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