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</code> is {@code true}.
048 *
049 * @version $Id: SizeFileComparator.java 1469107 2013-04-17 23:45:53Z sebb $
050 * @since 1.4
051 */
052public class SizeFileComparator extends AbstractFileComparator implements Serializable {
053
054    /** Size comparator instance - directories are treated as zero size */
055    public static final Comparator<File> SIZE_COMPARATOR = new SizeFileComparator();
056
057    /** Reverse size comparator instance - directories are treated as zero size */
058    public static final Comparator<File> SIZE_REVERSE = new ReverseComparator(SIZE_COMPARATOR);
059
060    /**
061     * Size comparator instance which sums the size of a directory's contents
062     * using {@link FileUtils#sizeOfDirectory(File)}
063     */
064    public static final Comparator<File> SIZE_SUMDIR_COMPARATOR = new SizeFileComparator(true);
065
066    /**
067     * Reverse size comparator instance which sums the size of a directory's contents
068     * using {@link FileUtils#sizeOfDirectory(File)}
069     */
070    public static final Comparator<File> SIZE_SUMDIR_REVERSE = new ReverseComparator(SIZE_SUMDIR_COMPARATOR);
071
072    /** Whether the sum of the directory's contents should be calculated. */
073    private final boolean sumDirectoryContents;
074
075    /**
076     * Construct a file size comparator instance (directories treated as zero size).
077     */
078    public SizeFileComparator() {
079        this.sumDirectoryContents = false;
080    }
081
082    /**
083     * Construct a file size comparator instance specifying whether the size of
084     * the directory contents should be aggregated.
085     * <p>
086     * If the <code>sumDirectoryContents</code> is {@code true} The size of
087     * directories is calculated using  {@link FileUtils#sizeOfDirectory(File)}.
088     *
089     * @param sumDirectoryContents {@code true} if the sum of the directoryies contents
090     *  should be calculated, otherwise {@code false} if directories should be treated
091     *  as size zero (see {@link FileUtils#sizeOfDirectory(File)}).
092     */
093    public SizeFileComparator(final boolean sumDirectoryContents) {
094        this.sumDirectoryContents = sumDirectoryContents;
095    }
096
097    /**
098     * Compare the length of two files.
099     * 
100     * @param file1 The first file to compare
101     * @param file2 The second file to compare
102     * @return a negative value if the first file's length
103     * is less than the second, zero if the lengths are the
104     * same and a positive value if the first files length
105     * is greater than the second file.
106     * 
107     */
108    public int compare(final File file1, final File file2) {
109        long size1 = 0;
110        if (file1.isDirectory()) {
111            size1 = sumDirectoryContents && file1.exists() ? FileUtils.sizeOfDirectory(file1) : 0;
112        } else {
113            size1 = file1.length();
114        }
115        long size2 = 0;
116        if (file2.isDirectory()) {
117            size2 = sumDirectoryContents && file2.exists() ? FileUtils.sizeOfDirectory(file2) : 0;
118        } else {
119            size2 = file2.length();
120        }
121        final long result = size1 - size2;
122        if (result < 0) {
123            return -1;
124        } else if (result > 0) {
125            return 1;
126        } else {
127            return 0;
128        }
129    }
130
131    /**
132     * String representation of this file comparator.
133     *
134     * @return String representation of this file comparator
135     */
136    @Override
137    public String toString() {
138        return super.toString() + "[sumDirectoryContents=" + sumDirectoryContents + "]";
139    }
140}