/// <summary>
        /// 添加一个日志记录器。
        /// </summary>
        /// <param name="writer"></param>
        public void AddLogWriter(LogWriter writer)
        {
            lock (mWriters) {
                mWriters.Add(writer);

                if (!writer.IsPrepared)
                    writer.Prepare();
            }
        }
 /// <summary>
 /// 删除一个日志记录器。如果本来就不存在,不会产生错误。
 /// </summary>
 public void RemoveWriter(LogWriter writer)
 {
     lock (mWriters) {
         mWriters.Remove(writer);
     }
 }