分布式异步队列学习总结7(交换机TopicExchange)

Topic类型交换机跟Direct类型交换机相比，key多了一个匹配模式，会根据路由规则把消息分配到不同的队列中，供消费者消费。

通过一个示例说明此类交换机的用法，项目结构：

代码实例：

生产者

using RabbitMQ.Client;
using System;
using System.Text;

namespace AspNetCore.RabbitMQ.MessageProducer.MessageProducer
{
    /// <summary>
    /// Topic类型交换机
    /// </summary>
    public class TopicExchange
    {
        public static void Show()
        {
            ConnectionFactory factory = new ConnectionFactory();
            factory.HostName = "localhost";//rabbitmq服务在本地运行
            factory.UserName = "guest";//用户名
            factory.Password = "guest";//密码

            //创建链接
            using (IConnection connection = factory.CreateConnection())
            {
                //创建信道
                using (IModel channel = connection.CreateModel())
                {
                    Console.ForegroundColor = ConsoleColor.Red;
                    Console.WriteLine("生产者已准备就绪......");

                    //声明交换机exchange
                    channel.ExchangeDeclare(exchange: "TopicExchange", type: ExchangeType.Topic, durable: true, autoDelete: false, arguments: null);


                    //声明两个队列
                    channel.QueueDeclare(queue: "ChinaQueue", durable: true, exclusive: false, autoDelete: false, arguments: null);
                    channel.QueueDeclare(queue: "NewsQueue", durable: true, exclusive: false, autoDelete: false, arguments: null);


                    //绑定exchange和queue
                    channel.QueueBind(queue: "ChinaQueue", exchange: "TopicExchange", routingKey: "China.#", arguments: null);
                    channel.QueueBind(queue: "NewsQueue", exchange: "TopicExchange", routingKey: "#.News", arguments: null);


                    //待发送的消息
                    {
                        string message = "来自中国的新闻消息";
                        var body = Encoding.UTF8.GetBytes(message);
                        channel.BasicPublish(exchange: "TopicExchange", routingKey: "China.News", basicProperties: null, body: body);
                        Console.WriteLine($"消息 {message} 已发送到队列");
                    }

                    {
                        string message = "来自中国的天气消息";
                        var body = Encoding.UTF8.GetBytes(message);
                        channel.BasicPublish(exchange: "TopicExchange", routingKey: "China.Weather", basicProperties: null, body: body);
                        Console.WriteLine($"消息 {message} 已发送到队列");
                    }

                    {
                        string message = "来自美国的新闻消息";
                        var body = Encoding.UTF8.GetBytes(message);
                        channel.BasicPublish(exchange: "TopicExchange", routingKey: "SUA.News", basicProperties: null, body: body);
                        Console.WriteLine($"消息 {message} 已发送到队列");
                    }

                    {
                        string message = "来自美国的天气消息";
                        var body = Encoding.UTF8.GetBytes(message);
                        channel.BasicPublish(exchange: "TopicExchange", routingKey: "SUA.Weather", basicProperties: null, body: body);
                        Console.WriteLine($"消息 {message} 已发送到队列");
                    }



                }
            }
        }
    }
}

生产者定义了两个队列ChinaQueue和NewsQueue，ChinaQueue的路由规则是以China开头的路由，消息都会进入到此队列中。NewsQueue的路由规则是以News结尾的路由，都会进入到此队列中。

main方法：

 class Program
    {
        static void Main(string[] args)
        {
            TopicExchange.Show();

            Console.ReadLine();
        }
    }

消费者一：消费队列ChinaQueue的消息

using RabbitMQ.Client;
using RabbitMQ.Client.Events;
using System;
using System.Text;

namespace AspNetCore.RabbitMQ.MessageConsumer_01.MessageConsumer
{
    /// <summary>
    /// 消费者 Topic类型交换机
    /// </summary>
    public class TopicExchange
    {
        public static void Show()
        {
            ConnectionFactory factory = new ConnectionFactory();
            factory.HostName = "localhost";//rabbitmq服务在本地运行
            factory.UserName = "guest";//用户名
            factory.Password = "guest";//密码

            //创建链接
            using (IConnection connection = factory.CreateConnection())
            {
                //创建信道
                using (IModel channel = connection.CreateModel())
                {
                    Console.ForegroundColor = ConsoleColor.Green;
                    try
                    {
                        //基于当前信道创建事件
                        var consumer = new EventingBasicConsumer(channel);
                        consumer.Received += (model, ea) =>
                        {
                            var body = ea.Body;
                            var message = Encoding.UTF8.GetString(body.ToArray());
                            Console.WriteLine($"接收成功 {message}");
                        };
       

                        //处理消息
                        channel.BasicConsume(queue: "ChinaQueue", autoAck: true, consumer: consumer);

                        Console.WriteLine("对来自中国的消息比较感兴趣的消费者");

                        Console.ReadLine();
                    }
                    catch (Exception ex)
                    {
                        Console.WriteLine(ex.Message);
                    }

                }
            }

        }
    }
}

main方法：

class Program
    {
        static void Main(string[] args)
        {
            TopicExchange.Show();

            Console.ReadLine();
        }
    }

消费者二：消费队列NewsQueue的消息

using RabbitMQ.Client;
using RabbitMQ.Client.Events;
using System;
using System.Text;

namespace AspNetCore.RabbitMQ.MessageConsumer_02.MessageConsumer
{
    /// <summary>
    /// 消费者 Topic类型交换机
    /// </summary>
    public class TopicExchange
    {
        public static void Show()
        {
            ConnectionFactory factory = new ConnectionFactory();
            factory.HostName = "localhost";//rabbitmq服务在本地运行
            factory.UserName = "guest";//用户名
            factory.Password = "guest";//密码

            //创建链接
            using (IConnection connection = factory.CreateConnection())
            {
                //创建信道
                using (IModel channel = connection.CreateModel())
                {
                    Console.ForegroundColor = ConsoleColor.Green;
                    try
                    {
                        //基于当前信道创建事件
                        var consumer = new EventingBasicConsumer(channel);
                        consumer.Received += (model, ea) =>
                        {
                            var body = ea.Body;
                            var message = Encoding.UTF8.GetString(body.ToArray());
                            Console.WriteLine($"接收成功 {message}");
                        };


                        //处理消息
                        channel.BasicConsume(queue: "NewsQueue", autoAck: true, consumer: consumer);

                        Console.WriteLine("对来自新闻的消息比较感兴趣的消费者");

                        Console.ReadLine();
                    }
                    catch (Exception ex)
                    {
                        Console.WriteLine(ex.Message);
                    }

                }
            }

        }
    }
}

main方法：

class Program
    {
        static void Main(string[] args)
        {
            TopicExchange.Show();

            Console.ReadLine();
        }
    }

运行结果：

总结：Topic类型交换机可以用于分组，可以根据交换机绑定队列的规则来指定不同的组。