Asp.net使用SignalR实现酷炫端对端聊天功能

 public interface IHubConnectionContext<T>
 {
  T All { get; } // 代表所有客户端

  T AllExcept(params string[] excludeConnectionIds); // 除了参数中的所有客户端
  T Client(string connectionId); // 特定的客户端，这个方法也就是我们实现端对端聊天的关键
  T Clients(IList<string> connectionIds); // 参数中的客户端端
  T Group(string groupName, params string[] excludeConnectionIds); // 指定客户端组，这个也是实现群聊的关键所在
  T Groups(IList<string> groupNames, params string[] excludeConnectionIds);
  T User(string userId); // 特定的用户
  T Users(IList<string> userIds); // 参数中的用户
 }

public class ChatHub : Hub
 {
  // 静态属性
  public static List<UserInfo> OnlineUsers = new List<UserInfo>(); // 在线用户列表

  /// <summary>
  /// 登录连线
  /// </summary>
  /// <param name="userId">用户Id</param>
  /// <param name="userName">用户名</param>
  public void Connect(string userId, string userName)
  {
   var connnectId = Context.ConnectionId;

   if (OnlineUsers.Count(x => x.ConnectionId == connnectId) == 0)
   {
    if (OnlineUsers.Any(x => x.UserId == userId))
    {
     var items = OnlineUsers.Where(x => x.UserId == userId).ToList();
     foreach (var item in items)
     {
      Clients.AllExcept(connnectId).onUserDisconnected(item.ConnectionId, item.UserName);
     }
     OnlineUsers.RemoveAll(x => x.UserId == userId);
    }

    //添加在线人员
    OnlineUsers.Add(new UserInfo
    {
     ConnectionId = connnectId,
     UserId = userId,
     UserName = userName,
     LastLoginTime = DateTime.Now
    });
   }

   // 所有客户端同步在线用户
   Clients.All.onConnected(connnectId, userName, OnlineUsers);
  }


  /// <summary>
  /// 发送私聊
  /// </summary>
  /// <param name="toUserId">接收方用户连接ID</param>
  /// <param name="message">内容</param>
  public void SendPrivateMessage(string toUserId, string message)
  {
   var fromUserId = Context.ConnectionId;

   var toUser = OnlineUsers.FirstOrDefault(x => x.ConnectionId == toUserId);
   var fromUser = OnlineUsers.FirstOrDefault(x => x.ConnectionId == fromUserId);

   if (toUser != null && fromUser != null)
   { 
    // send to 
    Clients.Client(toUserId).receivePrivateMessage(fromUserId, fromUser.UserName, message);

    // send to caller user
    // Clients.Caller.sendPrivateMessage(toUserId, fromUser.UserName, message);
   }
   else
   {
    //表示对方不在线
    Clients.Caller.absentSubscriber();
   }
  }

  /// <summary>
  /// 断线时调用
  /// </summary>
  /// <param name="stopCalled"></param>
  /// <returns></returns>
  public override Task OnDisconnected(bool stopCalled)
  {
   var user = OnlineUsers.FirstOrDefault(u => u.ConnectionId == Context.ConnectionId);

   // 判断用户是否存在,存在则删除
   if (user == null) return base.OnDisconnected(stopCalled);

   Clients.All.onUserDisconnected(user.ConnectionId, user.UserName); //调用客户端用户离线通知
   // 删除用户
   OnlineUsers.Remove(user);


   return base.OnDisconnected(stopCalled);
  }
 }

 <script type="text/javascript">
  var systemHub = $.connection.chatHub;
  / 连接IM服务器成功
  // 主要是更新在线用户
  systemHub.client.onConnected = function (id, userName, allUsers) {
   var node = chatCore.node, myf = node.list.eq(0), str = '', i = 0;
   myf.addClass('loading');
   onlinenum = allUsers.length;
   if (onlinenum > 0) {
    str += '<li class="ChatCore_parentnode ChatCore_liston">'
      + '<h5><i></i><span class="ChatCore_parentname">在线用户</span><em class="ChatCore_nums">（' + onlinenum + '）</em></h5>'
      + '<ul id="ChatCore_friend_list" class="ChatCore_chatlist">';
    for (; i < onlinenum; i++) {
     str += '<li id="userid-' + allUsers[i].UserID + '" data-id="' + allUsers[i].ConnectionId + '" class="ChatCore_childnode" type="one"><img src="/Content/Images/001.jpg?' + allUsers[i].UserID + '" class="ChatCore_oneface"><span class="ChatCore_onename">' + allUsers[i].UserName + '(' + ')</span><em class="ChatCore_time">' + allUsers[i].LoginTime + '</em></li>';
    }
    str += '</ul></li>';
    myf.html(str);
   } else {
    myf.html('<li class="ChatCore_errormsg">没有任何数据</li>');
   }
   myf.removeClass('loading');
  };
  //消息传输
 chatCore.transmit = function () {
  var node = chatCore.node, log = {};
  node.sendbtn = $('#ChatCore_sendbtn');
  node.imwrite = $('#ChatCore_write');

  //发送
  log.send = function () {
   var data = {
    content: node.imwrite.val(),
    id: chatCore.nowchat.id,
    sign_key: '', //密匙
    _: +new Date
   };

   if (data.content.replace(/\s/g, '') === '') {
    layer.tips('说点啥呗！', '#ChatCore_write', 2);
    node.imwrite.focus();
   } else {
    //此处皆为模拟
    var keys = chatCore.nowchat.type + chatCore.nowchat.id;

    //聊天模版
    log.html = function (param, type) {
     return '<li class="' + (type === 'me' ? 'ChatCore_chateme' : '') + '">'
      + '<div class="ChatCore_chatuser">'
       + function () {
        if (type === 'me') {
         return '<span class="ChatCore_chattime">' + param.time + '</span>'
           + '<span class="ChatCore_chatname">' + param.name + '</span>'
           + '<img src="' + param.face + '" >';
        } else {
         return '<img src="' + param.face + '" >'
           + '<span class="ChatCore_chatname">' + param.name + '</span>'
           + '<span class="ChatCore_chattime">' + param.time + '</span>';
        }
       }()
      + '</div>'
      + '<div class="ChatCore_chatsay">' + param.content + '<em class="ChatCore_zero"></em></div>'
     + '</li>';
    };

    log.imarea = chatCore.chatbox.find('#ChatCore_area' + keys);

    log.imarea.append(log.html({
     time: new Date().toLocaleString(),
     name: config.user.name,
     face: config.user.face,
     content: data.content
    }, 'me'));
    node.imwrite.val('').focus();
    log.imarea.scrollTop(log.imarea[0].scrollHeight);

    // 调用服务端sendPrivateMessage方法来转发消息
    systemHub.server.sendPrivateMessage(chatCore.nowchat.id, data.content);
   }

  };
  node.sendbtn.on('click', log.send);

  node.imwrite.keyup(function (e) {
   if (e.keyCode === 13) {
    log.send();
   }
  });
 };

  //用户离线
  systemHub.client.onUserDisconnected = function (id, userName) {
   onlinenum = onlinenum - 1;
   $(".ChatCore_nums").html("（" + onlinenum + "）");
   $("#ChatCore_friend_list li[data-id=" + id + "]").remove();
  };
  // 启动连接
  $.connection.hub.start().done(function () {
   systemHub.server.connect(userid, username); // 调用服务端connect方法
  });
 </script>