public partial class Form1 : Form{private MqttServer mqttServer = null;private MqttClient mqttClient = null;public Form1(){InitializeComponent();}private void button_启动服务端_Click(object sender, EventArgs e){MqttTrace.TraceMessagePublished += MqttTrace_TraceMessagePublished;if (this.mqttServer == null){try{var options = new MqttServerOptions{ConnectionValidator = p =>{if (p.ClientId == "SpecialClient"){if (p.Username != "USER" || p.Password != "PASS"){return MqttConnectReturnCode.ConnectionRefusedBadUsernameOrPassword;}}return MqttConnectReturnCode.ConnectionAccepted;}};mqttServer = new MqttServerFactory().CreateMqttServer(options);}catch (Exception ex){MessageBox.Show(ex.Message);return;}}mqttServer.Start();this.txt_服务器.AppendText( $">> 启动成功..." + Environment.NewLine);}private void MqttTrace_TraceMessagePublished(object sender, MqttTraceMessagePublishedEventArgs e){this.Invoke(new Action(() =>{this.txt_服务器.AppendText($">> [{e.ThreadId}] [{e.Source}] [{e.Level}]: {e.Message}" + Environment.NewLine);if (e.Exception != null){this.txt_服务器.AppendText( e.Exception + Environment.NewLine);}}));}private void button_停止服务端_Click(object sender, EventArgs e){if (mqttServer != null){mqttServer.Stop();}this.txt_服务器.AppendText( $">> 停止成功" + Environment.NewLine);}private async void button_启动客户端_Click(object sender, EventArgs e){if (this.mqttClient == null){var options = new MqttClientOptions{Server = "192.168.2.54",ClientId = "zbl",CleanSession = true};this.mqttClient = new MqttClientFactory().CreateMqttClient(options);this.mqttClient.ApplicationMessageReceived += MqttClient_ApplicationMessageReceived;this.mqttClient.Connected += MqttClient_Connected;this.mqttClient.Disconnected += MqttClient_Disconnected;}try{await this.mqttClient.ConnectAsync();}catch(Exception ex){this.txt_客户端.AppendText( $"### CONNECTING FAILED ###" + Environment.NewLine);}}private void MqttClient_Connected(object sender, EventArgs e){this.Invoke(new Action( async () =>{this.txt_客户端.AppendText( $"### CONNECTED WITH SERVER ###" + Environment.NewLine);await this.mqttClient.SubscribeAsync(new List<TopicFilter>{new TopicFilter("#", MqttQualityOfServiceLevel.AtMostOnce)});this.txt_客户端.AppendText($"### SUBSCRIBED  ###" + Environment.NewLine);}));}private void MqttClient_Disconnected(object sender, EventArgs e){this.Invoke(new Action(() =>{this.txt_客户端.AppendText( $"### DISCONNECTED FROM SERVER ###" + Environment.NewLine);}));}private void MqttClient_ApplicationMessageReceived(object sender, MQTTnet.Core.MqttApplicationMessageReceivedEventArgs e){this.Invoke(new Action(() =>{this.txt_客户端.AppendText( $">> Topic:{e.ApplicationMessage.Topic} Payload:{Encoding.UTF8.GetString(e.ApplicationMessage.Payload)} QoS:{e.ApplicationMessage.QualityOfServiceLevel}   Retain:{e.ApplicationMessage.Retain}" + Environment.NewLine);}));}private async void button_停止客户端_Click(object sender, EventArgs e){if (this.mqttClient != null){await this.mqttClient.DisconnectAsync();}this.txt_客户端.AppendText( $">> 停止成功" + Environment.NewLine);}private async void button_发送_Click(object sender, EventArgs e){//var options = new MqttClientOptions//{//    Server = "localhost"//};//var client = new MqttClientFactory().CreateMqttClient(options);//await client.ConnectAsync();var applicationMessage = new MqttApplicationMessage(this.txt_topic.Text,Encoding.UTF8.GetBytes(this.txt_message.Text), MqttQualityOfServiceLevel.AtMostOnce, false);await this.mqttClient.PublishAsync(applicationMessage);}private void button_清空服务端_Click(object sender, EventArgs e){this.txt_服务器.Text = "";}}