private bool FowardTo(MessageReceivedEventArgs e, string userName, Message msg)
{
//检测用户是否在线
if (!onlineUsers.Contains(userName))
{
//不在线，写入用户离线信息
database.AddUserMessage(userName, msg);
return(true);
}
else
{
//在线，直接发送给目标用户
NetworkStream targetStream = (onlineUsers[userName] as OnlineUser).StreamToRemote;
return(receiver.SendMessage(msg, targetStream));
}
}
