C#中MQTT的使用小结

using MQTTnet;
using MQTTnet.Client;
using MQTTnet.Client.Options;

// 创建MQTT工厂
var factory = new MqttFactory();

// 配置连接选项
var options = new MqttClientOptionsBuilder()
    .WithClientId("CSharpClient")
    .WithTcpServer("broker.hivemq.com", 1883) // 替换为你的MQTT服务器地址
    .WithCleanSession()
    .Build();

// 创建并连接客户端
var mqttClient = factory.CreateMqttClient();
var connectResult = await mqttClient.ConnectAsync(options);

if (connectResult.ResultCode == MqttClientConnectResultCode.Success)
{
    Console.WriteLine("已成功连接到MQTT服务器！");
    
    // 发布消息
    var message = new MqttApplicationMessageBuilder()
        .WithTopic("test/topic")
        .WithPayload("Hello from C# MQTT!")
        .WithQualityOfServiceLevel(MqttQualityOfServiceLevel.AtLeastOnce) // QoS 1
        .Build();
        
    await mqttClient.PublishAsync(message);
    
    // 订阅主题
    await mqttClient.SubscribeAsync("test/topic");
    
    // 处理收到的消息
    mqttClient.ApplicationMessageReceivedAsync += (e) => 
    {
        Console.WriteLine($"收到消息: {Encoding.UTF8.GetString(e.ApplicationMessage.Payload)}");
        return Task.CompletedTask;
    };
}

// 配置自动重连
var options = new MqttClientOptionsBuilder()
    .WithClientId("CSharpClient")
    .WithTcpServer("your-broker-address", 1883)
    .WithKeepAlivePeriod(TimeSpan.FromSeconds(30))
    .WithConnectionRetryInterval(TimeSpan.FromSeconds(5)) // 重连间隔
    .Build();

// 连接时处理重连
mqttClient.ConnectAsync(options);
mqttClient.DisconnectedAsync += (e) => 
{
    Console.WriteLine("连接已断开，正在尝试重连...");
    return Task.CompletedTask;
};

// 模拟传感器数据
var sensorData = new { Temperature = 25.5, Humidity = 60 };
var json = JsonConvert.SerializeObject(sensorData);

// 发布到MQTT
var message = new MqttApplicationMessageBuilder()
    .WithTopic("sensors/room1")
    .WithPayload(json)
    .WithQualityOfServiceLevel(MqttQualityOfServiceLevel.AtLeastOnce)
    .Build();
    
await mqttClient.PublishAsync(message);

// 从MQTT接收数据，转发到Modbus设备
private void HandleReceivedMessage(MqttApplicationMessageReceivedEventArgs e)
{
    var payload = Encoding.UTF8.GetString(e.ApplicationMessage.Payload);
    
    // 解析数据并写入Modbus设备
    ModbusWriter.WriteToDevice(payload);
}

try
{
    await mqttClient.ConnectAsync(options);
}
catch (Exception ex)
{
    // 记录错误并尝试重连
    Console.WriteLine($"连接失败: {ex.Message}");
}

.WithTls()
.WithTlsVersion(TlsVersion.Tls12)