前言

实际业务中，例如秒杀系统，秒杀商品成功会有截止时间，这时需要用到RabbitMQ延迟服务。

1、RabbitMQ延迟队列

1.1、方式1：RabbitMQ通过死信机制来实现延迟队列的功能

TTL ，即 Time-To-Live，存活时间，消息和队列都可以设置存活时间
Dead Letter，即死信，若给消息设置了存活时间，当超过存活时间后消息还没有被消费，则该消息变成了死信
Dead Letter Exchanges（DLX），即死信交换机
Dead Letter Routing Key （DLK），死信路由键

/***********************延迟队列*************************/
//创建立即消费队列
@Bean
public Queue immediateQueue(){return new Queue("immediateQueue");
}
//创建立即消费交换机
@Bean
public DirectExchange immediateExchange(){return new DirectExchange("immediateExchange");
}
@Bean
public Binding bindingImmediate(@Qualifier("immediateQueue") Queue queue,@Qualifier("immediateExchange") DirectExchange directExchange){return BindingBuilder.bind(queue).to(directExchange).with("immediateRoutingKey");
}//创建延迟队列
@Bean
public Queue delayQueue(){Map<String,Object> params = new HashMap<>();//死信队列转发的死信转发到立即处理信息的交换机params.put("x-dead-letter-exchange","immediateExchange");//死信转化携带的routing-keyparams.put("x-dead-letter-routing-key","immediateRoutingKey");//设置消息过期时间，单位：毫秒params.put("x-message-ttl",60 * 1000);return new Queue("delayQueue",true,false,false,params);
}@Bean
public DirectExchange delayExchange(){return new DirectExchange("delayExchange");
}@Bean
public Binding bindingDelay(@Qualifier("delayQueue") Queue queue,@Qualifier("delayExchange") DirectExchange directExchange){return BindingBuilder.bind(queue).to(directExchange).with("delayRoutingKey");
}

@Test
public void sendDelay(){this.rabbitTemplate.convertAndSend("delayExchange","delayRoutingKey","Hello world topic");
}

1.2、方式二：安装延迟队列插件

1.2.1、安装延迟队列插件：

https://github.com/rabbitmq/rabbitmq-delayed-message-exchange/releases/download/3.11.1/rabbitmq_delayed_message_exchange-3.11.1.ez
下载解压，到plugins目录，执行以下的命令：

rabbitmq-plugins enable rabbitmq_delayed_message_exchange

/**************延迟队列一个单一queue*******************/
@Bean
public Queue delayNewQueue(){return new Queue("delayNewQueue");
}
@Bean
public CustomExchange delayNewExchange(){Map<String, Object> args = new HashMap<>();// 设置类型，可以为fanout、direct、topicargs.put("x-delayed-type", "direct");return new CustomExchange("delayNewExchange","x-delayed-message", true,false,args);
}
@Bean
public Binding bindingNewDelay(@Qualifier("delayNewQueue") Queue queue,@Qualifier("delayNewExchange") CustomExchange customExchange){return BindingBuilder.bind(queue).to(customExchange).with("delayNewRoutingKey").noargs();
}

@Test
public void sendDelay() {//生产端写完了UserInfo userInfo = new UserInfo();userInfo.setPassword("13432432");userInfo.setUserAccount("tiger");this.rabbitTemplate.convertAndSend("delayNewExchange", "delayNewRoutingKey", userInfo, a -> {//单位毫秒a.getMessageProperties().setDelay(30000);return a;});
}

2、消息确认机制

消息确认分为两部分：生产确认和消费确认。

生产确认：生产者生产消息后，将消息发送到交换机，触发确认回调；交换机将消息转发到绑定队列，若失败则触发返回回调。
消费确认：默认情况下消息被消费者从队列中获取后即发送确认，不管消费者处理消息时是否失败，不需要额外代码，但是不能保证消息被正确消费。我们增加手动确认，则需要代码中明确进行消息确认。

2.1、生产确认

@Bean
public RabbitTemplate getTemplate(ConnectionFactory connectionFactory){RabbitTemplate template = new RabbitTemplate(connectionFactory);//消息发送到交换器Exchange后触发回调template.setConfirmCallback(new RabbitTemplate.ConfirmCallback() {@Overridepublic void confirm(CorrelationData correlationData, boolean ack, String cause) {//  可以进行消息入库操作log.info("消息唯一标识 correlationData = {}", correlationData);log.info("确认结果 ack = {}", ack);log.info("失败原因 cause = {}", cause);}});// 配置这个，下面的ReturnCallback 才会起作用template.setMandatory(true);// 如果消息从交换器发送到对应队列失败时触发（比如 根据发送消息时指定的routingKey找不到队列时会触发）template.setReturnsCallback(new RabbitTemplate.ReturnsCallback() {@Overridepublic void returnedMessage(ReturnedMessage returnedMessage) {//  可以进行消息入库操作log.info("消息主体 message = {}", returnedMessage.getMessage());log.info("回复码 replyCode = {}", returnedMessage.getReplyCode());log.info("回复描述 replyText = {}", returnedMessage.getReplyText());log.info("交换机名字 exchange = {}", returnedMessage.getExchange());log.info("路由键 routingKey = {}", returnedMessage.getRoutingKey());}});return template;
}

spring:cloud:nacos:discovery:server-addr: localhost:8848application:name: drp-user-service  #微服务名称datasource:username: rootpassword: rooturl: jdbc:mysql://127.0.0.1:3306/drpdriver-class-name: com.mysql.cj.jdbc.Driverrabbitmq:host: 127.0.0.1port: 5672username: tigerpassword: tigervirtual-host: tiger_vh# 确认消息已发送到交换机（Exchange）publisher-confirm-type: correlated# 确认消息已发送到队列publisher-returns: truelistener:simple:acknowledge-mode: manual # 开启消息消费手动确认retry:enabled: true

2.2、消费确认

@RabbitHandler
public void process(UserInfo data, Message message, Channel channel){log.info("收到directQueue队列信息：" + data);long deliveryTag = message.getMessageProperties().getDeliveryTag();try {//成功消费确认channel.basicAck(deliveryTag,true);log.info("消费成功确认完毕。。。。。");} catch (IOException e) {log.error("确认消息时抛出异常 ", e);        // 重新确认，成功确认消息try {Thread.sleep(50);channel.basicAck(deliveryTag, true);} catch (IOException | InterruptedException e1) {log.error("确认消息时抛出异常 ", e);// 可以考虑入库}}catch (Exception e){log.error("业务处理失败", e);try {// 失败确认channel.basicNack(deliveryTag, false, false);} catch (IOException e1) {log.error("消息失败确认失败", e1);}}
}