001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one
003     * or more contributor license agreements.  See the NOTICE file
004     * distributed with this work for additional information
005     * regarding copyright ownership.  The ASF licenses this file
006     * to you under the Apache License, Version 2.0 (the
007     * "License"); you may not use this file except in compliance
008     * with the License.  You may obtain a copy of the License at
009     *
010     * http://www.apache.org/licenses/LICENSE-2.0
011     *
012     * Unless required by applicable law or agreed to in writing,
013     * software distributed under the License is distributed on an
014     * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015     * KIND, either express or implied.  See the License for the
016     * specific language governing permissions and limitations
017     * under the License.
018     */
019    package org.apache.commons.compress.compressors.gzip;
020    
021    import java.util.LinkedHashMap;
022    import java.util.Map;
023    import org.apache.commons.compress.compressors.FileNameUtil;
024    
025    /**
026     * Utility code for the gzip compression format.
027     * @ThreadSafe
028     */
029    public class GzipUtils {
030    
031        private static final FileNameUtil fileNameUtil;
032    
033        static {
034            // using LinkedHashMap so .tgz is preferred over .taz as
035            // compressed extension of .tar as FileNameUtil will use the
036            // first one found
037            Map<String, String> uncompressSuffix =
038                new LinkedHashMap<String, String>();
039            uncompressSuffix.put(".tgz", ".tar");
040            uncompressSuffix.put(".taz", ".tar");
041            uncompressSuffix.put(".svgz", ".svg");
042            uncompressSuffix.put(".cpgz", ".cpio");
043            uncompressSuffix.put(".wmz", ".wmf");
044            uncompressSuffix.put(".emz", ".emf");
045            uncompressSuffix.put(".gz", "");
046            uncompressSuffix.put(".z", "");
047            uncompressSuffix.put("-gz", "");
048            uncompressSuffix.put("-z", "");
049            uncompressSuffix.put("_z", "");
050            fileNameUtil = new FileNameUtil(uncompressSuffix, ".gz");
051        }
052    
053        /** Private constructor to prevent instantiation of this utility class. */
054        private GzipUtils() {
055        }
056    
057        /**
058         * Detects common gzip suffixes in the given filename.
059         *
060         * @param filename name of a file
061         * @return {@code true} if the filename has a common gzip suffix,
062         *         {@code false} otherwise
063         */
064        public static boolean isCompressedFilename(String filename) {
065            return fileNameUtil.isCompressedFilename(filename);
066        }
067    
068        /**
069         * Maps the given name of a gzip-compressed file to the name that the
070         * file should have after uncompression. Commonly used file type specific
071         * suffixes like ".tgz" or ".svgz" are automatically detected and
072         * correctly mapped. For example the name "package.tgz" is mapped to
073         * "package.tar". And any filenames with the generic ".gz" suffix
074         * (or any other generic gzip suffix) is mapped to a name without that
075         * suffix. If no gzip suffix is detected, then the filename is returned
076         * unmapped.
077         *
078         * @param filename name of a file
079         * @return name of the corresponding uncompressed file
080         */
081        public static String getUncompressedFilename(String filename) {
082            return fileNameUtil.getUncompressedFilename(filename);
083        }
084    
085        /**
086         * Maps the given filename to the name that the file should have after
087         * compression with gzip. Common file types with custom suffixes for
088         * compressed versions are automatically detected and correctly mapped.
089         * For example the name "package.tar" is mapped to "package.tgz". If no
090         * custom mapping is applicable, then the default ".gz" suffix is appended
091         * to the filename.
092         *
093         * @param filename name of a file
094         * @return name of the corresponding compressed file
095         */
096        public static String getCompressedFilename(String filename) {
097            return fileNameUtil.getCompressedFilename(filename);
098        }
099    
100    }