/// <summary>
    /// 日志生產類
    /// Singleton模(mo)(mo)式和策略模(mo)(mo)式和工廠模(mo)(mo)式
    /// </summary>
    public sealed class LoggerFactory : ILogger
    {
        #region Logger有多種實現時,需要使用Singleton模式
        /// <summary>
        /// 對外不(bu)能創建類的實例
        /// </summary>
        private LoggerFactory()
        {
            string type = "file";
            switch (type)
            {
                case "file":
                    iLogger = new NormalLogger();
                    break;
                default:
                    throw new ArgumentException("請正確(que)配(pei)置AppSetting的(de)LoggerType節點（file，log4net，mongodb）");
            }

        }

        /// <summary>
        /// 日志(zhi)級別
        /// </summary>
        private static Level level = Level.DEBUG;
        /// <summary>
        /// 線程(cheng)鎖
        /// </summary>
        private static object lockObj = new object();
        /// <summary>
        /// 日志工廠
        /// </summary>
        private static LoggerFactory instance;
        /// <summary>
        /// 日志(zhi)提供者，只(zhi)在本類(lei)中實(shi)例化
        /// </summary>
        private ILogger iLogger;
        /// <summary>
        /// 單例模式(shi)的日志工廠(chang)對象
        /// </summary>
        public static LoggerFactory Instance
        {
            get
            {
                if (instance == null)
                {
                    lock (lockObj)
                    {
                        if (instance == null)
                        {
                            instance = new LoggerFactory();
                        }
                    }
                }
                return instance;
            }
        }

        #endregion

        #region ILogger 成員

        public void Logger_Debug(string message)
        {
            if (level <= Level.DEBUG)
                iLogger.Logger_Debug(message);
        }
        public void Logger_Info(string message)
        {
            if (level <= Level.INFO)
                iLogger.Logger_Info(message);
        }
        public void Logger_Warn(string message)
        {
            if (level <= Level.WARN)
                iLogger.Logger_Warn(message);
        }
        public void Logger_Error(Exception ex)
        {
            if (level <= Level.ERROR)
                iLogger.Logger_Error(ex);
        }
        public void Logger_Fatal(string message)
        {
            if (level <= Level.FATAL)
                iLogger.Logger_Fatal(message);
        }
        #endregion
    }