netcore下死RabbitMQ队列、死信队列、延时队列及小应用

关于安装rabbitmq这里一笔掠过了。

下面进入正题：

1.新建aspnetcorewebapi空项目，NormalQueue,删除controllers文件夹已经无关的文件，这里为了偷懒不用console控制台：

public class Program
    {
        public static void Main(string[] args)
        {
            var builder = WebApplication.CreateBuilder(args);

            // Add services to the container.

            builder.Services.AddControllers();
            // Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
            builder.Services.AddEndpointsApiExplorer();
            builder.Services.AddSwaggerGen();
            builder.Services.AddHostedService<ConsumerService>();
            builder.Services.AddHostedService<DeadLetterExchangeConsuerService>();
            builder.Services.AddHostedService<DelayExchangeConsumerService>();
            var app = builder.Build();

            // Configure the HTTP request pipeline.
            if (app.Environment.IsDevelopment())
            {
                app.UseSwagger();
                app.UseSwaggerUI();
            }
            app.MapGet("/normal/{message}", ([FromRoute] string message) =>
            {
                ConnectionFactory factory = new ConnectionFactory();
                factory.HostName = "localhost";
                factory.Port = 5672;
                using (IConnection connection = factory.CreateConnection())
                {
                    using (IModel channel = connection.CreateModel())
                    {
                        var queueName = "rbTest202301";
                        channel.QueueDeclare(queueName, true, false, false, null);

                        {
                            string sendMessage = string.Format("Message_{0}", message);
                            byte[] buffer = Encoding.UTF8.GetBytes(sendMessage);
                            IBasicProperties basicProperties = channel.CreateBasicProperties();
                            basicProperties.DeliveryMode = 2; //持久化  1=非持久化
                            channel.BasicPublish("", queueName, basicProperties, buffer);
                            Console.WriteLine("消息发送成功：" + sendMessage);
                        }
                    }
                }
            });

            app.MapGet("/deadletterexchange/{message}",([FromRoute] string message) =>{
                DeadLetterExchange.Send(message);
            });

            app.MapGet("/delayexchange/{message}", ([FromRoute] string message) => {
                DelayExchange.SendMessage(message);
            });
            app.UseHttpsRedirection();

            app.UseAuthorization();

            app.MapControllers();

            app.Run();
        }
    }

大概的介绍一下program文件：

这里有三个mini控制器，从这里发送对应的消息到rabbitmq

"/normal/{message}"   普通队列，

"/deadletterexchange/{message}" 死信队列

"/deadletterexchange/{message}"   延时队列

  　　　　　　builder.Services.AddHostedService<ConsumerService>();
            builder.Services.AddHostedService<DeadLetterExchangeConsuerService>();
            builder.Services.AddHostedService<DelayExchangeConsumerService>();

这里就是消费的服务，注册成HostedService。

ConsumerService代码如下：

 public class ConsumerService : BackgroundService
    {
        protected override async Task ExecuteAsync(CancellationToken stoppingToken)
        {
            Console.WriteLine("normal Rabbitmq消费端开始工作!");
            while (!stoppingToken.IsCancellationRequested)
            {
                ConnectionFactory factory = new ConnectionFactory();
                factory.HostName = "localhost";
                factory.Port = 5672;

                IConnection connection = factory.CreateConnection();
                {
                    IModel channel = connection.CreateModel();
                    {
                        var queueName = "rbTest202301";
                        channel.QueueDeclare(queueName, true, false, false, null);
                        //输入1，那如果接收一个消息，但是没有应答，则客户端不会收到下一个消息
                        channel.BasicQos(0, 1, false);
                        //在队列上定义一个消费者
                        var consumer = new EventingBasicConsumer(channel);
                        channel.BasicConsume(queueName, false, consumer);
                        consumer.Received += (ch, ea) =>
                        {
                            byte[] bytes = ea.Body.ToArray();
                            string str = Encoding.UTF8.GetString(bytes);
                            Console.WriteLine("队列消息:" + str.ToString());
                            //回复确认
                            channel.BasicAck(ea.DeliveryTag, false);
                        };
                    }
                }
                await Task.Delay(5000);
            }
        }
    }

DeadLetterExchangeConsuerService代码如下：

 public class DeadLetterExchangeConsuerService : BackgroundService
    {
        protected override async Task ExecuteAsync(CancellationToken stoppingToken)
        {
            Console.WriteLine("RabbitMQ消费端死信队列开始工作");
            while (!stoppingToken.IsCancellationRequested)
            {
                DeadLetterExchange.Consumer();
                await Task.Delay(5000);
            }
        }
    }

  public class DeadLetterExchange
    {
        public static string dlxExchange = "dlx.exchange";
        public static string dlxQueueName = "dlx.queue";
        static string exchange = "direct-exchange";
        static string queueName = "queue_Testdlx";
        static string dlxExchangeKey = "x-dead-letter-exchange";
        static string dlxQueueKey = "x-dead-letter-rounting-key";
        public static void Send(string message)
        {
            using (var connection = new ConnectionFactory() { HostName = "localhost", Port = 5672 }.CreateConnection())
            {
                using(var channel = connection.CreateModel())
                {

                    channel.ExchangeDeclare(exchange, ExchangeType.Direct, true, false); //创建交换机
                    channel.QueueDeclare(queueName, true, false, false,new Dictionary<string, object>
                    {
                        { dlxExchangeKey,dlxExchange },
                        {dlxQueueKey,dlxQueueName }
                    }); // 创建队列
                    channel.QueueBind(queueName, exchange, queueName);

                    var properties = channel.CreateBasicProperties();
                    properties.Persistent= true;//持久化
                    channel.BasicPublish(exchange,queueName,properties,Encoding.UTF8.GetBytes(message));
                    Console.WriteLine($"向队列:{queueName}发送消息:{message}");
                }
            }
        }

        public static void Consumer()
        {
            var connection = new ConnectionFactory() { HostName = "localhost", Port = 5672 }.CreateConnection();
            var channel = connection.CreateModel();
            channel.ExchangeDeclare(dlxExchange, ExchangeType.Direct, true, false); //创建sixin交换机
            channel.QueueDeclare(dlxQueueName, true, false, false); // 创建sixin队列
            channel.QueueBind(dlxQueueName, dlxExchange, dlxQueueName); //绑定sixin队列sixin交换机

            channel.ExchangeDeclare(exchange, ExchangeType.Direct, true, false); //创建交换机
            channel.QueueDeclare(queueName, true, false, false, new Dictionary<string, object>
                    {
                        { dlxExchangeKey,dlxExchange },
                        {dlxQueueKey,dlxQueueName }
                    }); // 创建队列
            channel.QueueBind(queueName, exchange, queueName);

            var consumer = new EventingBasicConsumer(channel);
            channel.BasicQos(0, 1, false);
            consumer.Received += (model, ea) =>
            {
                var message = Encoding.UTF8.GetString(ea.Body.ToArray());
                Console.WriteLine($"队列{queueName}消费消息:{message},不做ack确认");
                channel.BasicNack(ea.DeliveryTag, false, requeue: false);
            };
            channel.BasicConsume(queueName, autoAck: false, consumer);
        }
    }

DelayExchangeConsumerService代码如下：

 public class DelayExchangeConsumerService : BackgroundService
    {
        protected override async Task ExecuteAsync(CancellationToken stoppingToken)
        {
            Console.WriteLine("RabbitMQ消费端延迟队列开始工作");
            while (!stoppingToken.IsCancellationRequested)
            {

                DelayExchange.Consumer();
                await Task.Delay(5000);
            }
        }
    }

 public class DelayExchange
    {

        public static void SendMessage(string message)
        {
            //死信交换机
            string dlxexChange = "dlx.exchange";
            //死信队列
            string dlxQueueName = "dlx.queue";

            //消息交换机
            string exchange = "direct-exchange";
            //消息队列
            string queueName = "delay_queue";

            using (var connection = new ConnectionFactory() { HostName = "localhost", Port = 5672 }.CreateConnection())
            {
                using (var channel = connection.CreateModel())
                {
                    ////创建死信交换机
                    //channel.ExchangeDeclare(dlxexChange, type: ExchangeType.Direct, durable: true, autoDelete: false);
                    ////创建死信队列
                    //channel.QueueDeclare(dlxQueueName, durable: true, exclusive: false, autoDelete: false);
                    ////死信队列绑定死信交换机
                    //channel.QueueBind(dlxQueueName, dlxexChange, routingKey: dlxQueueName);

                    // 创建消息交换机
                    channel.ExchangeDeclare(exchange, type: ExchangeType.Direct, durable: true, autoDelete: false);
                    //创建消息队列,并指定死信队列，和设置这个队列的消息过期时间为10s
                    channel.QueueDeclare(queueName, durable: true, exclusive: false, autoDelete: false, arguments:
                                        new Dictionary<string, object> {
                                             { "x-dead-letter-exchange",dlxexChange}, //设置当前队列的DLX(死信交换机)
                                             { "x-dead-letter-routing-key",dlxQueueName}, //设置DLX的路由key，DLX会根据该值去找到死信消息存放的队列
                                             { "x-message-ttl",10000} //设置队列的消息过期时间
                                        });
                    //消息队列绑定消息交换机
                    channel.QueueBind(queueName, exchange, routingKey: queueName);

                    var properties = channel.CreateBasicProperties();
                    properties.Persistent = true;
                    //properties.Expiration = "5000";发布消息,延时5s
                    //发布消息
                    channel.BasicPublish(exchange: exchange,
                                         routingKey: queueName,
                                         basicProperties: properties,
                                         body: Encoding.UTF8.GetBytes(message));
                    Console.WriteLine($"{DateTime.Now},向队列:{queueName}发送消息:{message}");
                }
            }
        }

        public static void Consumer()
        {
            //死信交换机
            string dlxexChange = "dlx.exchange";
            //死信队列
            string dlxQueueName = "dlx.queue";
            var connection = new ConnectionFactory() { HostName = "localhost", Port = 5672 }.CreateConnection();
            {
                //创建信道
                var channel = connection.CreateModel();
                {
                    //创建死信交换机
                    channel.ExchangeDeclare(dlxexChange, type: ExchangeType.Direct, durable: true, autoDelete: false);
                    //创建死信队列
                    channel.QueueDeclare(dlxQueueName, durable: true, exclusive: false, autoDelete: false);
                    //死信队列绑定死信交换机
                    channel.QueueBind(dlxQueueName, dlxexChange, routingKey: dlxQueueName);

                    var consumer = new EventingBasicConsumer(channel);
                    channel.BasicQos(prefetchSize: 0, prefetchCount: 1, global: true);
                    consumer.Received += (model, ea) =>
                    {
                        //处理业务
                        var message = Encoding.UTF8.GetString(ea.Body.ToArray());
                        Console.WriteLine($"{DateTime.Now}，队列{dlxQueueName}消费消息:{message}");
                        channel.BasicAck(ea.DeliveryTag, false);
                    };
                    channel.BasicConsume(dlxQueueName, autoAck: false, consumer);
                }
            }
        }
    }

延时队列实际应用场景可能比较复杂，比如每条消息的过期时间不一样，收到的消息的顺序有可能会乱掉。这些不做深究，自行百度。

关于死信队列常见应用场景之一下单，支付，支付超时的各种场景，下面通过一个简单的例子模拟一下

同样的新建一个空的webapi项目DeadLetterQueue，

program代码如下：

public class Program
    {
        public static void Main(string[] args)
        {
            var builder = WebApplication.CreateBuilder(args);

            // Add services to the container.

            builder.Services.AddControllers();
            // Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
            builder.Services.AddEndpointsApiExplorer();
            builder.Services.AddSwaggerGen();
            builder.Services.AddHostedService<ConsumerService>();
            builder.Services.AddHostedService<DeadConsumerService>();
            var app = builder.Build();

            // Configure the HTTP request pipeline.
            if (app.Environment.IsDevelopment())
            {
                app.UseSwagger();
                app.UseSwaggerUI();
            }
            app.MapGet("/normal/{message}", ([FromRoute] string message) =>
            {
                ConnectionFactory factory = new ConnectionFactory();
                factory.HostName = "localhost";
                factory.Port = 5672;
                using (IConnection connection = factory.CreateConnection())
                {
                    using (IModel channel = connection.CreateModel())
                    {
                        var queueName = "rbTest2023010";

                        //channel.ExchangeDeclare("exchange.dlx", ExchangeType.Direct, true);
                        //channel.QueueDeclare("queue.dlx", true, false, false, null);
                        channel.ExchangeDeclare("exchange.normal", ExchangeType.Fanout, true);
                        channel.QueueDeclare(queueName, true, false, false,
                            new Dictionary<string, object>
                        {
                            { "x-message-ttl" ,10000},
                            {"x-dead-letter-exchange","exchange.dlx" },
                            {"x-dead-letter-routing-key","routingkey" }
                        }
                            );

                        channel.QueueBind(queueName, "exchange.normal", "");
                        {
                            string sendMessage = string.Format("Message_{0}", message);
                            byte[] buffer = Encoding.UTF8.GetBytes(sendMessage);
                            IBasicProperties basicProperties = channel.CreateBasicProperties();
                            basicProperties.DeliveryMode = 2; //持久化  1=非持久化
                            channel.BasicPublish("exchange.normal", queueName, basicProperties, buffer);
                            Console.WriteLine($"{DateTime.Now}消息发送成功：{sendMessage}" );
                        }
                    }
                }
            });
            app.UseHttpsRedirection();

            app.UseAuthorization();

            app.MapControllers();

            app.Run();
        }
    }

下单后消费代码ConsumerService如下

 public class ConsumerService : BackgroundService
    {
        protected override async Task ExecuteAsync(CancellationToken stoppingToken)
        {
            Console.WriteLine("normal Rabbitmq消费端开始工作!");
            while (!stoppingToken.IsCancellationRequested)
            {
                ConnectionFactory factory = new ConnectionFactory();
                factory.HostName = "localhost";
                factory.Port = 5672;

                IConnection connection = factory.CreateConnection();
                {
                    IModel channel = connection.CreateModel();
                    {
                        var queueName = "rbTest2023010";
                        channel.ExchangeDeclare("exchange.normal", ExchangeType.Fanout, true);
                        channel.QueueDeclare(queueName, true, false, false, new Dictionary<string, object>
                        {
                            { "x-message-ttl" ,10000},
                            {"x-dead-letter-exchange","exchange.dlx" },
                            {"x-dead-letter-routing-key","routingkey" }
                        });

                        channel.QueueBind(queueName, "exchange.normal", "");
                        //输入1，那如果接收一个消息，但是没有应答，则客户端不会收到下一个消息
                        channel.BasicQos(0, 1, false);
                        //在队列上定义一个消费者
                        var consumer = new EventingBasicConsumer(channel);
                        channel.BasicConsume(queueName, false, consumer);
                        consumer.Received += (ch, ea) =>
                        {
                            byte[] bytes = ea.Body.ToArray();
                            string str = Encoding.UTF8.GetString(bytes);
                            Console.WriteLine($"{DateTime.Now}来自死信队列获取的消息: {str.ToString()}");
                            //回复确认
                            if (str.Contains("跳过")) //假设超时不处理，留给后面deadconsumerservice处理
                            {
                                Console.WriteLine($"{DateTime.Now}来自死信队列获取的消息: {str.ToString()},该消息被拒绝");
                                channel.BasicNack(ea.DeliveryTag, false,false);
                            }
                            else  //正常消息处理
                            {
                                Console.WriteLine($"{DateTime.Now}来自死信队列获取的消息: {str.ToString()}，该消息被接受");
                                channel.BasicAck(ea.DeliveryTag, false);
                            }
                        };

                    }
                }
                await Task.Delay(5000);
            }
        }
    }

通过模拟发送的消息加入跳过两个字会拒收这条消息，这样就会跳到设置的exchange.dlx交换机队列去，如果没有跳过那么这条消息就正常处理掉，消费确认。

超时不处理后我们通过新的消费服务DeadConsumerService来处理这异常的消费，比如回复库存，订单状态改为取消等等

public class DeadConsumerService:BackgroundService
    {
        protected override async Task ExecuteAsync(CancellationToken stoppingToken)
        {
            Console.WriteLine("normal Rabbitmq消费端开始工作!");
            while (!stoppingToken.IsCancellationRequested)
            {
                ConnectionFactory factory = new ConnectionFactory();
                factory.HostName = "localhost";
                factory.Port = 5672;

                IConnection connection = factory.CreateConnection();
                {
                    IModel channel = connection.CreateModel();
                    {
                        var queueName = "queue.dlx";
                        channel.ExchangeDeclare("exchange.dlx", ExchangeType.Direct, true);
                        channel.QueueDeclare("queue.dlx", true, false, false, null);

                        channel.QueueDeclare(queueName, true, false, false, null);

                        channel.QueueBind(queueName, "exchange.dlx", "");
                        //输入1，那如果接收一个消息，但是没有应答，则客户端不会收到下一个消息
                        channel.BasicQos(0, 1, false);
                        //在队列上定义一个消费者
                        var consumer = new EventingBasicConsumer(channel);
                        channel.BasicConsume("queue.dlx", false, consumer);
                        consumer.Received += (ch, ea) =>
                        {
                            byte[] bytes = ea.Body.ToArray();
                            string str = Encoding.UTF8.GetString(bytes);
                            Console.WriteLine($"{DateTime.Now}超时未处理的消息: {str.ToString()}");
                            //回复确认
                            {
                                channel.BasicAck(ea.DeliveryTag, false);
                            }
                        };

                    }
                }
                await Task.Delay(5000);
            }
        }
    }

运行结果：

关于rabbitmq的死信队列和延时队列的介绍什么的这里不去贴baidu了，应用demo就这么多了，代码这里exercisebook/RabbitMQ.Test at main · liuzhixin405/exercisebook (github.com) 。小面分享一个完整一点的例子。

exercisebook/cat.seckill/cat.seckill at main · liuzhixin405/exercisebook (github.com)

感觉自己还是不合适写这些玩意儿，没有那么细心和耐心，有这时间真不如写写demo。