这个需求为控制智能家居工作，把控制智能家居的操作指令发到队列中，比如：扫地机、洗衣机到指定时间工作

一.什么是延迟队列？

延迟队列存储的对象是对应的延迟消息，所谓“延迟消息” 是指当消息被发送以后，并不想让消费者立刻拿到消息，而是等待特定时间后，消费者才能拿到这个消息进行消费。

二.如何设置延迟队列？

1.配置2个业务队列（扫地机执行命令业务队列，洗衣机执行命令业务队列），绑定到业务交换机上

2.为业务队列配置死信交换机和路由key

3.为死信交换机配置2个延迟队列（扫地机执行命令延迟队列，洗衣机执行命令延迟队列）

三.延迟队列代码落地

using MengLin.Shopping.RabbitMQ.Common;
using RabbitMQ.Client;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace MengLin.Shopping.RabbitMQ.MsgProducer.QueueType.Delay
{
    /// <summary>
    /// 延迟队列
    /// </summary>
    public class DelayQueue
    {
        public static void SendMessage()
        {
            //业务交换机
            var exchangeBusiness = "business-exchange";
            
            var queueBusinessSaoDiJiCommand = "SaoDiJiCommand-business-queue";//扫地机执行命令业务队列
            var routeKeyBusinessSaoDiJiCommand = "SaoDiJiCommand-business-routekey";//扫地机执行命令路由key

            var queueBusinessXiYiJiCommand = "XiYiJiCommand-business-queue";//洗衣机执行命令业务队列
            var routeKeyBusinessXiYiJiCommand = "XiYiJiCommand-business-routekey";//洗衣机执行命令路由key

            //死信交换机
            var exchangeDeadLetter = "deadLetter-exchange";

            //扫地机执行命令的延时队列和路由key
            var delaySaoDiJiCommandQueue = "SaoDiJiCommand-delay-queue";
            var routeKeyDelaySaoDiJi = "SaoDiJi-delay-routekey";

            //洗衣机执行命令的延时队列和路由key
            var delayXiYiJiCommandQueue = "XiYiJiCommand-delay-queue";
            var routeKeyDelayXiYiJi = "XiYiJi-delay-routekey";

            using (var connection = RabbitMQHelper.GetConnection())
            {
                using (var channel = connection.CreateModel())
                {
                    //创建死信交换机（死信交换机对交换机类型没有要求）
                    channel.ExchangeDeclare(exchange: exchangeDeadLetter, type: ExchangeType.Direct, durable: true, autoDelete: false);

                    //创建扫地机执行命令的延时队列
                    channel.QueueDeclare(queue: delaySaoDiJiCommandQueue, durable: true, exclusive: false, autoDelete: false);

                    //创建洗衣机执行命令的延时队列
                    channel.QueueDeclare(queue: delayXiYiJiCommandQueue, durable: true, exclusive: false, autoDelete: false);

                    //绑定死信交换机到扫地机执行命令的延时队列
                    channel.QueueBind(exchange: exchangeDeadLetter, queue: delaySaoDiJiCommandQueue, routingKey: routeKeyDelaySaoDiJi);

                    //绑定死信交换机到洗衣机执行命令的延时队列
                    channel.QueueBind(exchange: exchangeDeadLetter, queue: delayXiYiJiCommandQueue, routingKey: routeKeyDelayXiYiJi);

                    //创建业务交换机
                    channel.ExchangeDeclare(exchange: exchangeBusiness, type: ExchangeType.Direct, durable: true, autoDelete: false);

                    //创建扫地机命令业务队列
                    Dictionary<string, object> dic1 = new Dictionary<string, object>();
                    dic1.Add("x-expires", 30 * 6 * 10000); //30分钟后扫地机命令业务队列自动干掉
                    dic1.Add("x-message-ttl", 10 * 6 * 10000);//设置消息在扫地机命令业务队列中的存活时间，即过期时间（消息如果10分钟内没有消费，就会放入扫地机执行命令的延时队列里）
                    dic1.Add("x-dead-letter-exchange", exchangeDeadLetter);//过期消息转向路由  
                    dic1.Add("x-dead-letter-routing-key", routeKeyDelaySaoDiJi);//设置死信交换机的路由key，死信交换机会根据路由key去找到对应的延迟队列
                    channel.QueueDeclare(queue: queueBusinessSaoDiJiCommand, durable: true, exclusive: false, autoDelete: false, arguments:dic1);
                    //绑定业务交换机到扫地机命令业务队列
                    channel.QueueBind(queue: queueBusinessSaoDiJiCommand, exchange: exchangeBusiness, routingKey: routeKeyBusinessSaoDiJiCommand);


                    //创建洗衣机命令业务队列
                    Dictionary<string, object> dic2 = new Dictionary<string, object>();
                    dic2.Add("x-expires", 30 * 6 * 10000); //30分钟后洗衣机命令业务队列自动干掉
                    dic2.Add("x-message-ttl", 20 * 6 * 10000);//设置消息在洗衣机命令业务队列中的存活时间，即过期时间（消息如果20分钟内没有消费，就会放入洗衣机执行命令的延时队列里）
                    dic2.Add("x-dead-letter-exchange", exchangeDeadLetter);//过期消息转向路由  
                    dic2.Add("x-dead-letter-routing-key", routeKeyDelayXiYiJi);//过期消息转向路由相匹配routingkey  
                    channel.QueueDeclare(queue: queueBusinessXiYiJiCommand, durable: true, exclusive: false, autoDelete: false, arguments: dic2);
                    //绑定业务交换机到洗衣机命令业务队列
                    channel.QueueBind(queue: queueBusinessXiYiJiCommand, exchange: exchangeBusiness, routingKey: routeKeyBusinessXiYiJiCommand);

                    Console.WriteLine("请输入发送的内容:");
                    var message = Console.ReadLine();
                    var body = Encoding.UTF8.GetBytes(message);
                  

                    //消息持久化，既然都要用到死信队列了，说明这条消息还是比较重要的
                    var properties = channel.CreateBasicProperties();
                    properties.Persistent = true;

                    if(message.Contains("aa"))
                    {
                        //发布消息到扫地机命令业务队列
                        channel.BasicPublish(exchange: exchangeBusiness,
                                             routingKey: routeKeyBusinessSaoDiJiCommand,
                                             basicProperties: properties,
                                             body: body);
                    }
                    else
                    {
                        //发布消息洗衣机命令业务队列
                        channel.BasicPublish(exchange: exchangeBusiness,
                                             routingKey: routeKeyBusinessXiYiJiCommand,
                                             basicProperties: properties,
                                             body: body);
                    }

                } 
            }
        }
    }
}