    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 java.util.EnumSet;
    020    import java.util.Set;
    021    import javax.servlet.DispatcherType;
    022    import javax.servlet.FilterRegistration;
    023    import javax.servlet.ServletContainerInitializer;
    024    import javax.servlet.ServletContext;
    025    import javax.servlet.ServletException;
    026
    027    import org.apache.logging.log4j.Logger;
    028    import org.apache.logging.log4j.status.StatusLogger;
    029
    030    /**
    031     * In a Servlet 3.0 or newer environment, this initializer is responsible for starting up Log4j logging before anything
    032     * else happens in application initialization. For consistency across all containers, if the effective Servlet major
    033     * version of the application is less than 3.0, this initializer does nothing.
    034     */
    035    public class Log4jServletContainerInitializer implements ServletContainerInitializer {
    036
    037        private static final Logger LOGGER = StatusLogger.getLogger();
    038
    039        @Override
    040        public void onStartup(final Set<Class<?>> classes, final ServletContext servletContext) throws ServletException {
    041            if (servletContext.getMajorVersion() > 2 && servletContext.getEffectiveMajorVersion() > 2 &&
    042                    !"true".equalsIgnoreCase(servletContext.getInitParameter(
    043                            Log4jWebSupport.IS_LOG4J_AUTO_INITIALIZATION_DISABLED
    044                    ))) {
    045                LOGGER.debug("Log4jServletContainerInitializer starting up Log4j in Servlet 3.0+ environment.");
    046
    047                final FilterRegistration.Dynamic filter =
    048                        servletContext.addFilter("log4jServletFilter", Log4jServletFilter.class);
    049                if (filter == null) {
    050                    LOGGER.warn("WARNING: In a Servlet 3.0+ application, you should not define a " +
    051                        "log4jServletFilter in web.xml. Log4j 2 normally does this for you automatically. Log4j 2 " +
    052                        "web auto-initialization has been canceled.");
    053                    return;
    054                }
    055
    056                final Log4jWebLifeCycle initializer = WebLoggerContextUtils.getWebLifeCycle(servletContext);
    057                initializer.start();
    058                initializer.setLoggerContext(); // the application is just now starting to start up
    059
    060                servletContext.addListener(new Log4jServletContextListener());
    061
    062                filter.setAsyncSupported(true); // supporting async when the user isn't using async has no downsides
    063                filter.addMappingForUrlPatterns(EnumSet.allOf(DispatcherType.class), false, "/*");
    064            }
    065        }
    066    }