Question

in the system console I would like to log only messages from com.foo.* and not messages from an external library that I’m using com.bar.*

Here’s what I did:

<appender name="console" class="org.apache.log4j.ConsoleAppender">
    <layout class="org.apache.log4j.PatternLayout">
        <param name="ConversionPattern" value="%d %p %c - %m%n" />
    </layout>
</appender>

<appender name="bar" class="org.apache.log4j.FileAppender">
    <param name="File" value="logs/bar.log"/>
    <layout class="org.apache.log4j.PatternLayout">
        <param name="ConversionPattern" value="%d %p %c - %m%n" />
    </layout>
</appender>

<logger name="com.foo">
    <level value="ALL" />
    <appender-ref ref="console"/>
</logger>

<logger name="com.bar">
    <level value="ALL" />
    <appender-ref ref="bar"/>
</logger>

<root>
    <level value="ALL" />
    <appender-ref ref="console" />
            <appender-ref ref="bar" />
</root>

The problem is that log messages from com.bar.* are still displayed in the console.

Thanks.

Answer 1

If you want to log only com.foo to the console, then I think you can just remove the console appender reference from the root to get what you want.

If instead you want to prevent only com.bar from logging to the console, then I think this would work:

<logger name="com.foo">
    <level value="ALL" />
</logger>

<logger name="com.bar" additivity="false">
    <level value="ALL" />
    <appender-ref ref="bar"/>
</logger>

Keep in mind that loggers have additivity set to true by default. See: http://veerasundar.com/blog/2009/08/log4j-tutorial-additivity-what-and-why/ .