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 * <p>
033 * Example of sorting a list of files using the
034 * {@link #SIZE_COMPARATOR} singleton instance:
035 * </p>
036 * <pre>
037 *       List&lt;File&gt; list = ...
038 *       ((AbstractFileComparator) SizeFileComparator.SIZE_COMPARATOR).sort(list);
039 * </pre>
040 * <p>
041 * Example of doing a <i>reverse</i> sort of an array of files using the
042 * {@link #SIZE_REVERSE} singleton instance:
043 * </p>
044 * <pre>
045 *       File[] array = ...
046 *       ((AbstractFileComparator) SizeFileComparator.SIZE_REVERSE).sort(array);
047 * </pre>
048 * <p>
049 * <strong>N.B.</strong> Directories are treated as <b>zero size</b> unless
050 * {@code sumDirectoryContents} is {@code true}.
051 * </p>
052 * <h2>Deprecating Serialization</h2>
053 * <p>
054 * <em>Serialization is deprecated and will be removed in 3.0.</em>
055 * </p>
056 *
057 * @since 1.4
058 */
059public class SizeFileComparator extends AbstractFileComparator implements Serializable {
060
061    private static final long serialVersionUID = -1201561106411416190L;
062
063    /** Size comparator instance - directories are treated as zero size */
064    public static final Comparator<File> SIZE_COMPARATOR = new SizeFileComparator();
065
066    /** Reverse size comparator instance - directories are treated as zero size */
067    public static final Comparator<File> SIZE_REVERSE = new ReverseFileComparator(SIZE_COMPARATOR);
068
069    /**
070     * Size comparator instance which sums the size of a directory's contents
071     * using {@link FileUtils#sizeOfDirectory(File)}
072     */
073    public static final Comparator<File> SIZE_SUMDIR_COMPARATOR = new SizeFileComparator(true);
074
075    /**
076     * Reverse size comparator instance which sums the size of a directory's contents
077     * using {@link FileUtils#sizeOfDirectory(File)}
078     */
079    public static final Comparator<File> SIZE_SUMDIR_REVERSE = new ReverseFileComparator(SIZE_SUMDIR_COMPARATOR);
080
081    /** Whether the sum of the directory's contents should be calculated. */
082    private final boolean sumDirectoryContents;
083
084    /**
085     * Constructs a file size comparator instance (directories treated as zero size).
086     */
087    public SizeFileComparator() {
088        this.sumDirectoryContents = false;
089    }
090
091    /**
092     * Constructs a file size comparator instance specifying whether the size of
093     * the directory contents should be aggregated.
094     * <p>
095     * If the {@code sumDirectoryContents} is {@code true} The size of
096     * directories is calculated using  {@link FileUtils#sizeOfDirectory(File)}.
097     * </p>
098     *
099     * @param sumDirectoryContents {@code true} if the sum of the directories' contents
100     *  should be calculated, otherwise {@code false} if directories should be treated
101     *  as size zero (see {@link FileUtils#sizeOfDirectory(File)}).
102     */
103    public SizeFileComparator(final boolean sumDirectoryContents) {
104        this.sumDirectoryContents = sumDirectoryContents;
105    }
106
107    /**
108     * Compares the length of two files.
109     *
110     * @param file1 The first file to compare
111     * @param file2 The second file to compare
112     * @return a negative value if the first file's length
113     * is less than the second, zero if the lengths are the
114     * same and a positive value if the first files length
115     * is greater than the second file.
116     */
117    @Override
118    public int compare(final File file1, final File file2) {
119        final long size1;
120        if (file1.isDirectory()) {
121            size1 = sumDirectoryContents && file1.exists() ? FileUtils.sizeOfDirectory(file1) : 0;
122        } else {
123            size1 = file1.length();
124        }
125        final long size2;
126        if (file2.isDirectory()) {
127            size2 = sumDirectoryContents && file2.exists() ? FileUtils.sizeOfDirectory(file2) : 0;
128        } else {
129            size2 = file2.length();
130        }
131        final long result = size1 - size2;
132        if (result < 0) {
133            return -1;
134        }
135        if (result > 0) {
136            return 1;
137        }
138        return 0;
139    }
140
141    /**
142     * String representation of this file comparator.
143     *
144     * @return String representation of this file comparator
145     */
146    @Override
147    public String toString() {
148        return super.toString() + "[sumDirectoryContents=" + sumDirectoryContents + "]";
149    }
150}