RabbitMq入门与基本使用

这两天工作项目中用到了rabbitmq，顺便学习了一下。

RabbitMq主要的使用模式有三种：工作队列，发布订阅和RPC远程调用。

1.工作队列

生产者：

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

class NewTask
{
    public static void Main(string[] args)
    {
        var factory = new ConnectionFactory() { HostName = "localhost" };
        using(var connection = factory.CreateConnection())
        using(var channel = connection.CreateModel())
        {
　　　　　　　 //一定要声明队列，向队列发送消息
            channel.QueueDeclare(queue: "task_queue",
                                 durable: true,　　　　//队列是否持久化
                                 exclusive: false,
                                 autoDelete: false,
                                 arguments: null);

            var message = GetMessage(args);
            var body = Encoding.UTF8.GetBytes(message);

            var properties = channel.CreateBasicProperties();　　　　
            properties.SetPersistent(true);　　　　//消息是否持久化　　　　

            channel.BasicPublish(exchange: "",　　　　//没有定义exchange，会使用系统默认的exchange
                                 routingKey: "task_queue",
                                 basicProperties: properties,
                                 body: body);
            Console.WriteLine(" [x] Sent {0}", message);
        }

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

    private static string GetMessage(string[] args)
    {
        return ((args.Length > ) ? string.Join(" ", args) : "Hello World!");
    }
}

在方法

channel.BasicPublish("", "task_queue", null, bytes);

中的第一个参数是需要输入一个exchange。在RabbitMQ中，所有的消息都必须要通过exchange发送到各个queue里面去。发送者发送消息，其实也就是把消息放到exchange中去。而exchange知道应该把消息放到哪里去。在这个方法中，我们没有输入exchange的名称，只是定义了一个空的echange，而在第二个参数routeKey中输入了我们目标队列的名称。RabbitMQ会帮我定义一个默认的exchange，这个exchange会把消息直接投递到

我们输入的队列中，这样服务端只需要直接去这个定义了的队列中获取消息就可以了。

消费者：

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

class Worker
{
    public static void Main()
    {
        var factory = new ConnectionFactory() { HostName = "localhost" };
        using(var connection = factory.CreateConnection())
        using(var channel = connection.CreateModel())
        {
            channel.QueueDeclare(queue: "task_queue",
                                 durable: true,
                                 exclusive: false,
                                 autoDelete: false,
                                 arguments: null);

            //修改分发机制(原先是轮询分发)， prefetchCount = 1 变为 不向正在处理的worker发发任务，谁先有空就给谁
            //In order to defeat that we can use the basicQos method with the prefetchCount = 1 setting.
            //This tells RabbitMQ not to give more than one message to a worker at a time.
            //Or, in other words, don't dispatch a new message to a worker until it has processed and acknowledged the previous one.
            //Instead, it will dispatch it to the next worker that is not still busy.
            channel.BasicQos(prefetchSize: , prefetchCount: , global: false);

            Console.WriteLine(" [*] Waiting for messages.");

            var consumer = new EventingBasicConsumer(channel);
            consumer.Received += (model, ea) =>
            {
                var body = ea.Body;
                var message = Encoding.UTF8.GetString(body);
                Console.WriteLine(" [x] Received {0}", message);

                int dots = message.Split('.').Length - ;
                Thread.Sleep(dots * );

                Console.WriteLine(" [x] Done");
　　　　　　　　　　
　　　　　　　　　　//当noAck为false起作用，手动告知应答处理完成
                channel.BasicAck(deliveryTag: ea.DeliveryTag, multiple: false);
            };
            channel.BasicConsume(queue: "task_queue",
                                 noAck: false, 　　//是否不要手动应答(no manual Ack)，ture自动应答，自动删除处理消息；false手动应答，服务器的消息会等待应答结果才消除
                                 consumer: consumer);

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

这里要注意的，如果没有宿主进程，比如一个Console的后台程序，这个 Console.ReadLine(); 不能少，而且一定要加在这里。否则:

1.程序自动退出。2.相关的变量出了生命周期范围，已经释放！笔者在这里吃过亏，找了半天才发现。

2.发布订阅

Exchange类型为四种:direct，fanout，topic，headers。此模式中，由于是通过exchange和routingkey发送给多个队列，所以Publish中不用声明队列，只需声明exchange。

1、Routing - Exchange类型direct

他是根据交换器名称与routingkey来找队列的。

Publish:

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

class EmitLogDirect
{
    public static void Main(string[] args)
    {
        var factory = new ConnectionFactory() { HostName = "localhost" };
        using(var connection = factory.CreateConnection())
        using(var channel = connection.CreateModel())
        {
            channel.ExchangeDeclare(exchange: "direct_logs",
                                    type: "direct");

            var severity = (args.Length > ) ? args[] : "info";
            var message = (args.Length > )
                          ? string.Join(" ", args.Skip(  ).ToArray())
                          : "Hello World!";
            var body = Encoding.UTF8.GetBytes(message);
            channel.BasicPublish(exchange: "direct_logs",
                                 routingKey: severity,        //传来参数，指定的routekey
                                 basicProperties: null,
                                 body: body);
            Console.WriteLine(" [x] Sent '{0}':'{1}'", severity, message);
        }

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

subscribe

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

class ReceiveLogsDirect
{
    public static void Main(string[] args)
    {
        var factory = new ConnectionFactory() { HostName = "localhost" };
        using(var connection = factory.CreateConnection())
        using(var channel = connection.CreateModel())
        {
            channel.ExchangeDeclare(exchange: "direct_logs",
                                    type: "direct");
            var queueName = channel.QueueDeclare().QueueName;

            if(args.Length < )
            {
                Console.Error.WriteLine("Usage: {0} [info] [warning] [error]",
                                        Environment.GetCommandLineArgs()[]);
                Console.WriteLine(" Press [enter] to exit.");
                Console.ReadLine();
                Environment.ExitCode = ;
                return;
            }

            //同时绑定多个指定的routekey
            foreach(var severity in args)
            {
                channel.QueueBind(queue: queueName,
                                  exchange: "direct_logs",
                                  routingKey: severity);
            }

            Console.WriteLine(" [*] Waiting for messages.");

            var consumer = new EventingBasicConsumer(channel);
            consumer.Received += (model, ea) =>
            {
                var body = ea.Body;
                var message = Encoding.UTF8.GetString(body);
                var routingKey = ea.RoutingKey;
                Console.WriteLine(" [x] Received '{0}':'{1}'",
                                  routingKey, message);
            };
            channel.BasicConsume(queue: queueName,
                                 noAck: true,
                                 consumer: consumer);

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

2、Publish/Subscribe - Exchange类型fanout

这个类型忽略Routingkey，他为广播模式。

广播式时，Publish可以不指定queue和routekey。

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

class EmitLog
{
    public static void Main(string[] args)
    {
        var factory = new ConnectionFactory() { HostName = "localhost" };
        using(var connection = factory.CreateConnection())
        using(var channel = connection.CreateModel())
        {
            channel.ExchangeDeclare(exchange: "logs", type: "fanout");

            var message = GetMessage(args);
            var body = Encoding.UTF8.GetBytes(message);
            channel.BasicPublish(exchange: "logs",
                                 routingKey: "",
                                 basicProperties: null,
                                 body: body);
            Console.WriteLine(" [x] Sent {0}", message);
        }

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

    private static string GetMessage(string[] args)
    {
        return ((args.Length > )
               ? string.Join(" ", args)
               : "info: Hello World!");
    }
}

subscribe可以只用临时队列接收

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

class ReceiveLogs
{
    public static void Main()
    {
        var factory = new ConnectionFactory() { HostName = "localhost" };
        using(var connection = factory.CreateConnection())
        using(var channel = connection.CreateModel())
        {
            channel.ExchangeDeclare(exchange: "logs", type: "fanout");

            //这里生成了一个随机队列（string queue = "", bool durable = false, bool exclusive = true, bool autoDelete = true）
            //In the .NET client, when we supply no parameters to queueDeclare() we create a non-durable, exclusive,
            //autodelete queue with a generated name:
            var queueName = channel.QueueDeclare().QueueName;
            channel.QueueBind(queue: queueName,
                              exchange: "logs",
                              routingKey: "");

            Console.WriteLine(" [*] Waiting for logs.");

            var consumer = new EventingBasicConsumer(channel);
            consumer.Received += (model, ea) =>
            {
                var body = ea.Body;
                var message = Encoding.UTF8.GetString(body);
                Console.WriteLine(" [x] {0}", message);
            };
            channel.BasicConsume(queue: queueName,
                                 noAck: true,
                                 consumer: consumer);

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

有一种简写的方式，用Subscription类

/// <summary>
/// 获取消息并处理
/// </summary>
/// <param name="queueName">队列名称</param>
/// <param name="action">接收到消息后的Action</param>
public void Receive(string queueName, Action<byte[]> action, bool multThread = true)
        {
            ConnectionFactory cf = new ConnectionFactory();
            cf.UserName = this.UserName;
            cf.Password = this.PassWord;
            cf.HostName = this.HostName;
            cf.Port = this.Port;
            cf.VirtualHost = this.VitualHost;

            using (IConnection conn = cf.CreateConnection())
            {
                using (IModel ch = conn.CreateModel())
                {
                    //声明交换器
                    ch.ExchangeDeclare(exchange: "e_linke1", type: "direct",durable: false);
                    ch.QueueDeclare(queue: queueName,
                                         durable: false,
                                         exclusive: false,
                                         autoDelete: false,
                                         arguments: null);

                    //将队列绑定到交换器上
                    ch.QueueBind(queue: queueName,
                                      exchange: "e_linke1",
                                      routingKey: "elk");
                    using (Subscription sub = new Subscription(ch, queueName, true))
                    {
                        foreach (BasicDeliverEventArgs e in sub)
                        {
                            // handle the message contained in e ...
                            // ... and finally acknowledge it
                            if (multThread)
                            {
                                System.Threading.Tasks.Task.Factory.StartNew(() => { action(e.Body); });
                            }
                            else
                            {
                                action(e.Body);
                            }

                            sub.Ack(e);
                        }
                    }
                }
            }
        }

注：

如果有两个接收程序都是用了同一个的queue和相同的routingKey去绑定direct exchange的话，分发的行为是负载均衡的，也就是说第一个是程序1收到，第二个是程序2收到，以此类推。

如果有两个接收程序用了各自的queue，但使用相同的routingKey去绑定direct exchange的话，分发的行为是复制的，也就是说每个程序都会收到这个消息的副本。行为相当于fanout类型的exchange。

3、Exchange类型topic

这个类型的路由规则如果你掌握啦，那是相当的好用，与灵活。他是根据RoutingKey的设置，来做匹配的，其中这里还有两个通配符为：

*，代表任意的一个词。例如topic.zlh.*，他能够匹配到，topic.zlh.one ,topic.zlh.two ,topic.zlh.abc, ....

#，代表任意多个词。例如topic.#，他能够匹配到，topic.zlh.one ,topic.zlh.two ,topic.zlh.abc, ....

4、Headers Exchange

Headers类型的exchange使用的比较少，它也是忽略routingKey的一种路由方式。是使用Headers来匹配的。Headers是一个键值对，可以定义成Hashtable。发送者在发送的时候定义一些键值对，接收者也可以再绑定时候传入一些键值对，两者匹配的话，则对应的队列就可以收到消息。匹配有两种方式all和any。这两种方式是在接收端必须要用键值"x-mactch"来定义。all代表定义的多个键值对都要满足，而any则代码只要满足一个就可以了。之前的几种exchange的routingKey都需要要字符串形式的，而headers exchange则没有这个要求，因为键值对的值可以是任何类型。代码示例如下：

发送端:

channel.ExchangeDeclare("X1", "headers");

IBasicProperties properties = channel.CreateBasicProperties();
properties.Headers = new Hashtable();
properties.Headers.Add("Key1", );
properties.Headers.Add("Key2", );

XmlSerializer xs = new XmlSerializer(typeof(RequestMessage));
MemoryStream ms = new MemoryStream();
xs.Serialize(ms, message);
byte[] bytes = ms.ToArray();

channel.BasicPublish("X1", "", properties, bytes);

接收端:

channel.ExchangeDeclare("X1", "headers");
//随机创建一个队列
string queue_name = channel.QueueDeclare("headerssubscriber2", true, false, false, null);
//绑定
IDictionary ht = new Hashtable();
ht.Add("x-match", "any");
ht.Add("Key1", );
ht.Add("Key2", );
channel.QueueBind(queue_name, "X1", "", ht);
//定义这个队列的消费者
QueueingBasicConsumer consumer = new QueueingBasicConsumer(channel);
channel.BasicConsume(queue_name, true, consumer);

while (true)
{
    BasicDeliverEventArgs ea =
        (BasicDeliverEventArgs)consumer.Queue.Dequeue();

    byte[] bytes = ea.Body;

    XmlSerializer xs = new XmlSerializer(typeof(RequestMessage));
    using (MemoryStream ms = new MemoryStream(bytes))
    {
        RequestMessage message = (RequestMessage)xs.Deserialize(ms);
        Console.WriteLine("Receive a Message, Id:" + message.MessageId + " Message:" + message.Message);
    }
}

3.RPC远程调用

参考链接:

.Net使用RabbitMQ详解

RabbitMQ消息队列（三）：任务分发机制[转]

一个winform带你玩转rabbitMQ

.Net下RabbitMQ的使用(4) -- 订阅和发布  *

.Net下RabbitMQ的使用(5) -- 路由机制 *

.Net下RabbitMQ的使用(6) -- 持久化 *

.Net下RabbitMQ的使用(7) -- 消息的传输控制 *

.NET/C# Client API Guide [官网]

RabbitMQ Tutorials [官网]

.NET/C# Client API Guide [官网]