1. 참조에 NuGet으로 log4net추가.
2. app.config 파일 안에 <startup> 위에 추가
<configSections>
<section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net" />
</configSections>
<log4net>
<appender name="DebugAppender" type="log4net.Appender.DebugAppender">
<layout type="log4net.Layout.PatternLayout">
<!--<conversionPattern value="%date [%thread] %-5level %logger [%property{NDC}] - %message%newline" />-->
<!--<conversionPattern value="%d %-5p %p (%c:%4L) %m %r %u %n%n"/>-->
<conversionPattern value="(line:%4L) %date{HH:mm:ss,fff} %level - %message%newline" />
</layout>
</appender>
<!--
<appender name="ConsoleAppender" type="log4net.Appender.ConsoleAppender">
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%date [%thread] %-5level %logger [%property{NDC}] - %message%newline" />
</layout>
</appender>
-->
<root>
<level value="All" />
<appender-ref ref="DebugAppender" />
<!--<appender-ref ref="ConsoleAppender" />-->
</root>
</log4net>
3. .cs파일 안에 추가
// 전역 추가.
protected static readonly ILog log = LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
// 생성자에 추가.
log4net.Config.XmlConfigurator.Configure();
4. 호출.
log.Debug("msg");