如何使用C#在Bluemix上通过MQTT发布JSON数据？

using MQTTnet;
using MQTTnet.Client;
using MQTTnet.Client.Options;
using MQTTnet.Extensions.ManagedClient;

var mqttClient = new MqttFactory().CreateManagedMqttClient();
var options = new ManagedMqttClientOptionsBuilder()
    .WithAutoReconnectDelay(TimeSpan.FromSeconds(5))
    .WithClientOptions(new MqttClientOptionsBuilder()
        .WithTcpServer("mqtt.example.com", 1883) // 替换为MQTT服务器的地址和端口
        .WithCredentials("username", "password") // 替换为MQTT服务器的用户名和密码
        .WithCleanSession()
        .Build())
    .Build();

await mqttClient.StartAsync(options);

var jsonData = new
{
    key1 = "value1",
    key2 = "value2"
};
var jsonString = Newtonsoft.Json.JsonConvert.SerializeObject(jsonData);

var message = new MqttApplicationMessageBuilder()
    .WithTopic("topic") // 替换为要发布的主题
    .WithPayload(jsonString)
    .WithQualityOfServiceLevel(MqttQualityOfServiceLevel.AtLeastOnce)
    .WithRetainFlag(false)
    .Build();

await mqttClient.PublishAsync(message);