C#实现数据采集系统-数据反写（1）MQTT订阅接收消息

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C#实现数据采集系统-数据反写

实现步骤

1. MQTT订阅，接收消息
2. 反写内容写入通信类，添加到写入队列中 链接-消息内容处理和写入通信类队列
3. 实现Modbustcp通信写入

具体实现

1.MQTT订阅，接收消息

Mqtt实现采集数据转发

Mqtt控制类增加订阅方法

1. 增加一个通用的订阅方法，需要的参数是一个主题和一个委托，将主题跟对应的委托方法对应存储，然后再mqtt中订阅，收到对应的主题消息，然后执行对应的方法。

 public void SubscribeTopic(string topic, Action<string, string> topicAction){//订阅}

然后需要一个键值对用于存储这个关系

 private Dictionary<string, Action<string, string>> _topicActions;

订阅方法实现：订阅主题，添加到_topicActions，如果已经连接，则直接订阅，没有连接，则等待连上的时候自动订阅，增加锁来确保订阅成功

/// <summary>
/// 订阅主题，添加到_topicActions，如果已经连接，则直接订阅
/// </summary>
/// <param name="topic"></param>
/// <param name="topicAction"></param>
public void SubscribeTopic(string topic, Action<string, string> topicAction)
{lock (_topicActionsLock){if (!_topicActions.ContainsKey(topic)){_topicActions.Add(topic, topicAction);if (_mqttClient.IsConnected){_mqttClient.SubscribeAsync(topic);}}}}

在连接方法中，添加订阅

public void MqttConnect()
{while (!_mqttClient.IsConnected){try{Console.WriteLine($"正在连接……");_mqttClient.ConnectAsync(_clientOptions).GetAwaiter().GetResult();}catch (Exception ex){Task.Delay(1000).Wait();Console.WriteLine("连接mqtt服务器失败");}}lock (_topicActionsLock){foreach (var item in _topicActions){_mqttClient.SubscribeAsync(item.Key);}}}

1. 添加接收消息事件

 //客户端接收消息事件_mqttClient.ApplicationMessageReceivedAsync +=MqttClient_ApplicationMessageReceivedAsync;/// <summary>/// 接收消息/// </summary>/// <param name="args"></param>/// <returns></returns>private async Task MqttClient_ApplicationMessageReceivedAsync(MqttApplicationMessageReceivedEventArgs args){try{Console.WriteLine($"收到消息：{args.ApplicationMessage.Topic}");if (_topicActions.ContainsKey(args.ApplicationMessage.Topic)){_topicActions[args.ApplicationMessage.Topic].Invoke(args.ApplicationMessage.Topic,Encoding.UTF8.GetString(args.ApplicationMessage.Payload));}}catch (Exception ex){Console.WriteLine(ex.Message);}}

完整Mqtt代码

 public class MqttControllor{private MqttConfig _config;private string _clientId;MqttClientOptions _clientOptions;private IMqttClient _mqttClient;private readonly object _topicActionsLock = new object();private Dictionary<string, Action<string, string>> _topicActions;public MqttControllor(MqttConfig config, bool isAutoConnect = true){_topicActions = new Dictionary<string, Action<string, string>>();_config = config;_clientId = config.ClientId == "" ? Guid.NewGuid().ToString() : config.ClientId;MqttClientOptionsBuilder optionsBuilder = new MqttClientOptionsBuilder().WithTcpServer(_config.Ip, _config.Port).WithCredentials(_config.Username, _config.Password).WithClientId(_clientId);_clientOptions = optionsBuilder.Build();_mqttClient = new MqttFactory().CreateMqttClient();// 客户端连接关闭事件_mqttClient.DisconnectedAsync += MqttClient_DisconnectedAsync;//客户端接收消息事件_mqttClient.ApplicationMessageReceivedAsync +=MqttClient_ApplicationMessageReceivedAsync;if (isAutoConnect){Task.Run(() =>{MqttConnect();});}}/// <summary>/// 接收消息/// </summary>/// <param name="args"></param>/// <returns></returns>private async Task MqttClient_ApplicationMessageReceivedAsync(MqttApplicationMessageReceivedEventArgs args){try{Console.WriteLine($"收到消息：{args.ApplicationMessage.Topic}");if (_topicActions.ContainsKey(args.ApplicationMessage.Topic)){_topicActions[args.ApplicationMessage.Topic].Invoke(args.ApplicationMessage.Topic,Encoding.UTF8.GetString(args.ApplicationMessage.Payload));}}catch (Exception ex){Console.WriteLine(ex.Message);}}private Task MqttClient_DisconnectedAsync(MqttClientDisconnectedEventArgs arg){Console.WriteLine($"客户端已断开与服务端的连接……");//断开重连_mqttClient = new MqttFactory().CreateMqttClient();MqttConnect();return Task.CompletedTask;}public void MqttConnect(){while (!_mqttClient.IsConnected){try{Console.WriteLine($"正在连接……");_mqttClient.ConnectAsync(_clientOptions).GetAwaiter().GetResult();}catch (Exception ex){Task.Delay(1000).Wait();Console.WriteLine("连接mqtt服务器失败");}}Console.WriteLine($"客户端已连接到服务端……");//连接成功，订阅主题lock (_topicActionsLock){foreach (var item in _topicActions){_mqttClient.SubscribeAsync(item.Key);}}}/// <summary>/// 订阅主题，添加到_topicActions，如果已经连接，则直接订阅/// </summary>/// <param name="topic"></param>/// <param name="topicAction"></param>public void SubscribeTopic(string topic, Action<string, string> topicAction){lock (_topicActionsLock){if (!_topicActions.ContainsKey(topic)){_topicActions.Add(topic, topicAction);if (_mqttClient.IsConnected){_mqttClient.SubscribeAsync(topic);}}}}/// <summary>/// 推送消息/// </summary>/// <param name="topic">主题</param>/// <param name="data">消息内容</param>/// <param name="qsLevel"></param>/// <param name="retain"></param>public void Publish(string topic, string data, int qsLevel = 0, bool retain = false){qsLevel = Math.Clamp(qsLevel, 0, 2);if (!_mqttClient.IsConnected){throw new Exception("mqtt未连接");}var message = new MqttApplicationMessage{Topic = topic,PayloadSegment = Encoding.UTF8.GetBytes(data),QualityOfServiceLevel = (MqttQualityOfServiceLevel)qsLevel,Retain = retain // 服务端是否保留消息。true为保留，如果有新的订阅者连接，就会立马收到该消息。};_mqttClient.PublishAsync(message);}}

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