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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.core.web;
18  
19  import javax.servlet.ServletContext;
20  import javax.servlet.ServletContextEvent;
21  import javax.servlet.ServletContextListener;
22  import javax.servlet.UnavailableException;
23  
24  /**
25   * In environments older than Servlet 3.0, this initializer is responsible for starting up Log4j logging before anything
26   * else happens in application initialization. In all environments, this shuts down Log4j after the application shuts
27   * down.
28   */
29  public class Log4jServletContextListener implements ServletContextListener {
30  
31      private ServletContext servletContext;
32      private Log4jWebInitializer initializer;
33  
34      @Override
35      public void contextInitialized(final ServletContextEvent event) {
36          this.servletContext = event.getServletContext();
37          this.servletContext.log("Log4jServletContextListener ensuring that Log4j starts up properly.");
38  
39          this.initializer = Log4jWebInitializerImpl.getLog4jWebInitializer(this.servletContext);
40          try {
41              this.initializer.initialize();
42              this.initializer.setLoggerContext(); // the application is just now starting to start up
43          } catch (final UnavailableException e) {
44              throw new RuntimeException("Failed to initialize Log4j properly.", e);
45          }
46      }
47  
48      @Override
49      public void contextDestroyed(final ServletContextEvent event) {
50          if (this.servletContext == null || this.initializer == null) {
51              throw new IllegalStateException("Context destroyed before it was initialized.");
52          }
53          this.servletContext.log("Log4jServletContextListener ensuring that Log4j shuts down properly.");
54  
55          this.initializer.clearLoggerContext(); // the application is finished shutting down now
56          this.initializer.deinitialize();
57      }
58  }