    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     */
    017    package org.apache.logging.log4j.web;
    018
    019    import javax.servlet.ServletContext;
    020    import javax.servlet.ServletContextEvent;
    021    import javax.servlet.ServletContextListener;
    022
    023    import org.apache.logging.log4j.Logger;
    024    import 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     */
    031    public 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    }