Artikelserie zur C#-Netzwerkprogrammierung (8) UdpClient implementiert einen synchronisierten UDP-Server

In diesem Artikel wird vorgestellt

Die UdpClient-Klasse bietet einfache Methoden zum Senden und Empfangen verbindungsloser UDP-Pakete im synchronen Blockierungsmodus. Da UDP ein verbindungsloses Transportprotokoll ist, müssen Sie vor dem Senden und Empfangen von Daten keine Remote-Host-Verbindung herstellen. Sie müssen lediglich die Standardoptionen für den Remote-Host wie folgt einrichten:
Erstellen Sie eine Instanz der UdpClient-Klasse mit dem Namen des Remote-Hosts und der Portnummer als Parameter.
Erstellen Sie eine Instanz der UdpClient-Klasse und rufen Sie die Connect-Methode auf.
Sie können jede von UdpClient bereitgestellte Sendemethode verwenden, um Daten an das Remote-Gerät zu senden. Verwenden Sie dann die Methode „Receive“, um Daten vom Remote-Host zu empfangen.
Tipp: Wenn Sie einen Standard-Remote-Host angegeben haben, verwenden Sie nicht den Hostnamen oder IPEndPoint, um die Send-Methode aufzurufen. Wenn Sie dies tun, löst UdpClient eine Ausnahme aus.

Mit der UdpClient-Methode können Sie auch Multicast-Pakete senden und empfangen. UdpClient kann mithilfe der JoinMulticastGroup-Methode bei einer Multicast-Gruppe abonniert werden. Sie können auch die DropMulticastGroup-Methode verwenden, um einen UdpClient von einer Multicast-Gruppe abzumelden.

In diesem Abschnitt wird die Verwendung von UdpClient zum Implementieren eines synchronisierten UDP-Servers vorgestellt

UdpClient synchronisiert den UDP-Server

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net.Sockets;
using System.Net;
using System.Threading;

namespace NetFrame.Net.UDP.Listener.Synchronous
{
    /// <summary>
    /// UdpClient 实现同步UDP服务器
    /// </summary>
    public class UDPServer
    {
        #region Fields
        /// <summary>
        /// 服务器程序允许的最大客户端连接数
        /// </summary>
        private int _maxClient;

        /// <summary>
        /// 当前的连接的客户端数
        /// </summary>
        //private int _clientCount;

        /// <summary>
        /// 服务器使用的异步UdpClient
        /// </summary>
        private UdpClient _server;

        /// <summary>
        /// 客户端会话列表
        /// </summary>
        //private List<UDPState> _clients;

        private bool disposed = false;

        /// <summary>
        /// 数据接受缓冲区
        /// </summary>
        private byte[] _recvBuffer;

        #endregion

        #region Properties

        /// <summary>
        /// 服务器是否正在运行
        /// </summary>
        public bool IsRunning { get; private set; }
        /// <summary>
        /// 监听的IP地址
        /// </summary>
        public IPAddress Address { get; private set; }
        /// <summary>
        /// 监听的端口
        /// </summary>
        public int Port { get; private set; }
        /// <summary>
        /// 通信使用的编码
        /// </summary>
        public Encoding Encoding { get; set; }

        #endregion

        #region 构造函数

        /// <summary>
        /// 同步UdpClient UDP服务器
        /// </summary>
        /// <param name="listenPort">监听的端口</param>
        public UDPServer(int listenPort)
            : this(IPAddress.Any, listenPort,1024)
        {
        }

        /// <summary>
        /// 同步UdpClient UDP服务器
        /// </summary>
        /// <param name="localEP">监听的终结点</param>
        public UDPServer(IPEndPoint localEP)
            : this(localEP.Address, localEP.Port,1024)
        {
        }

        /// <summary>
        /// 同步UdpClient UDP服务器
        /// </summary>
        /// <param name="localIPAddress">监听的IP地址</param>
        /// <param name="listenPort">监听的端口</param>
        /// <param name="maxClient">最大客户端数量</param>
        public UDPServer(IPAddress localIPAddress, int listenPort, int maxClient)
        {
            this.Address = localIPAddress;
            this.Port = listenPort;
            this.Encoding = Encoding.Default;

            _maxClient = maxClient;
            //_clients = new List<AsyncUDPSocketState>();
            _server = new UdpClient(new IPEndPoint(this.Address, this.Port));

            _recvBuffer=new byte[_server.Client.ReceiveBufferSize];
        }

        #endregion

        #region Method
        /// <summary>
        /// 启动服务器
        /// </summary>
        /// <returns>异步TCP服务器</returns>
        public void Start()
        {
            if (!IsRunning)
            {
                IsRunning = true;
                _server.EnableBroadcast = true;
                new Thread(ReceiveData).Start();
            }
        }

        /// <summary>
        /// 停止服务器
        /// </summary>
        public void Stop()
        {
            if (IsRunning)
            {
                IsRunning = false;
                _server.Close();
                //TODO 关闭对所有客户端的连接

            }
        }

        /// <summary>
        /// 同步接收数据的方法
        /// </summary>
        /// <param name="ar"></param>
        private void ReceiveData()
        {
            IPEndPoint remote = null;
            while (true)
            {
                byte[] buffer = null;
                try
                {
                    buffer = _server.Receive(ref remote);
                }
                catch (Exception)
                {
                    //异常处理操作
                    return;
                }
                if (buffer == null || buffer.Length == 0) return;
                //TODO 数据包收到触发事件
                RaiseDataReceived(null);
            }
        }

        /// <summary>
        /// 同步发送数据
        /// </summary>
        /// <param name="msg"></param>
        /// <param name="remote"></param>
        public void Send(string msg, IPEndPoint remote)
        {
            byte[] data = Encoding.Default.GetBytes(msg);
            try
            {
                _server.Send(data, data.Length, remote);
            }
            catch (Exception)
            {
                //TODO 异常处理
                RaiseOtherException(null);
            }
        }

        #endregion

        #region 事件
        /// <summary>
        /// 接收到数据事件
        /// </summary>
        public event EventHandler<UDPEventArgs> DataReceived;

        private void RaiseDataReceived(UDPState state)
        {
            if (DataReceived != null)
            {
                DataReceived(this, new UDPEventArgs(state));
            }
        }

        /// <summary>
        /// 数据发送完毕事件
        /// </summary>
        public event EventHandler<UDPEventArgs> CompletedSend;

        /// <summary>
        /// 触发数据发送完毕的事件
        /// </summary>
        /// <param name="state"></param>
        private void RaiseCompletedSend(UDPState state)
        {
            if (CompletedSend != null)
            {
                CompletedSend(this, new UDPEventArgs(state));
            }
        }

        /// <summary>
        /// 网络错误事件
        /// </summary>
        public event EventHandler<UDPEventArgs> NetError;
        /// <summary>
        /// 触发网络错误事件
        /// </summary>
        /// <param name="state"></param>
        private void RaiseNetError(UDPState state)
        {
            if (NetError != null)
            {
                NetError(this, new UDPEventArgs(state));
            }
        }

        /// <summary>
        /// 异常事件
        /// </summary>
        public event EventHandler<UDPEventArgs> OtherException;
        /// <summary>
        /// 触发异常事件
        /// </summary>
        /// <param name="state"></param>
        private void RaiseOtherException(UDPState state, string descrip)
        {
            if (OtherException != null)
            {
                OtherException(this, new UDPEventArgs(descrip, state));
            }
        }
        private void RaiseOtherException(UDPState state)
        {
            RaiseOtherException(state, "");
        }
        #endregion

        #region Close
        /// <summary>
        /// 关闭一个与客户端之间的会话
        /// </summary>
        /// <param name="state">需要关闭的客户端会话对象</param>
        public void Close(UDPState state)
        {
            if (state != null)
            {
                //_clients.Remove(state);
                //_clientCount--;
                //TODO 触发关闭事件
            }
        }
        /// <summary>
        /// 关闭所有的客户端会话,与所有的客户端连接会断开
        /// </summary>
        public void CloseAllClient()
        {
            //foreach (AsyncUDPSocketState client in _clients)
            //{
            //    Close(client);
            //}
            //_clientCount = 0;
            //_clients.Clear();
        }

        #endregion

        #region 释放
        /// <summary>
        /// Performs application-defined tasks associated with freeing, 
        /// releasing, or resetting unmanaged resources.
        /// </summary>
        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }

        /// <summary>
        /// Releases unmanaged and - optionally - managed resources
        /// </summary>
        /// <param name="disposing"><c>true</c> to release 
        /// both managed and unmanaged resources; <c>false</c> 
        /// to release only unmanaged resources.</param>
        protected virtual void Dispose(bool disposing)
        {
            if (!this.disposed)
            {
                if (disposing)
                {
                    try
                    {
                        Stop();
                        if (_server != null)
                        {
                            _server = null;
                        }
                    }
                    catch (SocketException)
                    {
                        //TODO
                        RaiseOtherException(null);
                    }
                }
                disposed = true;
            }
        }
        #endregion
    }
}

Benutzerstatus-Kapselungsklasse

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net.Sockets;
using System.Net;

namespace NetFrame.Net.UDP.Listener.Synchronous
{
    public class UDPState
    {
        // Client   socket.
        public UdpClient udpClient = null;
        // Size of receive buffer.
        public const int BufferSize = 1024;
        // Receive buffer.
        public byte[] buffer = new byte[BufferSize];
        // Received data string.
        public StringBuilder sb = new StringBuilder();

        public IPEndPoint remote = new IPEndPoint(IPAddress.Any, 0);
    }
}

Server-Ereignisparameterklasse

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace NetFrame.Net.UDP.Listener.Synchronous
{
    /// <summary>
    /// UdpClient 同步UDP服务器事件类
    /// </summary>
    public class UDPEventArgs : EventArgs
    {
        /// <summary>
        /// 提示信息
        /// </summary>
        public string _msg;

        /// <summary>
        /// 客户端状态封装类
        /// </summary>
        public UDPState _state;

        /// <summary>
        /// 是否已经处理过了
        /// </summary>
        public bool IsHandled { get; set; }

        public UDPEventArgs(string msg)
        {
            this._msg = msg;
            IsHandled = false;
        }
        public UDPEventArgs(UDPState state)
        {
            this._state = state;
            IsHandled = false;
        }
        public UDPEventArgs(string msg, UDPState state)
        {
            this._msg = msg;
            this._state = state;
            IsHandled = false;
        }
    }
}

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