IsOnline(string playerID, out Player client)

    /// <summary>
    /// playerID玩家是否在线? 并且如果在线则out 在线玩家的对象
    /// </summary>
    /// <param name="playerID"></param>
    /// <returns></returns>
    public virtual bool IsOnline(string playerID, out Player client)
    {
        return Players.TryGetValue(playerID, out client);
    }