WebSocket，IsWebSocketRequest與AspNetWebSocketContext

asp.net新建一個服務端程式，用來處理鏈接服務端：

1，新建一個處理程式 .ashx

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.WebSockets;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Web;
using System.Web.WebSockets;
using SFellowEntity.Models;

namespace SchoolfellowCard.Handler
{
    /// <summary>
    /// WebSocketServer webSocket服務
    /// </summary>
    public class WebSocketServer : IHttpHandler
    {
        //用戶連接池
        private static Dictionary<string, WebSocket> connectPool = new Dictionary<string, WebSocket>();
        //離線消息池
        private static Dictionary<string, List<MessageInfo>> messagePool = new Dictionary<string, List<MessageInfo>>();

        public void ProcessRequest(HttpContext context)
        {
            if (context.IsWebSocketRequest)
            {
                context.AcceptWebSocketRequest(ProcessChat);
            } 
        }
        /// <summary>
        /// webSocket非同步作業
        /// </summary>
        /// <param name="context"></param>
        /// <returns></returns>
        private async Task ProcessChat(AspNetWebSocketContext context)
        {
            //WebSocket socket = context.WebSocket;
            //while (true)
            //{
            //    if (socket.State == WebSocketState.Open)
            //    {
            //        ArraySegment<byte> buffer = new ArraySegment<byte>(new byte[2048]);
            //        WebSocketReceiveResult result = await socket.ReceiveAsync(buffer, CancellationToken.None);
            //        string userMsg = Encoding.UTF8.GetString(buffer.Array, 0, result.Count);
            //        userMsg = "你發送了：" + userMsg + "於" + DateTime.Now.ToLongTimeString();
            //        buffer = new ArraySegment<byte>(Encoding.UTF8.GetBytes(userMsg));
            //        await socket.SendAsync(buffer, WebSocketMessageType.Text, true, CancellationToken.None);
            //    }
            //    else
            //    {
            //        break;
            //    }
            //}
            WebSocket socket = context.WebSocket;
            string user =string.Format("{0}", context.QueryString["user"]);

            try
            {
                #region 驗證用戶添加連接池

                //第一次open時，添加到連接池中
                if (!connectPool.ContainsKey(user))
                {
                    connectPool.Add(user, socket); //不存在，添加
                }
                else
                {
                    if (socket != connectPool[user]) //當前對象不一致，更新
                    {
                        connectPool[user] = socket;
                    }
                }
                
                #endregion

                #region 離線消息處理
                if (messagePool.ContainsKey(user))
                {
                    //TODO：離線消息可放入資料庫在此獲取離線消息並返回給對應的用戶
                    List<MessageInfo> msgs = messagePool[user];
                    foreach (MessageInfo item in msgs)
                    {
                        await socket.SendAsync(item.MsgContent, WebSocketMessageType.Text, true, CancellationToken.None);
                    }
                    messagePool.Remove(user);//移除離線消息
                    //TODO:處理完後標記離線消息已推送
                }
                #endregion

                string descUser = string.Empty;//目的用戶
                while (true)
                {
                    if (socket.State == WebSocketState.Open)
                    {
                        ArraySegment<byte> buffer = new ArraySegment<byte>(new byte[2048]);
                        //websocket接收消息
                        WebSocketReceiveResult result = await socket.ReceiveAsync(buffer, CancellationToken.None);

                        #region 消息處理（字元截取、消息轉發）
                        try
                        {
                            #region 關閉Socket處理，刪除連接池
                            if (socket.State != WebSocketState.Open)//連接關閉
                            {
                                if (connectPool.ContainsKey(user)) connectPool.Remove(user);//刪除連接池
                                break;
                            }
                            #endregion

                            string userMsg = Encoding.UTF8.GetString(buffer.Array, 0, result.Count);//發送過來的消息
                            string[] msgList = userMsg.Split('|');
                            if (msgList.Length == 2)
                            {
                                if (msgList[0].Trim().Length > 0)
                                    descUser = msgList[0].Trim();//記錄消息目的用戶//TODO:將消息接收者可放入資料庫存貯記錄
                                buffer = new ArraySegment<byte>(Encoding.UTF8.GetBytes(msgList[1]));
                            }
                            else
                                buffer = new ArraySegment<byte>(Encoding.UTF8.GetBytes(userMsg));

                            if (connectPool.ContainsKey(descUser))//判斷客戶端是否線上
                            {
                                WebSocket destSocket = connectPool[descUser];//目的客戶端
                                if (destSocket != null && destSocket.State == WebSocketState.Open)
                                    await destSocket.SendAsync(buffer, WebSocketMessageType.Text, true, CancellationToken.None);
                            }
                            else
                            {
                                Task.Run(() =>
                                {
                                    if (!messagePool.ContainsKey(descUser))//將用戶添加至離線消息池中
                                        messagePool.Add(descUser, new List<MessageInfo>());
                                    messagePool[descUser].Add(new MessageInfo(DateTime.Now, buffer));//添加離線消息
                                    //TODO:離線消息插入資料庫
                                });
                            }
                        }
                        catch (Exception exs)
                        {
                            //消息轉發異常處理，本次消息忽略 繼續監聽接下來的消息
                        }
                        #endregion
                    }
                    else
                    {
                        break;
                    }
                }//while end
            }
            catch (Exception ex)
            {
                //整體異常處理
                if (connectPool.ContainsKey(user)) connectPool.Remove(user);
            }
        }

        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }
}

其中，MessageInfo.cs

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

namespace SFellowEntity.Models
{
    /// <summary>
    /// 消息
    /// </summary>
    public class MessageInfo
    {
        /// <summary>
        /// 消息內容
        /// </summary>
        public ArraySegment<byte> MsgContent { get; set; }
        /// <summary>
        /// 消息時間
        /// </summary>
        public DateTime MsgTime { get; set; }
        /// <summary>
        /// 構造函數
        /// </summary>
        /// <param name="msgTime"></param>
        /// <param name="msgContent"></param>
        public MessageInfo(DateTime msgTime, ArraySegment<byte> msgContent)
        {
            MsgTime = msgTime;
            MsgContent = msgContent;
        }
    }
}

 頁面端：

2，頁面JavaScript創建WebSocket對象，併發起連接

            $('#conn').click(function () {
                ws = new WebSocket('ws://' + window.location.hostname + ':' + window.location.port + '/Handler/WebSocketServer.ashx?user=' + $("#user").val());
                $('#msg').append('<p>正在連接</p>');

                ws.onopen = function () {
                    $('#msg').append('<p>已經連接</p>');
                }
                ws.onmessage = function (evt) {
                    $('#msg').append('<p>' + evt.data + '</p>');
                }
                ws.onerror = function (evt) {
                    $('#msg').append('<p>' + JSON.stringify(evt) + '</p>');
                }
                ws.onclose = function () {
                    $('#msg').append('<p>已經關閉</p>');
                }
            });

            $('#close').click(function () {
                ws.close();
            });

            $('#send').click(function () {
                if (ws.readyState == WebSocket.OPEN) {
                    ws.send($("#to").val() + "|" + $('#content').val());
                }
                else {
                    $('#tips').text('連接已經關閉');
                }
            });