RabbitMQ --- Routing（路由）

目录

RabbitMQ --- Hello Mr.Tua

RabbitMQ --- Work Queues（工作队列）

RabbitMQ --- Publish/Subscribe（发布/订阅）

前言

在上一章中介绍了 Publish/Subscribe（发布/订阅），它是把每个消息发送给多个 Consumer，也就是说每个 Consumer 都是接收所有的消息，辣么问题来了，如果 Consumer 只接收它想要的某一部分消息，那该怎么办呢？可以通过 Routing（路由）的机制来实现。

Direct交换机（Direct exchange）

在上一章的示例中通过 Fanout exchange 把所有消息广播到多个 Consumer，这样是无法满足 Consumer 自定义接收消息的需求，为了解决这个问题就需要使用 Direct exchange ，它会使消息转发到 Routing key 和 Binding key 完全匹配的队列，而这两者不匹配的消息都会被丢弃。

也可以用相同的 Binding key 绑定多个队列，看上去和 Fanout exchange 的作用一样。

完整示例

现在修改上一章的示例代码，使 Consumer 可以自定义接收奇数（odd）或偶数（even）消息：

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

namespace Producer
{
    class Program
    {
        static void Main(string[] args)
        {
            var factory = new ConnectionFactory
            {
                HostName = "10.202.228.107",
                UserName = "Tua",
                Password = "Tua",
                Port = 5672
            };
            using (var connection = factory.CreateConnection())
            {
                using (var channel = connection.CreateModel())
                {
                    channel.ExchangeDeclare
                    (
                        exchange: "Tua",
                        type: ExchangeType.Direct//Direct交换机
                    );
                    for (int m = 0; m < 10; m++)
                    {
                        string marks = string.Empty;
                        for (int n = 0; n <= m; n++)
                        {
                            marks += ">";
                        }
                        string routingKey = string.Empty;
                        if(marks.Length % 2 != 0)
                        {
                            routingKey = "odd";//奇数
                        }
                        else
                        {
                            routingKey = "even";//偶数
                        }
                        string msg = "Mr.Tua" + marks + marks.Length + "s";
                        var body = Encoding.UTF8.GetBytes(msg);
                        channel.BasicPublish
                        (
                            exchange: "Tua",
                            routingKey: routingKey,//路由键
                            basicProperties: null,
                            body: body
                        );
                        Console.WriteLine("Producer sent message: {0}", msg);
                    }
                    Console.ReadLine();
                }
            }
        }
    }
}

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

namespace Consumer
{
    class Program
    {
        static void Main(string[] args)
        {
            var factory = new ConnectionFactory
            {
                HostName = "localhost"
            };
            using (var connection = factory.CreateConnection())
            {
                using (var channel = connection.CreateModel())
                {
                    channel.ExchangeDeclare
                    (
                        exchange: "Tua",
                        type: ExchangeType.Direct//Direct交换机
                    );
                    string queueName = channel.QueueDeclare().QueueName;
                    string[] bindingKeys = { "odd", "even" };
                    Random random = new Random();
                    int index = random.Next(2);
                    string bindingKey = bindingKeys[index];//随机生成绑定键
                    channel.QueueBind
                    (
                        queue: queueName,
                        exchange: "Tua",
                        routingKey: bindingKey//绑定键
                    );
                    var consumer = new EventingBasicConsumer(channel);
                    consumer.Received += (sender, e) =>
                    {
                        var body = e.Body;
                        var msg = Encoding.UTF8.GetString(body);
                        int marks = msg.ToCharArray().Where(c => c.ToString() == ">").Count();
                        Console.WriteLine("Consumer received {0} message: {1}", bindingKey, msg);
                        Thread.Sleep(marks * 1000);
                        Console.WriteLine("OK");
                    };
                    channel.BasicConsume
                    (
                        queue: queueName,
                        noAck: true,
                        consumer: consumer
                    );
                    Console.ReadLine();
                }
            }
        }
    }
}