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;
018
019 import java.io.File;
020 import java.io.IOException;
021
022 /**
023 * Strategy for deleting files.
024 * <p>
025 * There is more than one way to delete a file.
026 * You may want to limit access to certain directories, to only delete
027 * directories if they are empty, or maybe to force deletion.
028 * <p>
029 * This class captures the strategy to use and is designed for user subclassing.
030 *
031 * @version $Id: FileDeleteStrategy.java 1307461 2012-03-30 15:12:29Z ggregory $
032 * @since 1.3
033 */
034 public class FileDeleteStrategy {
035
036 /**
037 * The singleton instance for normal file deletion, which does not permit
038 * the deletion of directories that are not empty.
039 */
040 public static final FileDeleteStrategy NORMAL = new FileDeleteStrategy("Normal");
041 /**
042 * The singleton instance for forced file deletion, which always deletes,
043 * even if the file represents a non-empty directory.
044 */
045 public static final FileDeleteStrategy FORCE = new ForceFileDeleteStrategy();
046
047 /** The name of the strategy. */
048 private final String name;
049
050 //-----------------------------------------------------------------------
051 /**
052 * Restricted constructor.
053 *
054 * @param name the name by which the strategy is known
055 */
056 protected FileDeleteStrategy(String name) {
057 this.name = name;
058 }
059
060 //-----------------------------------------------------------------------
061 /**
062 * Deletes the file object, which may be a file or a directory.
063 * All <code>IOException</code>s are caught and false returned instead.
064 * If the file does not exist or is null, true is returned.
065 * <p>
066 * Subclass writers should override {@link #doDelete(File)}, not this method.
067 *
068 * @param fileToDelete the file to delete, null returns true
069 * @return true if the file was deleted, or there was no such file
070 */
071 public boolean deleteQuietly(File fileToDelete) {
072 if (fileToDelete == null || fileToDelete.exists() == false) {
073 return true;
074 }
075 try {
076 return doDelete(fileToDelete);
077 } catch (IOException ex) {
078 return false;
079 }
080 }
081
082 /**
083 * Deletes the file object, which may be a file or a directory.
084 * If the file does not exist, the method just returns.
085 * <p>
086 * Subclass writers should override {@link #doDelete(File)}, not this method.
087 *
088 * @param fileToDelete the file to delete, not null
089 * @throws NullPointerException if the file is null
090 * @throws IOException if an error occurs during file deletion
091 */
092 public void delete(File fileToDelete) throws IOException {
093 if (fileToDelete.exists() && doDelete(fileToDelete) == false) {
094 throw new IOException("Deletion failed: " + fileToDelete);
095 }
096 }
097
098 /**
099 * Actually deletes the file object, which may be a file or a directory.
100 * <p>
101 * This method is designed for subclasses to override.
102 * The implementation may return either false or an <code>IOException</code>
103 * when deletion fails. The {@link #delete(File)} and {@link #deleteQuietly(File)}
104 * methods will handle either response appropriately.
105 * A check has been made to ensure that the file will exist.
106 * <p>
107 * This implementation uses {@link File#delete()}.
108 *
109 * @param fileToDelete the file to delete, exists, not null
110 * @return true if the file was deleteds
111 * @throws NullPointerException if the file is null
112 * @throws IOException if an error occurs during file deletion
113 */
114 protected boolean doDelete(File fileToDelete) throws IOException {
115 return fileToDelete.delete();
116 }
117
118 //-----------------------------------------------------------------------
119 /**
120 * Gets a string describing the delete strategy.
121 *
122 * @return a string describing the delete strategy
123 */
124 @Override
125 public String toString() {
126 return "FileDeleteStrategy[" + name + "]";
127 }
128
129 //-----------------------------------------------------------------------
130 /**
131 * Force file deletion strategy.
132 */
133 static class ForceFileDeleteStrategy extends FileDeleteStrategy {
134 /** Default Constructor */
135 ForceFileDeleteStrategy() {
136 super("Force");
137 }
138
139 /**
140 * Deletes the file object.
141 * <p>
142 * This implementation uses <code>FileUtils.forceDelete() <code>
143 * if the file exists.
144 *
145 * @param fileToDelete the file to delete, not null
146 * @return Always returns {@code true}
147 * @throws NullPointerException if the file is null
148 * @throws IOException if an error occurs during file deletion
149 */
150 @Override
151 protected boolean doDelete(File fileToDelete) throws IOException {
152 FileUtils.forceDelete(fileToDelete);
153 return true;
154 }
155 }
156
157 }