1 | /**************************************************************** |
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2 | * Licensed to the Apache Software Foundation (ASF) under one * |
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3 | * or more contributor license agreements. See the NOTICE file * |
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4 | * distributed with this work for additional information * |
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5 | * regarding copyright ownership. The ASF licenses this file * |
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6 | * to you under the Apache License, Version 2.0 (the * |
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7 | * "License"); you may not use this file except in compliance * |
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8 | * with the License. You may obtain a copy of the License at * |
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9 | * * |
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10 | * http://www.apache.org/licenses/LICENSE-2.0 * |
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11 | * * |
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12 | * Unless required by applicable law or agreed to in writing, * |
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13 | * software distributed under the License is distributed on an * |
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14 | * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * |
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15 | * KIND, either express or implied. See the License for the * |
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16 | * specific language governing permissions and limitations * |
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17 | * under the License. * |
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18 | ****************************************************************/ |
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19 | |
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20 | package org.apache.james.mime4j.storage; |
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21 | |
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22 | import java.io.BufferedInputStream; |
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23 | import java.io.File; |
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24 | import java.io.FileInputStream; |
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25 | import java.io.FileOutputStream; |
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26 | import java.io.IOException; |
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27 | import java.io.InputStream; |
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28 | import java.io.OutputStream; |
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29 | import java.util.HashSet; |
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30 | import java.util.Iterator; |
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31 | import java.util.Set; |
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32 | |
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33 | /** |
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34 | * A {@link StorageProvider} that stores the data in temporary files. The files |
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35 | * are stored either in a user-specified directory or the default temporary-file |
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36 | * directory (specified by system property <code>java.io.tmpdir</code>). |
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37 | * <p> |
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38 | * Example usage: |
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39 | * |
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40 | * <pre> |
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41 | * File directory = new File("/tmp/mime4j"); |
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42 | * StorageProvider provider = new TempFileStorageProvider(directory); |
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43 | * DefaultStorageProvider.setInstance(provider); |
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44 | * </pre> |
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45 | */ |
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46 | public class TempFileStorageProvider extends AbstractStorageProvider { |
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47 | |
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48 | private static final String DEFAULT_PREFIX = "m4j"; |
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49 | |
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50 | private final String prefix; |
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51 | private final String suffix; |
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52 | private final File directory; |
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53 | |
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54 | /** |
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55 | * Equivalent to using constructor |
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56 | * <code>TempFileStorageProvider("m4j", null, null)</code>. |
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57 | */ |
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58 | public TempFileStorageProvider() { |
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59 | this(DEFAULT_PREFIX, null, null); |
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60 | } |
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61 | |
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62 | /** |
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63 | * Equivalent to using constructor |
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64 | * <code>TempFileStorageProvider("m4j", null, directory)</code>. |
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65 | */ |
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66 | public TempFileStorageProvider(File directory) { |
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67 | this(DEFAULT_PREFIX, null, directory); |
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68 | } |
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69 | |
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70 | /** |
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71 | * Creates a new <code>TempFileStorageProvider</code> using the given |
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72 | * values. |
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73 | * |
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74 | * @param prefix |
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75 | * prefix for generating the temporary file's name; must be at |
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76 | * least three characters long. |
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77 | * @param suffix |
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78 | * suffix for generating the temporary file's name; may be |
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79 | * <code>null</code> to use the suffix <code>".tmp"</code>. |
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80 | * @param directory |
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81 | * the directory in which the file is to be created, or |
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82 | * <code>null</code> if the default temporary-file directory is |
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83 | * to be used (specified by the system property |
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84 | * <code>java.io.tmpdir</code>). |
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85 | * @throws IllegalArgumentException |
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86 | * if the given prefix is less than three characters long or the |
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87 | * given directory does not exist and cannot be created (if it |
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88 | * is not <code>null</code>). |
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89 | */ |
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90 | public TempFileStorageProvider(String prefix, String suffix, File directory) { |
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91 | if (prefix == null || prefix.length() < 3) |
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92 | throw new IllegalArgumentException("invalid prefix"); |
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93 | |
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94 | if (directory != null && !directory.isDirectory() |
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95 | && !directory.mkdirs()) |
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96 | throw new IllegalArgumentException("invalid directory"); |
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97 | |
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98 | this.prefix = prefix; |
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99 | this.suffix = suffix; |
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100 | this.directory = directory; |
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101 | } |
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102 | |
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103 | public StorageOutputStream createStorageOutputStream() throws IOException { |
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104 | File file = File.createTempFile(prefix, suffix, directory); |
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105 | file.deleteOnExit(); |
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106 | |
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107 | return new TempFileStorageOutputStream(file); |
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108 | } |
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109 | |
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110 | private static final class TempFileStorageOutputStream extends |
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111 | StorageOutputStream { |
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112 | private File file; |
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113 | private OutputStream out; |
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114 | |
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115 | public TempFileStorageOutputStream(File file) throws IOException { |
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116 | this.file = file; |
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117 | this.out = new FileOutputStream(file); |
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118 | } |
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119 | |
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120 | @Override |
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121 | public void close() throws IOException { |
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122 | super.close(); |
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123 | out.close(); |
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124 | } |
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125 | |
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126 | @Override |
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127 | protected void write0(byte[] buffer, int offset, int length) |
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128 | throws IOException { |
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129 | out.write(buffer, offset, length); |
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130 | } |
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131 | |
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132 | @Override |
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133 | protected Storage toStorage0() throws IOException { |
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134 | // out has already been closed because toStorage calls close |
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135 | return new TempFileStorage(file); |
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136 | } |
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137 | } |
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138 | |
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139 | private static final class TempFileStorage implements Storage { |
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140 | |
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141 | private File file; |
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142 | |
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143 | private static final Set<File> filesToDelete = new HashSet<File>(); |
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144 | |
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145 | public TempFileStorage(File file) { |
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146 | this.file = file; |
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147 | } |
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148 | |
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149 | public void delete() { |
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150 | // deleting a file might not immediately succeed if there are still |
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151 | // streams left open (especially under Windows). so we keep track of |
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152 | // the files that have to be deleted and try to delete all these |
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153 | // files each time this method gets invoked. |
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154 | |
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155 | // a better but more complicated solution would be to start a |
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156 | // separate thread that tries to delete the files periodically. |
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157 | |
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158 | synchronized (filesToDelete) { |
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159 | if (file != null) { |
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160 | filesToDelete.add(file); |
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161 | file = null; |
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162 | } |
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163 | |
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164 | for (Iterator<File> iterator = filesToDelete.iterator(); iterator |
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165 | .hasNext();) { |
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166 | File file = iterator.next(); |
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167 | if (file.delete()) { |
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168 | iterator.remove(); |
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169 | } |
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170 | } |
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171 | } |
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172 | } |
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173 | |
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174 | public InputStream getInputStream() throws IOException { |
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175 | if (file == null) |
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176 | throw new IllegalStateException("storage has been deleted"); |
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177 | |
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178 | return new BufferedInputStream(new FileInputStream(file)); |
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179 | } |
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180 | |
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181 | } |
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182 | |
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183 | } |
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