public async Task <string> JoinAsUser(int userId)
{
if (!XueLeMeContext.Users.Where(u => u.Id == userId).Any())
{
return("账号不存在");
}
var groups = XueLeMeContext.GroupMemberships.Where(m => m.UserId == userId).Select(m => m.ChatGroupId).ToList();
if (ConnectionService.IsOnline(userId))
{
string connectionId = ConnectionService.GetConnectionId(userId);
if (connectionId != Context.ConnectionId)
{
Logger.LogInformation("Force Out connection {0}, uid = {1}", Context.ConnectionId, userId);
await Clients.Client(connectionId).SendAsync("OnNotify", (int)NotificationTypeEnum.ForceOut, "您的账号在别的设备被登录，可能是密码泄露，请重新登陆！");
ConnectionService.Detach(connectionId);
}
}
ConnectionService.Attach(Context.ConnectionId, userId);
foreach (var group in groups)
{
await Groups.AddToGroupAsync(Context.ConnectionId, group.ToString());
}
return("成功与服务器建立连接");
}
