javascript - 向特定用户或设备推送通知

Question

我有一个 WEB MVC 5 系统，我在其中实时使用 signalR 和 SqlDependency，但情况并非如此，我需要实现的是在兴趣发生变化时向系统管理员推送通知。具体来说，我需要的是一种向特定用户发送推送通知的机制，如果可能的话，即使他们没有连接，也就是说，即使他们没有使用系统。

我搜索了很多，我使用的是 push.js 库，但这不允许我这样做，或者我认为是这样。

任何能够满足我的需求或类似需求的机制都会被接受。

Answer 1

我编写了一个存储过程 (SP)，它根据用户返回事件详细信息。您可以创建一个表来保存您要发送通知的 ID，每次插入此表都会通知用户。

我有三个表，分别是“User”、“Events”、“UserEvents”。在 UserEvents 表中，userID 作为用户表的外键，eventID 作为事件表的外键。在我的系统中，当事件插入到上面的表中时，signalR 完成它的工作。UserEvents 表具有如下列:

   [Uev_ID]
  ,[Uev_UserID]
  ,[Uev_EventID]
  ,[Uev_IsRead]
  ,[Uev_ReadDate]
  ,[GuID]
  ,[Deleted]

我的事件模型如下:

    public class EventList
    {
    public Int64 EventID { get; set; }
    public string Title { get; set; }
    public string Description { get; set; }
    public DateTime Date { get; set; }
    public string Color { get; set; }
    }

应该有一个消息存储库来与数据库和模型进行交互和通信。此存储库将处理 dependency_OnChange 方法。

    public class MessagesRepository
    {
    internal static SqlCommand command = null;
    internal static SqlCommand command2 = null;
    internal static SqlDependency dependency = null;
    internal static SqlDependency dependency2 = null;
    readonly string _connString = 
                  ConfigurationManager.ConnectionStrings["signalr"].ConnectionString;
    private Int64 user { get; set; }
    public MessagesRepository(Int64 userID)
    {
        user = userID;
    }

    public IEnumerable<EventList> GetAllMessages()
    {
        var messages = new List<EventList>();
        using (var connection = new SqlConnection(_connString))
        {
            connection.Open();
            using (command = new SqlCommand("[sp_SysEvent]", connection))
            {
                command.CommandType = CommandType.StoredProcedure;
                command.Parameters.AddWithValue("@user", user);
                command.Notification = null;

                if (dependency == null)
                {
                    dependency = new SqlDependency(command);
                    dependency.OnChange += new OnChangeEventHandler(dependency_OnChange);
                }
                if (connection.State == ConnectionState.Closed)
                    connection.Open();

                var reader = command.ExecuteReader();

                while (reader.Read())
                {
                    messages.Add(item: new EventList { EventID = (Int64)reader["Evt_ID"], Description = (string)reader["Evt_Description"], Title = (string)reader["Evg_Title"], Date = (DateTime)reader["Evt_Date"], Color = (string)reader["Clr_Color"] });
                }
            }
        }
        return messages;
    }

    private void dependency_OnChange(object sender, SqlNotificationEventArgs e)
    {
        if (dependency != null)
        {
            dependency.OnChange -= dependency_OnChange;
            dependency = null;
        }
        if (e.Info == SqlNotificationInfo.Insert)
        {

            TestHub.SendUser(user);
        }
    }
}

我需要一个连接映射文档来向连接的用户发送通知。当用户连接时，我将其 ID 放入 HashSet 并在用户断开连接时从 HashSet 中删除。您可以使用它来检测哪个用户已连接。这是连接映射: 公共(public)类 ConnectionMapping { 私有(private)词典> _connections = 新词典>();

    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 IEnumerable<string> GetConnections2(T key)
    //{
    //    List<HashSet<string>> connections;
    //    if (_connections.Any(x => x.Key.ToString().Contains(key.ToString())))
    //    {
    //        connections = _connections.Where(x => x.Key.ToString().StartsWith(key.ToString() + "_")).Select(x => x.Value);
    //    }

    //    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);
                }
            }
        }
    }
}

Hub 文档是:

public class TestHub : Hub
{
    private readonly static ConnectionMapping<string> _connections = new ConnectionMapping<string>();
    public string GetUserGroup()
    {
        string abc = "";
        using (SqlConnection connection = new SqlConnection(ConfigurationManager.ConnectionStrings["signalr"].ConnectionString))
        {
            connection.Open();
            string sqltheme = "Select Usr_GroupID from SysUser where ID=" + Convert.ToInt32(HttpContext.Current.User.Identity.Name.Split('_')[1]) + "";
            using (SqlCommand command = new SqlCommand(sqltheme, connection))
            {
                abc = command.ExecuteScalar().ToString();
            }
        }
        return abc;
    }
    public override Task OnConnected()
    {
        string name = "";
        try
        {
            name = HttpContext.Current.User.Identity.Name.Split('_')[1];
            Groups.Add(Context.ConnectionId, GetUserGroup());
        }catch(Exception ex)
        {
            name = Context.ConnectionId;
        }
        if (_connections.GetConnections(name).Count() > 0)
        {
            _connections.Remove(name, _connections.GetConnections(name).ToString());
        }
        _connections.Add(name, Context.ConnectionId);
        return base.OnConnected();
    }
    [HubMethodName("send")]
    public void Send(string mes)
    {
        Clients.All.send(mes); // if you want to send all user use this.
    }
    [HubMethodName("sendUser")]
    public void SendUser(string[] who, int id, string title)
    {
        string name = Context.User.Identity.Name;
        foreach (var user in who)
        {
            foreach (var connectionId in _connections.GetConnections(user))
            {
                Clients.Client(connectionId).sendUser(id, title);
            }
        }
    }
    }

最后是调用 hub 函数的 javascript 代码:

var myhub = $.connection.testHub;
        $(function () {
            $.connection.hub.start();
            chat.client.sendUser = function (id, title) {
                var count = parseFloat($("#header_notification_bar > a > span").text()) + 1;
                $("#header_notification_bar > a > span").text(count);
                toastr.info('Bir Yeni Bildiriminiz Var.Görüntülemek İçin Tıklayınız.', 'Bildirim', {
                    closeButton: true, timeOut: 20000, onclick: function () {
                        window.location.href = '/tr/Notification/List';
                    }
                });
                $("#notification_list").prepend("<li><a href='javascript:;' style='background-color:#e6e6e6' class='okunmadi' id='" + id + "'><span class='time' style='min-width:100px;'>şimdi</span><span class='details'><span class='label label-sm label-icon label-success'><i class='fa fa-bullhorn'></i></span>" + title + "</span></a></li>");
            };

我希望它也适合你。