C#網頁程式設計系列文章(八)之UdpClient實作同步UDP伺服器

本文介紹

UdpClient 類別在同步阻塞模式中為發送和接收無連接的 UDP 封包而提供了簡單的方法。因為 UDP 是一種無連線的傳輸協議，所以你不需要在發送和接收資料之前建立任何遠端主機連線。你只需要按照下列方式來建立預設的遠端主機選項：
使用遠端主機名稱和連接埠號碼作為參數來建立 UdpClient 類別的實例。
建立 UdpClient 類別的實例然後呼叫 Connect 方法。
你可以使用任何由 UdpClient 所提供的傳送方法把資料傳送給遠端裝置。然後使用 Receive 方法來接收來自遠端主機的資料。
提示：如果你已經指定了一個預設的遠端主機，就不要使用主機名稱或 IPEndPoint 來呼叫 Send 方法。如果你這樣做，那麼 UdpClient 將會拋出一個例外。

UdpClient 方法同樣允許你傳送和接收多點傳送的資料包。而使用 JoinMulticastGroup 方法可以把 UdpClient 訂閱到多點傳送分組。也可以使用 DropMulticastGroup 方法把 UdpClient 從多點傳送分組的訂閱中取消。

本節介紹使用UdpClient實作一個同步的UDP伺服器

UdpClient同步UDP伺服器

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
    }
}

使用者狀態封裝類

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);
    }
}

伺服器事件參數類別

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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