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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.commons.fileupload.servlet;
18  
19  import javax.servlet.ServletContext;
20  import javax.servlet.ServletContextEvent;
21  import javax.servlet.ServletContextListener;
22  
23  import org.apache.commons.io.FileCleaningTracker;
24  
25  /**
26   * A servlet context listener, which ensures that the
27   * {@link FileCleaningTracker}'s reaper thread is terminated,
28   * when the web application is destroyed.
29   */
30  public class FileCleanerCleanup implements ServletContextListener {
31  
32      /**
33       * Attribute name, which is used for storing an instance of
34       * {@link FileCleaningTracker} in the web application.
35       */
36      public static final String FILE_CLEANING_TRACKER_ATTRIBUTE
37          = FileCleanerCleanup.class.getName() + ".FileCleaningTracker";
38  
39      /**
40       * Returns the instance of {@link FileCleaningTracker}, which is
41       * associated with the given {@link ServletContext}.
42       *
43       * @param servletContext The servlet context to query
44       * @return The contexts tracker
45       */
46      public static FileCleaningTracker getFileCleaningTracker(final ServletContext servletContext) {
47          return (FileCleaningTracker) servletContext.getAttribute(FILE_CLEANING_TRACKER_ATTRIBUTE);
48      }
49  
50      /**
51       * Sets the instance of {@link FileCleaningTracker}, which is
52       * associated with the given {@link ServletContext}.
53       *
54       * @param servletContext The servlet context to modify
55       * @param tracker The tracker to set
56       */
57      public static void setFileCleaningTracker(final ServletContext servletContext, final FileCleaningTracker tracker) {
58          servletContext.setAttribute(FILE_CLEANING_TRACKER_ATTRIBUTE, tracker);
59      }
60  
61      /**
62       * Constructs a new instance.
63       */
64      public FileCleanerCleanup() {
65          // empty
66      }
67  
68      /**
69       * Called when the web application is being destroyed.
70       * Calls {@link FileCleaningTracker#exitWhenFinished()}.
71       *
72       * @param sce The servlet context, used for calling
73       *     {@link #getFileCleaningTracker(ServletContext)}.
74       */
75      @Override
76      public void contextDestroyed(final ServletContextEvent sce) {
77          getFileCleaningTracker(sce.getServletContext()).exitWhenFinished();
78      }
79  
80      /**
81       * Called when the web application is initialized. Does
82       * nothing.
83       *
84       * @param sce The servlet context, used for calling
85       *   {@link #setFileCleaningTracker(ServletContext, FileCleaningTracker)}.
86       */
87      @Override
88      public void contextInitialized(final ServletContextEvent sce) {
89          setFileCleaningTracker(sce.getServletContext(),
90                  new FileCleaningTracker());
91      }
92  
93  }