信号器：当用户向特定用户发送消息时，无法发回消息

Question

I am new in using SignalR . When I send a message to a particular user are:

1. I do not get the message back (I do not see it on the screen).
2. The user receives a notice can not send a message back.

That means sending a message can only be in one direction. How to do that two users can send messages to each other?**

There is my classes i use:

[HubName("TSChatHub")]
[Authorize]
public class ChatHub : Hub
{

    private readonly static ConnectionMapping<string> _connections =
        new ConnectionMapping<string>();

    public void SendChatMessage(string who, string message)
    {
        string name = Context.User.Identity.Name;

        foreach (var connectionId in _connections.GetConnections(who))
        {
            Clients.Client(connectionId).addChatMessage(name + ": " + message);
        }
    }

    public override Task OnConnected()
    {
        string name = Context.User.Identity.Name;

        _connections.Add(name, Context.ConnectionId);

        return base.OnConnected();
    }

    public override Task OnDisconnected(bool stopCalled)
    {
        string name = Context.User.Identity.Name;

        _connections.Remove(name, Context.ConnectionId);

        return base.OnDisconnected(stopCalled);
    }

    public override Task OnReconnected()
    {
        string name = Context.User.Identity.Name;

        if (!_connections.GetConnections(name).Contains(Context.ConnectionId))
        {
            _connections.Add(name, Context.ConnectionId);
        }

        return base.OnReconnected();
    }
}

  public class ConnectionMapping<T>
{
    private readonly Dictionary<T, HashSet<string>> _connections =
       new Dictionary<T, HashSet<string>>();

    public int Count
    {
        get
        {
            return _connections.Count;
        }
    }

    public void Add(T key, string connectionId)
    {
        lock (_connections)
        {
            HashSet<string> connections;
            if (!_connections.TryGetValue(key, out connections))
            {
                connections = new HashSet<string>();
                _connections.Add(key, connections);
            }

            lock (connections)
            {
                connections.Add(connectionId);
            }
        }
    }

    public IEnumerable<string> GetConnections(T key)
    {
        HashSet<string> connections;
        if (_connections.TryGetValue(key, out connections))
        {
            return connections;
        }

        return Enumerable.Empty<string>();
    }

    public void Remove(T key, string connectionId)
    {
        lock (_connections)
        {
            HashSet<string> connections;
            if (!_connections.TryGetValue(key, out connections))
            {
                return;
            }

            lock (connections)
            {
                connections.Remove(connectionId);

                if (connections.Count == 0)
                {
                    _connections.Remove(key);
                }
            }
        }
    }
}

There is my View:

  <div class="chatcontainer">
    <input type="text" id="message" />
    <input type="button" id="sendmessage" value="Send" />
    <input type="hidden" id="displayname" />
    <ul id="discussion">
    </ul>
</div>

 $(function () {
        // Declare a proxy to reference the hub. 
        var chat = $.connection.TSChatHub;
        debugger;
        // Create a function that the hub can call to broadcast messages.
        chat.client.addChatMessage = function (name, message) {
            // Add the message to the page. 
            $('#discussion').append('<li><strong>' + htmlEncode(name)
                + '</strong>:&nbsp;&nbsp;' + htmlEncode(name) + '</li>');
        };
        // Get the user name and store it to prepend to messages.
       // $('#displayname').val(prompt('Enter your name:', ''));
        // Set initial focus to message input box.  
        $('#message').focus();
        // Start the connection.
        $.connection.hub.start().done(function () {
            console.log('Now connected, connection ID=' + $.connection.hub.id);
            $('#sendmessage').click(function () {
                // Call the Send method on the hub. 
                chat.server.sendChatMessage($('#message').val());
                // Clear text box and reset focus for next comment. 
                $('#message').val('').focus();
            });
        }).fail(function () { console.log("Could not connect"); });
    });

 // This optional function html-encodes messages for display in the page.
    function htmlEncode(value) {
        var encodedValue = $('<div />').text(value).html();
        return encodedValue;
    }

Anyone has a solution to help me

Answer 1

If I correctly understand you, you can send a message to specific user like this.

public void SendChatMessage(string who, string message)
{
    string name = Context.User.Identity.Name;

    //foreach (var connectionId in _connections.GetConnections(who))
    //{
        //Clients.Client(connectionId).addChatMessage(name + ": " + message);
    //}
    Clients.User(who).addChatMessage(name + ": " + message);
}

And "string who" should be receiver user username. Hope this help.

Answer 2

Just change your the arguments of your addChatMessage method

 public void SendChatMessage(string who, string message)
    {
        string name = Context.User.Identity.Name;

        foreach (var connectionId in _connections.GetConnections(who))
        {
            Clients.Client(connectionId).addChatMessage(name , message);
        }
    }

This line of code is calling your client side addChatMessage method that you have written on the View

Clients.Client(connectionId).addChatMessage(name , message);

The function was not getting mapped properly since the argument you were supplying from your cs page was different than expected by the client side method.

Your call

 Clients.Client(connectionId).addChatMessage(name + ": " + message);

params expected by client method

 chat.client.addChatMessage = function (name, message) 

you were supplying a single argument hence it was not getting mapped.

If still the problem persists try to check _connections dictionary in the SendChatMessage method the only reason a message will not come back to you is if your connection id is not added to this dictionary which is not possible since that is the first step that happens as soon as you run the app in the OnConnected event