protected override void WriteLog(LogEntry entry, Stream stream)
		{
			using(var writer = new StreamWriter(stream, System.Text.Encoding.UTF8))
			{
				writer.WriteLine(entry.ToString());
			}
		}
		public void Log(LogEntry entry)
		{
			if(entry == null)
				return;

			//根据日志级别来调整控制台的前景色
			switch(entry.Level)
			{
				case LogLevel.Trace:
					Console.ForegroundColor = ConsoleColor.Gray;
					break;
				case LogLevel.Debug:
					Console.ForegroundColor = ConsoleColor.DarkGray;
					break;
				case LogLevel.Warn:
					Console.ForegroundColor = ConsoleColor.Yellow;
					break;
				case LogLevel.Error:
				case LogLevel.Fatal:
					Console.ForegroundColor = ConsoleColor.Red;
					break;
			}

			try
			{
				//打印日志信息
				Console.WriteLine(entry);
			}
			finally
			{
				//恢复默认颜色
				Console.ResetColor();
			}
		}
		protected override void WriteLog(LogEntry entry, Stream stream)
		{
			//注意:此处不能关闭stream参数传入的流,该流由基类确保安全释放!
			using(var writer = new StreamWriter(stream, System.Text.Encoding.UTF8, 1024 * 16, true))
			{
				writer.WriteLine(entry.ToString());
			}
		}
		public void Log(LogEntry entry)
		{
			if(entry == null)
				return;

			var filePath = this.ResolveSequence(entry);

			if(string.IsNullOrWhiteSpace(filePath))
				throw new InvalidOperationException("Unspecified path of the log file.");

			//将日志实体加入内存队列中
			_queue.Enqueue(entry);

			//从线程池拉出一个后台线程进行具体的日志记录操作
			ThreadPool.QueueUserWorkItem(this.LogFile, filePath);
		}
		private string ResolveSequence(LogEntry entry)
		{
			const string PATTERN = @"(?<no>\d+)";
			const string SEQUENCE = "{sequence}";

			var maximum = 0;
			var result = string.Empty;
			var filePath = this.GetFilePath(entry);

			if(string.IsNullOrEmpty(filePath) || (!filePath.Contains(SEQUENCE)))
				return filePath;

			if(this.FileSize < 1)
				return filePath.Replace(SEQUENCE, string.Empty);

			var fileName = System.IO.Path.GetFileName(filePath);
			var infos = Zongsoft.IO.LocalFileSystem.Instance.Directory.GetFiles(System.IO.Path.GetDirectoryName(filePath), fileName.Replace(SEQUENCE, "|" + PATTERN + "|"), false);
			var pattern = string.Empty;
			int index = 0, position = 0;

			while((index = fileName.IndexOf(SEQUENCE, index)) >= 0)
			{
				if(index > 0)
					pattern += Zongsoft.IO.LocalFileSystem.LocalDirectoryProvider.EscapePattern(fileName.Substring(position, index - position));

				pattern += PATTERN;
				index += SEQUENCE.Length;
				position = index;
			}

			if(position < fileName.Length)
				pattern += Zongsoft.IO.LocalFileSystem.LocalDirectoryProvider.EscapePattern(fileName.Substring(position));

			//设置正则匹配模式为完整匹配
			if(pattern != null && pattern.Length > 0)
				pattern = "^" + pattern + "$";

			foreach(var info in infos)
			{
				var match = System.Text.RegularExpressions.Regex.Match(info.Name, pattern);

				if(match.Success)
				{
					var number = int.Parse(match.Groups["no"].Value);

					if(number > maximum)
					{
						maximum = number;

						if(info.Size < this.FileSize * KB)
							result = info.Path.Url;
					}
				}
			}

			if(string.IsNullOrEmpty(result))
				return filePath.Replace(SEQUENCE, (maximum + 1).ToString());

			return result;
		}
		protected virtual string GetFilePath(LogEntry entry)
		{
			var filePath = string.Empty;

			if(string.IsNullOrWhiteSpace(_filePath))
				filePath = string.IsNullOrWhiteSpace(entry.Source) ? string.Empty : entry.Source + ".log";
			else
				filePath = Logger.TemplateManager.Evaluate<string>(_filePath.Trim(), entry);

			if(string.IsNullOrWhiteSpace(filePath))
				return null;

			filePath = filePath.Replace((Path.DirectorySeparatorChar == '/' ? '\\' : '/'), Path.DirectorySeparatorChar).Trim();

			if(filePath[0] == '/' || filePath[0] == '\\')
			{
				filePath = Path.Combine(Path.GetPathRoot(Zongsoft.ComponentModel.ApplicationContextBase.Current.ApplicationDirectory), filePath.Substring(1));

				if(!Directory.Exists(Path.GetDirectoryName(filePath)))
					Directory.CreateDirectory(Path.GetDirectoryName(filePath));

				return filePath;
			}

			string directoryPath;

			if(filePath.StartsWith("~/") || filePath.StartsWith("~\\"))
				directoryPath = Zongsoft.ComponentModel.ApplicationContextBase.Current.EnsureDirectory(Path.GetDirectoryName(filePath.Substring(2)));
			else
				directoryPath = Zongsoft.ComponentModel.ApplicationContextBase.Current.EnsureDirectory(Path.GetDirectoryName(filePath));

			return Path.Combine(directoryPath, Path.GetFileName(filePath));
		}
		protected abstract void WriteLog(LogEntry entry, Stream output);
		private static void Log(LogEntry entry)
		{
			if(entry == null || _handlers == null)
				return;

			System.Threading.Tasks.Parallel.ForEach(_handlers, handler =>
			{
				if(handler != null)
					handler.Handle(entry);
			});
		}
		protected virtual void Log(LogEntry entry)
		{
			if(entry == null)
				return;

			var loggers = _selector.Select(_parameter);

			System.Threading.Tasks.Parallel.ForEach(loggers, logger =>
			{
				if(logger != null)
					logger.Log(entry);
			});
		}
		public void Log(LogEntry entry)
		{
			var dataAccess = this.DataAccess;

			if(dataAccess == null)
				return;

			var storage = this.Storage;
			Zongsoft.Collections.IQueue queue = null;

			foreach(Zongsoft.Options.Configuration.SettingElement parameter in _configuration.Parameters)
			{
				Logger.TemplateManager.Evaluate<string>(parameter.Value, entry);
			}

			throw new NotImplementedException();
		}
		public void Handle(LogEntry entry)
		{
			this.Execute(entry);
		}