    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}