C# MQTT通讯

前言

MQTTnet是Mqtt的net版本。国内MQTTnet教程比较老旧，都是2.x版本。MQTTnet在4.x版本版本代码逻辑有比较大的改动。所以最后还是面向Github编程。

EMQ X介绍及安装

长链接(MQTT)测试及工具MQTTX使用

MQTTnet

MQTTnet Github官网

MQTTnet简单案例

MQTTnet比较难，要熟练掌握Task异步方法的使用。

MQTT初始变量

//MqttClient工厂private MqttFactory mqttFactory = new MqttFactory();//MqttClient对象private IMqttClient mqttClient;//MqttClient连接选项private MqttClientOptions options;

生成option

options = new MqttClientOptionsBuilder().WithTcpServer(IP地址, 端口号).WithCredentials(用户名, 密码).WithClientId(ClientId).Build();

连接Mqtt服务器

public async Task Connect()
{await mqttClient.ConnectAsync(options);if (mqttClient.IsConnected){Console.WriteLine("连接成功！");}SubTopics.ForEach(async item =>{await mqttClient.SubscribeAsync(item);Console.WriteLine($"订阅:{item}");});HMACSHA256("fa34e04e-43b2-5309-817d-953e9576a07d", "2020050617");Console.WriteLine("服务器连接成功！");}

发送数据

        /// <summary>/// 发送/// </summary>public Task Send(string topic, object payload){var msg = new MqttApplicationMessageBuilder().WithTopic(topic).WithPayload(JsonConvert.SerializeObject(payload)).Build();Console.WriteLine("发送信息");Console.WriteLine($"{topic}");Console.WriteLine($"{JsonConvert.SerializeObject(payload)}");return mqttClient.PublishAsync(msg);}

添加订阅

//订阅事件
await mqttClient.SubscribeAsync(item);

//订阅事件消息接收
mqttClient.ApplicationMessageReceivedAsync += e =>{Console.WriteLine("收到消息");Console.WriteLine($"Topic:{e.ApplicationMessage.Topic}");Console.WriteLine($"Message:{e.ApplicationMessage.ConvertPayloadToString()}");return Task.CompletedTask;};

我们一般主要做的是客户端，详情请看MQTTnet 客户端Github示例