C# 使用M2Mqtt库开发MQTT通信协议

直接上代码：

第一步：使用NugGet 安装 M2Mqtt 工具，选择最新版本即可；

第二步：输入服务器的IP 及端口，创建客户端：

cs 复制代码

        MqttClient client;
        public MqttApi()
        {
            // MQTT服务器IP地址
            string host = "172.16.60.122";
            int serverPort = 1883;
            // 实例化Mqtt客户端 
            client = new MqttClient(host, Convert.ToInt32(serverPort), false, null, null, MqttSslProtocols.TLSv1_2);
        }

第三步：设置主题，订阅主题，然后发送信息

cs 复制代码

   public void SendProgram()
   {
       // MQTT的主题 topic  设备类型
       string topic = "/fac/sensor/data";

       string clientId = Guid.NewGuid().ToString();
       client.Connect(clientId, "admin", "admin123");  // 设置用户名和密码（如果需要）

       // 订阅主题 "/mqtt/test"， 订阅质量 QoS 2 
       client.Subscribe(new string[] { topic }, new byte[] { MqttMsgBase.QOS_LEVEL_EXACTLY_ONCE });

       // 发布消息
       //var msg = "{\"deviceCode\":\"SM001\",\"Program\":{\"ProgramName\":\"ee\",\"WaferMappingFileName\":\"rr\"}}";
       var msg = "{\"deviceCode\":\"SM001\",\"devicestatusInfo\":{\"description\":\"停止\",\"descriptioncode\":2,\"devicestatus\":1,\"preDeviceStatus\":\"\",\"preStatusStartTime\":\"\",\"remark\":\"\",\"statusStarTime\":1712651038054}}";

      var res=  client.Publish(topic, Encoding.UTF8.GetBytes(msg), MqttMsgBase.QOS_LEVEL_AT_LEAST_ONCE, false);

       // 处理消息接收事件(现在 回复消息 可以不订阅这个主题)
       client.MqttMsgPublishReceived += Client_MqttMsgPublishReceived;
   }

   public void Client_MqttMsgPublishReceived(object sender, MqttMsgPublishEventArgs e)
   {
       string message = Encoding.UTF8.GetString(e.Message);
       Console.WriteLine($"Mqtt Received: {message}");
   }

完成。