一、添加动态库

?PS：动态库版本>2.0.0,否则异常会无法输出

二、帮助类

 public class Log
    {
        private static NLog.Logger logger = NLog.LogManager.GetCurrentClassLogger();

        public static void Debug(string msg, params object[] args)
        {
            logger.Debug(msg, args);
        }

        public static void Debug(string msg, Exception err)
        {
            logger.Debug(msg, err);
        }

        public static void Info(string msg, params object[] args)
        {
            logger.Info(msg, args);
        }

        public static void Info(string msg, Exception err)
        {
            logger.Info(msg, err);
        }

        public static void Trace(string msg, params object[] args)
        {
            logger.Trace(msg, args);
        }

        public static void Trace(string msg, Exception err)
        {
            logger.Trace(msg, err);
        }

        public static void Error(string msg, params object[] args)
        {
            logger.Error(msg, args);
        }

        public static void Error(string msg, Exception err)
        {
            logger.Error(msg, err);
        }

        public static void Fatal(string msg, params object[] args)
        {
            logger.Fatal(msg, args);
        }

        public static void Fatal(string msg, Exception err)
        {
            logger.Fatal(msg, err);
        }

        /// <summary>
        /// 删除指定日期前的日志
        /// </summary>
        /// <param name="time"></param>
        public static void DelLogFile(DateTime time)
        {
            try
            {
                string directorypath = AppDomain.CurrentDomain.BaseDirectory + "Logs";
                if (System.IO.Directory.Exists(directorypath))
                {
                    DirectoryInfo thisOne = new DirectoryInfo(directorypath);
                    DirectoryInfo[] subDirectories = thisOne.GetDirectories(); //获得目录
                    //删除错误日志
                    if (subDirectories != null)
                    {
                        foreach (DirectoryInfo item in subDirectories)
                        {
                            DateTime filedate = DateTime.Now;
                            DateTime.TryParse(item.Name, out filedate);
                            if (time > filedate)
                            {
                                System.IO.Directory.Delete(item.FullName, true);
                            }
                        }
                    }
                }
            }
            catch (Exception)
            {

            }
        }
    }

三、配置文件

<?xml version="1.0" encoding="utf-8" ?>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
	<targets>
		<!--屏幕打印消息-->
		<target name="console" xsi:type="ColoredConsole"
						layout="${date:format=HH\:mm\:ss}> ${message}"/>

		<!--vs输出窗口-->
		<target name="vsdebugger" xsi:type="Debugger"
					   layout="[${date:format=HH\:mm\:ss}][${level:padding=5:uppercase=true}] ${message}"/>

		<!--保存debug至文件-->
		<target name="debugger" xsi:type="File" maxArchiveFiles="30"
						fileName="${basedir}/Logs/${shortdate}/debug.txt"
						layout="[${date:format=HH\:mm\:ss}][${level:padding=5:uppercase=true}] ${message}"/>

		<!--保存erorr至文件-->
		<target name="error_file" xsi:type="File" maxArchiveFiles="30"
						fileName="${basedir}/Logs/${shortdate}/error.txt"
						layout="[${longdate}][${level:uppercase=true:padding=5}] ${message} | ${onexception:${exception:format=message} ${newline} ${stacktrace}" />

		<!--保存fatal至文件-->
		<target name="fatal_file" xsi:type="File" maxArchiveFiles="30"
						fileName="${basedir}/Logs/${shortdate}/fatal.txt"
						layout="[${longdate}][${level:uppercase=true:padding=5}] ${message} | ${onexception:${exception:format=message} ${newline} ${stacktrace}" />


		<!--保存info至文件-->
		<target name="info_file" xsi:type="File" maxArchiveFiles="30"
						fileName="${basedir}/Logs/${shortdate}/info.txt"
						layout="[${longdate}][${level:uppercase=true:padding=5}] ${message} | ${exception}" />
	</targets>
	<rules>
		<logger name="*" writeTo="console" />
		<logger name="*" minlevel="Trace" writeTo="vsdebugger"/>
		<logger name="*" levels="Debug" writeTo="debugger" />
		<logger name="*" levels="Error" writeTo="error_file" />
		<logger name="*" levels="Fatal" writeTo="fatal_file" />
		<logger name="*" levels="Info" writeTo="info_file" />
	</rules>
</nlog>

四、实例

 public Main()
 {          
      Log.Trace("Trace");
      Log.Debug("Debug");
      Log.Info("Info");
      Log.Error("Error");
      Log.Fatal("Info");
}