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; 025import java.util.Objects; 026import java.util.stream.Stream; 027 028import org.apache.commons.io.IOCase; 029 030/** 031 * Filters file names for a certain prefix. 032 * <p> 033 * For example, to print all files and directories in the 034 * current directory whose name starts with {@code Test}: 035 * </p> 036 * <h2>Using Classic IO</h2> 037 * <pre> 038 * File dir = FileUtils.current(); 039 * String[] files = dir.list(new PrefixFileFilter("Test")); 040 * for (String file : files) { 041 * System.out.println(file); 042 * } 043 * </pre> 044 * 045 * <h2>Using NIO</h2> 046 * <pre> 047 * final Path dir = PathUtils.current(); 048 * final AccumulatorPathVisitor visitor = AccumulatorPathVisitor.withLongCounters(new PrefixFileFilter("Test")); 049 * // 050 * // Walk one dir 051 * Files.<b>walkFileTree</b>(dir, Collections.emptySet(), 1, visitor); 052 * System.out.println(visitor.getPathCounters()); 053 * System.out.println(visitor.getFileList()); 054 * // 055 * visitor.getPathCounters().reset(); 056 * // 057 * // Walk dir tree 058 * Files.<b>walkFileTree</b>(dir, visitor); 059 * System.out.println(visitor.getPathCounters()); 060 * System.out.println(visitor.getDirList()); 061 * System.out.println(visitor.getFileList()); 062 * </pre> 063 * <h2>Deprecating Serialization</h2> 064 * <p> 065 * <em>Serialization is deprecated and will be removed in 3.0.</em> 066 * </p> 067 * 068 * @since 1.0 069 * @see FileFilterUtils#prefixFileFilter(String) 070 * @see FileFilterUtils#prefixFileFilter(String, IOCase) 071 */ 072public class PrefixFileFilter extends AbstractFileFilter implements Serializable { 073 074 private static final long serialVersionUID = 8533897440809599867L; 075 076 /** The file name prefixes to search for */ 077 private final String[] prefixes; 078 079 /** Whether the comparison is case-sensitive. */ 080 private final IOCase isCase; 081 082 /** 083 * Constructs a new Prefix file filter for a list of prefixes. 084 * 085 * @param prefixes the prefixes to allow, must not be null 086 * @throws NullPointerException if the prefix list is null 087 * @throws ClassCastException if the list does not contain Strings 088 */ 089 public PrefixFileFilter(final List<String> prefixes) { 090 this(prefixes, IOCase.SENSITIVE); 091 } 092 093 /** 094 * Constructs a new Prefix file filter for a list of prefixes 095 * specifying case-sensitivity. 096 * 097 * @param prefixes the prefixes to allow, must not be null 098 * @param ioCase how to handle case sensitivity, null means case-sensitive 099 * @throws NullPointerException if the prefix list is null 100 * @throws ClassCastException if the list does not contain Strings 101 * @since 1.4 102 */ 103 public PrefixFileFilter(final List<String> prefixes, final IOCase ioCase) { 104 Objects.requireNonNull(prefixes, "prefixes"); 105 this.prefixes = prefixes.toArray(EMPTY_STRING_ARRAY); 106 this.isCase = IOCase.value(ioCase, IOCase.SENSITIVE); 107 } 108 109 /** 110 * Constructs a new Prefix file filter for a single prefix. 111 * 112 * @param prefix the prefix to allow, must not be null 113 * @throws IllegalArgumentException if the prefix is null 114 */ 115 public PrefixFileFilter(final String prefix) { 116 this(prefix, IOCase.SENSITIVE); 117 } 118 119 /** 120 * Constructs a new Prefix file filter for any of an array of prefixes. 121 * <p> 122 * The array is not cloned, so could be changed after constructing the 123 * instance. This would be inadvisable however. 124 * 125 * @param prefixes the prefixes to allow, must not be null 126 * @throws IllegalArgumentException if the prefix array is null 127 */ 128 public PrefixFileFilter(final String... prefixes) { 129 this(prefixes, IOCase.SENSITIVE); 130 } 131 132 /** 133 * Constructs a new Prefix file filter for a single prefix 134 * specifying case-sensitivity. 135 * 136 * @param prefix the prefix to allow, must not be null 137 * @param ioCase how to handle case sensitivity, null means case-sensitive 138 * @throws IllegalArgumentException if the prefix is null 139 * @since 1.4 140 */ 141 public PrefixFileFilter(final String prefix, final IOCase ioCase) { 142 Objects.requireNonNull(prefix, "prefix"); 143 this.prefixes = new String[] {prefix}; 144 this.isCase = IOCase.value(ioCase, IOCase.SENSITIVE); 145 } 146 147 /** 148 * Constructs a new Prefix file filter for any of an array of prefixes 149 * specifying case-sensitivity. 150 * 151 * @param prefixes the prefixes to allow, must not be null 152 * @param ioCase how to handle case sensitivity, null means case-sensitive 153 * @throws IllegalArgumentException if the prefix is null 154 * @since 1.4 155 */ 156 public PrefixFileFilter(final String[] prefixes, final IOCase ioCase) { 157 Objects.requireNonNull(prefixes, "prefixes"); 158 this.prefixes = prefixes.clone(); 159 this.isCase = IOCase.value(ioCase, IOCase.SENSITIVE); 160 } 161 162 /** 163 * Checks to see if the file name starts with the prefix. 164 * 165 * @param file the File to check 166 * @return true if the file name starts with one of our prefixes 167 */ 168 @Override 169 public boolean accept(final File file) { 170 return accept(file == null ? null : file.getName()); 171 } 172 173 /** 174 * Checks to see if the file name starts with the prefix. 175 * 176 * @param file the File directory 177 * @param name the file name 178 * @return true if the file name starts with one of our prefixes 179 */ 180 @Override 181 public boolean accept(final File file, final String name) { 182 return accept(name); 183 } 184 185 /** 186 * Checks to see if the file name starts with the prefix. 187 * @param file the File to check 188 * 189 * @return true if the file name starts with one of our prefixes 190 * @since 2.9.0 191 */ 192 @Override 193 public FileVisitResult accept(final Path file, final BasicFileAttributes attributes) { 194 final Path fileName = file.getFileName(); 195 return toFileVisitResult(accept(fileName == null ? null : fileName.toFile())); 196 } 197 198 private boolean accept(final String name) { 199 return Stream.of(prefixes).anyMatch(prefix -> isCase.checkStartsWith(name, prefix)); 200 } 201 202 /** 203 * Provide a String representation of this file filter. 204 * 205 * @return a String representation 206 */ 207 @Override 208 public String toString() { 209 final StringBuilder buffer = new StringBuilder(); 210 buffer.append(super.toString()); 211 buffer.append("("); 212 append(prefixes, buffer); 213 buffer.append(")"); 214 return buffer.toString(); 215 } 216 217}