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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 javax.servlet.ServletContext;
20  import javax.servlet.ServletContextEvent;
21  import javax.servlet.ServletContextListener;
22  
23  import org.apache.logging.log4j.Logger;
24  import org.apache.logging.log4j.status.StatusLogger;
25  
26  /**
27   * In environments older than Servlet 3.0, this initializer is responsible for starting up Log4j logging before anything
28   * else happens in application initialization. In all environments, this shuts down Log4j after the application shuts
29   * down.
30   */
31  public class Log4jServletContextListener implements ServletContextListener {
32  
33      private static final Logger LOGGER = StatusLogger.getLogger();
34  
35      private ServletContext servletContext;
36      private Log4jWebLifeCycle initializer;
37  
38      @Override
39      public void contextInitialized(final ServletContextEvent event) {
40          this.servletContext = event.getServletContext();
41          LOGGER.debug("Log4jServletContextListener ensuring that Log4j starts up properly.");
42  
43          this.initializer = WebLoggerContextUtils.getWebLifeCycle(this.servletContext);
44          try {
45              this.initializer.start();
46              this.initializer.setLoggerContext(); // the application is just now starting to start up
47          } catch (final IllegalStateException e) {
48              throw new IllegalStateException("Failed to initialize Log4j properly.", e);
49          }
50      }
51  
52      @Override
53      public void contextDestroyed(final ServletContextEvent event) {
54          if (this.servletContext == null || this.initializer == null) {
55              LOGGER.warn("Context destroyed before it was initialized.");
56              return;
57          }
58          LOGGER.debug("Log4jServletContextListener ensuring that Log4j shuts down properly.");
59  
60          this.initializer.clearLoggerContext(); // the application is finished shutting down now
61          this.initializer.stop();
62      }
63  }