import org.springframework.amqp.core.*;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class RabbitConfig {
    //定义延时队列
    @Bean("delayQueue")
    public Queue delayQueue(){
        //设置死信交换机和路由key
        return QueueBuilder.durable("delayQueue")
                //如果消息过时，则会被投递到当前对应的my-dlx-exchange
                .withArgument("x-dead-letter-exchange","my-dlx-exchange")
                //如果消息过时，my-dlx-exchange会更具routing-key-delay投递消息到对应的队列
                .withArgument("x-dead-letter-routing-key","routing-key-delay").build();
    }
    //定义死信队列
    @Bean("dlxQueue")
    public Queue dlxQueue(){
        return QueueBuilder.durable("my-dlx-queue").build();
    }
    //定义死信交换机
    @Bean("dlxExchange")
    public Exchange dlxExchange(){
        return ExchangeBuilder.directExchange("my-dlx-exchange").build();
    }
    //绑定死信队列与交换机
    @Bean("dlxBinding")
    public Binding dlxBinding(@Qualifier("dlxExchange") Exchange exchange,@Qualifier("dlxQueue") Queue queue){
        return BindingBuilder.bind(queue).to(exchange).with("routing-key-delay").noargs();
    }
}

4.编写生产者

@Override
	//这里的carid是我刚刚添加物品到购物车后的id，把car存到队列里面去
    public void sendCarToQueue(Integer carid) {
        Car car = carDao.findCarById(carid);
        Map<String,Car> map = new HashMap<>();
        map.put("msg",car);
        rabbitTemplate.convertAndSend("delayQueue", map, new MessagePostProcessor() {
            @Override
            public Message postProcessMessage(Message message) throws AmqpException {
                //延迟队列延迟30秒后，发消息给死信交换机，
                message.getMessageProperties().setExpiration("30000");
                return message;
            }
        });
    }

import com.example.pojo.Car;
import com.example.service.CarService;
import org.springframework.amqp.rabbit.annotation.RabbitHandler;
import org.springframework.amqp.rabbit.annotation.RabbitListener;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import java.util.HashMap;
import java.util.List;

@Component
@RabbitListener(queues = "my-dlx-queue")
public class CarAddListener {
    @Autowired
    CarService carService;
    @RabbitHandler
    public void receive(HashMap<String,Car> map){
        //c是rabbitMQ里面是购物车数据car
        for (Car c : map.values()){
            //我在这里根据用户id获取了购物车表里面的数据
            List<Car> carlist = carService.findByUserid(c.getUserid());
            for (Car car1 : carlist) {
            //通过遍历查看购物车里面的数据和rabbitMQ队列里面的数据是否一致[就是30秒内，购物车某一条数据的购买数量是否变化]
                if(c.getOrdernumber().equals(car1.getOrdernumber()) && c.getUserid().equals(car1.getUserid())){
                    carService.deleteById(c.getId());
                }
            }
        }   
    }    
}