    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.comparator;
    018
    019import java.io.File;
    020import java.io.Serializable;
    021import java.util.Comparator;
    022
    023import org.apache.commons.io.FileUtils;
    024
    025/**
    026 * Compare the <b>length/size</b> of two files for order (see
    027 * {@link File#length()} and {@link FileUtils#sizeOfDirectory(File)}).
    028 * <p>
    029 * This comparator can be used to sort lists or arrays of files
    030 * by their length/size.
    031 * <p>
    032 * Example of sorting a list of files using the
    033 * {@link #SIZE_COMPARATOR} singleton instance:
    034 * <pre>
    035 *       List&lt;File&gt; list = ...
    036 *       ((AbstractFileComparator) SizeFileComparator.SIZE_COMPARATOR).sort(list);
    037 * </pre>
    038 * <p>
    039 * Example of doing a <i>reverse</i> sort of an array of files using the
    040 * {@link #SIZE_REVERSE} singleton instance:
    041 * <pre>
    042 *       File[] array = ...
    043 *       ((AbstractFileComparator) SizeFileComparator.SIZE_REVERSE).sort(array);
    044 * </pre>
    045 * <p>
    046 * <strong>N.B.</strong> Directories are treated as <b>zero size</b> unless
    047 * {@code sumDirectoryContents} is {@code true}.
    048 *
    049 * @since 1.4
    050 */
    051public class SizeFileComparator extends AbstractFileComparator implements Serializable {
    052
    053    private static final long serialVersionUID = -1201561106411416190L;
    054
    055    /** Size comparator instance - directories are treated as zero size */
    056    public static final Comparator<File> SIZE_COMPARATOR = new SizeFileComparator();
    057
    058    /** Reverse size comparator instance - directories are treated as zero size */
    059    public static final Comparator<File> SIZE_REVERSE = new ReverseFileComparator(SIZE_COMPARATOR);
    060
    061    /**
    062     * Size comparator instance which sums the size of a directory's contents
    063     * using {@link FileUtils#sizeOfDirectory(File)}
    064     */
    065    public static final Comparator<File> SIZE_SUMDIR_COMPARATOR = new SizeFileComparator(true);
    066
    067    /**
    068     * Reverse size comparator instance which sums the size of a directory's contents
    069     * using {@link FileUtils#sizeOfDirectory(File)}
    070     */
    071    public static final Comparator<File> SIZE_SUMDIR_REVERSE = new ReverseFileComparator(SIZE_SUMDIR_COMPARATOR);
    072
    073    /** Whether the sum of the directory's contents should be calculated. */
    074    private final boolean sumDirectoryContents;
    075
    076    /**
    077     * Construct a file size comparator instance (directories treated as zero size).
    078     */
    079    public SizeFileComparator() {
    080        this.sumDirectoryContents = false;
    081    }
    082
    083    /**
    084     * Construct a file size comparator instance specifying whether the size of
    085     * the directory contents should be aggregated.
    086     * <p>
    087     * If the {@code sumDirectoryContents} is {@code true} The size of
    088     * directories is calculated using  {@link FileUtils#sizeOfDirectory(File)}.
    089     *
    090     * @param sumDirectoryContents {@code true} if the sum of the directories' contents
    091     *  should be calculated, otherwise {@code false} if directories should be treated
    092     *  as size zero (see {@link FileUtils#sizeOfDirectory(File)}).
    093     */
    094    public SizeFileComparator(final boolean sumDirectoryContents) {
    095        this.sumDirectoryContents = sumDirectoryContents;
    096    }
    097
    098    /**
    099     * Compare the length of two files.
    100     *
    101     * @param file1 The first file to compare
    102     * @param file2 The second file to compare
    103     * @return a negative value if the first file's length
    104     * is less than the second, zero if the lengths are the
    105     * same and a positive value if the first files length
    106     * is greater than the second file.
    107     *
    108     */
    109    @Override
    110    public int compare(final File file1, final File file2) {
    111        final long size1;
    112        if (file1.isDirectory()) {
    113            size1 = sumDirectoryContents && file1.exists() ? FileUtils.sizeOfDirectory(file1) : 0;
    114        } else {
    115            size1 = file1.length();
    116        }
    117        final long size2;
    118        if (file2.isDirectory()) {
    119            size2 = sumDirectoryContents && file2.exists() ? FileUtils.sizeOfDirectory(file2) : 0;
    120        } else {
    121            size2 = file2.length();
    122        }
    123        final long result = size1 - size2;
    124        if (result < 0) {
    125            return -1;
    126        }
    127        if (result > 0) {
    128            return 1;
    129        }
    130        return 0;
    131    }
    132
    133    /**
    134     * String representation of this file comparator.
    135     *
    136     * @return String representation of this file comparator
    137     */
    138    @Override
    139    public String toString() {
    140        return super.toString() + "[sumDirectoryContents=" + sumDirectoryContents + "]";
    141    }
    142}