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();
            }