向特定用户或设备推送通知

Question

我有一个WEB MVC 5系统，在该系统中我实时使用signalR和SqlDependency，但事实并非如此，我需要实现的是在发生感兴趣的更改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，即使他们不使用系统。

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

任何能满足我需求或类似需求的机制都会收到。

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要发送通知的ID，并且每个插入到该表的内容都会通知用户。

我有三个表，分别是"用户"、"事件"one_answers"用户事件"。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就完成了它的工作。UserEvents表的列如下：

[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中移除。您可以使用它来检测连接的用户。以下是连接映射：公共类ConnectionMapping{private Dictionary>_connections=new Dictionary>((；

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，调用集线器函数的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>");
};

我希望它也适用于你。