zhuangpei-mesbackend/Infrastructure/Helper/MqttHelper.cs

using MQTTnet;
using MQTTnet.Formatter;
using MQTTnet.Protocol;
using System;
using System.Threading.Tasks;
namespace DOAN.Infrastructure.Helper
{

    /// <summary>
    /// MQTT 消息发送工具类
    /// </summary>
    public class MqttHelper : IDisposable
    {
        // MQTT Broker 配置（可外部设置或配置文件读取）
        public string MqttBrokerUrl { get; set; } = "broker.hivemq.com";
        public int MqttBrokerPort { get; set; } = 1883;
        public string MqttUsername { get; set; } = null;
        public string MqttPassword { get; set; } = null;

        private IMqttClient _mqttClient;

        private bool _disposed = false;

        /// <summary>
        /// 构造函数 - 使用默认配置
        /// </summary>
        public MqttHelper() { }

        /// <summary>
        /// 构造函数 - 自定义配置
        /// </summary>
        public MqttHelper(string brokerUrl, int brokerPort, string username = null, string password = null)
        {
            MqttBrokerUrl = brokerUrl;
            MqttBrokerPort = brokerPort;
            MqttUsername = username;
            MqttPassword = password;
        }

        /// <summary>
        /// 连接到 MQTT Broker
        /// </summary>
        public async Task<bool> ConnectAsync()
        {
            try
            {
                if (_mqttClient?.IsConnected == true)
                {
                    Console.WriteLine("MQTT 客户端已经连接");
                    return true;
                }

                var factory = new MqttClientFactory();
                _mqttClient = factory.CreateMqttClient();

                var options = new MqttClientOptionsBuilder()
                    .WithTcpServer(MqttBrokerUrl, MqttBrokerPort)
                    .WithCredentials(MqttUsername, MqttPassword)
                    .WithCleanSession()
                    .Build();

                Console.WriteLine($"正在连接到 MQTT Broker: {MqttBrokerUrl}:{MqttBrokerPort}...");
                await _mqttClient.ConnectAsync(options);

                Console.WriteLine(" MQTT 连接成功！");
                return true;
            }
            catch (Exception ex)
            {
                Console.WriteLine($" MQTT 连接失败: {ex.Message}");
                return false;
            }
        }

        /// <summary>
        /// 发送消息到指定主题
        /// </summary>
        /// <param name="topic">目标主题</param>
        /// <param name="messageContent">消息内容</param>
        /// <param name="qosLevel">QoS 级别，默认为 AtLeastOnce(1)</param>
        /// <param name="retain">是否保留消息，默认为 false</param>
        public async Task<bool> PublishMessageAsync(string topic, string messageContent,
            MqttQualityOfServiceLevel qosLevel = MqttQualityOfServiceLevel.AtLeastOnce,
            bool retain = false)
        {
            try
            {
                if (_mqttClient?.IsConnected != true)
                {
                    Console.WriteLine("MQTT 客户端未连接，尝试重新连接...");
                    if (!await ConnectAsync())
                    {
                        Console.WriteLine(" 重连失败，无法发送消息");
                        return false;
                    }
                }

                var message = new MqttApplicationMessageBuilder()
                    .WithTopic(topic)
                    .WithPayload(messageContent)
                    .WithQualityOfServiceLevel(qosLevel)
                    .WithRetainFlag(retain)
                    .Build();

                Console.WriteLine($"正在向主题 '{topic}' 发送消息: {messageContent}");
                await _mqttClient.PublishAsync(message);

                Console.WriteLine(" 消息发送成功！");
                return true;
            }
            catch (Exception ex)
            {
                Console.WriteLine($" 消息发送失败: {ex.Message}");
                return false;
            }
        }

        /// <summary>
        /// 发送消息（使用默认主题配置）
        /// </summary>
        /// <param name="messageContent">消息内容</param>
        /// <param name="qosLevel">QoS 级别</param>
        /// <param name="retain">是否保留消息</param>
        public async Task<bool> PublishMessageAsync(string messageContent,
            MqttQualityOfServiceLevel qosLevel = MqttQualityOfServiceLevel.AtLeastOnce,
            bool retain = false)
        {
            return await PublishMessageAsync("product/topic", messageContent, qosLevel, retain);
        }

        /// <summary>
        /// 断开 MQTT 连接
        /// </summary>
        public async Task DisconnectAsync()
        {
            try
            {
                if (_mqttClient?.IsConnected == true)
                {
                    await _mqttClient.DisconnectAsync();
                    Console.WriteLine(" MQTT 已断开连接");
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine($" 断开连接时发生错误: {ex.Message}");
            }
        }

        /// <summary>
        /// 检查是否已连接
        /// </summary>
        public bool IsConnected => _mqttClient?.IsConnected == true;

        /// <summary>
        /// 释放资源
        /// </summary>
        public void Dispose()
        {
            if (!_disposed)
            {
                DisconnectAsync().Wait();
                _mqttClient?.Dispose();
                _disposed = true;
            }
        }
    }

}