    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.io;
    018
    019import java.io.File;
    020
    021/**
    022 * Keeps track of files awaiting deletion, and deletes them when an associated
    023 * marker object is reclaimed by the garbage collector.
    024 * <p>
    025 * This utility creates a background thread to handle file deletion.
    026 * Each file to be deleted is registered with a handler object.
    027 * When the handler object is garbage collected, the file is deleted.
    028 * <p>
    029 * In an environment with multiple class loaders (a servlet container, for
    030 * example), you should consider stopping the background thread if it is no
    031 * longer needed. This is done by invoking the method
    032 * {@link #exitWhenFinished}, typically in
    033 * {@code javax.servlet.ServletContextListener.contextDestroyed(javax.servlet.ServletContextEvent)} or similar.
    034 *
    035 * @deprecated Use {@link FileCleaningTracker}
    036 */
    037@Deprecated
    038public class FileCleaner {
    039    /**
    040     * The instance to use for the deprecated, static methods.
    041     */
    042    static final FileCleaningTracker theInstance = new FileCleaningTracker();
    043
    044    /**
    045     * Track the specified file, using the provided marker, deleting the file
    046     * when the marker instance is garbage collected.
    047     * The {@link FileDeleteStrategy#NORMAL normal} deletion strategy will be used.
    048     *
    049     * @param file  the file to be tracked, not null
    050     * @param marker  the marker object used to track the file, not null
    051     * @throws NullPointerException if the file is null
    052     * @deprecated Use {@link FileCleaningTracker#track(File, Object)}.
    053     */
    054    @Deprecated
    055    public static void track(final File file, final Object marker) {
    056        theInstance.track(file, marker);
    057    }
    058
    059    /**
    060     * Track the specified file, using the provided marker, deleting the file
    061     * when the marker instance is garbage collected.
    062     * The specified deletion strategy is used.
    063     *
    064     * @param file  the file to be tracked, not null
    065     * @param marker  the marker object used to track the file, not null
    066     * @param deleteStrategy  the strategy to delete the file, null means normal
    067     * @throws NullPointerException if the file is null
    068     * @deprecated Use {@link FileCleaningTracker#track(File, Object, FileDeleteStrategy)}.
    069     */
    070    @Deprecated
    071    public static void track(final File file, final Object marker, final FileDeleteStrategy deleteStrategy) {
    072        theInstance.track(file, marker, deleteStrategy);
    073    }
    074
    075    /**
    076     * Track the specified file, using the provided marker, deleting the file
    077     * when the marker instance is garbage collected.
    078     * The {@link FileDeleteStrategy#NORMAL normal} deletion strategy will be used.
    079     *
    080     * @param path  the full path to the file to be tracked, not null
    081     * @param marker  the marker object used to track the file, not null
    082     * @throws NullPointerException if the path is null
    083     * @deprecated Use {@link FileCleaningTracker#track(String, Object)}.
    084     */
    085    @Deprecated
    086    public static void track(final String path, final Object marker) {
    087        theInstance.track(path, marker);
    088    }
    089
    090    /**
    091     * Track the specified file, using the provided marker, deleting the file
    092     * when the marker instance is garbage collected.
    093     * The specified deletion strategy is used.
    094     *
    095     * @param path  the full path to the file to be tracked, not null
    096     * @param marker  the marker object used to track the file, not null
    097     * @param deleteStrategy  the strategy to delete the file, null means normal
    098     * @throws NullPointerException if the path is null
    099     * @deprecated Use {@link FileCleaningTracker#track(String, Object, FileDeleteStrategy)}.
    100     */
    101    @Deprecated
    102    public static void track(final String path, final Object marker, final FileDeleteStrategy deleteStrategy) {
    103        theInstance.track(path, marker, deleteStrategy);
    104    }
    105
    106    /**
    107     * Retrieve the number of files currently being tracked, and therefore
    108     * awaiting deletion.
    109     *
    110     * @return the number of files being tracked
    111     * @deprecated Use {@link FileCleaningTracker#getTrackCount()}.
    112     */
    113    @Deprecated
    114    public static int getTrackCount() {
    115        return theInstance.getTrackCount();
    116    }
    117
    118    /**
    119     * Call this method to cause the file cleaner thread to terminate when
    120     * there are no more objects being tracked for deletion.
    121     * <p>
    122     * In a simple environment, you don't need this method as the file cleaner
    123     * thread will simply exit when the JVM exits. In a more complex environment,
    124     * with multiple class loaders (such as an application server), you should be
    125     * aware that the file cleaner thread will continue running even if the class
    126     * loader it was started from terminates. This can constitute a memory leak.
    127     * <p>
    128     * For example, suppose that you have developed a web application, which
    129     * contains the commons-io jar file in your WEB-INF/lib directory. In other
    130     * words, the FileCleaner class is loaded through the class loader of your
    131     * web application. If the web application is terminated, but the servlet
    132     * container is still running, then the file cleaner thread will still exist,
    133     * posing a memory leak.
    134     * <p>
    135     * This method allows the thread to be terminated. Simply call this method
    136     * in the resource cleanup code, such as
    137     * {@code javax.servlet.ServletContextListener.contextDestroyed(javax.servlet.ServletContextEvent)}.
    138     * One called, no new objects can be tracked by the file cleaner.
    139     * @deprecated Use {@link FileCleaningTracker#exitWhenFinished()}.
    140     */
    141    @Deprecated
    142    public static synchronized void exitWhenFinished() {
    143        theInstance.exitWhenFinished();
    144    }
    145
    146    /**
    147     * Returns the singleton instance, which is used by the deprecated, static methods.
    148     * This is mainly useful for code, which wants to support the new
    149     * {@link FileCleaningTracker} class while maintain compatibility with the
    150     * deprecated {@link FileCleaner}.
    151     *
    152     * @return the singleton instance
    153     */
    154    public static FileCleaningTracker getInstance() {
    155        return theInstance;
    156    }
    157}