Rabbitmq消息丢失-消费者消息丢失（二）-编程知识

说明：消费端在处理消息的过程中出现异常，例如：业务逻辑异常，或者消费者被停机，或者网络断开连接等，以上等情况使消息没有得到正确恰当的处理，也会使消息丢失。

分析：分析就是说明中的例如！

解决：ACK确认机制

所谓的ACK就是：首先关闭自动确认【自动ACK】，消费者收到一个消息后，就可以发一个确认【ACK】给MQ，当然什么时候发送确认【ACK】是程序员决定的，也就是说每次在确保处理完这个消息相关的业务后，程序员可以手动发送确认【ACK】，之后把消息从MQ中干掉！这样即使出现了异常也可以有效的消费消息。

工程图：

1.pom.xml

<?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><parent><artifactId>spring-boot-starter-parent</artifactId>  <!-- 被继承的父项目的构件标识符 --><groupId>org.springframework.boot</groupId>  <!-- 被继承的父项目的全球唯一标识符 --><version>2.2.2.RELEASE</version>  <!-- 被继承的父项目的版本 --></parent><groupId>MqLossDemoTwo</groupId><artifactId>MqLossDemoTwo</artifactId><version>1.0-SNAPSHOT</version><packaging>war</packaging><name>MqLossDemoTwo Maven Webapp</name><!-- FIXME change it to the project's website --><url>http://www.example.com</url><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><maven.compiler.source>1.8</maven.compiler.source><maven.compiler.target>1.8</maven.compiler.target></properties><dependencies><!--spring boot核心--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter</artifactId></dependency><!--spring boot 测试--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><!--springmvc web--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><!--开发环境调试--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-devtools</artifactId><optional>true</optional></dependency><!--amqp 支持--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-amqp</artifactId></dependency><!--redis--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-redis</artifactId><version>2.1.7.RELEASE</version></dependency><dependency><groupId>com.alibaba</groupId><artifactId>fastjson</artifactId><version>1.2.78</version></dependency><dependency><groupId>commons-lang</groupId><artifactId>commons-lang</artifactId><version>2.6</version></dependency><!--lombok--><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>1.16.10</version></dependency></dependencies><build><finalName>MqLossDemoTwo</finalName><pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) --><plugins><plugin><artifactId>maven-clean-plugin</artifactId><version>3.1.0</version></plugin><!-- see http://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_war_packaging --><plugin><artifactId>maven-resources-plugin</artifactId><version>3.0.2</version></plugin><plugin><artifactId>maven-compiler-plugin</artifactId><version>3.8.0</version></plugin><plugin><artifactId>maven-surefire-plugin</artifactId><version>2.22.1</version></plugin><plugin><artifactId>maven-war-plugin</artifactId><version>3.2.2</version></plugin><plugin><artifactId>maven-install-plugin</artifactId><version>2.5.2</version></plugin><plugin><artifactId>maven-deploy-plugin</artifactId><version>2.8.2</version></plugin></plugins></pluginManagement></build>
</project>

2.application.yml

server:port: 8080
spring:rabbitmq:port: 5672host: 你的 rabbitmq IPusername: adminpassword: adminvirtual-host: /listener:simple:concurrency: 10max-concurrency: 10prefetch: 1auto-startup: truedefault-requeue-rejected: true# 设置消费端手动 ackacknowledge-mode: manual# 是否支持重试retry:enabled: true

3.RabbitMqQueueConfig

package com.dev.config;import org.springframework.amqp.core.Binding;
import org.springframework.amqp.core.BindingBuilder;
import org.springframework.amqp.core.DirectExchange;
import org.springframework.amqp.core.Queue;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;/*** 类名称：** @author 李庆伟* @date 2024年03月04日 14:12*/
@Configuration
public class RabbitMqQueueConfig {//绑定键public final static String QUEUE_ONE = "loss_queue";public final static String EXCHANGE_ONE = "loss_exchange";@Beanpublic Queue directQueue() {return new Queue(RabbitMqQueueConfig.QUEUE_ONE);}//Direct交换机 起名：directExchange@BeanDirectExchange directExchange() {return new DirectExchange(RabbitMqQueueConfig.EXCHANGE_ONE,true,false);}//绑定  将队列和交换机绑定, 并设置用于匹配键：directRoutingKey@BeanBinding bindingDirect() {return BindingBuilder.bind(directQueue()).to(directExchange()).with("directRoutingKey");}}

4.RabbitController

package com.dev.controller;import com.alibaba.fastjson.JSONObject;
import com.dev.config.RabbitMqQueueConfig;
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.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;import java.util.HashMap;
import java.util.Map;
import java.util.UUID;/*** 类名称：消息丢失问题** @author lqw* @date 2024年02月27日 14:47*/
@Slf4j
@RestController
@RequestMapping("loss")
public class RabbitController {@AutowiredRabbitTemplate rabbitTemplate;  //使用RabbitTemplate,这提供了接收/发送等等方法/*** 消息丢失* @return*/@GetMapping("/sendMessage")public String sendMessage() {String id = UUID.randomUUID().toString().replace("-","");Map<String,Object> addMap = new HashMap<>();//添加用户信息addMap.put("id",id);addMap.put("name","张龙");Message msg = MessageBuilder.withBody(JSONObject.toJSONString(addMap).getBytes()).setMessageId(id).build();rabbitTemplate.convertAndSend(RabbitMqQueueConfig.EXCHANGE_ONE, "directRoutingKey", msg);return "ok";}}

5.RabbitMqListener

package com.dev.listener;import com.alibaba.fastjson.JSON;
import com.rabbitmq.client.Channel;
import org.springframework.amqp.core.Message;
import org.springframework.amqp.rabbit.annotation.RabbitHandler;
import org.springframework.amqp.rabbit.annotation.RabbitListener;
import org.springframework.stereotype.Component;import java.util.Map;/*** 类名称：** @author 李庆伟* @date 2024年03月04日 16:54*/@Component
public class RabbitMqListener {@RabbitListener(queues = "loss_queue")@RabbitHandlerpublic void process(Message msg, Channel channel) {System.out.println("Rabbitmq Direct : " + msg);//设置的唯一id,可以用来处理重复消费String id = msg.getMessageProperties().getMessageId();//消息队列自身设置的唯一标识long tag = msg.getMessageProperties().getDeliveryTag();//int a = 1/0;try {//监听到要添加的用户信息String dataStr = new String(msg.getBody());Map<String,Object> addMap = JSON.parseObject(dataStr,Map.class);//先去redis中查询是否已经添加过了该用户//如果未添加[重复消费]if(true){ //如果未添加//添加用户业务//....add(addMap);//告诉队列该消息已经消费channel.basicAck(tag,false);} else {//如果已添加//告诉队列该消息已经消费channel.basicAck(tag,false);}} catch (Exception e) {try {//tag：消息序号//multiple：消息的标识，是否确认多条，false只确认当前一个消息收到，//                               true确认所有consumer获得的消息（成功消费，消息从队列中删除)//requeue：是否要退回到队列 true 将消息再次放到mq队列中，false是不把消息放到队列中channel.basicNack(tag, true, false);//channel.basicNack(tag, true, true); //如果能走到此处，这样会把消息在放到队列中，会在次被监听到，陷入死循环//channel.basicNack(tag, false, true); //如果能走到此处，这样会把消息在放到队列中，会在次被监听到，陷入死循环//channel.basicNack(tag, false, false); //如果能走到此处，如果是扇形交换机，其他消费者也会再次消费此信息//可以把添加用户业务数据保存起来//...} catch (Exception ex) {ex.printStackTrace();}}}}

6.App

package com.dev;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;/*** 类名称：** @author 李庆伟* @date 2024年03月04日 14:11*/
@SpringBootApplication
public class App {public static void main(String[] args) {SpringApplication.run(App.class);}}