Filter.java

/***************************************************************************
 * Project file:    NPlugins - NCore - Filter.java                         *
 * Full Class name: fr.ribesg.bukkit.ncore.common.logging.Filter           *
 *                                                                         *
 *                Copyright (c) 2012-2014 Ribesg - www.ribesg.fr           *
 *   This file is under GPLv3 -> http://www.gnu.org/licenses/gpl-3.0.txt   *
 *    Please contact me at ribesg[at]yahoo.fr if you improve this file!    *
 ***************************************************************************/

package fr.ribesg.bukkit.ncore.common.logging;
/**
 * Represents a simple Log filter.
 *
 * @author Ribesg
 */
public interface Filter {

	/**
	 * Check if this Filter denies a message or not.
	 *
	 * @param message the message to check
	 *
	 * @return true if this Filter prevents this message from being logged,
	 * false otherwise
	 */
	public boolean denies(final String message);
}

FilterManager.java

/***************************************************************************
 * Project file:    NPlugins - NCore - FilterManager.java                  *
 * Full Class name: fr.ribesg.bukkit.ncore.common.logging.FilterManager    *
 *                                                                         *
 *                Copyright (c) 2012-2014 Ribesg - www.ribesg.fr           *
 *   This file is under GPLv3 -> http://www.gnu.org/licenses/gpl-3.0.txt   *
 *    Please contact me at ribesg[at]yahoo.fr if you improve this file!    *
 ***************************************************************************/

package fr.ribesg.bukkit.ncore.common.logging;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.LoggerContext;
import org.apache.logging.log4j.core.config.Configuration;
import org.apache.logging.log4j.core.config.LoggerConfig;
import org.apache.logging.log4j.core.filter.AbstractFilter;
import org.apache.logging.log4j.core.filter.RegexFilter;

/**
 * Manages log4j2 filters
 *
 * @author Ribesg
 */
public class FilterManager {

	/**
	 * Adds a new RegexFilter to log4j2.
	 *
	 * @param regex a regex String
	 */
	public void addRegexFilter(final String regex) {
		addFilter(RegexFilter.createFilter(regex, "FALSE", "DENY", "NEUTRAL"));
	}

	/**
	 * Adds a new CustomFilter to log4j2.
	 *
	 * @param filter the filter
	 */
	public void addCustomFilter(final Filter filter) {
		addFilter(new CustomFilter(filter));
	}

	/**
	 * Adds a new log4j Filter to log4j.
	 *
	 * @param log4jFilter a log4j filter
	 */
	private void addFilter(final org.apache.logging.log4j.core.Filter log4jFilter) {
		final LoggerContext context = (LoggerContext) LogManager.getContext();
		final Configuration config = context.getConfiguration();
		final LoggerConfig loggerConfig = config.getLoggerConfig(LogManager.getRootLogger().getName());
		loggerConfig.addFilter(log4jFilter);
		context.updateLoggers();
	}

	/**
	 * Represents a Custom log4j2 filter
	 */
	private class CustomFilter extends AbstractFilter {

		/**
		 * The actual filter
		 */
		private final Filter filter;

		/**
		 * Builds a CustomFilter from a Filter.
		 *
		 * @param filter a Filter
		 */
		private CustomFilter(final Filter filter) {
			this.filter = filter;
		}

		@Override
		public Result filter(final LogEvent event) {
			return filter.denies(event.getMessage().getFormattedMessage()) ? Result.DENY : Result.NEUTRAL;
		}
	}
}