RabbitMQ与.net core(二)Producer与Exchange

Producer：消息的生产者，也就是创建消息的对象

Exchange：消息的接受者，也就是用来接收消息的对象，Exchange接收到消息后将消息按照规则发送到与他绑定的Queue中。下面我们来定义一个Producer与Exchange。

1.新建.netcore console项目，并引入RabbitMQ.Client的Nuget包

2.创建Exchange

using RabbitMQ.Client;

namespace RabbitMQConsole
{
    class Program
    {
        static void Main(string[] args)
        {
            ConnectionFactory factory = new ConnectionFactory();
            factory.HostName = "39.**.**.**";
            factory.Port = 5672;
            factory.VirtualHost = "/";
            factory.UserName = "root";
            factory.Password = "root";

            var exchange = "change2";
            var route = "route2";
            var queue = "queue2";

            using (var connection = factory.CreateConnection())
            {
                using (var channel = connection.CreateModel())
                {
                    channel.ExchangeDeclare(exchange, type:"direct", durable: true, autoDelete: false);   //创建Exchange
                    
                }
            }
        }
    }
}

可以看到Echange的参数有：

type：可选项为，fanout，direct，topic，headers。区别如下：

　　　　fanout：发送到所有与当前Exchange绑定的Queue中

　　　　direct：发送到与消息的routeKey相同的Rueue中

　　　　topic：fanout的模糊版本

　　　　headers：发送到与消息的header属性相同的Queue中

durable：持久化

autoDelete：当最后一个绑定（队列或者exchange）被unbind之后，该exchange自动被删除。

 运行程序，可以在可视化界面看到change2

接下来我们可以创建与change2绑定的queue

3.创建Queue

                using (var channel = connection.CreateModel())
                {
                    channel.ExchangeDeclare(exchange, type: "direct", durable: true, autoDelete: false);
                    channel.QueueDeclare(queue, durable: true, exclusive: false, autoDelete: false);  #创建queue2
                    channel.QueueBind(queue, exchange, route);　　#将queue2绑定到exchange2
                }

可以看到Echange的参数有：

durable：持久化

exclusive：如果为true，则queue只在channel存在时存在，channel关闭则queue消失

autoDelete：当最后一个绑定（队列或者exchange）被unbind之后，该exchange自动被删除。

去可视化界面看Queue

4.发送消息

                using (var channel = connection.CreateModel())
                {
                    channel.ExchangeDeclare(exchange, type: "direct", durable: true, autoDelete: false);
                    channel.QueueDeclare(queue, durable: true, exclusive: false, autoDelete: false);
                    channel.QueueBind(queue, exchange, route);
                    var props = channel.CreateBasicProperties();
                    props.Persistent = true; #持久化
                    channel.BasicPublish(exchange, route, true, props, Encoding.UTF8.GetBytes("hello rabbit"));
                }

5.消费消息

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

namespace RabbitMQClient
{
    class Program
    {
        private static readonly ConnectionFactory rabbitMqFactory = new ConnectionFactory()
        {
            HostName = "39.**.**.**",
            Port = 5672,
            UserName = "root",
            Password = "root",
            VirtualHost = "/"
        };
        static void Main(string[] args)
        {
            var exchange = "change2";
            var route = "route2";
            var queue = "queue2";


            using (IConnection conn = rabbitMqFactory.CreateConnection())
            using (IModel channel = conn.CreateModel())
            {
                channel.ExchangeDeclare(exchange, "direct", durable: true, autoDelete: false);
                channel.QueueDeclare(queue, durable: true, exclusive: false, autoDelete: false);
                channel.QueueBind(queue, exchange, route);
                while (true)
                {
                    var message = channel.BasicGet(queue, true);  #第二个参数说明自动释放消息，如为false需手动释放消息
                    if(message!=null)
                    {
                        var msgBody = Encoding.UTF8.GetString(message.Body);
                        Console.WriteLine(string.Format("***接收时间:{0}，消息内容：{1}", DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss"), msgBody));
                    }
                    System.Threading.Thread.Sleep(TimeSpan.FromSeconds(1));
                }
            }
        }
    }
}

运行查看结果

查看可视化界面

6.手动释放消息

                while (true)
                {
                    var message = channel.BasicGet(queue, false);#设置为手动释放
                    if(message!=null)
                    {
                        var msgBody = Encoding.UTF8.GetString(message.Body);
                        Console.WriteLine(string.Format("***接收时间:{0}，消息内容：{1}", DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss"), msgBody));
                    }
                    channel.BasicAck(message.DeliveryTag, false); #手动释放
                    System.Threading.Thread.Sleep(TimeSpan.FromSeconds(1));
                }

我们再发一条消息，然后开始消费，加个断点调试一下

查看一下Queue中消息状态

然后直接取消调试，不让程序走到释放的那一步，再查看一下消息状态

这么说来只要不走到 channel.BasicAck(message.DeliveryTag, false);这一行，消息就不会被释放掉，我们让程序直接走到这一行代码，查看一下消息的状态

如图已经被释放了

7.让失败的消息回到队列中

                while (true)
                {
                    var message = channel.BasicGet(queue, false);
                    if(message!=null)
                    {
                        var msgBody = Encoding.UTF8.GetString(message.Body);
                        Console.WriteLine(string.Format("***接收时间:{0}，消息内容：{1}", DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss"), msgBody));
                        Console.WriteLine(message.DeliveryTag);　　　　#当前消息被处理的次序数
                        if (1==1)
                            channel.BasicReject(message.DeliveryTag, true);
                    }
                    
                    System.Threading.Thread.Sleep(TimeSpan.FromSeconds(1));
                }

重新发送4条消息

开始消费

我们可以看到消息一直没有没消费，因为消息被处理之后又放到了队尾

8.监听消息

 using (IConnection conn = rabbitMqFactory.CreateConnection())
            using (IModel channel = conn.CreateModel())
            {
                channel.ExchangeDeclare(exchange, "direct", durable: true, autoDelete: false);
                channel.QueueDeclare(queue, durable: true, exclusive: false, autoDelete: false);
                channel.QueueBind(queue, exchange, route);

                channel.BasicQos(prefetchSize: 0, prefetchCount: 10, global: false);  #一次接受10条消息，否则rabbit会把所有的消息一次性推到client，会增大client的负荷
                EventingBasicConsumer consumer = new EventingBasicConsumer(channel);
                consumer.Received += (model, ea) =>
                {
                    Byte[] body = ea.Body;
                    String message = Encoding.UTF8.GetString(body);
                    Console.WriteLine( message+Thread.CurrentThread.ManagedThreadId);
                    channel.BasicAck(deliveryTag: ea.DeliveryTag, multiple: false);
                };

                channel.BasicConsume(queue: queue, autoAck: false, consumer: consumer);
                Console.ReadLine();
            }