Logback: the reliable, generic, fast and flexible logging framework.
Copyright (C) 1999-2015, QOS.ch. All rights reserved.
This program and the accompanying materials are dual-licensed under
either the terms of the Eclipse Public License v1.0 as published by
the Eclipse Foundation
  or (per the licensee's choosing)
under the terms of the GNU Lesser General Public License version 2.1
as published by the Free Software Foundation.
/**
 * Logback: the reliable, generic, fast and flexible logging framework.
 * Copyright (C) 1999-2015, QOS.ch. All rights reserved.
 *
 * This program and the accompanying materials are dual-licensed under
 * either the terms of the Eclipse Public License v1.0 as published by
 * the Eclipse Foundation
 *
 *   or (per the licensee's choosing)
 *
 * under the terms of the GNU Lesser General Public License version 2.1
 * as published by the Free Software Foundation.
 */
package ch.qos.logback.classic.jul;

import ch.qos.logback.classic.Level;
import ch.qos.logback.classic.Logger;
import ch.qos.logback.classic.LoggerContext;
import ch.qos.logback.classic.spi.LoggerContextListener;
import ch.qos.logback.core.spi.ContextAwareBase;
import ch.qos.logback.core.spi.LifeCycle;

import java.util.Enumeration;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.logging.LogManager;

Propagate level changes made to a logback logger into the equivalent logger in j.u.l.
/**
 * Propagate level changes made to a logback logger into the equivalent logger in j.u.l.
 */
public class LevelChangePropagator extends ContextAwareBase implements LoggerContextListener, LifeCycle {

    private Set<java.util.logging.Logger> julLoggerSet = new HashSet<java.util.logging.Logger>();
    boolean isStarted = false;
    boolean resetJUL = false;

    public void setResetJUL(boolean resetJUL) {
        this.resetJUL = resetJUL;
    }

    public boolean isResetResistant() {
        return false;
    }

    public void onStart(LoggerContext context) {
    }

    public void onReset(LoggerContext context) {
    }

    public void onStop(LoggerContext context) {
    }

    public void onLevelChange(Logger logger, Level level) {
        propagate(logger, level);
    }

    private void propagate(Logger logger, Level level) {
        addInfo("Propagating " + level + " level on " + logger + " onto the JUL framework");
        java.util.logging.Logger julLogger = JULHelper.asJULLogger(logger);
        // prevent garbage collection of jul loggers whose level we set
        // see also http://jira.qos.ch/browse/LBCLASSIC-256
        julLoggerSet.add(julLogger);
        java.util.logging.Level julLevel = JULHelper.asJULLevel(level);
        julLogger.setLevel(julLevel);
    }

    public void resetJULLevels() {
        LogManager lm = LogManager.getLogManager();

        Enumeration<String> e = lm.getLoggerNames();
        while (e.hasMoreElements()) {
            String loggerName = e.nextElement();
            java.util.logging.Logger julLogger = lm.getLogger(loggerName);
            if (JULHelper.isRegularNonRootLogger(julLogger) && julLogger.getLevel() != null) {
                addInfo("Setting level of jul logger [" + loggerName + "] to null");
                julLogger.setLevel(null);
            }
        }
    }

    private void propagateExistingLoggerLevels() {
        LoggerContext loggerContext = (LoggerContext) context;
        List<Logger> loggerList = loggerContext.getLoggerList();
        for (Logger l : loggerList) {
            if (l.getLevel() != null) {
                propagate(l, l.getLevel());
            }
        }
    }

    public void start() {
        if (resetJUL) {
            resetJULLevels();
        }
        propagateExistingLoggerLevels();

        isStarted = true;
    }

    public void stop() {
        isStarted = false;
    }

    public boolean isStarted() {
        return isStarted;
    }
}