How to log different log level to different log appender in log4net

问题

I have a WinForm that it display log information but I want it to display to only INFO level but I want the log in the log file to contain DEBUG level as well.

Below is my configuration:

<?xml version="1.0" encoding="utf-8" ?>
<!-- This section contains the log4net configuration settings -->
<log4net>
  <!-- Define some output appenders -->

  <appender name="LogFileAppender" type="log4net.Appender.RollingFileAppender">
    <file value="${ALLUSERSPROFILE}\\Application Data\\logs\\Gateway" />
    <appendToFile value="true" />
    <rollingStyle value="Date" />
    <param name="StaticLogFileName" value="false" />
    <datePattern value=".yyyyMMdd.lo\g" />
    <layout type="log4net.Layout.PatternLayout">
      <conversionPattern value="%date | [%thread] | %-5level | %logger | %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>

  <appender name="ColoredConsoleAppender" type="log4net.Appender.ColoredConsoleAppender">
    <mapping>
      <level value="DEBUG" />
      <backColor value="Blue" />
    </mapping>
    <mapping>
      <level value="INFO" />
      <backColor value="Green" />
    </mapping>
    <mapping>
      <level value="WARN" />
      <backColor value="Yellow" />
    </mapping>
    <mapping>
      <level value="ERROR" />
      <backColor value="Red" />
    </mapping>
    <mapping>
      <level value="FATAL" />
      <backColor value="Red, HighIntensity" />
    </mapping>
    <layout type="log4net.Layout.PatternLayout">
      <conversionPattern value="%date [%thread] %-5level %logger - %message%newline" />
    </layout>
  </appender>

  <appender name="RichTextBoxAppender" type="Gateway.RichTextBoxAppender,Gateway" >
    <layout type="log4net.Layout.PatternLayout">
      <param name="Header" value="[Header]\r\n"/>
      <param name="Footer" value="[Footer]\r\n"/>
      <param name="ConversionPattern" value="%d [%t] %-5p %c [%x] - %m%n" />
    </layout>
    <mapping>
      <level value="DEBUG" />
      <textColorName value="DarkGreen" />
    </mapping>
    <mapping>
      <level value="INFO" />
      <textColorName value="ControlText" />
    </mapping>
    <mapping>
      <level value="WARN" />
      <textColorName value="Blue" />
    </mapping>
    <mapping>
      <level value="ERROR" />
      <textColorName value="Red" />
      <bold value="true" />
      <pointSize value="10" />
    </mapping>
    <mapping>
      <level value="FATAL" />
      <textColorName value="Black" />
      <backColorName value="Red" />
      <bold value="true" />
      <pointSize value="12" />
      <fontFamilyName value="Lucida Console" />
    </mapping>
  </appender>


  <!-- Setup the root category, add the appenders and set the default level -->
  <root>
    <level value="WARN" />
    <appender-ref ref="LogFileAppender" />
    <appender-ref ref="ColoredConsoleAppender" />
    <appender-ref ref="RichTextBoxAppender" />
  </root>

  <logger name ="Gateway" additivity="false">
    <level value="INFO" />
    <appender-ref ref="LogFileAppender" />
    <appender-ref ref="ColoredConsoleAppender" />
    <appender-ref ref="RichTextBoxAppender" />
  </logger>



</log4net>

Right now it is set to INFO for both LogFileAppender and RichTextBoxAppender. I tried taking out the LogFileAppender in Gateway logger and move to another logger and set to "DEBUG" level for this new logger but it is still doing one or the other. How do I configure it so that the LogFileAppender has DEBUG level and RichTextBoxAppender has INFO level?

回答1:

You should be able to add a filter to both of your appenders.

<filter type="log4net.Filter.LevelRangeFilter">
         <levelMin value="INFO" />
         <levelMax value="FATAL" />
</filter>

This way one appender will only log to a certain level while the other to a different level even though they are defined by the same logger.

回答2:

I agree with @gwhitake that you can use the level range filter. I also want to add, however, that you can use the LevelMatch filter if you just want to select one level. This filter allows you to add another filter at the end of it as well so that you could create a filter that had two or more levels even if they aren't next to each other in the order.

For example, the following filter will capture only DEBUG and ERROR messages (just as an example):

<filter type="log4net.Filter.LevelMatchFilter">
  <levelToMatch value="DEBUG"/>
</filter>
<filter type="log4net.Filter.LevelMatchFilter">
  <levelToMatch value="ERROR"/>
</filter>
<filter type="log4net.Filter.DenyAllFilter" />

The one key here is that we need to have the DenyAllFilter at the end. This tells the logger that if it reaches this line, don't log it. That way it will log DEBUG messages, ERROR messages, and nothing else.

There are a lot of ways to manipulate the filter to get exactly what you want. Here is an article (full disclaimer: I wrote it) that shows you how to do a number of different things with the filter besides just level range:

http://www.codeproject.com/KB/dotnet/Log4net_Tutorial.aspx

来源：https://stackoverflow.com/questions/6346521/how-to-log-different-log-level-to-different-log-appender-in-log4net