    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;
    020import java.io.IOException;
    021
    022/**
    023 * Strategy for deleting files.
    024 * <p>
    025 * There is more than one way to delete a file.
    026 * You may want to limit access to certain directories, to only delete
    027 * directories if they are empty, or maybe to force deletion.
    028 * </p>
    029 * <p>
    030 * This class captures the strategy to use and is designed for user subclassing.
    031 * </p>
    032 *
    033 * @since 1.3
    034 */
    035public class FileDeleteStrategy {
    036
    037    /**
    038     * Force file deletion strategy.
    039     */
    040    static class ForceFileDeleteStrategy extends FileDeleteStrategy {
    041        /** Default Constructor */
    042        ForceFileDeleteStrategy() {
    043            super("Force");
    044        }
    045
    046        /**
    047         * Deletes the file object.
    048         * <p>
    049         * This implementation uses <code>FileUtils.forceDelete()</code>
    050         * if the file exists.
    051         * </p>
    052         *
    053         * @param fileToDelete  the file to delete, not null
    054         * @return Always returns {@code true}
    055         * @throws NullPointerException if the file is null
    056         * @throws IOException if an error occurs during file deletion
    057         */
    058        @Override
    059        protected boolean doDelete(final File fileToDelete) throws IOException {
    060            FileUtils.forceDelete(fileToDelete);
    061            return true;
    062        }
    063    }
    064
    065    /**
    066     * The singleton instance for normal file deletion, which does not permit
    067     * the deletion of directories that are not empty.
    068     */
    069    public static final FileDeleteStrategy NORMAL = new FileDeleteStrategy("Normal");
    070
    071    /**
    072     * The singleton instance for forced file deletion, which always deletes,
    073     * even if the file represents a non-empty directory.
    074     */
    075    public static final FileDeleteStrategy FORCE = new ForceFileDeleteStrategy();
    076
    077    /** The name of the strategy. */
    078    private final String name;
    079
    080    /**
    081     * Restricted constructor.
    082     *
    083     * @param name  the name by which the strategy is known
    084     */
    085    protected FileDeleteStrategy(final String name) {
    086        this.name = name;
    087    }
    088
    089    /**
    090     * Deletes the file object, which may be a file or a directory.
    091     * If the file does not exist, the method just returns.
    092     * <p>
    093     * Subclass writers should override {@link #doDelete(File)}, not this method.
    094     * </p>
    095     *
    096     * @param fileToDelete  the file to delete, not null
    097     * @throws NullPointerException if the file is null
    098     * @throws IOException if an error occurs during file deletion
    099     */
    100    public void delete(final File fileToDelete) throws IOException {
    101        if (fileToDelete.exists() && doDelete(fileToDelete) == false) {
    102            throw new IOException("Deletion failed: " + fileToDelete);
    103        }
    104    }
    105
    106    /**
    107     * Deletes the file object, which may be a file or a directory.
    108     * All <code>IOException</code>s are caught and false returned instead.
    109     * If the file does not exist or is null, true is returned.
    110     * <p>
    111     * Subclass writers should override {@link #doDelete(File)}, not this method.
    112     * </p>
    113     *
    114     * @param fileToDelete  the file to delete, null returns true
    115     * @return true if the file was deleted, or there was no such file
    116     */
    117    public boolean deleteQuietly(final File fileToDelete) {
    118        if (fileToDelete == null || fileToDelete.exists() == false) {
    119            return true;
    120        }
    121        try {
    122            return doDelete(fileToDelete);
    123        } catch (final IOException ex) {
    124            return false;
    125        }
    126    }
    127
    128    /**
    129     * Actually deletes the file object, which may be a file or a directory.
    130     * <p>
    131     * This method is designed for subclasses to override.
    132     * The implementation may return either false or an <code>IOException</code>
    133     * when deletion fails. The {@link #delete(File)} and {@link #deleteQuietly(File)}
    134     * methods will handle either response appropriately.
    135     * A check has been made to ensure that the file will exist.
    136     * </p>
    137     * <p>
    138     * This implementation uses {@link File#delete()}.
    139     * </p>
    140     *
    141     * @param fileToDelete  the file to delete, exists, not null
    142     * @return true if the file was deleted
    143     * @throws NullPointerException if the file is null
    144     * @throws IOException if an error occurs during file deletion
    145     */
    146    protected boolean doDelete(final File fileToDelete) throws IOException {
    147        return fileToDelete.delete();
    148    }
    149
    150    /**
    151     * Gets a string describing the delete strategy.
    152     *
    153     * @return a string describing the delete strategy
    154     */
    155    @Override
    156    public String toString() {
    157        return "FileDeleteStrategy[" + name + "]";
    158    }
    159
    160}