用C#配置log4net

log4net Tutorial - The Complete Guide for beginners and pros
https://www.codeproject.com/Articles/140911/log-net-Tutorial

var hierarchy = (Hierarchy)LogManager.GetRepository();

PatternLayout patternLayout = new PatternLayout
{
    ConversionPattern = "%date %level %message%newline"
};
patternLayout.ActivateOptions();

var coloredConsoleAppender = new ColoredConsoleAppender();
coloredConsoleAppender.AddMapping(new ColoredConsoleAppender.LevelColors
{
    BackColor = ColoredConsoleAppender.Colors.Red,
    ForeColor = ColoredConsoleAppender.Colors.White,
    Level = Level.Error
});
coloredConsoleAppender.Layout = patternLayout;

var rollingFileAppender = new RollingFileAppender
{
    File = "logfile",
    AppendToFile = true,
    RollingStyle = RollingFileAppender.RollingMode.Date,
    DatePattern = "yyyyMMdd-HHmm",
    Layout = patternLayout
};

hierarchy.Root.AddAppender(coloredConsoleAppender);
hierarchy.Root.AddAppender(rollingFileAppender);
hierarchy.Root.Level = Level.All;
hierarchy.Configured = true;

BasicConfigurator.Configure(hierarchy);

<log4net>
  <appender name="ColoredConsoleAppender" type="log4net.Appender.ColoredConsoleAppender">
    <mapping>
      <level value="ERROR" />
      <foreColor value="White" />
      <backColor value="Red, HighIntensity" />
    </mapping>
    <layout type="log4net.Layout.PatternLayout">
      <conversionPattern value="%date %level %message%newline" />
    </layout>
  </appender>
  <appender name="RollingFileAppender" type="log4net.Appender.RollingFileAppender">
    <file value="logfile" />
    <appendToFile value="true" />
    <rollingStyle value="Date" />
    <datePattern value="yyyyMMdd-HHmm" />
    <layout type="log4net.Layout.PatternLayout">
      <conversionPattern value="%date %level %message%newline" />
    </layout>
  </appender>
  <root>
    <level value="ALL" />
    <appender-ref ref="ColoredConsoleAppender" />
    <appender-ref ref="RollingFileAppender" />
  </root>
</log4net>