RabbitMQ保证消息不丢失

消息丢失的情况

（1）生产者方面：生产者发送消息至MQ的数据丢失
（2）RabbitMQ方面：MQ收到消息，暂存内存中，还没消费，自己挂掉，数据会都丢失
（3）消费者方面：消费者刚拿到消息，还没处理，挂掉了，MQ又以为消费者处理完

解决方法

1.配置文件中添加

#消息已发送到交换机(Exchange)时返回
spring.rabbitmq.publisher-/confirm/i-type=correlated
# 消息在未被队列收到的情况下返回
spring.rabbitmq.template.mandatory=true
spring.rabbitmq.publisher-returns=true 
# 开启消息手动确认机制
spring.rabbitmq.listener.simple.acknowledge-mode=manual

2.config类配置

package com.example.demo.config;


import org.springframework.amqp.core.*;
import org.springframework.amqp.rabbit.connection.ConnectionFactory;
import org.springframework.amqp.rabbit.connection.CorrelationData;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.annotation.PostConstruct;

@Configuration
public class RabbitmqConfig {
    @Autowired
    AmqpAdmin amqpAdmin;

    @Autowired
    RabbitTemplate rabbitTemplate;

    @Bean
    public RabbitTemplate createRabbitTemplate(ConnectionFactory connectionFactory){
        RabbitTemplate rabbitTemplate = new RabbitTemplate();
        rabbitTemplate.setConnectionFactory(connectionFactory);
        //发送到exchange时调用回调函数

        rabbitTemplate.set/confirm/iCallback(new RabbitTemplate./confirm/iCallback() {
            @Override
            public void /confirm/i(CorrelationData correlationData, boolean ack, String cause) {
                System.out.println("/confirm/iCallback:"+"相关数据："+correlationData+" /confirm/iCallback:"+"确认情况："+ack+" /confirm/iCallback:"+"原因："+cause);

            }
        });

        //设置消息抵达队列的失败回调
        rabbitTemplate.setReturnsCallback(new RabbitTemplate.ReturnsCallback() {
            @Override
            public void returnedMessage(ReturnedMessage returned) {
                System.out.println("二位热热我热太热");
            }
        });
        return rabbitTemplate;
    }

    
    @Bean
    public void createNormalExchange(){
        DirectExchange mydirect = new DirectExchange("mydirect3", true, false);
        amqpAdmin.declareExchange(mydirect);
    }
}

3.监听类改写

package com.example.demo.service.impl;


import com.rabbitmq.client.Channel;
import org.springframework.amqp.core.Message;
import org.springframework.amqp.core.MessageProperties;
import org.springframework.amqp.rabbit.annotation.RabbitListener;
import org.springframework.stereotype.Service;

import java.io.IOException;

@Service
public class RabbitmqTest2Impl {

    @RabbitListener(queues = {"mybe"})
    public void getMessage(Message message, Channel channel) throws Exception {
        long deliveryTag = message.getMessageProperties().getDeliveryTag();
        try {
            byte[] body = message.getBody();
            MessageProperties messageProperties = message.getMessageProperties();
            Thread.sleep(2000);
            String s = new String(body);
            System.out.println("消费消息完成"+s);

            channel.basicAck(deliveryTag,false);
        } catch (IOException e) {
            //消息消费方错误后的处理
            //deliveryTag消息id
            //multiple – true to reject all messages up to and including the supplied delivery tag; false to reject just the supplied delivery tag.
            // requeue是否重新入队
            channel.basicNack(deliveryTag,false,false);

            e.printStackTrace();
        }
    }
}