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    1   /*
    2    * Licensed to the Apache Software Foundation (ASF) under one or more
    3    * contributor license agreements. See the NOTICE file distributed with
    4    * this work for additional information regarding copyright ownership.
    5    * The ASF licenses this file to You under the Apache license, Version 2.0
    6    * (the "License"); you may not use this file except in compliance with
    7    * the License. You may obtain a copy of the License at
    8    *
    9    *      http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the license for the specific language governing permissions and
    15   * limitations under the license.
    16   */
    17  package org.apache.logging.log4j.web;
    18
    19  import java.util.EnumSet;
    20  import java.util.Set;
    21  import javax.servlet.DispatcherType;
    22  import javax.servlet.FilterRegistration;
    23  import javax.servlet.ServletContainerInitializer;
    24  import javax.servlet.ServletContext;
    25  import javax.servlet.ServletException;
    26
    27  import org.apache.logging.log4j.Logger;
    28  import org.apache.logging.log4j.status.StatusLogger;
    29
    30  /**
    31   * In a Servlet 3.0 or newer environment, this initializer is responsible for starting up Log4j logging before anything
    32   * else happens in application initialization. For consistency across all containers, if the effective Servlet major
    33   * version of the application is less than 3.0, this initializer does nothing.
    34   */
    35  public class Log4jServletContainerInitializer implements ServletContainerInitializer {
    36
    37      private static final Logger LOGGER = StatusLogger.getLogger();
    38
    39      @Override
    40      public void onStartup(final Set<Class<?>> classes, final ServletContext servletContext) throws ServletException {
    41          if (servletContext.getMajorVersion() > 2 && servletContext.getEffectiveMajorVersion() > 2 &&
    42                  !"true".equalsIgnoreCase(servletContext.getInitParameter(
    43                          Log4jWebSupport.IS_LOG4J_AUTO_INITIALIZATION_DISABLED
    44                  ))) {
    45              LOGGER.debug("Log4jServletContainerInitializer starting up Log4j in Servlet 3.0+ environment.");
    46
    47              final FilterRegistration.Dynamic filter =
    48                      servletContext.addFilter("log4jServletFilter", Log4jServletFilter.class);
    49              if (filter == null) {
    50                  LOGGER.warn("WARNING: In a Servlet 3.0+ application, you should not define a " +
    51                      "log4jServletFilter in web.xml. Log4j 2 normally does this for you automatically. Log4j 2 " +
    52                      "web auto-initialization has been canceled.");
    53                  return;
    54              }
    55
    56              final Log4jWebLifeCycle initializer = WebLoggerContextUtils.getWebLifeCycle(servletContext);
    57              initializer.start();
    58              initializer.setLoggerContext(); // the application is just now starting to start up
    59
    60              servletContext.addListener(new Log4jServletContextListener());
    61
    62              filter.setAsyncSupported(true); // supporting async when the user isn't using async has no downsides
    63              filter.addMappingForUrlPatterns(EnumSet.allOf(DispatcherType.class), false, "/*");
    64          }
    65      }
    66  }