谈谈rabbitmq中的死信队列-爱代码爱编程
那什么消息是死信(dead message)呢？
被拒绝（basic.reject或basic.nack）并且requeue=false的消息
TTL过期消息的消息
队列达到最大长度（队列满了，无法再添加数据到mq中）的消息
DLX（Dead Letter Exchanges）死信队列，本身也是一个普通的消息队列，在创建队列的时候，通过设置一些关键参数x-dead-letter-exchange，可以将一个普通的消息队列设置为死信队列
当这个队列中有死信时, RabbitMQ就会自动将这个消息重新发布到设置的Exchange上去, 进而被路由到另一个队列
package com.qiyexue.api.dlx;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;
import java.util.HashMap;
import java.util.Map;
/**
* 消费者
*
* @author 七夜雪
* @date 2018-12-15 20:07
*/
public class Consumer {
public static void main(String[] args) throws Exception {
// 1. 创建连接工厂并设置属性
ConnectionFactory factory = new ConnectionFactory();;
factory.setHost("192.168.72.138");
factory.setPort(5672);
factory.setVirtualHost("/");
// 2. 创建连接
Connection connection = factory.newConnection();
// 3. 创建channel
Channel channel = connection.createChannel();
// 4. 声明死信队列Exchange和Queue
channel.exchangeDeclare("dlx.exchange", "topic");
channel.queueDeclare("dlx.queue", true, false, false, null);
channel.queueBind("dlx.queue", "dlx.exchange", "#");
// 5. 声明普通Exchange
String exchangeName = "test_dlx_exchange";
String exchangeType = "topic";
String routingKey = "dlx.*";
channel.exchangeDeclare(exchangeName, exchangeType, true, false, null);
// 6. 声明消息队列, 指定死信队列为dlx.exchange
String queueName = "test_dlx_queue";
Map<String, Object> arguments = new HashMap<>();
// x-dead-leeter-exchange属性用于指定死信队列为dlx.exchange
arguments.put("x-dead-letter-exchange", "dlx.exchange");
channel.queueDeclare(queueName, true, false, false, arguments);
// 6. 绑定队列和Exchange
channel.queueBind(queueName, exchangeName, routingKey);
}
}