MainForm.cs窗體程式碼:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Net;
using System.Text;
using System.Windows.Forms;

namespace IocpServer
{
    public partial class MainForm : Form
    {
        public delegate void
 
 SetListBoxCallBack(string str);
        public SetListBoxCallBack setlistboxcallback;
        public void SetListBox(string str)
        {
            infoList.Items.Insert(0, str);
            infoList.SelectedIndex = 0;
        }

        private IoServer iocp = new IoServer(2, 1024);

        public
 
 MainForm()
        {
            InitializeComponent();
            #region 初始化IP 和埠號
            IPAddress[] addressList = Dns.GetHostEntry(Environment.MachineName).AddressList;
            ipStr.Text = addressList[addressList.Length - 1].ToString();

            portStr.Text = "1086";
            #endregion
 

            setlistboxcallback = new SetListBoxCallBack(SetListBox);
        }

        private void startBtn_Click(object sender, EventArgs e)
        {
            iocp.Start(1086);
            iocp.mainForm = this;
            startBtn.Enabled = false;
            stopBtn.Enabled = true;
            SetListBox("監聽開啟...");
        }

        private void stopBtn_Click(object sender, EventArgs e)
        {
            iocp.Stop();
            startBtn.Enabled = true;
            stopBtn.Enabled = false;
            SetListBox("監聽停止...");
        }

        private void exitBtn_Click(object sender, EventArgs e)
        {
            if (stopBtn.Enabled)
                iocp.Stop();
            this.Close();
        }

        private void clearBtn_Click(object sender, EventArgs e)
        {
            infoList.Items.Clear();
        }

    }
}

IoServer.cs

基於SocketAsyncEventArgs 實現 IOCP 伺服器

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

namespace IocpServer
{
    /// <summary>
    /// 基於SocketAsyncEventArgs 實現 IOCP 伺服器
    /// </summary>
    internal sealed class IoServer
    {
        /// <summary>
        /// 監聽Socket，用於接受客戶端的連線請求
        /// </summary>
        private Socket listenSocket;

        /// <summary>
        /// 用於伺服器執行的互斥同步物件
        /// </summary>
        private static Mutex mutex = new Mutex();

        /// <summary>
        /// 用於每個I/O Socket操作的緩衝區大小
        /// </summary>
        private Int32 bufferSize;

        /// <summary>
        /// 伺服器上連線的客戶端總數
        /// </summary>
        private Int32 numConnectedSockets;

        /// <summary>
        /// 伺服器能接受的最大連線數量
        /// </summary>
        private Int32 numConnections;

        /// <summary>
        /// 完成埠上進行投遞所用的IoContext物件池
        /// </summary>
        private IoContextPool ioContextPool;

        public MainForm mainForm;

        /// <summary>
        /// 建構函式，建立一個未初始化的伺服器例項
        /// </summary>
        /// <param name="numConnections">伺服器的最大連線資料</param>
        /// <param name="bufferSize"></param>
        internal IoServer(Int32 numConnections, Int32 bufferSize)
        {
            this.numConnectedSockets = 0;
            this.numConnections = numConnections;
            this.bufferSize = bufferSize;

            this.ioContextPool = new IoContextPool(numConnections);

            // 為IoContextPool預分配SocketAsyncEventArgs物件
            for (Int32 i = 0; i < this.numConnections; i++)
            {
                SocketAsyncEventArgs ioContext = new SocketAsyncEventArgs();
                ioContext.Completed += new EventHandler<SocketAsyncEventArgs>(OnIOCompleted);
                ioContext.SetBuffer(new Byte[this.bufferSize], 0, this.bufferSize);

                // 將預分配的物件加入SocketAsyncEventArgs物件池中
                this.ioContextPool.Add(ioContext);
            }
        }

        /// <summary>
        /// 當Socket上的傳送或接收請求被完成時，呼叫此函式
        /// </summary>
        /// <param name="sender">激發事件的物件</param>
        /// <param name="e">與傳送或接收完成操作相關聯的SocketAsyncEventArg物件</param>
        private void OnIOCompleted(object sender, SocketAsyncEventArgs e)
        {
            // Determine which type of operation just completed and call the associated handler.
            switch (e.LastOperation)
            {
                case SocketAsyncOperation.Receive:
                    this.ProcessReceive(e);
                    break;
                case SocketAsyncOperation.Send:
                    this.ProcessSend(e);
                    break;
                default:
                    throw new ArgumentException("The last operation completed on the socket was not a receive or send");
            }
        }

        /// <summary>
        ///接收完成時處理函式
        /// </summary>
        /// <param name="e">與接收完成操作相關聯的SocketAsyncEventArg物件</param>
        private void ProcessReceive(SocketAsyncEventArgs e)
        {
            // 檢查遠端主機是否關閉連線
            if (e.BytesTransferred > 0)
            {
                if (e.SocketError == SocketError.Success)
                {
                    Socket s = (Socket)e.UserToken;
                    //判斷所有需接收的資料是否已經完成
                    if (s.Available == 0)
                    {

                        //獲取接收到的資料
                        byte[] ByteArray = new byte[e.BytesTransferred];
                        Array.Copy(e.Buffer, 0, ByteArray, 0, ByteArray.Length);

                        //設定傳送資料（自定義資料）
                        //byte[] bt = new byte[10] { 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01 };
                        //e.SetBuffer(e.Offset, bt.Length);
                        //Array.Copy(bt, 0, e.Buffer, 0, bt.Length);
                        //e.SetBuffer(e.Offset, bt.Length);

                        //設定傳送的資料（原樣返回）
                        Array.Copy(e.Buffer, 0, e.Buffer, e.BytesTransferred, e.BytesTransferred);
                        e.SetBuffer(e.Offset, e.BytesTransferred);


                        if (!s.SendAsync(e))        //投遞傳送請求，這個函式有可能同步傳送出去，這時返回false，並且不會引發SocketAsyncEventArgs.Completed事件
                        {
                            // 同步傳送時處理髮送完成事件
                            this.ProcessSend(e);
                        }
                    }
                    else if (!s.ReceiveAsync(e))    //為接收下一段資料，投遞接收請求，這個函式有可能同步完成，這時返回false，並且不會引發SocketAsyncEventArgs.Completed事件
                    {
                        // 同步接收時處理接收完成事件
                        this.ProcessReceive(e);
                    }
                }
                else
                {
                    this.ProcessError(e);
                }
            }
            else
            {
                this.CloseClientSocket(e);
            }
        }

        /// <summary>
        /// 傳送完成時處理函式
        /// </summary>
        /// <param name="e">與傳送完成操作相關聯的SocketAsyncEventArg物件</param>
        private void ProcessSend(SocketAsyncEventArgs e)
        {
            if (e.SocketError == SocketError.Success)
            {
                Socket s = (Socket)e.UserToken;

                //接收時根據接收的位元組數收縮了緩衝區的大小，因此投遞接收請求時，恢復緩衝區大小
                e.SetBuffer(0, bufferSize);
                if (!s.ReceiveAsync(e))     //投遞接收請求
                {
                    // 同步接收時處理接收完成事件
                    this.ProcessReceive(e);
                }
            }
            else
            {
                this.ProcessError(e);
            }
        }

        /// <summary>
        /// 處理socket錯誤
        /// </summary>
        /// <param name="e"></param>
        private void ProcessError(SocketAsyncEventArgs e)
        {
            Socket s = e.UserToken as Socket;
            IPEndPoint localEp = s.LocalEndPoint as IPEndPoint;

            this.CloseClientSocket(s, e);

            string outStr = String.Format("套接字錯誤 {0}, IP {1}, 操作 {2}。", (Int32)e.SocketError, localEp, e.LastOperation);
            mainForm.Invoke(mainForm.setlistboxcallback, outStr);
            //Console.WriteLine("Socket error {0} on endpoint {1} during {2}.", (Int32)e.SocketError, localEp, e.LastOperation);
        }

        /// <summary>
        /// 關閉socket連線
        /// </summary>
        /// <param name="e">SocketAsyncEventArg associated with the completed send/receive operation.</param>
        private void CloseClientSocket(SocketAsyncEventArgs e)
        {
            Socket s = e.UserToken as Socket;
            this.CloseClientSocket(s, e);
        }

        private void CloseClientSocket(Socket s, SocketAsyncEventArgs e)
        {
            Interlocked.Decrement(ref this.numConnectedSockets);

            // SocketAsyncEventArg 物件被釋放，壓入可重用佇列。
            this.ioContextPool.Push(e);            
            string outStr = String.Format("客戶 {0} 斷開, 共有 {1} 個連線。", s.RemoteEndPoint.ToString(), this.numConnectedSockets);
            mainForm.Invoke(mainForm.setlistboxcallback, outStr);            
            //Console.WriteLine("A client has been disconnected from the server. There are {0} clients connected to the server", this.numConnectedSockets);
            try
            {
                s.Shutdown(SocketShutdown.Send);
            }
            catch (Exception)
            {
                // Throw if client has closed, so it is not necessary to catch.
            }
            finally
            {
                s.Close();
            }
        }

        /// <summary>
        /// accept 操作完成時回撥函式
        /// </summary>
        /// <param name="sender">Object who raised the event.</param>
        /// <param name="e">SocketAsyncEventArg associated with the completed accept operation.</param>
        private void OnAcceptCompleted(object sender, SocketAsyncEventArgs e)
        {
            this.ProcessAccept(e);
        }

        /// <summary>
        /// 監聽Socket接受處理
        /// </summary>
        /// <param name="e">SocketAsyncEventArg associated with the completed accept operation.</param>
        private void ProcessAccept(SocketAsyncEventArgs e)
        {
            Socket s = e.AcceptSocket;
            if (s.Connected)
            {
                try
                {
                    SocketAsyncEventArgs ioContext = this.ioContextPool.Pop();
                    if (ioContext != null)
                    {
                        // 從接受的客戶端連線中取資料配置ioContext

                        ioContext.UserToken = s;

                        Interlocked.Increment(ref this.numConnectedSockets);
                        string outStr = String.Format("客戶 {0} 連入, 共有 {1} 個連線。",  s.RemoteEndPoint.ToString(),this.numConnectedSockets);
                        mainForm.Invoke(mainForm.setlistboxcallback,outStr);
                        //Console.WriteLine("Client connection accepted. There are {0} clients connected to the server",
                            //this.numConnectedSockets);

                        if (!s.ReceiveAsync(ioContext))
                        {
                            this.ProcessReceive(ioContext);
                        }
                    }
                    else        //已經達到最大客戶連線數量，在這接受連線，傳送“連線已經達到最大數”，然後斷開連線
                    {
                        s.Send(Encoding.Default.GetBytes("連線已經達到最大數!"));
                        string outStr = String.Format("連線已滿，拒絕 {0} 的連線。", s.RemoteEndPoint);
                        mainForm.Invoke(mainForm.setlistboxcallback, outStr);
                        s.Close();
                   }
                }
                catch (SocketException ex)
                {
                    Socket token = e.UserToken as Socket;
                    string outStr = String.Format("接收客戶 {0} 資料出錯, 異常資訊： {1} 。", token.RemoteEndPoint, ex.ToString());
                    mainForm.Invoke(mainForm.setlistboxcallback, outStr);
                    //Console.WriteLine("Error when processing data received from {0}:\r\n{1}", token.RemoteEndPoint, ex.ToString());
                }
                catch (Exception ex)
                {
                    mainForm.Invoke(mainForm.setlistboxcallback, "異常：" + ex.ToString());
                }
                // 投遞下一個接受請求
                this.StartAccept(e);
            }
        }

        /// <summary>
        /// 從客戶端開始接受一個連線操作
        /// </summary>
        /// <param name="acceptEventArg">The context object to use when issuing 
        /// the accept operation on the server's listening socket.</param>
        private void StartAccept(SocketAsyncEventArgs acceptEventArg)
        {
            if (acceptEventArg == null)
            {
                acceptEventArg = new SocketAsyncEventArgs();
                acceptEventArg.Completed += new EventHandler<SocketAsyncEventArgs>(OnAcceptCompleted);
            }
            else
            {
                // 重用前進行物件清理
                acceptEventArg.AcceptSocket = null;
            }

            if (!this.listenSocket.AcceptAsync(acceptEventArg))
            {
                this.ProcessAccept(acceptEventArg);
            }
        }

        /// <summary>
        /// 啟動服務，開始監聽
        /// </summary>
        /// <param name="port">Port where the server will listen for connection requests.</param>
        internal void Start(Int32 port)
        {
            // 獲得主機相關資訊
            IPAddress[] addressList = Dns.GetHostEntry(Environment.MachineName).AddressList;
            IPEndPoint localEndPoint = new IPEndPoint(addressList[addressList.Length - 1], port);

            // 建立監聽socket
            this.listenSocket = new Socket(localEndPoint.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
            this.listenSocket.ReceiveBufferSize = this.bufferSize;
            this.listenSocket.SendBufferSize = this.bufferSize;

            if (localEndPoint.AddressFamily == AddressFamily.InterNetworkV6)
            {
                // 配置監聽socket為 dual-mode (IPv4 & IPv6) 
                // 27 is equivalent to IPV6_V6ONLY socket option in the winsock snippet below,
                this.listenSocket.SetSocketOption(SocketOptionLevel.IPv6, (SocketOptionName)27, false);
                this.listenSocket.Bind(new IPEndPoint(IPAddress.IPv6Any, localEndPoint.Port));
            }
            else
            {
                this.listenSocket.Bind(localEndPoint);
            }

            // 開始監聽
            this.listenSocket.Listen(this.numConnections);

            // 在監聽Socket上投遞一個接受請求。
            this.StartAccept(null);

            // Blocks the current thread to receive incoming messages.
            mutex.WaitOne();
        }

        /// <summary>
        /// 停止服務
        /// </summary>
        internal void Stop()
        {
            this.listenSocket.Close();
            mutex.ReleaseMutex();
        }

    }
}

IoContextPool.cs

完成埠上進行投遞所用的IoContext物件池

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

namespace IocpServer
{
    /// <summary>
    /// 與每個客戶Socket相關聯，進行Send和Receive投遞時所需要的引數
    /// </summary>
    internal sealed class IoContextPool
    {
        List<SocketAsyncEventArgs> pool;        //為每一個Socket客戶端分配一個SocketAsyncEventArgs，用一個List管理，在程式啟動時建立。
        Int32 capacity;                         //pool物件池的容量
        Int32 boundary;                         //已分配和未分配物件的邊界，大的是已經分配的，小的是未分配的

        internal IoContextPool(Int32 capacity)
        {
            this.pool = new List<SocketAsyncEventArgs>(capacity);
            this.boundary = 0;
            this.capacity = capacity;
        }

        /// <summary>
        /// 往pool物件池中增加新建立的物件，因為這個程式在啟動時會建立好所有物件，
        /// 故這個方法只在初始化時會被呼叫,因此，沒有加鎖。
        /// </summary>
        /// <param name="arg"></param>
        /// <returns></returns>
        internal bool Add(SocketAsyncEventArgs arg)
        {
            if (arg != null && pool.Count < capacity)
            {
                pool.Add(arg);
                boundary++;
                return true;
            }
            else
                return false;
        }

        /// <summary>
        /// 取出集合中指定物件，內部使用
        /// </summary>
        /// <param name="index"></param>
        /// <returns></returns>
        //internal SocketAsyncEventArgs Get(int index)
        //{
        //    if (index >= 0 && index < capacity)
        //        return pool[index];
        //    else
        //        return null;
        //}

        /// <summary>
        /// 從物件池中取出一個物件，交給一個socket來進行投遞請求操作
        /// </summary>
        /// <returns></returns>
        internal SocketAsyncEventArgs Pop()
        {
            lock (this.pool)
            {
                if (boundary > 0)
                {
                    --boundary;
                    return pool[boundary];
                }
                else
                    return null;
            }
        }

        /// <summary>
        /// 一個socket客戶斷開，與其相關的IoContext被釋放，重新投入Pool中，備用。
        /// </summary>
        /// <param name="arg"></param>
        /// <returns></returns>
        internal bool Push(SocketAsyncEventArgs arg)
        {
            if (arg != null)
            {
                lock (this.pool)
                {
                    int index = this.pool.IndexOf(arg, boundary);  //找出被斷開的客戶,此處一定能查到，因此index不可能為-1，必定要大於0。
                    if (index == boundary)         //正好是邊界元素
                        boundary++;
                    else
                    {
                        this.pool[index] = this.pool[boundary];     //將斷開客戶移到邊界上，邊界右移
                        this.pool[boundary++] = arg;
                    }
                }
                return true;
            }
            else
                return false;
        }
    }
}

執行結果如圖: