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     */
017    package org.apache.commons.io.comparator;
018    
019    import java.io.File;
020    import java.io.Serializable;
021    import java.util.Comparator;
022    
023    import 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     *       Collections.sort(list, LengthFileComparator.LENGTH_COMPARATOR);
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     *       Arrays.sort(array, LengthFileComparator.LENGTH_REVERSE);
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</code>.
048     *
049     * @version $Revision: 609243 $ $Date: 2008-01-06 00:30:42 +0000 (Sun, 06 Jan 2008) $
050     * @since Commons IO 1.4
051     */
052    public class SizeFileComparator implements Comparator, Serializable {
053    
054        /** Size comparator instance - directories are treated as zero size */
055        public static final Comparator SIZE_COMPARATOR = new SizeFileComparator();
056    
057        /** Reverse size comparator instance - directories are treated as zero size */
058        public static final Comparator 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 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 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</code> The size of
087         * directories is calculated using  {@link FileUtils#sizeOfDirectory(File)}.
088         *
089         * @param sumDirectoryContents <code>true</code> if the sum of the directoryies contents
090         *  should be calculated, otherwise <code>false</code> if directories should be treated
091         *  as size zero (see {@link FileUtils#sizeOfDirectory(File)}).
092         */
093        public SizeFileComparator(boolean sumDirectoryContents) {
094            this.sumDirectoryContents = sumDirectoryContents;
095        }
096    
097        /**
098         * Compare the length of two files.
099         * 
100         * @param obj1 The first file to compare
101         * @param obj2 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(Object obj1, Object obj2) {
109            File file1 = (File)obj1;
110            File file2 = (File)obj2;
111            long size1 = 0;
112            if (file1.isDirectory()) {
113                size1 = sumDirectoryContents && file1.exists() ? FileUtils.sizeOfDirectory(file1) : 0;
114            } else {
115                size1 = file1.length();
116            }
117            long size2 = 0;
118            if (file2.isDirectory()) {
119                size2 = sumDirectoryContents && file2.exists() ? FileUtils.sizeOfDirectory(file2) : 0;
120            } else {
121                size2 = file2.length();
122            }
123            long result = size1 - size2;
124            if (result < 0) {
125                return -1;
126            } else if (result > 0) {
127                return 1;
128            } else {
129                return 0;
130            }
131        }
132    }