Creating multiple log files of different content with log4j

This should get you started:

log4j.rootLogger=QuietAppender, LoudAppender, TRACE
# setup A1
log4j.appender.QuietAppender=org.apache.log4j.RollingFileAppender
log4j.appender.QuietAppender.Threshold=INFO
log4j.appender.QuietAppender.File=quiet.log
...


# setup A2
log4j.appender.LoudAppender=org.apache.log4j.RollingFileAppender
log4j.appender.LoudAppender.Threshold=DEBUG
log4j.appender.LoudAppender.File=loud.log
...

log4j.logger.com.yourpackage.yourclazz=TRACE

Perhaps something like this?

<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
 <!-- general application log -->
 <appender name="MainLogFile" class="org.apache.log4j.FileAppender">
  <param name="File" value="server.log" />
  <param name="Threshold" value="INFO" />
  <layout class="org.apache.log4j.PatternLayout">
   <param name="ConversionPattern" value="%-5p %t [%-40.40c] %x - %m%n"/>
  </layout>
 </appender> 
 <!-- additional fooSystem logging -->
 <appender name="FooLogFile" class="org.apache.log4j.FileAppender">
  <param name="File" value="foo.log" />
  <layout class="org.apache.log4j.PatternLayout">
   <param name="ConversionPattern" value="%-5p %t [%-40.40c] %x - %m%n"/>
  </layout>
 </appender>
 <!-- foo logging -->
 <logger name="com.example.foo">
  <level value="DEBUG"/>
  <appender-ref ref="FooLogFile"/>
 </logger>
 <!-- default logging -->
 <root>
  <level value="INFO"/>
  <appender-ref ref="MainLogFile"/>
 </root>
</log4j:configuration>

Thus, all info messages are written to server.log; by contrast, foo.log contains only com.example.foo messages, including debug-level messages.