();
                 System.out.println("消息需求者获取消息："+take.getId()+":"+take.getName());
             } catch (InterruptedException e) {
                 e.printStackTrace();
             }
         }
     }

 }

DelayQueueTest.java

 package com.ccy.concurrent;

 import java.util.concurrent.DelayQueue;


 public class DelayQueueTest {
     public static void main(String[] args) {
         DelayQueue<Message> queue = new DelayQueue<Message>();
         new Thread(new Producer(queue)).start();
         new Thread(new Consumer(queue)).start();
     }
 }

4.效果

5.其他学习资源

http://zhangyp.net/rabbitmq-delayqueue/

...

6.后记

作者将学习Apache的ActiveMQ消息总线，其可以支持定时、延迟投递、重复投递和Cron调度。

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