mqttnet3.0用法

.net常用的mqtt类库有2个，m2mqtt和mqttnet两个类库

当然了，这两个库的教程网上一搜一大把

但mqttnet搜到的教程全是2.7及以下版本的，但3.0版语法却不再兼容，升级版本会导致很多问题，今天进行了成功的升级，现记录下来

参考文档地址：https://github.com/chkr1011/MQTTnet/wiki/Client

上代码：

 ///开源库地址：https://github.com/chkr1011/MQTTnet
 ///对应文档：https://github.com/chkr1011/MQTTnet/wiki/Client
 
 using MQTTnet;
 using MQTTnet.Client;
 using MQTTnet.Client.Options;
 using System;
 using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
 using System.Windows.Forms;
 
 namespace MqttServerTest
 {
     public partial class mqtt测试工具 : Form
     {
         private IMqttClient mqttClient = null;
         private bool isReconnect = true;
 
         public mqtt测试工具()
         {
             InitializeComponent();
         }
 
         private void Form1_Load(object sender, EventArgs e)
         {
 
         }
 
         private async void BtnPublish_Click(object sender, EventArgs e)
         {
             await Publish();
         }
 
         private async void BtnSubscribe_ClickAsync(object sender, EventArgs e)
         {
             await Subscribe();
         }
 
         private async Task Publish()
         {
             string topic = txtPubTopic.Text.Trim();
 
             if (string.IsNullOrEmpty(topic))
             {
                 MessageBox.Show("发布主题不能为空！");
                 return;
             }
 
             string inputString = txtSendMessage.Text.Trim();
             try
             {
 
                 var message = new MqttApplicationMessageBuilder()
         .WithTopic(topic)
         .WithPayload(inputString)
         .WithExactlyOnceQoS()
         .WithRetainFlag()
         .Build();
 
                 await mqttClient.PublishAsync(message);
             }
             catch (Exception ex)
             {
 
                 Invoke((new Action(() =>
                 {
                     txtReceiveMessage.AppendText($"发布主题失败！" + Environment.NewLine + ex.Message + Environment.NewLine);
                 })));
             }
 
         }
 
         private async Task Subscribe()
         {
             string topic = txtSubTopic.Text.Trim();
 
             if (string.IsNullOrEmpty(topic))
             {
                 MessageBox.Show("订阅主题不能为空！");
                 return;
             }
 
             if (!mqttClient.IsConnected)
             {
                 MessageBox.Show("MQTT客户端尚未连接！");
                 return;
             }
 
             // Subscribe to a topic
             await mqttClient.SubscribeAsync(new TopicFilterBuilder()
                 .WithTopic(topic)
                 .WithAtMostOnceQoS()
                 .Build()
                 );
             Invoke((new Action(() =>
             {
                 txtReceiveMessage.AppendText($"已订阅[{topic}]主题{Environment.NewLine}");
             })));
 
         }
 
         private async Task ConnectMqttServerAsync()
         {
             // Create a new MQTT client.
 
             if (mqttClient == null)
             {
                 try
                 {
                     var factory = new MqttFactory();
                     mqttClient = factory.CreateMqttClient();
 
                     var options = new MqttClientOptionsBuilder()
                         .WithTcpServer(txtIp.Text, Convert.ToInt32(txtPort.Text)).WithCredentials(txtUsername.Text, txtPsw.Text).WithClientId(txtClientId.Text) // Port is optional
                         .Build();
 
                     await mqttClient.ConnectAsync(options, CancellationToken.None);
                     Invoke((new Action(() =>
                     {
                         txtReceiveMessage.AppendText($"连接到MQTT服务器成功！" + txtIp.Text);
                     })));
                     mqttClient.UseApplicationMessageReceivedHandler(e =>
                     {
 
                         Invoke((new Action(() =>
                         {
                             txtReceiveMessage.AppendText($"收到订阅消息！" + Encoding.UTF8.GetString(e.ApplicationMessage.Payload));
                         })));
 
                     });
                 }
                 catch (Exception ex)
                 {
 
                     Invoke((new Action(() =>
                     {
                         txtReceiveMessage.AppendText($"连接到MQTT服务器失败！" + Environment.NewLine + ex.Message + Environment.NewLine);
                     })));
                 }
             }
         }
 
         private void MqttClient_Connected(object sender, EventArgs e)
         {
             Invoke((new Action(() =>
             {
                 txtReceiveMessage.Clear();
                 txtReceiveMessage.AppendText("已连接到MQTT服务器！" + Environment.NewLine);
             })));
         }
 
         private void MqttClient_Disconnected(object sender, EventArgs e)
         {
             Invoke((new Action(() =>
             {
                 txtReceiveMessage.Clear();
                 DateTime curTime = new DateTime();
                 curTime = DateTime.UtcNow;
                 txtReceiveMessage.AppendText($">> [{curTime.ToLongTimeString()}]");
                 txtReceiveMessage.AppendText("已断开MQTT连接！" + Environment.NewLine);
             })));
 
             //Reconnecting
             if (isReconnect)
             {
                 Invoke((new Action(() =>
                 {
                     txtReceiveMessage.AppendText("正在尝试重新连接" + Environment.NewLine);
                 })));
 
                 var options = new MqttClientOptionsBuilder()
                     .WithClientId(txtClientId.Text)
                     .WithTcpServer(txtIp.Text, Convert.ToInt32(txtPort.Text))
                     .WithCredentials(txtUsername.Text, txtPsw.Text)
                     //.WithTls()
                     .WithCleanSession()
                     .Build();
                 Invoke((new Action(async () =>
                 {
                     await Task.Delay(TimeSpan.FromSeconds());
                     try
                     {
                         await mqttClient.ConnectAsync(options);
                     }
                     catch
                     {
                         txtReceiveMessage.AppendText("### RECONNECTING FAILED ###" + Environment.NewLine);
                     }
                 })));
             }
             else
             {
                 Invoke((new Action(() =>
                 {
                     txtReceiveMessage.AppendText("已下线！" + Environment.NewLine);
                 })));
             }
         }
 
         private void MqttClient_ApplicationMessageReceived(object sender, MqttApplicationMessageReceivedEventArgs e)
         {
             Invoke((new Action(() =>
             {
                 txtReceiveMessage.AppendText($">> {"### RECEIVED APPLICATION MESSAGE ###"}{Environment.NewLine}");
             })));
             Invoke((new Action(() =>
             {
                 txtReceiveMessage.AppendText($">> Topic = {e.ApplicationMessage.Topic}{Environment.NewLine}");
             })));
             Invoke((new Action(() =>
             {
                 txtReceiveMessage.AppendText($">> Payload = {Encoding.UTF8.GetString(e.ApplicationMessage.Payload)}{Environment.NewLine}");
             })));
             Invoke((new Action(() =>
             {
                 txtReceiveMessage.AppendText($">> QoS = {e.ApplicationMessage.QualityOfServiceLevel}{Environment.NewLine}");
             })));
             Invoke((new Action(() =>
             {
                 txtReceiveMessage.AppendText($">> Retain = {e.ApplicationMessage.Retain}{Environment.NewLine}");
             })));
         }
 
         private void btnLogIn_Click(object sender, EventArgs e)
         {
             isReconnect = true;
             Task.Run(async () => { await ConnectMqttServerAsync(); });
         }
 
         private void btnLogout_Click(object sender, EventArgs e)
         {
             isReconnect = false;
             Task.Run(async () => { await mqttClient.DisconnectAsync(); });
         }
 
     }
 }