MQTT客户端Paho实现C#应用

1、打开C#工程，然后 打开“工具”-“Nuget包管理器”-“程序包管理器控制台”。

2、输入命令，安装M2Mqtt 包。

NuGet\Install-Package M2Mqtt -Version 4.3.0

3、MQTT服务器。

• Broker: broker.emqx.io
• TCP Port: 1883
• WebSocket Port: 8083

4、测试代码。

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using uPLibrary.Networking.M2Mqtt;
using uPLibrary.Networking.M2Mqtt.Messages;

namespace mqtt
{
    public partial class FormMain : Form
    {
        public FormMain()
        {
            InitializeComponent();
        }

        /// <summary>
        /// 连接
        /// </summary>
        /// <param name="broker"></param>
        /// <param name="port"></param>
        /// <param name="clientId"></param>
        /// <param name="username"></param>
        /// <param name="password"></param>
        /// <returns></returns>
        static MqttClient ConnectMQTT(string broker, int port, string clientId, string username, string password)
        {
            MqttClient client = new MqttClient(broker, port, false, MqttSslProtocols.None, null, null);
            client.Connect(clientId, username, password);
            if (client.IsConnected)
            {
                Console.WriteLine("Connected to MQTT Broker");
            }
            else
            {
                Console.WriteLine("Failed to connect");
            }
            return client;
        }

        /// <summary>
        /// 发布
        /// </summary>
        /// <param name="client"></param>
        /// <param name="topic"></param>
        static void Publish(MqttClient client, string topic)
        {
            int msg_count = 0;
            while (true)
            {
                System.Threading.Thread.Sleep(1 * 1000);
                string msg = "messages: " + msg_count.ToString();
                client.Publish(topic, System.Text.Encoding.UTF8.GetBytes(msg));
                Console.WriteLine("Send `{0}` to topic `{1}`", msg, topic);
                msg_count++;
            }
        }

        /// <summary>
        /// 订阅
        /// </summary>
        /// <param name="client"></param>
        /// <param name="topic"></param>
        static void Subscribe(MqttClient client, string topic)
        {
            client.MqttMsgPublishReceived += client_MqttMsgPublishReceived;
            client.Subscribe(new string[] { topic }, new byte[] { MqttMsgBase.QOS_LEVEL_AT_MOST_ONCE });
        }
        
        /// <summary>
        /// 消息接收
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        static void client_MqttMsgPublishReceived(object sender, MqttMsgPublishEventArgs e)
        {
            string payload = System.Text.Encoding.Default.GetString(e.Message);
            Console.WriteLine("Received `{0}` from `{1}` topic", payload, e.Topic.ToString());
        }

        /// <summary>
        /// 启动
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btnStart_Click(object sender, EventArgs e)
        {
            //tbLogLine.BeginInvoke(new Action(() => { tbLogLine.AppendText("" + Environment.NewLine); }));

            string broker = "broker.emqx.io";
            int port = 1883;
            string topic = "Csharp/mqtt";
            string clientId = Guid.NewGuid().ToString();
            string username = "emqx";
            string password = "public";
            MqttClient client = ConnectMQTT(broker, port, clientId, username, password);
            Subscribe(client, topic);
            Publish(client, topic);
        }
    }
}