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.bzip2; 020 021 import java.util.HashMap; 022 import java.util.Locale; 023 import java.util.Map; 024 025 /** 026 * Utility code for the BZip2 compression format. 027 * @ThreadSafe 028 * @since Commons Compress 1.1 029 */ 030 public abstract class BZip2Utils { 031 032 /** 033 * Map from common filename suffixes of bzip2ed files to the corresponding 034 * suffixes of uncompressed files. For example: from ".tbz2" to ".tar". 035 * <p> 036 * This map also contains bzip2-specific suffixes like ".bz2". These 037 * suffixes are mapped to the empty string, as they should simply be 038 * removed from the filename when the file is uncompressed. 039 */ 040 private static final Map<String, String> uncompressSuffix = 041 new HashMap<String, String>(); 042 043 static { 044 uncompressSuffix.put(".tbz2", ".tar"); 045 uncompressSuffix.put(".tbz", ".tar"); 046 uncompressSuffix.put(".bz2", ""); 047 uncompressSuffix.put(".bz", ""); 048 } 049 // N.B. if any shorter or longer keys are added, ensure the for loop limits are changed 050 051 /** Private constructor to prevent instantiation of this utility class. */ 052 private BZip2Utils() { 053 } 054 055 /** 056 * Detects common bzip2 suffixes in the given filename. 057 * 058 * @param filename name of a file 059 * @return <code>true</code> if the filename has a common bzip2 suffix, 060 * <code>false</code> otherwise 061 */ 062 public static boolean isCompressedFilename(String filename) { 063 String lower = filename.toLowerCase(Locale.ENGLISH); 064 int n = lower.length(); 065 // Shortest suffix is three letters (.bz), longest is five (.tbz2) 066 for (int i = 3; i <= 5 && i < n; i++) { 067 if (uncompressSuffix.containsKey(lower.substring(n - i))) { 068 return true; 069 } 070 } 071 return false; 072 } 073 074 /** 075 * Maps the given name of a bzip2-compressed file to the name that the 076 * file should have after uncompression. Commonly used file type specific 077 * suffixes like ".tbz" or ".tbz2" are automatically detected and 078 * correctly mapped. For example the name "package.tbz2" is mapped to 079 * "package.tar". And any filenames with the generic ".bz2" suffix 080 * (or any other generic bzip2 suffix) is mapped to a name without that 081 * suffix. If no bzip2 suffix is detected, then the filename is returned 082 * unmapped. 083 * 084 * @param filename name of a file 085 * @return name of the corresponding uncompressed file 086 */ 087 public static String getUncompressedFilename(String filename) { 088 String lower = filename.toLowerCase(Locale.ENGLISH); 089 int n = lower.length(); 090 // Shortest suffix is three letters (.bz), longest is five (.tbz2) 091 for (int i = 3; i <= 5 && i < n; i++) { 092 Object suffix = uncompressSuffix.get(lower.substring(n - i)); 093 if (suffix != null) { 094 return filename.substring(0, n - i) + suffix; 095 } 096 } 097 return filename; 098 } 099 100 /** 101 * Maps the given filename to the name that the file should have after 102 * compression with bzip2. Currently this method simply appends the suffix 103 * ".bz2" to the filename based on the standard behaviour of the "bzip2" 104 * program, but a future version may implement a more complex mapping if 105 * a new widely used naming pattern emerges. 106 * 107 * @param filename name of a file 108 * @return name of the corresponding compressed file 109 */ 110 public static String getCompressedFilename(String filename) { 111 return filename + ".bz2"; 112 } 113 114 }