RabbitMQ的DLX（Dead-Letter-Exchange 死信交换机，死信交换器，死信邮箱）（重要）

1、RabbitMQ死信队列

RabbitMQ死信队列也有叫 死信交换机、死信邮箱等说法。
DLX: Dead-Letter-Exchange 死信交换器，死信邮箱。
1-2、生产者发送一个消息到正常交换机
2-4、正常交换机接收到消息发送到正常队列
4、正常队列设置了队列过期时间，超时消息会自动删除
4-6、原本过期自动删除的消息发送到了死信交换机
6-8、死信交换机将消息发送到了死信队列

如上情况下一个消息会进入DLX（Dead Letter Exchange）死信交换机。

2、代码示例

2.1、队列过期

2.1.1、配置类RabbitConfig（关键代码）

package com.power.config;import org.springframework.amqp.core.*;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;import java.util.HashMap;
import java.util.Map;@Configuration
public class RabbitConfig {@Value("${my.exchangeNormalName}")private String exchangeNormalName;@Value("${my.queueNormalName}")private String queueNormalName;@Value("${my.exchangeDlxName}")private String exchangeDlxName;@Value("${my.queueDlxName}")private String queueDlxName;/*** 正常交换机* @return*/@Beanpublic DirectExchange normalExchange(){return ExchangeBuilder.directExchange(exchangeNormalName).build();}/*** 正常队列* @return*/@Beanpublic Queue normalQueue(){Map<String, Object> arguments = new HashMap<>();arguments.put("x-message-ttl",20000);//设置队列的过期时间为20秒//重点：设置这两个参数arguments.put("x-dead-letter-exchange",exchangeDlxName);    //设置队列的死信交换机arguments.put("x-dead-letter-routing-key","error");//设置死信路由key，要跟死信交换机和死信队列绑定的路由key一致return QueueBuilder.durable(queueNormalName).withArguments(arguments)       //设置队列的过期时间.build();}/*** 正常交换机和正常队列绑定* @param normalExchange* @param normalQueue* @return*/@Beanpublic Binding bingNormal(DirectExchange normalExchange,Queue normalQueue){return BindingBuilder.bind(normalQueue).to(normalExchange).with("order");}/*** 死信交换机* @return*/@Beanpublic DirectExchange dlxExchange(){return ExchangeBuilder.directExchange(exchangeDlxName).build();}/*** 死信队列* @return*/@Beanpublic Queue dlxQueue(){return QueueBuilder.durable(queueDlxName).build();}/*** 死信交换机和死信队列绑定* @param dlxExchange* @param dlxQueue* @return*/@Beanpublic Binding bindDlx(DirectExchange dlxExchange,Queue dlxQueue){return BindingBuilder.bind(dlxQueue).to(dlxExchange).with("error");}
}

2.1.2、业务类MessageService

package com.power.service;import lombok.extern.slf4j.Slf4j;
import org.springframework.amqp.core.Message;
import org.springframework.amqp.core.MessageBuilder;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.context.annotation.Bean;
import org.springframework.stereotype.Service;import javax.annotation.Resource;
import java.util.Date;@Service
@Slf4j
public class MessageService {@Resourceprivate RabbitTemplate rabbitTemplate;@Beanpublic void sendMsg(){Message message = MessageBuilder.withBody("hello world".getBytes()).build();rabbitTemplate.convertAndSend("exchange.normal.a","order",message);log.info("消息发送完毕，发送时间是："+new Date());}
}

2.1.3、配置文件application.yml

server:port: 8080
spring:application:name: dlx-test01rabbitmq:host: 你的服务器IPport: 5672username: 你的账号password: 你的密码virtual-host: powermy:exchangeNormalName: exchange.normal.a   #正常交换机queueNormalName: queue.normal.a         #正常队列，没有消费组，设置过期时间exchangeDlxName: exchange.dlx.a         #死信交换机queueDlxName: queue.dlx.a               #死信队列

2.1.4、启动类

package com.power;import com.power.service.MessageService;
import org.springframework.boot.ApplicationArguments;
import org.springframework.boot.ApplicationRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;import javax.annotation.Resource;@SpringBootApplication
public class Application implements ApplicationRunner {@Resourceprivate MessageService messageService;public static void main(String[] args) {SpringApplication.run(Application.class);}@Overridepublic void run(ApplicationArguments args) throws Exception {messageService.sendMsg();}
}

2.1.5、配置文件

<?xml version="1.0" encoding="UTF-8"?>
<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"><modelVersion>4.0.0</modelVersion><groupId>com.power</groupId><artifactId>rabbit_06_dlx01</artifactId><version>1.0-SNAPSHOT</version><name>rabbit_06_dlx01</name><properties><maven.compiler.source>8</maven.compiler.source><maven.compiler.target>8</maven.compiler.target><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding></properties><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.6.13</version><relativePath/></parent><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>1.18.24</version></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-amqp</artifactId></dependency></dependencies><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build></project>

2.1.6、测试

启动程序，发送消息：

消息会先被发送到正常队列queue.normal.a中，超时未被消费，
则消息会被发送到死信队列queue.dlx.a 中

2.2、消息过期

2.2.1、配置类RabbitConfig

package com.power.config;import org.springframework.amqp.core.*;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;import java.util.HashMap;
import java.util.Map;@Configuration
public class RabbitConfig {@Value("${my.exchangeNormalName}")private String exchangeNormalName;@Value("${my.queueNormalName}")private String queueNormalName;@Value("${my.exchangeDlxName}")private String exchangeDlxName;@Value("${my.queueDlxName}")private String queueDlxName;/*** 正常交换机* @return*/@Beanpublic DirectExchange normalExchange(){return ExchangeBuilder.directExchange(exchangeNormalName).build();}/*** 正常队列* @return*/@Beanpublic Queue normalQueue(){Map<String, Object> arguments = new HashMap<>();//重点：设置这两个参数//设置队列的死信交换机arguments.put("x-dead-letter-exchange",exchangeDlxName);//设置死信路由key，要跟死信交换机和死信队列绑定的路由key一致arguments.put("x-dead-letter-routing-key","error");return QueueBuilder.durable(queueNormalName).withArguments(arguments)       //设置队列的过期时间.build();}/*** 正常交换机和正常队列绑定* @param normalExchange* @param normalQueue* @return*/@Beanpublic Binding bingNormal(DirectExchange normalExchange,Queue normalQueue){return BindingBuilder.bind(normalQueue).to(normalExchange).with("order");}/*** 死信交换机* @return*/@Beanpublic DirectExchange dlxExchange(){return ExchangeBuilder.directExchange(exchangeDlxName).build();}/*** 死信队列* @return*/@Beanpublic Queue dlxQueue(){return QueueBuilder.durable(queueDlxName).build();}/*** 死信交换机和死信队列绑定* @param dlxExchange* @param dlxQueue* @return*/@Beanpublic Binding bindDlx(DirectExchange dlxExchange,Queue dlxQueue){return BindingBuilder.bind(dlxQueue).to(dlxExchange).with("error");}
}

2.2.2、业务类MessageService（关键代码）

package com.power.service;import lombok.extern.slf4j.Slf4j;
import org.springframework.amqp.core.Message;
import org.springframework.amqp.core.MessageBuilder;
import org.springframework.amqp.core.MessageProperties;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.context.annotation.Bean;
import org.springframework.stereotype.Service;import javax.annotation.Resource;
import java.util.Date;@Service
@Slf4j
public class MessageService {@Resourceprivate RabbitTemplate rabbitTemplate;@Beanpublic void sendMsg(){try {MessageProperties messageProperties = new MessageProperties();//设置单条消息的过期时间，单位为毫秒，数据类型为字符串messageProperties.setExpiration("20000");Message message = MessageBuilder.withBody("hello world".getBytes()).andProperties(messageProperties).build();rabbitTemplate.convertAndSend("exchange.normal.02","order",message);}catch (Exception e){e.printStackTrace();log.info("消息发送失败："+new Date());}log.info("消息发送完毕，发送时间是："+new Date());}
}

2.2.3、配置文件application.yml

server:port: 8080
spring:application:name: dlx-test01rabbitmq:host: 你的服务器IPport: 5672username: 你的账号password: 你的密码virtual-host: powermy:exchangeNormalName: exchange.normal.02   #正常交换机queueNormalName: queue.normal.02         #正常队列，没有消费组，设置过期时间exchangeDlxName: exchange.dlx.02         #死信交换机queueDlxName: queue.dlx.02               #死信队列

2.2.4、启动类同上

2.2.5、配置文件同上

2.2.6、测试

启动程序发送消息

登录rabbitmq后台：
消息先进入正常队列queue.normal.02中，超时未消费，
消息超过过期时间，则进入queue.dlx.02死信队列

2.3、队列达到最大长度（先入队的消息会被发送到DLX）

2.3.1、配置类RabbitConfig（关键代码）

package com.power.config;import org.springframework.amqp.core.*;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;import java.util.HashMap;
import java.util.Map;@Configuration
public class RabbitConfig {@Value("${my.exchangeNormalName}")private String exchangeNormalName;@Value("${my.queueNormalName}")private String queueNormalName;@Value("${my.exchangeDlxName}")private String exchangeDlxName;@Value("${my.queueDlxName}")private String queueDlxName;/*** 正常交换机* @return*/@Beanpublic DirectExchange normalExchange(){return ExchangeBuilder.directExchange(exchangeNormalName).build();}/*** 正常队列* @return*/@Beanpublic Queue normalQueue(){Map<String, Object> arguments = new HashMap<>();//设置队列的最大长度arguments.put("x-max-length",5);//重点：设置这两个参数//设置队列的死信交换机arguments.put("x-dead-letter-exchange",exchangeDlxName);//设置死信路由key，要跟死信交换机和死信队列绑定的路由key一致arguments.put("x-dead-letter-routing-key","error");return QueueBuilder.durable(queueNormalName).withArguments(arguments)       //设置队列的参数.build();}/*** 正常交换机和正常队列绑定* @param normalExchange* @param normalQueue* @return*/@Beanpublic Binding bingNormal(DirectExchange normalExchange,Queue normalQueue){return BindingBuilder.bind(normalQueue).to(normalExchange).with("order");}/*** 死信交换机* @return*/@Beanpublic DirectExchange dlxExchange(){return ExchangeBuilder.directExchange(exchangeDlxName).build();}/*** 死信队列* @return*/@Beanpublic Queue dlxQueue(){return QueueBuilder.durable(queueDlxName).build();}/*** 死信交换机和死信队列绑定* @param dlxExchange* @param dlxQueue* @return*/@Beanpublic Binding bindDlx(DirectExchange dlxExchange,Queue dlxQueue){return BindingBuilder.bind(dlxQueue).to(dlxExchange).with("error");}
}

2.3.2、业务类MessageService（关键代码）

package com.power.service;import lombok.extern.slf4j.Slf4j;
import org.springframework.amqp.core.Message;
import org.springframework.amqp.core.MessageBuilder;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.context.annotation.Bean;
import org.springframework.stereotype.Service;import javax.annotation.Resource;
import java.util.Date;@Service
@Slf4j
public class MessageService {@Resourceprivate RabbitTemplate rabbitTemplate;@Beanpublic void sendMsg(){for (int i = 1; i < 8; i++) {String msg = "hello world "+ i;Message message = MessageBuilder.withBody(msg.getBytes()).build();rabbitTemplate.convertAndSend("exchange.normal.03","order",message);log.info("消息发送完毕，发送时间是："+new Date());}}
}

2.3.3、配置文件application.yml

server:port: 8080
spring:application:name: dlx-test01rabbitmq:host: 你的服务器IPport: 5672username: 你的账号password: 你的密码virtual-host: powermy:exchangeNormalName: exchange.normal.03   #正常交换机queueNormalName: queue.normal.03         #正常队列，没有消费组，设置过期时间exchangeDlxName: exchange.dlx.03         #死信交换机queueDlxName: queue.dlx.03               #死信队列

2.3.4、启动类同上

2.3.5、配置文件pom.xml同上

2.3.6、测试

启动项目，发送消息

登录rabbitmq后台：
两条消息进入死信队列
查看消息发现，是前两条消息进入了死信队列，

2.4、消费者拒绝消息不进行重新投递

消费者从正常的队列接收消息，但是消费者对消息不进行确认，并且不对消息进行重新投递，此时消息就进入死信队列。

2.4.1、生产者

2.4.1.1、生产者application.yml

server:port: 8080
spring:application:name: dlx-test04rabbitmq:host: 你的服务器IPport: 5672username: 你的账号password: 你的密码virtual-host: powermy:exchangeNormalName: exchange.normal.04   #正常交换机queueNormalName: queue.normal.04         #正常队列，没有消费组，设置过期时间exchangeDlxName: exchange.dlx.04         #死信交换机queueDlxName: queue.dlx.04               #死信队列

2.4.1.2、生产者发送消息

package com.power.service;import lombok.extern.slf4j.Slf4j;
import org.springframework.amqp.core.Message;
import org.springframework.amqp.core.MessageBuilder;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.context.annotation.Bean;
import org.springframework.stereotype.Service;import javax.annotation.Resource;
import java.util.Date;@Service
@Slf4j
public class MessageService {@Resourceprivate RabbitTemplate rabbitTemplate;@Beanpublic void sendMsg(){String msg = "hello world";Message message = MessageBuilder.withBody(msg.getBytes()).build();rabbitTemplate.convertAndSend("exchange.normal.04","order",message);log.info("消息发送完毕，发送时间是："+new Date());}
}

2.4.1.3、生产者配置类

package com.power.config;import org.springframework.amqp.core.*;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;import java.util.HashMap;
import java.util.Map;@Configuration
public class RabbitConfig {@Value("${my.exchangeNormalName}")private String exchangeNormalName;@Value("${my.queueNormalName}")private String queueNormalName;@Value("${my.exchangeDlxName}")private String exchangeDlxName;@Value("${my.queueDlxName}")private String queueDlxName;/*** 正常交换机* @return*/@Beanpublic DirectExchange normalExchange(){return ExchangeBuilder.directExchange(exchangeNormalName).build();}/*** 正常队列* @return*/@Beanpublic Queue normalQueue(){Map<String, Object> arguments = new HashMap<>();//重点：设置这两个参数//设置队列的死信交换机arguments.put("x-dead-letter-exchange",exchangeDlxName);//设置死信路由key，要跟死信交换机和死信队列绑定的路由key一致arguments.put("x-dead-letter-routing-key","error");return QueueBuilder.durable(queueNormalName).withArguments(arguments)       //设置队列的参数.build();}/*** 正常交换机和正常队列绑定* @param normalExchange* @param normalQueue* @return*/@Beanpublic Binding bingNormal(DirectExchange normalExchange,Queue normalQueue){return BindingBuilder.bind(normalQueue).to(normalExchange).with("order");}/*** 死信交换机* @return*/@Beanpublic DirectExchange dlxExchange(){return ExchangeBuilder.directExchange(exchangeDlxName).build();}/*** 死信队列* @return*/@Beanpublic Queue dlxQueue(){return QueueBuilder.durable(queueDlxName).build();}/*** 死信交换机和死信队列绑定* @param dlxExchange* @param dlxQueue* @return*/@Beanpublic Binding bindDlx(DirectExchange dlxExchange,Queue dlxQueue){return BindingBuilder.bind(dlxQueue).to(dlxExchange).with("error");}
}

2.4.2、消费者

2.4.2.1、消费者application.yml 启动手动确认

server:port: 9090
spring:application:name: dlx04-receiverrabbitmq:host: 你的服务器IPport: 5672username: 你的账号password: 你的密码virtual-host: powerlistener:simple:acknowledge-mode: manual

关键配置

2.4.2.2、消费者接收消息

package com.power.service;import com.rabbitmq.client.Channel;
import lombok.extern.slf4j.Slf4j;
import org.springframework.amqp.core.Message;
import org.springframework.amqp.core.MessageProperties;
import org.springframework.amqp.rabbit.annotation.RabbitListener;
import org.springframework.stereotype.Component;import java.io.IOException;
import java.util.Date;@Component
@Slf4j
public class MessageReceive {@RabbitListener(queues={"queue.normal.04"})public void receiveMsg(Message message, Channel channel){//获取消息属性MessageProperties messageProperties = message.getMessageProperties();//获取消息的唯一标识，类似学号和身份证号long deliveryTag = messageProperties.getDeliveryTag();try{byte[] body = message.getBody();String msg = new String(body);log.info("监听到的消息是："+msg+",接收的时间是："+new Date());//TODO 业务逻辑处理int a=1/0;//消费者的手动确认，false：只确认当前消息，true：批量确认channel.basicAck(deliveryTag,false);}catch (Exception e){log.error("接收者出现问题：{}",e.getMessage());try {//消费者的手动不确认，参数3：是重新入队//不会进入死信队列
//                channel.basicNack(deliveryTag,false,true);//消费者的手动不确认，参数3：false 不重新入队（不重新投递），就会变成死信channel.basicNack(deliveryTag,false,false);}catch (IOException ex){throw new RuntimeException(ex);}}}}

关键代码

2.4.3、测试

启动生产者：发送消息

启动消费者：
因业务代码出错，程序处理异常，消息进入死信队列