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。
