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     */
017    package org.apache.commons.io.filefilter;
018    
019    import java.io.File;
020    import java.io.Serializable;
021    import java.util.regex.Pattern;
022    
023    import org.apache.commons.io.IOCase;
024    
025    /**
026     * Filters files using supplied regular expression(s).
027     * <p/>
028     * See java.util.regex.Pattern for regex matching rules
029     * <p/>
030     *
031     * <p/>
032     * e.g.
033     * <pre>
034     * File dir = new File(".");
035     * FileFilter fileFilter = new RegexFileFilter("^.*[tT]est(-\\d+)?\\.java$");
036     * File[] files = dir.listFiles(fileFilter);
037     * for (int i = 0; i < files.length; i++) {
038     *   System.out.println(files[i]);
039     * }
040     * </pre>
041     *
042     * @author Oliver Siegmar
043     * @version $Revision: 659817 $
044     * @since Commons IO 1.4
045     */
046    public class RegexFileFilter extends AbstractFileFilter implements Serializable {
047    
048        /** The regular expression pattern that will be used to match filenames */
049        private final Pattern pattern;
050    
051        /**
052         * Construct a new regular expression filter.
053         *
054         * @param pattern regular string expression to match
055         * @throws IllegalArgumentException if the pattern is null
056         */
057        public RegexFileFilter(String pattern) {
058            if (pattern == null) {
059                throw new IllegalArgumentException("Pattern is missing");
060            }
061    
062            this.pattern = Pattern.compile(pattern);
063        }
064    
065        /**
066         * Construct a new regular expression filter with the specified flags case sensitivity.
067         *
068         * @param pattern regular string expression to match
069         * @param caseSensitivity  how to handle case sensitivity, null means case-sensitive
070         * @throws IllegalArgumentException if the pattern is null
071         */
072        public RegexFileFilter(String pattern, IOCase caseSensitivity) {
073            if (pattern == null) {
074                throw new IllegalArgumentException("Pattern is missing");
075            }
076            int flags = 0;
077            if (caseSensitivity != null && !caseSensitivity.isCaseSensitive()) {
078                flags = Pattern.CASE_INSENSITIVE;
079            }
080            this.pattern = Pattern.compile(pattern, flags);
081        }
082    
083        /**
084         * Construct a new regular expression filter with the specified flags.
085         *
086         * @param pattern regular string expression to match
087         * @param flags pattern flags - e.g. {@link Pattern#CASE_INSENSITIVE}
088         * @throws IllegalArgumentException if the pattern is null
089         */
090        public RegexFileFilter(String pattern, int flags) {
091            if (pattern == null) {
092                throw new IllegalArgumentException("Pattern is missing");
093            }
094            this.pattern = Pattern.compile(pattern, flags);
095        }
096    
097        /**
098         * Construct a new regular expression filter for a compiled regular expression
099         *
100         * @param pattern regular expression to match
101         * @throws IllegalArgumentException if the pattern is null
102         */
103        public RegexFileFilter(Pattern pattern) {
104            if (pattern == null) {
105                throw new IllegalArgumentException("Pattern is missing");
106            }
107    
108            this.pattern = pattern;
109        }
110    
111        /**
112         * Checks to see if the filename matches one of the regular expressions.
113         *
114         * @param dir   the file directory
115         * @param name  the filename
116         * @return true if the filename matches one of the regular expressions
117         */
118        @Override
119        public boolean accept(File dir, String name) {
120            return (pattern.matcher(name).matches());
121        }
122    
123    }