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 */ 017package org.apache.commons.io.filefilter; 018 019import java.io.File; 020import java.io.Serializable; 021import java.nio.file.FileVisitResult; 022import java.nio.file.Path; 023import java.nio.file.attribute.BasicFileAttributes; 024import java.util.List; 025 026import org.apache.commons.io.IOCase; 027 028/** 029 * Filters file names for a certain prefix. 030 * <p> 031 * For example, to print all files and directories in the 032 * current directory whose name starts with {@code Test}: 033 * </p> 034 * <h2>Using Classic IO</h2> 035 * <pre> 036 * File dir = new File("."); 037 * String[] files = dir.list(new PrefixFileFilter("Test")); 038 * for (String file : files) { 039 * System.out.println(file); 040 * } 041 * </pre> 042 * 043 * <h2>Using NIO</h2> 044 * <pre> 045 * final Path dir = Paths.get(""); 046 * final AccumulatorPathVisitor visitor = AccumulatorPathVisitor.withLongCounters(new PrefixFileFilter("Test")); 047 * // 048 * // Walk one dir 049 * Files.<b>walkFileTree</b>(dir, Collections.emptySet(), 1, visitor); 050 * System.out.println(visitor.getPathCounters()); 051 * System.out.println(visitor.getFileList()); 052 * // 053 * visitor.getPathCounters().reset(); 054 * // 055 * // Walk dir tree 056 * Files.<b>walkFileTree</b>(dir, visitor); 057 * System.out.println(visitor.getPathCounters()); 058 * System.out.println(visitor.getDirList()); 059 * System.out.println(visitor.getFileList()); 060 * </pre> 061 * 062 * @since 1.0 063 * @see FileFilterUtils#prefixFileFilter(String) 064 * @see FileFilterUtils#prefixFileFilter(String, IOCase) 065 */ 066public class PrefixFileFilter extends AbstractFileFilter implements Serializable { 067 068 private static final long serialVersionUID = 8533897440809599867L; 069 070 /** The file name prefixes to search for */ 071 private final String[] prefixes; 072 073 /** Whether the comparison is case sensitive. */ 074 private final IOCase caseSensitivity; 075 076 /** 077 * Constructs a new Prefix file filter for a list of prefixes. 078 * 079 * @param prefixes the prefixes to allow, must not be null 080 * @throws IllegalArgumentException if the prefix list is null 081 * @throws ClassCastException if the list does not contain Strings 082 */ 083 public PrefixFileFilter(final List<String> prefixes) { 084 this(prefixes, IOCase.SENSITIVE); 085 } 086 087 /** 088 * Constructs a new Prefix file filter for a list of prefixes 089 * specifying case-sensitivity. 090 * 091 * @param prefixes the prefixes to allow, must not be null 092 * @param caseSensitivity how to handle case sensitivity, null means case-sensitive 093 * @throws IllegalArgumentException if the prefix list is null 094 * @throws ClassCastException if the list does not contain Strings 095 * @since 1.4 096 */ 097 public PrefixFileFilter(final List<String> prefixes, final IOCase caseSensitivity) { 098 if (prefixes == null) { 099 throw new IllegalArgumentException("The list of prefixes must not be null"); 100 } 101 this.prefixes = prefixes.toArray(EMPTY_STRING_ARRAY); 102 this.caseSensitivity = caseSensitivity == null ? IOCase.SENSITIVE : caseSensitivity; 103 } 104 105 /** 106 * Constructs a new Prefix file filter for a single prefix. 107 * 108 * @param prefix the prefix to allow, must not be null 109 * @throws IllegalArgumentException if the prefix is null 110 */ 111 public PrefixFileFilter(final String prefix) { 112 this(prefix, IOCase.SENSITIVE); 113 } 114 115 /** 116 * Constructs a new Prefix file filter for any of an array of prefixes. 117 * <p> 118 * The array is not cloned, so could be changed after constructing the 119 * instance. This would be inadvisable however. 120 * 121 * @param prefixes the prefixes to allow, must not be null 122 * @throws IllegalArgumentException if the prefix array is null 123 */ 124 public PrefixFileFilter(final String... prefixes) { 125 this(prefixes, IOCase.SENSITIVE); 126 } 127 128 /** 129 * Constructs a new Prefix file filter for a single prefix 130 * specifying case-sensitivity. 131 * 132 * @param prefix the prefix to allow, must not be null 133 * @param caseSensitivity how to handle case sensitivity, null means case-sensitive 134 * @throws IllegalArgumentException if the prefix is null 135 * @since 1.4 136 */ 137 public PrefixFileFilter(final String prefix, final IOCase caseSensitivity) { 138 if (prefix == null) { 139 throw new IllegalArgumentException("The prefix must not be null"); 140 } 141 this.prefixes = new String[] {prefix}; 142 this.caseSensitivity = caseSensitivity == null ? IOCase.SENSITIVE : caseSensitivity; 143 } 144 145 /** 146 * Constructs a new Prefix file filter for any of an array of prefixes 147 * specifying case-sensitivity. 148 * 149 * @param prefixes the prefixes to allow, must not be null 150 * @param caseSensitivity how to handle case sensitivity, null means case-sensitive 151 * @throws IllegalArgumentException if the prefix is null 152 * @since 1.4 153 */ 154 public PrefixFileFilter(final String[] prefixes, final IOCase caseSensitivity) { 155 if (prefixes == null) { 156 throw new IllegalArgumentException("The array of prefixes must not be null"); 157 } 158 this.prefixes = new String[prefixes.length]; 159 System.arraycopy(prefixes, 0, this.prefixes, 0, prefixes.length); 160 this.caseSensitivity = caseSensitivity == null ? IOCase.SENSITIVE : caseSensitivity; 161 } 162 163 /** 164 * Checks to see if the file name starts with the prefix. 165 * 166 * @param file the File to check 167 * @return true if the file name starts with one of our prefixes 168 */ 169 @Override 170 public boolean accept(final File file) { 171 return accept(file == null ? null : file.getName()); 172 } 173 174 /** 175 * Checks to see if the file name starts with the prefix. 176 * 177 * @param file the File directory 178 * @param name the file name 179 * @return true if the file name starts with one of our prefixes 180 */ 181 @Override 182 public boolean accept(final File file, final String name) { 183 return accept(name); 184 } 185 186 /** 187 * Checks to see if the file name starts with the prefix. 188 * @param file the File to check 189 * 190 * @return true if the file name starts with one of our prefixes 191 * @since 2.9.0 192 */ 193 @Override 194 public FileVisitResult accept(final Path file, final BasicFileAttributes attributes) { 195 final Path fileName = file.getFileName(); 196 return toFileVisitResult(accept(fileName == null ? null : fileName.toFile()), file); 197 } 198 199 private boolean accept(final String name) { 200 for (final String prefix : prefixes) { 201 if (caseSensitivity.checkStartsWith(name, prefix)) { 202 return true; 203 } 204 } 205 return false; 206 } 207 208 /** 209 * Provide a String representation of this file filter. 210 * 211 * @return a String representation 212 */ 213 @Override 214 public String toString() { 215 final StringBuilder buffer = new StringBuilder(); 216 buffer.append(super.toString()); 217 buffer.append("("); 218 if (prefixes != null) { 219 for (int i = 0; i < prefixes.length; i++) { 220 if (i > 0) { 221 buffer.append(","); 222 } 223 buffer.append(prefixes[i]); 224 } 225 } 226 buffer.append(")"); 227 return buffer.toString(); 228 } 229 230}