RabbitMQ学习路由模式(以C#代码为例)

路由模式（Routing）

有选择地（Routing key）接收消息，发送消息到交换机并且要指定路由key ，消费者将队列绑定到交换机时需要指定路由key，仅消费指定路由key的消息

Exchange不再把消息交给每一个绑定的队列，而是根据消息的RoutingKey进行判断，只有队列的RoutingKey与消息的RoutingKey完全一致，才会接收消息，路由模式使用的Exchange类型为Direct类型

应用场景： 如在商品库存中增加了1台iphone12，iphone12促销活动消费者指定routing key为iphone12，只有此促销活动会接收到消息，其它促销活动不关心也不会消费此routing key的消息

Demo 架构与订阅模式一样

生产者类WeatherDirect.cs

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Text;
 4 using RabbitMQ.Client;
 5 using RabbitMQ.Common;
 6 
 7 namespace RabbitMQ.Producer.Producer
 8 {
 9     public class WeatherDirect
10     {
11         public static void SendWeather()
12         {
13             Dictionary<string, string> area = new Dictionary<string, string>();
14             area.Add("china.hunan.changsha.20211231", "中国湖南长沙20211231天气数据");
15             area.Add("china.hubei.wuhan.20211231", "中国湖北武汉20211231天气数据");
16             area.Add("china.hubei.xiangyang.20211231", "中国湖北襄阳20211231天气数据");
17             area.Add("us.cal.lsj.20211231", "美国加州洛杉矶20211231天气数据");
18 
19             using (var connection = RabbitUtils.GetConnection().CreateConnection())
20             {
21                 using (var channel = connection.CreateModel())
22                 {
23                     foreach (var item in area)
24                     {
25                         channel.BasicPublish(RabbitConstant.EXCHANGE_WEATHER_ROUTING, item.Key, null, Encoding.UTF8.GetBytes(item.Value));
26                     }
27                     Console.WriteLine("气象信息发送成功！");
28                     Console.WriteLine("Press [Enter] to exit");
29                     Console.ReadLine();
30                 }
31             }
32         }
33     }
34 }

消费者1 WeatherDirect.cs

 1 using RabbitMQ.Client;
 2 using RabbitMQ.Client.Events;
 3 using RabbitMQ.Common;
 4 using System;
 5 using System.Collections.Generic;
 6 using System.Text;
 7 
 8 namespace RabbitMQ.Consumer01.Consumer
 9 {
10     public class WeatherDirect
11     {
12         public static void ReceiveWeatherInfo()
13         {
14             using (var connection = RabbitUtils.GetConnection().CreateConnection())
15             {
16                 using (var channel = connection.CreateModel())
17                 {
18                     channel.ExchangeDeclare(RabbitConstant.EXCHANGE_WEATHER_ROUTING, ExchangeType.Direct);
19                     channel.QueueDeclare(RabbitConstant.QUEUE_BAIDU, true, false, false, null);
20                     /*
21                      * QueueBind用于将队列与交换机绑定
22                      * queue:队列名
23                      * exchange:交换机名
24                      * routingKey：路由key
25                      */
26                     channel.QueueBind(queue: RabbitConstant.QUEUE_BAIDU,
27                                       exchange: RabbitConstant.EXCHANGE_WEATHER_ROUTING,
28                                       routingKey: "china.hunan.changsha.20211231");
29                     channel.QueueBind(queue: RabbitConstant.QUEUE_BAIDU,
30                                     exchange: RabbitConstant.EXCHANGE_WEATHER_ROUTING,
31                                     routingKey: "china.hubei.wuhan.20211231");
32                     channel.BasicQos(0, 1, false);
33                     var consumer = new EventingBasicConsumer(channel);
34 
35                     consumer.Received += (model, ea) =>
36                     {
37                         var message = Encoding.UTF8.GetString(ea.Body.ToArray());
38                         Console.WriteLine($"百度收到的气象信息：{message}");
39                         channel.BasicAck(ea.DeliveryTag, false);
40                     };
41                     channel.BasicConsume(queue: RabbitConstant.QUEUE_BAIDU,
42                                  autoAck: false,
43                                  consumer: consumer);
44                     Console.WriteLine(" Press [enter] to exit.");
45                     Console.ReadLine();
46                 }
47             }
48         }
49     }
50 }

消费者2 WeatherDirect.cs

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Text;
 4 using RabbitMQ.Client;
 5 using RabbitMQ.Client.Events;
 6 using RabbitMQ.Common;
 7 
 8 namespace RabbitMQ.Consumer02.Consumer
 9 {
10     public class WeatherDirect
11     {
12         public static void ReceiveWeatherInfo()
13         {
14             using (var connection = RabbitUtils.GetConnection().CreateConnection())
15             {
16                 using (var channel = connection.CreateModel())
17                 {
18                     channel.ExchangeDeclare(RabbitConstant.EXCHANGE_WEATHER_ROUTING, ExchangeType.Direct);
19                     channel.QueueDeclare(RabbitConstant.QUEUE_SINA, true, false, false, null);
20                     /*
21                      * QueueBind用于将队列与交换机绑定
22                      * queue:队列名
23                      * exchange:交换机名
24                      * routingKey：路由key
25                      */
26                     channel.QueueBind(queue: RabbitConstant.QUEUE_SINA,
27                                       exchange: RabbitConstant.EXCHANGE_WEATHER_ROUTING,
28                                       routingKey: "china.hubei.xiangyang.20211231");
29                     channel.QueueBind(queue: RabbitConstant.QUEUE_SINA,
30                                     exchange: RabbitConstant.EXCHANGE_WEATHER_ROUTING,
31                                     routingKey: "china.hubei.wuhan.20211231");
32                     channel.QueueBind(queue: RabbitConstant.QUEUE_SINA,
33                                     exchange: RabbitConstant.EXCHANGE_WEATHER_ROUTING,
34                                     routingKey: "us.cal.lsj.20211231");
35                     channel.BasicQos(0, 1, false);
36                     var consumer = new EventingBasicConsumer(channel);
37 
38                     consumer.Received += (model, ea) =>
39                     {
40                         var message = Encoding.UTF8.GetString(ea.Body.ToArray());
41                         Console.WriteLine($"新浪收到的气象信息：{message}");
42                         channel.BasicAck(ea.DeliveryTag, false);
43                     };
44                     channel.BasicConsume(queue: RabbitConstant.QUEUE_SINA,
45                                  autoAck: false,
46                                  consumer: consumer);
47                     Console.WriteLine(" Press [enter] to exit.");
48                     Console.ReadLine();
49                 }
50             }
51         }
52     }
53 }

执行结果

备注：若执行报错：'PRECONDITION_FAILED - inequivalent arg 'type' for exchange

原因：一旦创建了exchange, RabbitMQ是不允许对其改变的,不然会报错

解决方法：在web上Exchanges模块把之前的exchange删除。

参考连接：https://www.bilibili.com/video/BV1GU4y1w7Yq?p=8

https://mp.weixin.qq.com/s/QG3uXhhpkE_Uo6Me15mxdg

https://blog.csdn.net/adviceuser2014/article/details/102259145