Update: For an all configuration based approach using Groovy see Dean Hiller's answer.
--
You can do some interesting things with Logback filters. The below configuration will only print warn and error messages to stderr, and everything else to stdout.
logback.xml
<appender name="stdout" class="ch.qos.logback.core.ConsoleAppender">
<target>System.out</target>
<filter class="com.foo.StdOutFilter" />
...
</appender>
<appender name="stderr" class="ch.qos.logback.core.ConsoleAppender">
<target>System.err</target>
<filter class="com.foo.ErrOutFilter" />
...
</appender>
<logger name="mylogger" level="debug">
<appender-ref ref="stdout" />
<appender-ref ref="stderr" />
</logger>
com.foo.StdOutFilter
public class StdOutFilter extends ch.qos.logback.core.filter.AbstractMatcherFilter
{
@Override
public FilterReply decide(Object event)
{
if (!isStarted())
{
return FilterReply.NEUTRAL;
}
LoggingEvent loggingEvent = (LoggingEvent) event;
List<Level> eventsToKeep = Arrays.asList(Level.TRACE, Level.DEBUG, Level.INFO);
if (eventsToKeep.contains(loggingEvent.getLevel()))
{
return FilterReply.NEUTRAL;
}
else
{
return FilterReply.DENY;
}
}
}
com.foo.ErrOutFilter
public class ErrOutFilter extends ch.qos.logback.core.filter.AbstractMatcherFilter
{
@Override
public FilterReply decide(Object event)
{
if (!isStarted())
{
return FilterReply.NEUTRAL;
}
LoggingEvent loggingEvent = (LoggingEvent) event;
List<Level> eventsToKeep = Arrays.asList(Level.WARN, Level.ERROR);
if (eventsToKeep.contains(loggingEvent.getLevel()))
{
return FilterReply.NEUTRAL;
}
else
{
return FilterReply.DENY;
}
}
}