SignalR使用

ChatHub.cs

namespace AmyChat.Hubs
{
    public class ChatHub : Hub
    {
        UserDAL userDAL = new UserDAL();

        public void Hello(string str,string val)
        {
            var userId = Context.User.Identity.GetUserId();
            var userList = userDAL.GetFriendList(userId);
            var ids = from u in userList select u.Id;
            Clients.Users(ids.ToList());
            Clients.All.takeYou(str);
        }
    }
}

UserDAL.cs

public class UserDAL
    {
        private ApplicationDbContext _db = new ApplicationDbContext();

        public IEnumerable<ApplicationUser> GetFriendList(string userId)
        {
            IEnumerable<ApplicationUser> friendList =
               from u in _db.Users
               join fr in _db.Friends on u.Id equals fr.BId
               where fr.AId == userId
               select u;
            return friendList;
        }
    }

Index.cshtml

@{
    ViewBag.Title = "Index";
    var select1 = (SelectList)ViewData["select1"];
}

@section Scripts{
    <script src="~/Scripts/jquery-3.1.1.js"></script>
    <script src="~/Scripts/jquery.signalR-2.2.1.js"></script>
    <script src="/signalr/hubs"></script>
    <script>
        $(function () {
            var chat = $.connection.chatHub;
            $.connection.hub.start();

            //console.log(chat.client);

            chat.client.takeYou = function (str) {
                //console.log(str);
                $("#divMsg").append(str);
            };

            $("#btnSend").click(function () {
                var content = $("#content").val();
                chat.server.hello(content, $(friendId).val());
            });
        });
    </script>
}

<label for="friendId">好友</label>
@Html.DropDownList("friendId", select1, new { id="friendId"})
<input type="text" name="content" id="content" value="" />
<button type="button" id="btnSend">发送</button>
<div id="divMsg"></div>

ChatController

[Authorize]
    public class ChatController : Controller
    {
        ApplicationDbContext _db = new ApplicationDbContext();
        UserDAL userDAL = new UserDAL();
        // GET: Chat
        public ActionResult Index()
        {
            var friendList = userDAL.GetFriendList(User.Identity.GetUserId());
            SelectList select1 = new SelectList(friendList, "Id", "UserName");
            ViewData["select1"] = select1;
            return View();
        }
    }