消息延时在日常随处可见：
1、订单创建10min之后不发起支付，自动取消。
2、30min定时推送一次邮件信息。
最常用到方式后台定时任务轮训，量小的时候可以使用，量大会出现数据读取会性能问题。RabbitMQ并没有直接实现延时队列，但是可以利用RabbitMQ两个属性实现延时队列。
1、x-message-ttl：消息过期时间（Time To Live，TTL），超过过期时间之后即变为死信（Dead-letter），不会再被其他消费者消费。设置TTL有两种方式：创建队列时指定x-message-ttl，此时整个队列具有统一到过期时间；发送消息为每个消息设置expiration，此时消息之间过期时间不同。 消息过期时间取两者最小。
2、x-dead-letter-exchange ：过期消息路由转发，当消息达到过期时间由该exchange按照配置的x-dead-letter-routing-key转发到指定队列，最后被消费者消费。
示例：
spring整合rabbitMQ ：
pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <parent> <artifactId>learning-demo</artifactId> <groupId>com.nancy</groupId> <version>1.0-SNAPSHOT</version> </parent> <modelVersion>4.0.0</modelVersion> <artifactId>demo-jms</artifactId> <packaging>jar</packaging> <name>demo-jms</name> <url>http://maven.apache.org</url> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <spring.version>5.0.0.RELEASE</spring.version> </properties> <dependencies> <dependency> <groupId>org.aspectj</groupId> <artifactId>aspectjweaver</artifactId> <version>1.8.6</version> </dependency> <!--依赖包 --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-jms</artifactId> <version>${spring.version}</version> </dependency> <!--rabbit MQ --> <dependency> <groupId>org.springframework.amqp</groupId> <artifactId>spring-amqp</artifactId> <version>1.6.6.RELEASE</version> <exclusions> <exclusion> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> </exclusion> </exclusions> </dependency> <dependency> <groupId>org.springframework.amqp</groupId> <artifactId>spring-rabbit</artifactId> <version>1.6.6.RELEASE</version> <exclusions> <exclusion> <groupId>org.springframework</groupId> <artifactId>spring-web</artifactId> </exclusion> <exclusion> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> </exclusion> <exclusion> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> </exclusion> <exclusion> <groupId>org.springframework</groupId> <artifactId>spring-tx</artifactId> </exclusion> <exclusion> <groupId>org.springframework</groupId> <artifactId>spring-messaging</artifactId> </exclusion> </exclusions> </dependency> <!--spring --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-aspects</artifactId> <version>${spring.version}</version> <exclusions> <exclusion> <groupId>org.aspectj</groupId> <artifactId>aspectjweaver</artifactId> </exclusion> </exclusions> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context-support</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-test</artifactId> <version>${spring.version}</version> </dependency> <!--junit --> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.8.1</version> <scope>test</scope> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> </dependency> </dependencies> </project>
application.xml
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsd"> <import resource="spring-rabbitmq.xml" /> <!-- 扫描指定package下所有带有如@controller,@services,@resource,@ods并把所注释的注册为Spring Beans --> <context:component-scan base-package="com.nancy.rabbitmq" /> <!-- 激活annotation功能 --> <context:annotation-config /> <!-- 激活annotation功能 --> <context:spring-configured /> </beans>
spring-rabbitmq.xml ：
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:util="http://www.springframework.org/schema/util" xmlns:context="http://www.springframework.org/schema/context" xmlns:rabbit="http://www.springframework.org/schema/rabbit" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.1.xsd http://www.springframework.org/schema/rabbit http://www.springframework.org/schema/rabbit/spring-rabbit-1.6.xsd"> <!--配置connection-factory，指定连接rabbit server参数 --> <rabbit:connection-factory id="connectionFactory" username="guest" password="guest" host="127.0.0.1" port="5672" publisher-confirms="true"/> <!-- 延时队列 --> <rabbit:direct-exchange id="exchange_delay_begin" name="exchange_delay_begin" durable="false" auto-delete="false" > <rabbit:bindings> <rabbit:binding queue="queue_delay_begin" key="delay" /> </rabbit:bindings> </rabbit:direct-exchange> <rabbit:queue name="queue_delay_begin" durable="false"> <rabbit:queue-arguments> <!-- 队列过期时间 --> <entry key="x-message-ttl" value="30000" value-type="java.lang.Long" /> <entry key="x-dead-letter-exchange" value="exchange_delay_done" /> <entry key="x-dead-letter-routing-key" value="delay" /> </rabbit:queue-arguments> </rabbit:queue> <rabbit:direct-exchange id="exchange_delay_done" name="exchange_delay_done" durable="false" auto-delete="false" > <rabbit:bindings> <rabbit:binding queue="queue_delay_done" key="delay" /> <!-- binding key 相同为 【delay】exchange转发消息到多个队列 --> <!--<rabbit:binding queue="queue_delay_done_two" key="delay" />--> </rabbit:bindings> </rabbit:direct-exchange> <rabbit:queue name="queue_delay_done" durable="false"/> <rabbit:template id="delayMsgTwoTemplate" connection-factory="connectionFactory" /> <bean id="messageConsumer" class="com.nancy.rabbitmq.demo.MessageConsumer"></bean> <!-- 消息接收者 --> <rabbit:listener-container connection-factory="connectionFactory" channel-transacted="false" > <rabbit:listener queues="queue_delay_done" ref="messageConsumer" /> </rabbit:listener-container> </beans>
DelayMessageProducer.java
@Service public class DelayMessageProducer { @Resource(name="delayMsgTwoTemplate") private AmqpTemplate delayMsgTwoTemplate; public void delayMsgTwo(String exchange, String routingKey, Object msg) { delayMsgTwoTemplate.convertAndSend(exchange, routingKey, msg, new MessagePostProcessor() { @Override public Message postProcessMessage(Message message) throws AmqpException { message.getMessageProperties().setExpiration(String.valueOf(10000)); return message; } }); } }
MessageConsumer.java
import org.springframework.amqp.core.Message; import org.springframework.amqp.core.MessageListener; public class MessageConsumer implements MessageListener { @Override public void onMessage(Message message) { System.out.println("consumer receive message 22------->:{}"+ message); } }
DelayQueueTest.java
package com.nancy.rabbitmq; import com.alibaba.fastjson.JSONObject; import com.nancy.rabbitmq.delay.DelayMessageProducer; import org.junit.Test; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class DelayQueueTest { private ApplicationContext context = null; // @Ignore @org.junit.Before public void setUp() throws Exception { context = new ClassPathXmlApplicationContext("rabbitmq/application.xml"); } // @Ignore @Test public void delayQueueTest() throws Exception { DelayMessageProducer messageProducer = context.getBean(DelayMessageProducer.class); int a = 10; while (a > 0) { System.out.println("send "+ a); messageProducer.delayMsgTwo("exchange_delay_begin","delay", "hello world delay2 :" + a--); try { Thread.sleep(10); } catch (InterruptedException e) { e.printStackTrace(); } } System.out.println("sended "); Thread.sleep(1000*60); } }
运行结果： 发送消息 10s之后， 消费监听到消息 消费。
send 10 send 9 send 8 send 7 send 6 send 5 send 4 send 3 send 2 send 1 sended consumer receive message 22------->:{}(Body:'hello world delay2 :10' MessageProperties [headers={x-first-death-exchange=exchange_delay_begin, x-death=[{reason=expired, original-expiration=10000, count=1, exchange=exchange_delay_begin, time=Sun Jul 01 18:33:19 CST 2018, routing-keys=[delay], queue=queue_delay_begin}], x-first-death-reason=expired, x-first-death-queue=queue_delay_begin}, timestamp=null, messageId=null, userId=null, receivedUserId=null, appId=null, clusterId=null, type=null, correlationId=null, correlationIdString=null, replyTo=null, contentType=text/plain, contentEncoding=UTF-8, contentLength=0, deliveryMode=null, receivedDeliveryMode=PERSISTENT, expiration=null, priority=0, redelivered=false, receivedExchange=exchange_delay_done, receivedRoutingKey=delay, receivedDelay=1000, deliveryTag=1, messageCount=0, consumerTag=amq.ctag-oOJzeYHEJYrLFL4HbHWZcA, consumerQueue=queue_delay_done]) consumer receive message 22------->:{}(Body:'hello world delay2 :9' MessageProperties [headers={x-first-death-exchange=exchange_delay_begin, x-death=[{reason=expired, original-expiration=10000, count=1, exchange=exchange_delay_begin, time=Sun Jul 01 18:33:19 CST 2018, routing-keys=[delay], queue=queue_delay_begin}], x-first-death-reason=expired, x-first-death-queue=queue_delay_begin}, timestamp=null, messageId=null, userId=null, receivedUserId=null, appId=null, clusterId=null, type=null, correlationId=null, correlationIdString=null, replyTo=null, contentType=text/plain, contentEncoding=UTF-8, contentLength=0, deliveryMode=null, receivedDeliveryMode=PERSISTENT, expiration=null, priority=0, redelivered=false, receivedExchange=exchange_delay_done, receivedRoutingKey=delay, receivedDelay=1000, deliveryTag=2, messageCount=0, consumerTag=amq.ctag-oOJzeYHEJYrLFL4HbHWZcA, consumerQueue=queue_delay_done]) consumer receive message 22------->:{}(Body:'hello world delay2 :8' MessageProperties [headers={x-first-death-exchange=exchange_delay_begin, x-death=[{reason=expired, original-expiration=10000, count=1, exchange=exchange_delay_begin, time=Sun Jul 01 18:33:19 CST 2018, routing-keys=[delay], queue=queue_delay_begin}], x-first-death-reason=expired, x-first-death-queue=queue_delay_begin}, timestamp=null, messageId=null, userId=null, receivedUserId=null, appId=null, clusterId=null, type=null, correlationId=null, correlationIdString=null, replyTo=null, contentType=text/plain, contentEncoding=UTF-8, contentLength=0, deliveryMode=null, receivedDeliveryMode=PERSISTENT, expiration=null, priority=0, redelivered=false, receivedExchange=exchange_delay_done, receivedRoutingKey=delay, receivedDelay=1000, deliveryTag=3, messageCount=0, consumerTag=amq.ctag-oOJzeYHEJYrLFL4HbHWZcA, consumerQueue=queue_delay_done]) consumer receive message 22------->:{}(Body:'hello world delay2 :7' MessageProperties [headers={x-first-death-exchange=exchange_delay_begin, x-death=[{reason=expired, original-expiration=10000, count=1, exchange=exchange_delay_begin, time=Sun Jul 01 18:33:19 CST 2018, routing-keys=[delay], queue=queue_delay_begin}], x-first-death-reason=expired, x-first-death-queue=queue_delay_begin}, timestamp=null, messageId=null, userId=null, receivedUserId=null, appId=null, clusterId=null, type=null, correlationId=null, correlationIdString=null, replyTo=null, contentType=text/plain, contentEncoding=UTF-8, contentLength=0, deliveryMode=null, receivedDeliveryMode=PERSISTENT, expiration=null, priority=0, redelivered=false, receivedExchange=exchange_delay_done, receivedRoutingKey=delay, receivedDelay=1000, deliveryTag=4, messageCount=0, consumerTag=amq.ctag-oOJzeYHEJYrLFL4HbHWZcA, consumerQueue=queue_delay_done]) consumer receive message 22------->:{}(Body:'hello world delay2 :6' MessageProperties [headers={x-first-death-exchange=exchange_delay_begin, x-death=[{reason=expired, original-expiration=10000, count=1, exchange=exchange_delay_begin, time=Sun Jul 01 18:33:19 CST 2018, routing-keys=[delay], queue=queue_delay_begin}], x-first-death-reason=expired, x-first-death-queue=queue_delay_begin}, timestamp=null, messageId=null, userId=null, receivedUserId=null, appId=null, clusterId=null, type=null, correlationId=null, correlationIdString=null, replyTo=null, contentType=text/plain, contentEncoding=UTF-8, contentLength=0, deliveryMode=null, receivedDeliveryMode=PERSISTENT, expiration=null, priority=0, redelivered=false, receivedExchange=exchange_delay_done, receivedRoutingKey=delay, receivedDelay=1000, deliveryTag=5, messageCount=0, consumerTag=amq.ctag-oOJzeYHEJYrLFL4HbHWZcA, consumerQueue=queue_delay_done]) consumer receive message 22------->:{}(Body:'hello world delay2 :5' MessageProperties [headers={x-first-death-exchange=exchange_delay_begin, x-death=[{reason=expired, original-expiration=10000, count=1, exchange=exchange_delay_begin, time=Sun Jul 01 18:33:19 CST 2018, routing-keys=[delay], queue=queue_delay_begin}], x-first-death-reason=expired, x-first-death-queue=queue_delay_begin}, timestamp=null, messageId=null, userId=null, receivedUserId=null, appId=null, clusterId=null, type=null, correlationId=null, correlationIdString=null, replyTo=null, contentType=text/plain, contentEncoding=UTF-8, contentLength=0, deliveryMode=null, receivedDeliveryMode=PERSISTENT, expiration=null, priority=0, redelivered=false, receivedExchange=exchange_delay_done, receivedRoutingKey=delay, receivedDelay=1000, deliveryTag=6, messageCount=0, consumerTag=amq.ctag-oOJzeYHEJYrLFL4HbHWZcA, consumerQueue=queue_delay_done]) consumer receive message 22------->:{}(Body:'hello world delay2 :4' MessageProperties [headers={x-first-death-exchange=exchange_delay_begin, x-death=[{reason=expired, original-expiration=10000, count=1, exchange=exchange_delay_begin, time=Sun Jul 01 18:33:19 CST 2018, routing-keys=[delay], queue=queue_delay_begin}], x-first-death-reason=expired, x-first-death-queue=queue_delay_begin}, timestamp=null, messageId=null, userId=null, receivedUserId=null, appId=null, clusterId=null, type=null, correlationId=null, correlationIdString=null, replyTo=null, contentType=text/plain, contentEncoding=UTF-8, contentLength=0, deliveryMode=null, receivedDeliveryMode=PERSISTENT, expiration=null, priority=0, redelivered=false, receivedExchange=exchange_delay_done, receivedRoutingKey=delay, receivedDelay=1000, deliveryTag=7, messageCount=0, consumerTag=amq.ctag-oOJzeYHEJYrLFL4HbHWZcA, consumerQueue=queue_delay_done]) consumer receive message 22------->:{}(Body:'hello world delay2 :3' MessageProperties [headers={x-first-death-exchange=exchange_delay_begin, x-death=[{reason=expired, original-expiration=10000, count=1, exchange=exchange_delay_begin, time=Sun Jul 01 18:33:19 CST 2018, routing-keys=[delay], queue=queue_delay_begin}], x-first-death-reason=expired, x-first-death-queue=queue_delay_begin}, timestamp=null, messageId=null, userId=null, receivedUserId=null, appId=null, clusterId=null, type=null, correlationId=null, correlationIdString=null, replyTo=null, contentType=text/plain, contentEncoding=UTF-8, contentLength=0, deliveryMode=null, receivedDeliveryMode=PERSISTENT, expiration=null, priority=0, redelivered=false, receivedExchange=exchange_delay_done, receivedRoutingKey=delay, receivedDelay=1000, deliveryTag=8, messageCount=0, consumerTag=amq.ctag-oOJzeYHEJYrLFL4HbHWZcA, consumerQueue=queue_delay_done]) consumer receive message 22------->:{}(Body:'hello world delay2 :2' MessageProperties [headers={x-first-death-exchange=exchange_delay_begin, x-death=[{reason=expired, original-expiration=10000, count=1, exchange=exchange_delay_begin, time=Sun Jul 01 18:33:19 CST 2018, routing-keys=[delay], queue=queue_delay_begin}], x-first-death-reason=expired, x-first-death-queue=queue_delay_begin}, timestamp=null, messageId=null, userId=null, receivedUserId=null, appId=null, clusterId=null, type=null, correlationId=null, correlationIdString=null, replyTo=null, contentType=text/plain, contentEncoding=UTF-8, contentLength=0, deliveryMode=null, receivedDeliveryMode=PERSISTENT, expiration=null, priority=0, redelivered=false, receivedExchange=exchange_delay_done, receivedRoutingKey=delay, receivedDelay=1000, deliveryTag=9, messageCount=0, consumerTag=amq.ctag-oOJzeYHEJYrLFL4HbHWZcA, consumerQueue=queue_delay_done]) consumer receive message 22------->:{}(Body:'hello world delay2 :1' MessageProperties [headers={x-first-death-exchange=exchange_delay_begin, x-death=[{reason=expired, original-expiration=10000, count=1, exchange=exchange_delay_begin, time=Sun Jul 01 18:33:19 CST 2018, routing-keys=[delay], queue=queue_delay_begin}], x-first-death-reason=expired, x-first-death-queue=queue_delay_begin}, timestamp=null, messageId=null, userId=null, receivedUserId=null, appId=null, clusterId=null, type=null, correlationId=null, correlationIdString=null, replyTo=null, contentType=text/plain, contentEncoding=UTF-8, contentLength=0, deliveryMode=null, receivedDeliveryMode=PERSISTENT, expiration=null, priority=0, redelivered=false, receivedExchange=exchange_delay_done, receivedRoutingKey=delay, receivedDelay=1000, deliveryTag=10, messageCount=0, consumerTag=amq.ctag-oOJzeYHEJYrLFL4HbHWZcA, consumerQueue=queue_delay_done])
参考资料：
DLX： https://www.rabbitmq.com/dlx.html
RabbitMQ如何实现延迟队列？：https://blog.csdn.net/u013256816/article/details/55106401
消息队列之 RabbitMQ ：https://www.jianshu.com/p/79ca08116d57