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 */
017package org.apache.commons.fileupload.servlet;
018
019import javax.servlet.ServletContext;
020import javax.servlet.ServletContextEvent;
021import javax.servlet.ServletContextListener;
022
023import org.apache.commons.io.FileCleaningTracker;
024
025/**
026 * A servlet context listener, which ensures that the
027 * {@link FileCleaningTracker}'s reaper thread is terminated,
028 * when the web application is destroyed.
029 */
030public class FileCleanerCleanup implements ServletContextListener {
031
032    /**
033     * Attribute name, which is used for storing an instance of
034     * {@link FileCleaningTracker} in the web application.
035     */
036    public static final String FILE_CLEANING_TRACKER_ATTRIBUTE
037        = FileCleanerCleanup.class.getName() + ".FileCleaningTracker";
038
039    /**
040     * Returns the instance of {@link FileCleaningTracker}, which is
041     * associated with the given {@link ServletContext}.
042     *
043     * @param servletContext The servlet context to query
044     * @return The contexts tracker
045     */
046    public static FileCleaningTracker getFileCleaningTracker(final ServletContext servletContext) {
047        return (FileCleaningTracker) servletContext.getAttribute(FILE_CLEANING_TRACKER_ATTRIBUTE);
048    }
049
050    /**
051     * Sets the instance of {@link FileCleaningTracker}, which is
052     * associated with the given {@link ServletContext}.
053     *
054     * @param servletContext The servlet context to modify
055     * @param tracker The tracker to set
056     */
057    public static void setFileCleaningTracker(final ServletContext servletContext, final FileCleaningTracker tracker) {
058        servletContext.setAttribute(FILE_CLEANING_TRACKER_ATTRIBUTE, tracker);
059    }
060
061    /**
062     * Constructs a new instance.
063     */
064    public FileCleanerCleanup() {
065        // empty
066    }
067
068    /**
069     * Called when the web application is being destroyed.
070     * Calls {@link FileCleaningTracker#exitWhenFinished()}.
071     *
072     * @param sce The servlet context, used for calling
073     *     {@link #getFileCleaningTracker(ServletContext)}.
074     */
075    @Override
076    public void contextDestroyed(final ServletContextEvent sce) {
077        getFileCleaningTracker(sce.getServletContext()).exitWhenFinished();
078    }
079
080    /**
081     * Called when the web application is initialized. Does
082     * nothing.
083     *
084     * @param sce The servlet context, used for calling
085     *   {@link #setFileCleaningTracker(ServletContext, FileCleaningTracker)}.
086     */
087    @Override
088    public void contextInitialized(final ServletContextEvent sce) {
089        setFileCleaningTracker(sce.getServletContext(),
090                new FileCleaningTracker());
091    }
092
093}