Spring Cloud Bus

好东西

RabbitMQ延时消息的实现

1. 将消息放到一个延迟队列中
2. 该延迟队列设置了过去时间，代表消息只能活这么久
3. 延迟队列会把消息发送到死信交换机
4. 死信交换机通过路由把消息发送到一个死信队列里
   

实现延迟队列

1. 创建一个延迟队列

	@Bean 
	public Queue delayQueue() {
		Map<String, Object> arguments = new HashMap<>();
		arguments.put("x-message-ttl", 10*1000);
		arguments.put("x-dead-letter-exchange", "dead-letter-exchange");
		arguments.put("x-dead-letter-routing-key", "dead-letter-routing-key");
		return new Queue("delayQueue", false, false, false, arguments);
	}

2. 准备一个死信交换机（直连交换机）

	@Bean
	public DirectExchange directExchange() {
		return new DirectExchange("dead-letter-exchange");
	}

3. 准备一个死信队列（普通的队列）,绑定死信队列

	@Bean
	public Queue deadLetterQueue() {
		return new Queue("deadLetterQueue");
	}
	@Bean
	public Binding delayBind() {
		return BindingBuilder.bind(deadLetterQueue()).to(directExchange()).with("dead-letter-routing-key");
	}

4. 设置一个监听器

@Component
@RabbitListener(queues = "deadLetterQueue")
public class DelayMessageListener {

	@RabbitHandler
	public void handler(String object, Message message, Channel channel) {
		MessageProperties messageProperties = message.getMessageProperties();
		long deliveryTag = messageProperties.getDeliveryTag();
		System.out.println("收到消息了, deliveryTag ： " + deliveryTag);
		try {
			channel.basicAck(deliveryTag, false);
		} catch (IOException e) {
			e.printStackTrace();
		}
		
	}
	
	
}

5. 测试

@GetMapping("/rabbit/delay")
	public String delay() {
		Object message = "qiuxian is kind of cute animal";
		rabbitTemplate.convertAndSend("delayQueue", message, new MessagePostProcessor() {
			
			@Override
			public Message postProcessMessage(Message message) throws AmqpException {
				message.getMessageProperties().setExpiration("12000");
				return message;
			}
		});
		return "直连消息发送成功";
	}