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