WebIM组件设计

其实对于一个WebIM来说，我们一般都几种方式来实现

1.服务器拉送方式：就是客户端主动定时的去服务器端获取信息，一般我们可以通过 Ajax控件+定时器  来实现，优点：实现简单，缺点：服务器承受的压力重

2.服务器推送方式：就是服务器主动将获取到的信息，发送给客户端，Asp.net我们可以通过 IHttpAsyncHandler这个接口来实现，优点：服务器承受的压力小 缺点：服务器 和客户端同时配合编写（js)

3.Flash Socket方式：通过在网页中嵌入Flash，编写Socket程序 通过AS 3.0语言，Socket编程，优点：并发量大，服务器压力小，缺点：浏览器中要支持Flash,加载Flash

下面我实现的是第二种： 

它实现的原理很简单，浏览器向服务器发送一个异步请求，服务器接到请求之后，去内存中查找信息，如果有，就直接处理该请求，如果没有，我们可以把该请求暂存到服务器一段时间，如果在该时间段内，有符合自己信息的到来，我们就直接处理，否则我们要丢掉该请求（其实请求丢掉之后，如果客户端任然在线，客户端会重新在次发送请求，就像是心跳包）

using System;
using System.Collections.Generic;
using System.Collections;
using System.Text;
using System.Web;
namespace DNCCFrameWork.Chat
{
    /// <summary>
    /// Chat聊天异步处理程序
    /// </summary>
    public class ChatAsyncHandler : IHttpAsyncHandler
    {

        //接受客户端请求
        public IAsyncResult BeginProcessRequest(HttpContext context, AsyncCallback cb, Object extraData)
        {
            System.IO.Stream stream = context.Request.InputStream;
            byte[] b = ReadDate(stream);
            string str = context.Server.UrlDecode(context.Request.ContentEncoding.GetString(b));
            Hashtable ht = SplitRequestPara(str);
            string type = ht["type"] as string;
            string message = ht["content"] as string;
            string sendUser = ht["sendusers"] as string;
            string receiveUser = ht["receiveusers"] as string;
            IChatMessage chatMessage = new ChatMessage();
            chatMessage.Type = type;
            chatMessage.Content = message;
            chatMessage.SendUser = sendUser;
            chatMessage.ReceiveUser = receiveUser;
            ChatAsyncResult chatAsyncResult = new ChatAsyncResult(context, cb, extraData, chatMessage);
            IChat chat = new ChatDefault();

            chat.IM(chatAsyncResult);

            return chatAsyncResult;

        }

        #region 读流中的全部数据
        private byte[] ReadDate(System.IO.Stream stream)
        {
            byte[] buff = new byte[stream.Length];
            int curOffset = 0;
            int totalCount = 0;
            int readCount = 0;
            int size = buff.Length;
            while (totalCount < size)
            {
                int exceptSize = size - totalCount;
                readCount = stream.Read(buff, curOffset, exceptSize);
                curOffset += readCount;
                totalCount += readCount;
            }
            return buff;
        }
        #endregion

        #region 分离请求数据
        private Hashtable SplitRequestPara(string str)
        {
            Hashtable ht = new Hashtable();
            string[] str1 = str.Split(new char[] { '&' });
            foreach (string temp in str1)
            {
                string[] str2 = temp.Split(new char[] { '=' });
                if (str2.Length == 2)
                {
                    if (!ht.ContainsKey(str2[0].ToLower().ToString()))
                    {
                        ht.Add(str2[0].ToLower().ToString(), str2[1].ToString());
                    }
                }
            }
            return ht;

        }
        #endregion

        public void EndProcessRequest(IAsyncResult result)
        {

        }

        #region IHttpHandler接口
        public bool IsReusable
        {
            get { return false; }
        }
        public void ProcessRequest(HttpContext context)
        {

        }
        #endregion

        #region 请求检测
        private bool RequestCheck(IChatMessage cm)
        {
            bool status = true;
            if (string.IsNullOrEmpty(cm.Type))
            {
                status = false;

            }
            else
            {
                try
                {
                    cm.Type = Common.Security.CryptoTextBase.ProcessText(cm.Type, false);
                }
                catch
                {
                    status = false;
                }
            }
            if (string.IsNullOrEmpty(cm.SendUser))
            {
                status = false;
            }
            if (string.IsNullOrEmpty(cm.ReceiveUser))
            {
                status = false;
            }
            return status;
        }
        #endregion

    }
}

using System;
using System.Collections.Generic;
using System.Text;
using System.Collections;
namespace DNCCFrameWork.Chat
{
    public class ChatMessageDispatcherDefault : IChatMessageDispatcher
    {
        private  IChatMessageSendStrategy m_chatMessageSendStrategy = new ChatMessageSendStrategyDefault();
        private  IChatMessageHook m_chatMessageHook = new ChatMessageHookDefault();
        private  IChatMessageSpy m_chatMessageSpy = new ChatMessageSpyDefault();
        private  IChatMessageDeal m_chatMessageDeal;
        private  IChatMessageManager m_chatMessageManager = new ChatMessageManagerDefault();
        private  IChatRequestManager m_chatRequestManager = new ChatRequestManagerDefault();
        private static object o = new object();
        public  void Dispatcher(ChatAsyncResult chatAsyncResult)
        {
            ChatAsyncResult car = Receive(chatAsyncResult);//接受请求
            m_chatMessageDeal = ChatMessageDealFactory.GetChatMessageDeal(car);//获取请求对应的处理器
            if (m_chatMessageDeal != null)
            {
                m_chatMessageDeal.Deal(car);//处理器处理消息,保存消息，或保存请求    
                lock (o)
                {
                    DispatcherSend();//发送消息 
                }
            }
        }
        public void DispatcherSend()
        {
            int count = m_chatRequestManager.Count();
            for (int i = 0; i < count; i++)
            {
                IChatRequest chatRequest = m_chatRequestManager.Pop();
                if (chatRequest != null)
                {
                    Dictionary<string, string> dic = new Dictionary<string, string>();
                    dic.Add("SendUser", chatRequest.ChatAsyncResult.ChatMessage.SendUser);
                    dic.Add("ReceiveUser", chatRequest.ChatAsyncResult.ChatMessage.ReceiveUser);
                    dic.Add("Type", chatRequest.ChatAsyncResult.ChatMessage.Type);
                    IList lt = m_chatMessageManager.Find(dic);
                    if (lt.Count <= 0)
                    {
                        TimeSpan ts = DateTime.Now - chatRequest.ChatAsyncResult.ChatMessage.CreateDate;
                        if (ts.TotalSeconds < 600)//请求超时系统丢弃请求
                        {
                            m_chatRequestManager.Push(chatRequest);
                        }
                    }
                    else
                    {
                        IList temp = new ArrayList(); ;
                        foreach (IChatMessage chatMessage in lt)
                        {
                            IChatMessage cm = Send(chatMessage);
                            temp.Add(cm);//发送消息前   

                        }
                        StringBuilder sb = new StringBuilder();
                        for (int j = 0; j < temp.Count; j++)
                        {
                            IChatMessage cha = temp[j] as IChatMessage;
                            sb.Append(cha.ToString()).Append("<br/>");
                        }
                        chatRequest.ChatAsyncResult.ChatMessage.Content = sb.ToString();
                        m_chatMessageSendStrategy.Send(null, chatRequest);
                    }
                }

            }
        }
        public  IChatMessage Send(IChatMessage chatAsyncResult)
        {
            IChatMessage car = m_chatMessageHook.Send(chatAsyncResult);
            car = m_chatMessageSpy.Send(car);
            return car;
        }
        public  ChatAsyncResult Receive(ChatAsyncResult chatAsyncResult)
        {
            ChatAsyncResult car = m_chatMessageHook.Receive(chatAsyncResult);
            car = m_chatMessageSpy.Receive(car);
            return car;
        }
    }
}

using System;
using System.Collections.Generic;
using System.Text;
using System.Collections;
using System.Configuration;
namespace DNCCFrameWork.Chat
{
    public class ChatMessageStoreageMemory : IChatMessageStorage
    {
        private static Dictionary<string, LinkedList<IChatMessage>> m_SendUserReceiveChatMessage = new Dictionary<string, LinkedList<IChatMessage>>();
        private static ChatMessageStoreageDataBase db = new ChatMessageStoreageDataBase();
        private static Dictionary<string, object> m_Lock = new Dictionary<string, object>();
        private static int m_ChatGroupALiveTime = 5;
        private static int m_ChatMessageGC = 5;
        private static DateTime m_LastChatMessageGC = DateTime.Now;
        private static System.Timers.Timer GC = new System.Timers.Timer(m_ChatMessageGC * 60 * 1000);
        static ChatMessageStoreageMemory()
        {
            IList lt = db.Find();//获取数据库中为发送信息
            foreach (IChatMessage chatMessage in lt)
            {
                BackChatMessage(chatMessage);
            }
            int.TryParse(ConfigurationManager.AppSettings["ChatGroupALiveTime"], out m_ChatGroupALiveTime);
            int.TryParse(ConfigurationManager.AppSettings["ChatMessageGC"], out m_ChatMessageGC);
            GC.Interval = m_ChatMessageGC * 60 * 1000;
            GC.Elapsed += new System.Timers.ElapsedEventHandler(GC_Elapsed);
            GC.Enabled = true;
            GC.Start();
        }

        static void GC_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
        {
            ChatMessageGC();
        }
        private static void BackChatMessage(IChatMessage chatMessage)
        {
            string key = "";
            string key2 = "";
            if (chatMessage.Type.Equals(ChatType.oneTonoeSend))
            {
                key = chatMessage.SendUser + "<-->" + chatMessage.ReceiveUser;
                key2 = chatMessage.ReceiveUser + "<-->" + chatMessage.SendUser;
            }
            if (chatMessage.Type.Equals(ChatType.manyTomanySend))
            {
                key = key2 = chatMessage.ReceiveUser;
            }
            if (!m_SendUserReceiveChatMessage.ContainsKey(key) || !m_SendUserReceiveChatMessage.ContainsKey(key2))
            {
                lock (m_SendUserReceiveChatMessage)
                {
                    if (!m_SendUserReceiveChatMessage.ContainsKey(key) && !m_SendUserReceiveChatMessage.ContainsKey(key2))
                    {
                        m_SendUserReceiveChatMessage.Add(key, new LinkedList<IChatMessage>());
                        m_Lock.Add(key, new object());
                    }
                }

            }
            if (m_SendUserReceiveChatMessage.ContainsKey(key))
            {
                lock (m_Lock[key])
                {
                    if (m_SendUserReceiveChatMessage.ContainsKey(key))
                    {
                        if (m_SendUserReceiveChatMessage[key].Count >= 1)
                        {
                            bool status = false;
                            IChatMessage temp = null;
                            foreach (IChatMessage cm in m_SendUserReceiveChatMessage[key])
                            {
                                if (cm.CreateDate > chatMessage.CreateDate)
                                {
                                    temp = cm;
                                    status = true; break;
                                }
                            }
                            if (status)
                            {
                                m_SendUserReceiveChatMessage[key].AddBefore(m_SendUserReceiveChatMessage[key].Find(temp), chatMessage);
                            }
                            if (!status)
                            {
                                m_SendUserReceiveChatMessage[key].AddLast(chatMessage);
                            }
                        }
                        else
                        {
                            m_SendUserReceiveChatMessage[key].AddFirst(chatMessage);
                        }
                    }
                }
            }
            else
            {
                lock (m_Lock[key2])
                {
                    if (m_SendUserReceiveChatMessage.ContainsKey(key2))
                    {
                        if (m_SendUserReceiveChatMessage[key2].Count >= 1)
                        {
                            bool status = false;
                            IChatMessage temp = null;
                            foreach (IChatMessage cm in m_SendUserReceiveChatMessage[key2])
                            {
                                if (cm.CreateDate > chatMessage.CreateDate)
                                {
                                    temp = cm;
                                    status = true;
                                    break;
                                }
                            }
                            if (status)
                            {
                                m_SendUserReceiveChatMessage[key2].AddBefore(m_SendUserReceiveChatMessage[key2].Find(temp), chatMessage);
                            }
                            if (!status)
                            {
                                m_SendUserReceiveChatMessage[key2].AddLast(chatMessage);
                            }
                        }
                        else
                        {
                            m_SendUserReceiveChatMessage[key2].AddFirst(chatMessage);
                        }
                    }
                }
            }
        }
        public void Add(IChatMessage chatMessage)
        {
            string key = "";
            string key2 = "";
            if (chatMessage.Type.Equals(ChatType.oneTonoeSend))
            {
                key = chatMessage.SendUser + "<-->" + chatMessage.ReceiveUser;
                key2 = chatMessage.ReceiveUser + "<-->" + chatMessage.SendUser;
            }
            if (chatMessage.Type.Equals(ChatType.manyTomanySend))
            {
                key = key2 = chatMessage.ReceiveUser;
            }
            if (!m_SendUserReceiveChatMessage.ContainsKey(key) || !m_SendUserReceiveChatMessage.ContainsKey(key2))
            {
                lock (m_SendUserReceiveChatMessage)
                {
                    if (!m_SendUserReceiveChatMessage.ContainsKey(key) && !m_SendUserReceiveChatMessage.ContainsKey(key2))
                    {
                        m_SendUserReceiveChatMessage.Add(key, new LinkedList<IChatMessage>());
                        m_Lock.Add(key, new object());
                    }
                }

            }
            if (m_SendUserReceiveChatMessage.ContainsKey(key))
            {
                lock (m_Lock[key])
                {
                    if (m_SendUserReceiveChatMessage.ContainsKey(key))
                    {
                        if (m_SendUserReceiveChatMessage[key].Count >= 1)
                        {
                            bool status = false;
                            IChatMessage temp = null;
                            foreach (IChatMessage cm in m_SendUserReceiveChatMessage[key])
                            {
                                if (cm.CreateDate > chatMessage.CreateDate)
                                {
                                    temp = cm;
                                    status = true; break;
                                }
                            }
                            if (status)
                            {
                                m_SendUserReceiveChatMessage[key].AddBefore(m_SendUserReceiveChatMessage[key].Find(temp), chatMessage);
                            }
                            if (!status)
                            {
                                m_SendUserReceiveChatMessage[key].AddLast(chatMessage);
                            }
                        }
                        else
                        {
                            m_SendUserReceiveChatMessage[key].AddFirst(chatMessage);
                        }
                        cb c = new cb(db.Add);
                        c.BeginInvoke(chatMessage, null, null);//异步写入数据库 
                    }
                }
            }
            else
            {
                lock (m_Lock[key2])
                {
                    if (m_SendUserReceiveChatMessage.ContainsKey(key2))
                    {
                        if (m_SendUserReceiveChatMessage[key2].Count >= 1)
                        {
                            bool status = false;
                            IChatMessage temp = null;
                            foreach (IChatMessage cm in m_SendUserReceiveChatMessage[key2])
                            {
                                if (cm.CreateDate > chatMessage.CreateDate)
                                {
                                    temp = cm;
                                    status = true;
                                    break;
                                }
                            }
                            if (status)
                            {
                                m_SendUserReceiveChatMessage[key2].AddBefore(m_SendUserReceiveChatMessage[key2].Find(temp), chatMessage);
                            }
                            if (!status)
                            {
                                m_SendUserReceiveChatMessage[key2].AddLast(chatMessage);
                            }
                        }
                        else
                        {
                            m_SendUserReceiveChatMessage[key2].AddFirst(chatMessage);
                        }
                        cb c = new cb(db.Add);
                        c.BeginInvoke(chatMessage, null, null);//写入数据库 
                    }
                }
            }
        }
        public IList Find(Dictionary<string, string> dic)
        {

            string key = "";
            if (dic["Type"].Equals(ChatType.oneTooneReceive))
            {
                key = dic["SendUser"] + "<-->" + dic["ReceiveUser"];
            }
            if (dic["Type"].Equals(ChatType.manyTomanyReceive))
            {
                key = dic["ReceiveUser"];
            }
            IList lt = new ArrayList();

            if (m_SendUserReceiveChatMessage.ContainsKey(key))
            {
                lock (m_Lock[key])
                {
                    if (m_SendUserReceiveChatMessage.ContainsKey(key))
                    {
                        foreach (IChatMessage chatMessage in m_SendUserReceiveChatMessage[key])
                        {
                            if (!chatMessage.IsSend(dic["SendUser"]) && !chatMessage.IsOver)
                            {
                                chatMessage.SendUserList.Add(dic["SendUser"]);
                                chatMessage.ReadDateList.Add(DateTime.Now.ToString());
                                ChatMessageOverCheck(chatMessage);
                                cb c = new cb(db.Update);
                                c.BeginInvoke(chatMessage.Clone(), null, null);//异步更新数据库     
                                lt.Add(chatMessage);
                            }
                        }
                    }
                }
            }
            else
            {
                if (dic["Type"].Equals(ChatType.oneTooneReceive))
                {
                    key = dic["ReceiveUser"] + "<-->" + dic["SendUser"];
                }
                if (dic["Type"].Equals(ChatType.manyTomanyReceive))
                {
                    key = dic["ReceiveUser"];
                }
                if (m_SendUserReceiveChatMessage.ContainsKey(key))
                {
                    lock (m_Lock[key])
                    {
                        if (m_SendUserReceiveChatMessage.ContainsKey(key))
                        {
                            foreach (IChatMessage chatMessage in m_SendUserReceiveChatMessage[key])
                            {
                                if (!chatMessage.IsSend(dic["SendUser"]) && !chatMessage.IsOver)
                                {
                                    chatMessage.SendUserList.Add(dic["SendUser"]);
                                    chatMessage.ReadDateList.Add(DateTime.Now.ToString());
                                    ChatMessageOverCheck(chatMessage);
                                    cb c = new cb(db.Update);
                                    c.BeginInvoke(chatMessage.Clone(), null, null);//异步更新数据库                                
                                    lt.Add(chatMessage);
                                }
                            }
                        }
                    }
                }
            }
            return lt;

        }
        public void Clear(Dictionary<string, string> dic)
        {
        }
        public void Clear(IList lt)
        {

        }

        #region 定时内存清理
        private static void ChatMessageGC()
        {
            foreach (KeyValuePair<string, LinkedList<IChatMessage>> kvp in m_SendUserReceiveChatMessage)
            {
                if (kvp.Value.Count > 0)
                {
                    lock (m_Lock[kvp.Key])
                    {
                        if (kvp.Value.Count > 0)
                        {
                            IList lt = new ArrayList();
                            foreach (IChatMessage cm in kvp.Value)
                            {
                                if (!cm.IsOver)
                                {
                                    ChatMessageOverCheck(cm);
                                }
                                if (cm.IsOver)
                                {
                                    lt.Add(cm);
                                }
                            }
                            foreach (IChatMessage cm in lt)
                            {
                                kvp.Value.Remove(cm);
                                cb b = new cb(db.Add2);
                                b.BeginInvoke(cm.Clone(), null, null);//进入历史数据库
                            }
                        }
                    }
                }


            }

        }
        #endregion

        #region 消息完成结束检测
        private static void ChatMessageOverCheck(IChatMessage cm)
        {
            if (cm.Type.Equals(ChatType.oneTonoeSend) && cm.SendUserList.Count >= 2)
            {
                cm.OverDate = DateTime.Now;
                cm.IsOver = true;
            }
            if (cm.Type.Equals(ChatType.manyTomanySend))
            {
                TimeSpan ts = DateTime.Now - cm.CreateDate;
                if (ts.TotalMinutes > m_ChatGroupALiveTime)
                {
                    cm.OverDate = DateTime.Now;
                    cm.IsOver = true;
                }
            }
        }
        #endregion
    }
    public delegate void cb(IChatMessage chatMessage);
}

所有的消息都先存储在内存中，然后异步更新到数据库中（相当于内存快照，一旦应用程序重启，没有被处理完过的消息，将重新加载到内存中），一旦消息被处理过（一对一聊天，双方都接受到）则消息标记为已处理过，消息就会从内存中清除，同时被异步更新到历史库表中 

 JS部分：

    <script src="../Js/jquery-1.4.3.js" type="text/javascript" language="javascript"></script>

    <script type="text/javascript">  
        $(document).ready(function () {

            function send() 
            {
                var str=$.trim($("#ctl00_ContentPlaceHolder1_tbMSGInput").val());             
                var sendUser = $.trim('<% = MyUid %>');
                var receiveUser = $.trim('<% = ToUID %>');
                if(sendUser.length<1&&receive.length<1)
                {
                    return;
                }
                if(str.length>1)
                {        
                    $.ajax({
                        type: "post",
                        url: "IM.aspx",
                        timeout:30000,    
                        data:{ content: str, type: "0", sendUsers: sendUser, receiveUsers: receiveUser } ,
                        dataType:"html",
                        success:   function (data, status) 
                                   {    
                                      if(data!="发送成功")
                                        {
                                             var result = $("#ctl00_ContentPlaceHolder1_lbChatShow");
                                             result.html(result.html()+data+"<br/>");    
                                        }
                                     else
                                        {                  
                                              $("#ctl00_ContentPlaceHolder1_tbMSGInput").val("");
                                        }
           
                                    },          
                      error: function(XMLHttpRequest, textStatus, errorThrown)
                                {        
                                      var result = $("#ctl00_ContentPlaceHolder1_lbChatShow");
                                      result.html(result.html()+textStatus+"<br/>");                                        
                                }
                       });
                        $("#ctl00_ContentPlaceHolder1_tbMSGInput").val("");
                }         
            }

            function wait() 
                {
                    var sendUser = $.trim('<% = MyUid %>');
                    var receiveUser = $.trim('<% = ToUID %>');
                    if(sendUser.length<1&&receive.length<1)
                      {
                               return;
                      }        
                    $.ajax({
                        type: "post",
                        url: "IM.aspx",
                        timeout:30000,    
                        data:{ content: "", type: "1", sendUsers: sendUser, receiveUsers: receiveUser } ,
                        dataType:"html",
                        success:function (data, status) 
                        {
                            var result = $("#ctl00_ContentPlaceHolder1_lbChatShow");
                            result.html(result.html()+data);
                            var outerHeight = $("#ctl00_ContentPlaceHolder1_lbChatShow").outerHeight(); 
                            var innerHeight = $("#div_Message").innerHeight();
                            var scrollTop = outerHeight - innerHeight + 20;
                             $("#div_Message").scrollTop(scrollTop);
                             wait();
                        },          
                        error: function(XMLHttpRequest, textStatus, errorThrown)
                        {    
                            wait();
                        }
                        });                 
              };            

            //初始化连接
             wait();
            $("#btnSend").click(function () { send(); });         
            $("#ctl00_ContentPlaceHolder1_tbMSGInput").keypress(function (event) {
                if (event.keyCode == 13) {
                    send();
                }
            });
        });
    </script>

 部署方式：

在Web.config httpHandlers中加入即可

 <add path="IM.aspx" type="DNCCFrameWork.Chat.ChatAsyncHandler" verb="POST,Get"/>