C#教程之C#教程之RabbitMQ基础入门篇

下载安装

Erlang
RabbitMQ

启动RabbitMQ管理平台插件

DOS下进入到安装目录\sbin,执行以下命令

rabbitmq-plugins enable rabbitmq_management   

当出现以下结果时，重启RabbitMQ服务

set 3 plugins.
Offline change; changes will take effect at broker restart.

访问http://localhost:15672（账号密码：guest）

注意：以下为C#代码，请引用NuGet包：RabbitMQ.Client

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参考文章

RabbitMQ快速入门

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名词解析

P（Publisher）：生产者
C（Consumer）：消费者
Channel：信道
Queue：队列
Exchange：信息交换机

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简单演示

信息发送端

static void Send()
{
    //1. 实例化连接工厂
    var factory = new ConnectionFactory() { HostName = "localhost" };
    //2. 建立连接
    using (var connection = factory.CreateConnection())
    {
        //3. 创建信道
        using (var channel = connection.CreateModel())
        {
            //4. 声明队列
            channel.QueueDeclare(queue: "rabbitmq",
                                 durable: false,
                                 exclusive: false,
                                 autoDelete: false,
                                 arguments: null);

            //5. 构建字节数据包
            var message = "Hello RabbitMQ!";
            var body = Encoding.UTF8.GetBytes(message);

            //6. 发送数据包
            channel.BasicPublish(exchange: "",
                                 routingKey: "rabbitmq",
                                 basicProperties: null,
                                 body: body);

            Console.WriteLine(" [x] Sent {0}", message);
        }
    }
}

信息接收端

static void Receive()
{
    //1. 实例化连接工厂
    var factory = new ConnectionFactory() { HostName = "localhost" };
    //2. 建立连接
    using (var connection = factory.CreateConnection())
    {
        //3. 创建信道
        using (var channel = connection.CreateModel())
        {
            //4. 声明队列
            channel.QueueDeclare(queue: "rabbitmq",
                                 durable: false,
                                 exclusive: false,
                                 autoDelete: false,
                                 arguments: null);

            //5. 构造消费者实例
            var consumer = new EventingBasicConsumer(channel);

            //6. 绑定消息接收后的事件委托
            consumer.Received += (model, ea) =>
            {
                var message = Encoding.UTF8.GetString(ea.Body);
                Console.WriteLine(" [x] Received {0}", message);
            };
            //7. 启动消费者
            channel.BasicConsume(queue: "rabbitmq",
                                 autoAck: true,
                                 consumer: consumer);

            Console.WriteLine(" Press [enter] to exit.");
            Console.ReadLine();

        }
    }
}

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轮询调度

P生产的多个任务进入到队列中，多个C间可以并行处理任务。默认情况下，RabbitMQ把信息按顺序发送给每一个C。平均每个C将获得同等数量的信息。

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信息确认

按照最简单的演示来说，信息一旦发送到C中，则该信息就会从队列中移除。一旦中间信息处理异常/失败，C端程序退出等，都将会导致信息未处理完成，而此时队列中已将信息移除了，那么就会导致一系列的问题。我们可以在C端设置手动确认信息，从而解决上述问题的发生。
Receive代码块

//6. 绑定消息接收后的事件委托
consumer.Received += (model, ea) =>
{
    var message = Encoding.UTF8.GetString(ea.Body);
    Console.WriteLine(" [x] Received {0}", message);
    Thread.Sleep(5000);//模拟耗时
    Console.WriteLine(" [x] Done");

    // 发送信息确认信号（手动信息确认）
    channel.BasicAck(ea.DeliveryTag, false);
};
//7. 启动消费者
/*
 autoAck参数属性

    true：自动信息确认，当C端接收到信息后，自动发送ack信号，不管信息是否处理完毕

    false：关闭自动信息确认，通过调用BasicAck方法手动进行信息确认
 */
channel.BasicConsume(queue: "rabbitmq",
                     autoAck: false,
                     consumer: consumer);

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信息持久化

当RabbitMQ退出或死机时会清空队列和信息。通过将队列和信息标记为持久的，来告知RabbitMQ将信息持久化。

Send代码块

//4. 声明队列
//durable设置为true，表示此队列为持久的。
//注意：RabbitMQ不允许你使用不同的参数重新定义一个已经存在的队列，所以你需要重启服务/更改队列名称
channel.QueueDeclare(queue: "rabbitmq",
                     durable: true, //标记队列持久
                     exclusive: false,
                     autoDelete: false,
                     arguments: null);
//设置IbasicProperties.SetPersistent属性值为true来标记我们的消息持久化
var properties = channel.CreateBasicProperties();
properties.Persistent = true;
 
//5. 构建字节数据包
var message = "Hello RabbitMQ!";
var body = Encoding.UTF8.GetBytes(message);
 
//6. 发送数据包
channel.BasicPublish(exchange: "",
                     routingKey: "rabbitmq",
                     basicProperties: properties, //指定BasicProperties
                     body: body);

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公平调度

上述演示中，如果队列中存在多个信息，在开启多个C的情况下，只有一个C忙个不停，另外的却一直处于空闲状态。通过调用BasicQos，告知RabbitMQ在某个C信息处理完毕，并且已经收到信息确认之后，才可以继续发送信息到这个C。否则，将会把信息分发到另外空闲的C。

Receive代码块

//4. 声明队列
channel.QueueDeclare(queue: "rabbitmq",
                     durable: true,
                     exclusive: false,
                     autoDelete: false,
                     arguments: null);
////设置prefetchCount为1来告知RabbitMQ在未收到消费端的消息确认时，不再分发消息
channel.BasicQos(prefetchSize: 0,
                 prefetchCount: 1,
                 global: false);

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发布/订阅

上述中的演示，P推送信息至队列中，C从队列中处理信息。但是如果需要将P推送的信息至每个订阅的C中处理信息，那么我们就可以使用Exchange。

fanout（将信息分发到exchange上绑定的所有队列上）

Send代码块

//1. 实例化连接工厂
var factory = new ConnectionFactory() { HostName = "localhost" };
//2. 建立连接
using (var connection = factory.CreateConnection())
{
    //3. 创建信道
    using (var channel = connection.CreateModel())
    {
        //4. 声明信息交换机
        channel.ExchangeDeclare(exchange: "fanoutDemo",
                                type: "fanout");
 
        //5. 构建字节数据包
        var message = "Hello RabbitMQ!";
        var body = Encoding.UTF8.GetBytes(message);
         
        //6. 发布到指定exchange，fanout类型的会忽视routingKey的值，所以无需填写
        channel.BasicPublish(exchange: "fanoutDemo",
                             routingKey: "",
                             basicProperties: null,
                             body: body);
 
        Console.WriteLine(" [x] Sent {0}", message);
    }
}

Receive代码块

//1. 实例化连接工厂
var factory = new ConnectionFactory() { HostName = "localhost" };
//2. 建立连接
using (var connection = factory.CreateConnection())
{
    //3. 创建信道
    using (var channel = connection.CreateModel())
    {
        //4. 声明信息交换机
        channel.ExchangeDeclare(exchange: "fanoutDemo",
                                type: "fanout");
        //生成随机队列名称
        var queueName = channel.QueueDeclare().QueueName;
        //绑定队列到指定fanout类型exchange
        channel.QueueBind(queue: queueName,
                          exchange: "fanoutDemo",
                          routingKey: "");
         
        //5. 构造消费者实例
        var consumer = new EventingBasicConsumer(channel);
 
        //6. 绑定消息接收后的事件委托
        consumer.Received += (model, ea) =>
        {
            var message = Encoding.UTF8.GetString(ea.Body);
            Console.WriteLine(" [x] Received {0}", message);
        };
 
        channel.BasicConsume(queue: queueName,
                             autoAck: true,
                             consumer: consumer);
 
        Console.WriteLine(" Press [enter] to exit.");
        Console.ReadLine();
 
    }
}

direct（C绑定的队列名称须和P发布指定的路由名称一致）

Send代码块

//4. 声明信息交换机
channel.ExchangeDeclare(exchange: "directDemo",
                        type: "direct");

//5. 构建字节数据包
var message = "Hello RabbitMQ!";
var body = Encoding.UTF8.GetBytes(message);

//6. 发布到指定exchange
channel.BasicPublish(exchange: "directDemo",
                     routingKey: "a",
                     basicProperties: null,
                     body: body);

Receive代码块

//4. 声明信息交换机
channel.ExchangeDeclare(exchange: "directDemo",
                        type: "direct");
//生成随机队列名称
var queueName = channel.QueueDeclare().QueueName;
//绑定队列到指定direct类型exchange
channel.QueueBind(queue: queueName,
                  exchange: "directDemo",
                  routingKey: "b");

topic（支持通配符的路由规则）

通配字符：

• *：匹配一个单词
• #：匹配0个或多个单词
• .：仅作为分隔符

Send代码块

//4. 声明信息交换机
channel.ExchangeDeclare(exchange: "topicDemo",
                        type: "topic");
 
//5. 构建字节数据包
var message = "Hello RabbitMQ!";
var body = Encoding.UTF8.GetBytes(message);
 
//6. 发布到指定exchange
channel.BasicPublish(exchange: "topicDemo",
                     routingKey: "admin.user.error", //模拟后台用户错误
                     basicProperties: null,
                     body: body);

Receive代码块

//4. 声明信息交换机
channel.ExchangeDeclare(exchange: "topicDemo",
                        type: "topic");
//生成随机队列名称
var queueName = channel.QueueDeclare().QueueName;
//绑定队列到指定topic类型exchange
channel.QueueBind(queue: queueName,
                  exchange: "topicDemo",
                  routingKey: "admin.*.#"); //订阅所有后台异常错误

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RPC（远程过程调用）

1. 进行远程调用的客户端需要指定接收远程回调的队列，并申明消费者监听此队列。
2. 远程调用的服务端除了要申明消费端接收远程调用请求外，还要将结果发送到客户端用来监听的结果的队列中去。

客户端代码块

var factory = new ConnectionFactory() { HostName = "localhost" };
using (var connection = factory.CreateConnection())
{
    using (var channel = connection.CreateModel())
    {
        var correlationId = Guid.NewGuid().ToString();
        var replyQueue = channel.QueueDeclare().QueueName;
 
        var properties = channel.CreateBasicProperties();
        properties.ReplyTo = replyQueue;
        properties.CorrelationId = correlationId;
 
        string number = args.Length > 0 ? args[0] : "30";
        var body = Encoding.UTF8.GetBytes(number);
        //发布消息
        channel.BasicPublish(exchange: "", routingKey: "rpc_queue", basicProperties: properties, body: body);
 
        Console.WriteLine($"[*] Request fib({number})");
 
        // //创建消费者用于消息回调
        var callbackConsumer = new EventingBasicConsumer(channel);
        channel.BasicConsume(queue: replyQueue, autoAck: true, consumer: callbackConsumer);
 
        callbackConsumer.Received += (model, ea) =>
        {
            if (ea.BasicProperties.CorrelationId == correlationId)
            {
                var responseMsg = $"Get Response: {Encoding.UTF8.GetString(ea.Body)}";
 
                Console.WriteLine($"[x]: {responseMsg}");
            }
        };
 
        Console.ReadLine();
 
    }
}

服务端代码块

static void Main(string[] args)
{
    var factory = new ConnectionFactory() { HostName = "localhost" };
    using (var conection = factory.CreateConnection())
    {
        using (var channel = conection.CreateModel())
        {
            channel.QueueDeclare(queue: "rpc_queue", durable: false,
                exclusive: false, autoDelete: false, arguments: null);
 
            var consumer = new EventingBasicConsumer(channel);
            Console.WriteLine("[*] Waiting for message.");
 
            consumer.Received += (model, ea) =>
            {
                var message = Encoding.UTF8.GetString(ea.Body);
                int n = int.Parse(message);
                Console.WriteLine($"Receive request of Fib({n})");
                int result = Fib(n);
 
                var properties = ea.BasicProperties;
                var replyProerties = channel.CreateBasicProperties();
                replyProerties.CorrelationId = properties.CorrelationId;
 
                channel.BasicPublish(exchange: "", routingKey: properties.ReplyTo,
                    basicProperties: replyProerties, body: Encoding.UTF8.GetBytes(result.ToString()));
 
                channel.BasicAck(ea.DeliveryTag, false);
                Console.WriteLine($"Return result: Fib({n})= {result}");
 
            };
            channel.BasicConsume(queue: "rpc_queue", autoAck: false, consumer: consumer);
 
            Console.ReadLine();
        }
    }
 
}
 
private static int Fib(int n)
{
    if (n == 0 || n == 1)
    {
        return n;
    }
    return Fib(n - 1) + Fib(n - 2);
}