001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache license, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the license for the specific language governing permissions and
015 * limitations under the license.
016 */
017package org.apache.logging.log4j.web;
018
019import javax.servlet.ServletContext;
020import javax.servlet.ServletContextEvent;
021import javax.servlet.ServletContextListener;
022
023import org.apache.logging.log4j.Logger;
024import org.apache.logging.log4j.status.StatusLogger;
025
026/**
027 * In environments older than Servlet 3.0, this initializer is responsible for starting up Log4j logging before anything
028 * else happens in application initialization. In all environments, this shuts down Log4j after the application shuts
029 * down.
030 */
031public class Log4jServletContextListener implements ServletContextListener {
032
033    private static final Logger LOGGER = StatusLogger.getLogger();
034
035    private ServletContext servletContext;
036    private Log4jWebLifeCycle initializer;
037
038    @Override
039    public void contextInitialized(final ServletContextEvent event) {
040        this.servletContext = event.getServletContext();
041        LOGGER.debug("Log4jServletContextListener ensuring that Log4j starts up properly.");
042
043        this.initializer = WebLoggerContextUtils.getWebLifeCycle(this.servletContext);
044        try {
045            this.initializer.start();
046            this.initializer.setLoggerContext(); // the application is just now starting to start up
047        } catch (final IllegalStateException e) {
048            throw new IllegalStateException("Failed to initialize Log4j properly.", e);
049        }
050    }
051
052    @Override
053    public void contextDestroyed(final ServletContextEvent event) {
054        if (this.servletContext == null || this.initializer == null) {
055            throw new IllegalStateException("Context destroyed before it was initialized.");
056        }
057        LOGGER.debug("Log4jServletContextListener ensuring that Log4j shuts down properly.");
058
059        this.initializer.clearLoggerContext(); // the application is finished shutting down now
060        this.initializer.stop();
061    }
062}