Logback to log different messages to two files

Question

I am using logback/slf4j to do my logging. I want to parse my log file to analyze some data, so instead of parsing a great big file (mostly consisting of debug statements) I want to have two logger instances which each log to a separate file; one for analytics and one for all purpose logging. Does anyone know if this is possible with Logback, or any other logger for that matter?

Answer 1

It's very possible to do something like this in logback. Here's an example configuration:

<?xml version="1.0"?>
<configuration>
    <appender name="FILE" class="ch.qos.logback.core.FileAppender">
        <file>logfile.log</file>
        <append>true</append>
        <encoder>
            <pattern>%-4relative [%thread] %-5level %logger{35} - %msg %n</pattern>
        </encoder>
    </appender>
    <appender name="ANALYTICS-FILE" class="ch.qos.logback.core.FileAppender">
        <file>analytics.log</file>
        <append>true</append>
        <encoder>
            <pattern>%-4relative [%thread] %-5level %logger{35} - %msg %n</pattern>
        </encoder>
    </appender>
    <!-- additivity=false ensures analytics data only goes to the analytics log -->
    <logger name="analytics" level="DEBUG" additivity="false">
        <appender-ref ref="ANALYTICS-FILE"/>
    </logger>
    <root>
        <appender-ref ref="FILE"/>
    </root>
</configuration>

Then you'd setup two separate loggers, one for everything and one to log analytics data like so:

Logger analytics = LoggerFactory.getLogger("analytics");