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 }