1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 package org.apache.commons.io.filefilter; 18 19 import java.io.File; 20 import java.io.Serializable; 21 import java.nio.file.FileVisitResult; 22 import java.nio.file.Files; 23 import java.nio.file.Path; 24 import java.nio.file.attribute.BasicFileAttributes; 25 26 /** 27 * This filter accepts {@link File}s that can be read. 28 * <p> 29 * Example, showing how to print out a list of the current directory's <i>readable</i> files: 30 * </p> 31 * <h2>Using Classic IO</h2> 32 * <pre> 33 * File dir = FileUtils.current(); 34 * String[] files = dir.list(CanReadFileFilter.CAN_READ); 35 * for (String file : files) { 36 * System.out.println(file); 37 * } 38 * </pre> 39 * 40 * <p> 41 * Example, showing how to print out a list of the current directory's <i>un-readable</i> files: 42 * 43 * <pre> 44 * File dir = FileUtils.current(); 45 * String[] files = dir.list(CanReadFileFilter.CANNOT_READ); 46 * for (String file : files) { 47 * System.out.println(file); 48 * } 49 * </pre> 50 * 51 * <p> 52 * Example, showing how to print out a list of the current directory's <i>read-only</i> files: 53 * 54 * <pre> 55 * File dir = FileUtils.current(); 56 * String[] files = dir.list(CanReadFileFilter.READ_ONLY); 57 * for (String file : files) { 58 * System.out.println(file); 59 * } 60 * </pre> 61 * <h2>Deprecating Serialization</h2> 62 * <p> 63 * <em>Serialization is deprecated and will be removed in 3.0.</em> 64 * </p> 65 * 66 * @since 1.3 67 */ 68 public class CanReadFileFilter extends AbstractFileFilter implements Serializable { 69 70 /** Singleton instance of <i>readable</i> filter */ 71 public static final IOFileFilter CAN_READ = new CanReadFileFilter(); 72 73 /** Singleton instance of not <i>readable</i> filter */ 74 public static final IOFileFilter CANNOT_READ = CAN_READ.negate(); 75 76 /** Singleton instance of <i>read-only</i> filter */ 77 public static final IOFileFilter READ_ONLY = CAN_READ.and(CanWriteFileFilter.CANNOT_WRITE); 78 79 private static final long serialVersionUID = 3179904805251622989L; 80 81 /** 82 * Restrictive constructor. 83 */ 84 protected CanReadFileFilter() { 85 } 86 87 /** 88 * Checks to see if the file can be read. 89 * 90 * @param file the File to check. 91 * @return {@code true} if the file can be read, otherwise {@code false}. 92 */ 93 @Override 94 public boolean accept(final File file) { 95 return file.canRead(); 96 } 97 98 /** 99 * Checks to see if the file can be read. 100 * @param file the File to check. 101 * 102 * @return {@code true} if the file can be read, otherwise {@code false}. 103 * @since 2.9.0 104 */ 105 @Override 106 public FileVisitResult accept(final Path file, final BasicFileAttributes attributes) { 107 return toFileVisitResult(Files.isReadable(file)); 108 } 109 110 }