Adding a context listener

Instances of the LoggerContextListener interface listen to events pertaining to the lifecycle of a logger context.

JMXConfigurator is one implementation of the LoggerContextListener interface. It is described in a subsequent chapter.

LevelChangePropagator

As of version 0.9.25, logback-classic ships with LevelChangePropagator, an implementation of LoggerContextListener which propagates changes made to the level of any logback-classic logger onto the java.util.logging framework. Such propagation eliminates the performance impact of disabled log statements. Instances of LogRecord will be sent to logback (via SLF4J) only for enabled log statements. This makes it reasonable for real-world applications to use the jul-to-slf4j bridge.

The contextListener element can be used to install LevelChangePropagator as shown next.

<configuration debug="true">
  <contextListener class="ch.qos.logback.classic.jul.LevelChangePropagator"/>
  .... 
</configuration>

Setting the resetJUL property of LevelChangePropagator will reset all previous level configurations of all j.u.l. loggers. However, previously installed handlers will be left untouched.

<configuration debug="true">
  <contextListener class="ch.qos.logback.classic.jul.LevelChangePropagator">
    <resetJUL>true</resetJUL>
  </contextListener>
  ....
</configuration>