    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    /**
    046     * Track the specified file, using the provided marker, deleting the file
    047     * when the marker instance is garbage collected.
    048     * The {@link FileDeleteStrategy#NORMAL normal} deletion strategy will be used.
    049     *
    050     * @param file  the file to be tracked, not null
    051     * @param marker  the marker object used to track the file, not null
    052     * @throws NullPointerException if the file is null
    053     * @deprecated Use {@link FileCleaningTracker#track(File, Object)}.
    054     */
    055    @Deprecated
    056    public static void track(final File file, final Object marker) {
    057        theInstance.track(file, marker);
    058    }
    059
    060    /**
    061     * Track the specified file, using the provided marker, deleting the file
    062     * when the marker instance is garbage collected.
    063     * The specified deletion strategy is used.
    064     *
    065     * @param file  the file to be tracked, not null
    066     * @param marker  the marker object used to track the file, not null
    067     * @param deleteStrategy  the strategy to delete the file, null means normal
    068     * @throws NullPointerException if the file is null
    069     * @deprecated Use {@link FileCleaningTracker#track(File, Object, FileDeleteStrategy)}.
    070     */
    071    @Deprecated
    072    public static void track(final File file, final Object marker, final FileDeleteStrategy deleteStrategy) {
    073        theInstance.track(file, marker, deleteStrategy);
    074    }
    075
    076    /**
    077     * Track the specified file, using the provided marker, deleting the file
    078     * when the marker instance is garbage collected.
    079     * The {@link FileDeleteStrategy#NORMAL normal} deletion strategy will be used.
    080     *
    081     * @param path  the full path to the file to be tracked, not null
    082     * @param marker  the marker object used to track the file, not null
    083     * @throws NullPointerException if the path is null
    084     * @deprecated Use {@link FileCleaningTracker#track(String, Object)}.
    085     */
    086    @Deprecated
    087    public static void track(final String path, final Object marker) {
    088        theInstance.track(path, marker);
    089    }
    090
    091    /**
    092     * Track the specified file, using the provided marker, deleting the file
    093     * when the marker instance is garbage collected.
    094     * The specified deletion strategy is used.
    095     *
    096     * @param path  the full path to the file to be tracked, not null
    097     * @param marker  the marker object used to track the file, not null
    098     * @param deleteStrategy  the strategy to delete the file, null means normal
    099     * @throws NullPointerException if the path is null
    100     * @deprecated Use {@link FileCleaningTracker#track(String, Object, FileDeleteStrategy)}.
    101     */
    102    @Deprecated
    103    public static void track(final String path, final Object marker, final FileDeleteStrategy deleteStrategy) {
    104        theInstance.track(path, marker, deleteStrategy);
    105    }
    106
    107    //-----------------------------------------------------------------------
    108    /**
    109     * Retrieve the number of files currently being tracked, and therefore
    110     * awaiting deletion.
    111     *
    112     * @return the number of files being tracked
    113     * @deprecated Use {@link FileCleaningTracker#getTrackCount()}.
    114     */
    115    @Deprecated
    116    public static int getTrackCount() {
    117        return theInstance.getTrackCount();
    118    }
    119
    120    /**
    121     * Call this method to cause the file cleaner thread to terminate when
    122     * there are no more objects being tracked for deletion.
    123     * <p>
    124     * In a simple environment, you don't need this method as the file cleaner
    125     * thread will simply exit when the JVM exits. In a more complex environment,
    126     * with multiple class loaders (such as an application server), you should be
    127     * aware that the file cleaner thread will continue running even if the class
    128     * loader it was started from terminates. This can constitute a memory leak.
    129     * <p>
    130     * For example, suppose that you have developed a web application, which
    131     * contains the commons-io jar file in your WEB-INF/lib directory. In other
    132     * words, the FileCleaner class is loaded through the class loader of your
    133     * web application. If the web application is terminated, but the servlet
    134     * container is still running, then the file cleaner thread will still exist,
    135     * posing a memory leak.
    136     * <p>
    137     * This method allows the thread to be terminated. Simply call this method
    138     * in the resource cleanup code, such as
    139     * {@code javax.servlet.ServletContextListener.contextDestroyed(javax.servlet.ServletContextEvent)}.
    140     * One called, no new objects can be tracked by the file cleaner.
    141     * @deprecated Use {@link FileCleaningTracker#exitWhenFinished()}.
    142     */
    143    @Deprecated
    144    public static synchronized void exitWhenFinished() {
    145        theInstance.exitWhenFinished();
    146    }
    147
    148    /**
    149     * Returns the singleton instance, which is used by the deprecated, static methods.
    150     * This is mainly useful for code, which wants to support the new
    151     * {@link FileCleaningTracker} class while maintain compatibility with the
    152     * deprecated {@link FileCleaner}.
    153     *
    154     * @return the singleton instance
    155     */
    156    public static FileCleaningTracker getInstance() {
    157        return theInstance;
    158    }
    159}