C#实现MQTT服务端与客户端通讯功能

public class MainViewModel : ViewModelBase
    {
        /// <summary>
        /// Initializes a new instance of the MainViewModel class.
        /// </summary>
        public MainViewModel()
        {
            ClientInsTances = new ObservableCollection<ClientInstance>();
        }

        IMqttServer mqttServer;  //MQTT服务端实例

        string message; 

        /// <summary>
        /// 消息   用于界面显示
        /// </summary>
        public string Message
        {
            get { return message; }
            set { message = value; RaisePropertyChanged(); }
        }


        ObservableCollection<ClientInstance> clientInstances; //客户端登陆缓存信息

        /// <summary>
        /// 客户端实例
        /// </summary>
        public ObservableCollection<ClientInstance> ClientInsTances
        {
            get { return clientInstances; }
            set { clientInstances = value; RaisePropertyChanged(); }
        }
　　　　　//开启MQTT服务
        public void OpenMqttServer()
        {
            mqttServer = new MqttFactory().CreateMqttServer();
            var options = new MqttServerOptions();

            //拦截登录
            options.ConnectionValidator = c =>
            {
                try
                {
                    Message += string.FORMat("用户尝试登录:用户ID：{0}\t用户信息：{1}\t用户密码：{2}", c.ClientId, c.Username, c.PassWord) + "\r\n";
                    if (string.IsNullOrWhiteSpace(c.Username))
                    {
                        Message += string.Format("用户：{0}登录失败，用户信息为空", c.ClientId) + "\r\n";

                        c.ReturnCode = MQTTnet.Protocol.MqttConnectReturnCode.ConnectionRefusedBadUsernameOrPassword;
                        return;
                    }
                    //解析用户名和密码，这个地方需要改成查找我们自己创建的用户名和密码。
                    if (c.Username == "admin" && c.Password == "123456")
                    {
                        c.ReturnCode = MqttConnectReturnCode.ConnectionAccepted;
                        Message += c.ClientId + " 登录成功" + "\r\n";
                        ClientInsTances.Add(new ClientInstance()
                        {
                            ClientID = c.ClientId,
                            UserName = c.Username,
                            PassWord = c.Password
                        });
                        return;
                    }
                    else
                    {
                        c.ReturnCode = MqttConnectReturnCode.ConnectionRefusedBadUsernameOrPassword;
                        Message += "用户名密码错误登陆失败" + "\r\n";
                        return;
                    }
                }
                catch (Exception ex)
                {
                    Console.WriteLine("登录失败:" + ex.Message);
                    c.ReturnCode = MqttConnectReturnCode.ConnectionRefusedIdentifierRejected;
                    return;
                }
            };
            //拦截订阅
            options.SubscriptionInterceptor = async context =>
            {
                try
                {
                    Message += "用户" + context.ClientId + "订阅" + "\r\n";
                }
                catch (Exception ex)
                {
                    Console.WriteLine("订阅失败:" + ex.Message);
                    context.AcceptSubscription = false;
                }
            };
            //拦截消息
            options.ApplicationMessageInterceptor = context =>
            {
                try
                {
                    //一般不需要处理消息拦截
                    // Console.WriteLine(Encoding.UTF8.GetString(context.ApplicationMessage.Payload));
                }
                catch (Exception ex)
                {
                    Console.WriteLine("消息拦截:" + ex.Message);
                }
            };

            mqttServer.ClientDisconnected += ClientDisconnected;
            mqttServer.ClientConnected += MqttServer_ClientConnected;
            mqttServer.Started += MqttServer_Started;
            mqttServer.StartAsync(options);

        }


        private void MqttServer_Started(object sender, EventArgs e)
        {
            Message += "消息服务启动成功：任意键退出" + "\r\n";
        }

        private void MqttServer_ClientConnected(object sender, MqttClientConnectedEventArgs e)
        {
            //客户端链接
            Message += e.ClientId + "连接" + "\r\n";
        }

        private void ClientDisconnected(object sender, MqttClientDisconnectedEventArgs e)
        {
            //客户端断开
            Message += e.ClientId + "断开" + "\r\n";
        }

        /// <summary>
        /// 客户端推送信息    -  用于测试服务推送
        /// </summary>
        /// <param name="clientID"></param>
        /// <param name="message"></param>
        public void SendMessage(string clientID, string message)
        {
            mqttServer.PublishAsync(new MqttApplicationMessage
            {
                Topic = clientID,
                QualityOfServiceLevel = MqttQualityOfServiceLevel.ExactlyOnce,
                Retain = false,
                Payload = Encoding.UTF8.GetBytes(message),
            });
        }
    }

    /// <summary>
    /// 登陆客户端信息
    /// </summary>
    public class ClientInstance : ViewModelBase
    {
        private string clientID;
        private string userName;
        private string passWord;

        /// <summary>
        /// 识别ID
        /// </summary>
        public string ClientID
        {
            get { return clientID; }
            set { clientID = value; RaisePropertyChanged(); }
        }

        /// <summary>
        /// 账户
        /// </summary>
        public string UserName
        {
            get { return userName; }
            set { userName = value; RaisePropertyChanged(); }
        }

        /// <summary>
        /// 密码
        /// </summary>
        public string PassWord
        {
            get { return passWord; }
            set { passWord = value; RaisePropertyChanged(); }
        }


    }

public class MainViewModel : ViewModelBase
    {
        /// <summary>
        /// Initializes a new instance of the MainViewModel class.
        /// </summary>
        public MainViewModel()
        {
            clientID = new Random().Next(999, 9999) + ""; //测试随机生成ClientID
        }

        IMqttClient mqttClient;  //MQTT客户端实例

        string clientID; //机器ID


        string message;

        public string Message  //用于接收当前 消息
        {
            get { return message; }
            set { message = value; RaisePropertyChanged(); }
        }
        //开启MQTT连接
        public async void SignMqttServer()
        {
            var options = new MqttClientOptionsBuilder()
             .WithClientId(clientID) //传递ClientID 
             .WithTcpServer("127.0.0.1", 1883)  //MQTT服务的地址
             .WithCredentials("admin", "123456") //传递账号密码
             .WithCleanSession()
             .Build();
            mqttClient = new MqttFactory().CreateMqttClient();// .CreateManagedMqttClient();
            mqttClient.Connected += MqttClient_Connected;
            mqttClient.Disconnected += MqttClient_Disconnected;
            mqttClient.ApplicationMessageReceived += MqttClient_ApplicationMessageReceived; //创建消息接受事件

            await mqttClient.ConnectAsync(options);
            //await mqttClient.SubscribeAsync(clientID);
        }

        private void MqttClient_ApplicationMessageReceived(object sender, MqttApplicationMessageReceivedEventArgs e)
        {
            Message += "收到的信息:" + Encoding.UTF8.GetString(e.ApplicationMessage.Payload) + "\r\n";
        }

        private void MqttClient_Disconnected(object sender, MqttClientDisconnectedEventArgs e)
        {
            Message += "客户端断开";
        }

        private void MqttClient_Connected(object sender, MqttClientConnectedEventArgs e)
        {
            Message += "客户端已连接" + "\r\n";
            mqttClient.SubscribeAsync(new TopicFilterBuilder().WithTopic(clientID).Build()); //关联服务端订阅, 用于接受服务端推送信息

        }
    }