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 * @author Stephen Colebourne
032 * @version $Id: FileDeleteStrategy.java 723942 2008-12-06 01:24:06Z sebb $
033 * @since Commons IO 1.3
034 */
035 public class FileDeleteStrategy {
036
037 /**
038 * The singleton instance for normal file deletion, which does not permit
039 * the deletion of directories that are not empty.
040 */
041 public static final FileDeleteStrategy NORMAL = new FileDeleteStrategy("Normal");
042 /**
043 * The singleton instance for forced file deletion, which always deletes,
044 * even if the file represents a non-empty directory.
045 */
046 public static final FileDeleteStrategy FORCE = new ForceFileDeleteStrategy();
047
048 /** The name of the strategy. */
049 private final String name;
050
051 //-----------------------------------------------------------------------
052 /**
053 * Restricted constructor.
054 *
055 * @param name the name by which the strategy is known
056 */
057 protected FileDeleteStrategy(String name) {
058 this.name = name;
059 }
060
061 //-----------------------------------------------------------------------
062 /**
063 * Deletes the file object, which may be a file or a directory.
064 * All <code>IOException</code>s are caught and false returned instead.
065 * If the file does not exist or is null, true is returned.
066 * <p>
067 * Subclass writers should override {@link #doDelete(File)}, not this method.
068 *
069 * @param fileToDelete the file to delete, null returns true
070 * @return true if the file was deleted, or there was no such file
071 */
072 public boolean deleteQuietly(File fileToDelete) {
073 if (fileToDelete == null || fileToDelete.exists() == false) {
074 return true;
075 }
076 try {
077 return doDelete(fileToDelete);
078 } catch (IOException ex) {
079 return false;
080 }
081 }
082
083 /**
084 * Deletes the file object, which may be a file or a directory.
085 * If the file does not exist, the method just returns.
086 * <p>
087 * Subclass writers should override {@link #doDelete(File)}, not this method.
088 *
089 * @param fileToDelete the file to delete, not null
090 * @throws NullPointerException if the file is null
091 * @throws IOException if an error occurs during file deletion
092 */
093 public void delete(File fileToDelete) throws IOException {
094 if (fileToDelete.exists() && doDelete(fileToDelete) == false) {
095 throw new IOException("Deletion failed: " + fileToDelete);
096 }
097 }
098
099 /**
100 * Actually deletes the file object, which may be a file or a directory.
101 * <p>
102 * This method is designed for subclasses to override.
103 * The implementation may return either false or an <code>IOException</code>
104 * when deletion fails. The {@link #delete(File)} and {@link #deleteQuietly(File)}
105 * methods will handle either response appropriately.
106 * A check has been made to ensure that the file will exist.
107 * <p>
108 * This implementation uses {@link File#delete()}.
109 *
110 * @param fileToDelete the file to delete, exists, not null
111 * @return true if the file was deleteds
112 * @throws NullPointerException if the file is null
113 * @throws IOException if an error occurs during file deletion
114 */
115 protected boolean doDelete(File fileToDelete) throws IOException {
116 return fileToDelete.delete();
117 }
118
119 //-----------------------------------------------------------------------
120 /**
121 * Gets a string describing the delete strategy.
122 *
123 * @return a string describing the delete strategy
124 */
125 @Override
126 public String toString() {
127 return "FileDeleteStrategy[" + name + "]";
128 }
129
130 //-----------------------------------------------------------------------
131 /**
132 * Force file deletion strategy.
133 */
134 static class ForceFileDeleteStrategy extends FileDeleteStrategy {
135 /** Default Constructor */
136 ForceFileDeleteStrategy() {
137 super("Force");
138 }
139
140 /**
141 * Deletes the file object.
142 * <p>
143 * This implementation uses <code>FileUtils.forceDelete() <code>
144 * if the file exists.
145 *
146 * @param fileToDelete the file to delete, not null
147 * @return Always returns <code>true</code>
148 * @throws NullPointerException if the file is null
149 * @throws IOException if an error occurs during file deletion
150 */
151 @Override
152 protected boolean doDelete(File fileToDelete) throws IOException {
153 FileUtils.forceDelete(fileToDelete);
154 return true;
155 }
156 }
157
158 }