1 . 搭建MQTT服务器

找到上传中的 emqx-5.3.2-windows-amd64 打开bin如下：
链接: emqx-5.3.2-windows-amd64

如果安装失败 在上传中找到链接: VC_redist.x64.exe 安装。
正确后在浏览器输入 http://127.0.0.1:18083 会有如下mqtt服务端管理页面：

进入客户端认证，创建一个服务端池。里面设置用户名密码。



c# 中 mqtt 客户端端口用 ip :1883
websoket 端口用 8083

c# 客户端连接

管理NuGet程序包 添加mqttnet

界面

using MQTTnet;
using MQTTnet.Core;
using MQTTnet.Core.Client;
using MQTTnet.Core.Packets;
using MQTTnet.Core.Protocol;
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;namespace WindowsFormsApplication1
{public partial class Form1 : Form{private MqttClient mqttClient = null;public Form1(){InitializeComponent();}private void Form1_Load(object sender, EventArgs e){}//连接方法private async Task ConnectMqttServerAsync(){if (mqttClient == null){mqttClient = new MqttClientFactory().CreateMqttClient() as MqttClient;//创建客户端mqttClient.ApplicationMessageReceived += MqttClient_ApplicationMessageReceived;//接收订阅数据mqttClient.Connected += MqttClient_Connected;//连接成功后mqttClient.Disconnected += MqttClient_Disconnected;//连接不成功}try{var options = new MqttClientTcpOptions{Server = textBox5.Text,// "172.16.6.133",Port =Convert.ToInt32(textBox7.Text),// 1883,ClientId = Guid.NewGuid().ToString().Substring(0, 5),//这个只要不重复就行UserName = textBox3.Text,// "yado",Password = textBox6.Text // "yado123"};await mqttClient.ConnectAsync(options);//根据参数连接}catch (Exception ex){Invoke((new Action(() => {txtReceiveMessage.AppendText($"连接到MQTT服务器失败！" + Environment.NewLine + ex.Message + Environment.NewLine);})));}}//成功连接回调private void MqttClient_Connected(object sender, EventArgs e){Invoke((new Action(() => {txtReceiveMessage.AppendText("已连接到MQTT服务器！" + Environment.NewLine);})));}//断开回调private void MqttClient_Disconnected(object sender, EventArgs e){Invoke((new Action(() => {txtReceiveMessage.AppendText("已断开MQTT连接！" + Environment.NewLine);})));}//接收到订阅消息private void MqttClient_ApplicationMessageReceived(object sender, MqttApplicationMessageReceivedEventArgs e){Invoke((new Action(() => {txtReceiveMessage.AppendText($">> {Encoding.UTF8.GetString(e.ApplicationMessage.Payload)}{Environment.NewLine}");})));}//点击连接private void button3_Click(object sender, EventArgs e){Task.Run(async () => { await ConnectMqttServerAsync(); });}//发布主题private void button1_Click(object sender, EventArgs e){try{string topic = textBox1.Text.Trim();if (string.IsNullOrEmpty(topic)){MessageBox.Show("发布主题不能为空！");return;}string inputString = textBox2.Text.Trim();var appMsg = new MqttApplicationMessage(topic, Encoding.UTF8.GetBytes(inputString), MqttQualityOfServiceLevel.AtMostOnce, false);mqttClient.PublishAsync(appMsg);}catch (Exception ex) {MessageBox.Show(ex.Message);}}//订阅private void button2_Click(object sender, EventArgs e){string topic = textBox4.Text.Trim();if (string.IsNullOrEmpty(topic)){MessageBox.Show("订阅主题不能为空！");return;}if (!mqttClient.IsConnected){MessageBox.Show("MQTT客户端尚未连接！");