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    }