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1 /* |
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2 * Copyright 2007-2009 Sun Microsystems, Inc. All Rights Reserved. |
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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4 * |
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5 * This code is free software; you can redistribute it and/or modify it |
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6 * under the terms of the GNU General Public License version 2 only, as |
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7 * published by the Free Software Foundation. Sun designates this |
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8 * particular file as subject to the "Classpath" exception as provided |
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9 * by Sun in the LICENSE file that accompanied this code. |
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10 * |
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11 * This code is distributed in the hope that it will be useful, but WITHOUT |
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12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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14 * version 2 for more details (a copy is included in the LICENSE file that |
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15 * accompanied this code). |
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16 * |
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17 * You should have received a copy of the GNU General Public License version |
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18 * 2 along with this work; if not, write to the Free Software Foundation, |
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19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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20 * |
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21 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
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22 * CA 95054 USA or visit www.sun.com if you need additional information or |
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23 * have any questions. |
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24 */ |
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25 |
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26 package java.nio.file; |
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27 |
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28 import java.nio.file.attribute.*; |
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29 import java.nio.file.spi.FileSystemProvider; |
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30 import java.util.Set; |
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31 import java.io.Closeable; |
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32 import java.io.IOException; |
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33 |
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34 /** |
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35 * Provides an interface to a file system and is the factory for objects to |
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36 * access files and other objects in the file system. |
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37 * |
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38 * <p> The default file system, obtained by invoking the {@link FileSystems#getDefault |
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39 * FileSystems.getDefault} method, provides access to the file system that is |
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40 * accessible to the Java virtual machine. The {@link FileSystems} class defines |
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41 * methods to create file systems that provide access to other types of file |
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42 * systems. |
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43 * |
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44 * <p> A file system is the factory for several types of objects: |
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45 * |
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46 * <ul> |
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47 * <li><p> The {@link #getPath getPath} method converts a system dependent |
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48 * <em>path string</em>, returning a {@link Path} object that may be used |
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49 * to locate and access a file. </p></li> |
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50 * <li><p> The {@link #getPathMatcher getPathMatcher} method is used |
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51 * to create a {@link PathMatcher} that performs match operations on |
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52 * paths. </p></li> |
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53 * <li><p> The {@link #getFileStores getFileStores} method returns an iterator |
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54 * over the underlying {@link FileStore file-stores}. </p></li> |
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55 * <li><p> The {@link #getUserPrincipalLookupService getUserPrincipalLookupService} |
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56 * method returns the {@link UserPrincipalLookupService} to lookup users or |
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57 * groups by name. </p></li> |
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58 * <li><p> The {@link #newWatchService newWatchService} method creates a |
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59 * {@link WatchService} that may be used to watch objects for changes and |
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60 * events. </p></li> |
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61 * </ul> |
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62 * |
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63 * <p> File systems vary greatly. In some cases the file system is a single |
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64 * hierarchy of files with one top-level root directory. In other cases it may |
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65 * have several distinct file hierarchies, each with its own top-level root |
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66 * directory. The {@link #getRootDirectories getRootDirectories} method may be |
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67 * used to iterate over the root directories in the file system. A file system |
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68 * is typically composed of one or more underlying {@link FileStore file-stores} |
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69 * that provide the storage for the files. Theses file stores can also vary in |
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70 * the features they support, and the file attributes or <em>meta-data</em> that |
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71 * they associate with files. |
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72 * |
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73 * <p> A file system is open upon creation and can be closed by invoking its |
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74 * {@link #close() close} method. Once closed, any further attempt to access |
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75 * objects in the file system cause {@link ClosedFileSystemException} to be |
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76 * thrown. File systems created by the default {@link FileSystemProvider provider} |
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77 * cannot be closed. |
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78 * |
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79 * <p> A {@code FileSystem} can provide read-only or read-write access to the |
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80 * file system. Whether or not a file system provides read-only access is |
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81 * established when the {@code FileSystem} is created and can be tested by invoking |
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82 * its {@link #isReadOnly() isReadOnly} method. Attempts to write to file stores |
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83 * by means of an object associated with a read-only file system throws {@link |
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84 * ReadOnlyFileSystemException}. |
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85 * |
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86 * <p> File systems are safe for use by multiple concurrent threads. The {@link |
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87 * #close close} method may be invoked at any time to close a file system but |
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88 * whether a file system is <i>asynchronously closeable</i> is provider specific |
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89 * and therefore unspecified. In other words, if a thread is accessing an |
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90 * object in a file system, and another thread invokes the {@code close} method |
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91 * then it may require to block until the first operation is complete. Closing |
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92 * a file system causes all open channels, watch services, and other {@link |
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93 * Closeable closeable} objects associated with the file system to be closed. |
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94 * |
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95 * @since 1.7 |
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96 */ |
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97 |
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98 public abstract class FileSystem |
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99 implements Closeable |
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100 { |
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101 /** |
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102 * Initializes a new instance of this class. |
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103 */ |
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104 protected FileSystem() { |
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105 } |
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106 |
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107 /** |
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108 * Returns the provider that created this file system. |
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109 * |
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110 * @return The provider that created this file system. |
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111 */ |
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112 public abstract FileSystemProvider provider(); |
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113 |
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114 /** |
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115 * Closes this file system. |
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116 * |
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117 * <p> After a file system is closed then all subsequent access to the file |
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118 * system, either by methods defined by this class or on objects associated |
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119 * with this file system, throw {@link ClosedFileSystemException}. If the |
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120 * file system is already closed then invoking this method has no effect. |
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121 * |
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122 * <p> Closing a file system will close all open {@link |
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123 * java.nio.channels.Channel channels}, {@link DirectoryStream directory-streams}, |
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124 * {@link WatchService watch-service}, and other closeable objects associated |
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125 * with this file system. The {@link FileSystems#getDefault default} file |
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126 * system cannot be closed. |
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127 * |
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128 * @throws IOException |
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129 * If an I/O error occurs |
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130 * @throws UnsupportedOperationException |
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131 * Thrown in the case of the default file system |
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132 */ |
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133 @Override |
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134 public abstract void close() throws IOException; |
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135 |
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136 /** |
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137 * Tells whether or not this file system is open. |
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138 * |
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139 * <p> File systems created by the default provider are always open. |
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140 * |
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141 * @return {@code true} if, and only if, this file system is open |
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142 */ |
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143 public abstract boolean isOpen(); |
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144 |
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145 /** |
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146 * Tells whether or not this file system allows only read-only access to |
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147 * its file stores. |
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148 * |
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149 * @return {@code true} if, and only if, this file system provides |
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150 * read-only access |
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151 */ |
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152 public abstract boolean isReadOnly(); |
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153 |
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154 /** |
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155 * Returns the name separator, represented as a string. |
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156 * |
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157 * <p> The name separator is used to separate names in a path string. An |
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158 * implementation may support multiple name separators in which case this |
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159 * method returns an implementation specific <em>default</em> name separator. |
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160 * This separator is used when creating path strings by invoking the {@link |
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161 * Path#toString() toString()} method. |
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162 * |
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163 * <p> In the case of the default provider, this method returns the same |
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164 * separator as {@link java.io.File#separator}. |
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165 * |
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166 * @return The name separator |
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167 */ |
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168 public abstract String getSeparator(); |
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169 |
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170 /** |
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171 * Returns an object to iterate over the paths of the root directories. |
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172 * |
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173 * <p> A file system provides access to a file store that may be composed |
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174 * of a number of distinct file hierarchies, each with its own top-level |
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175 * root directory. Unless denied by the security manager, each element in |
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176 * the returned iterator corresponds to the root directory of a distinct |
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177 * file hierarchy. The order of the elements is not defined. The file |
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178 * hierarchies may change during the lifetime of the Java virtual machine. |
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179 * For example, in some implementations, the insertion of removable media |
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180 * may result in the creation of a new file hierarchy with its own |
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181 * top-level directory. |
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182 * |
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183 * <p> When a security manager is installed, it is invoked to check access |
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184 * to the each root directory. If denied, the root directory is not returned |
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185 * by the iterator. In the case of the default provider, the {@link |
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186 * SecurityManager#checkRead(String)} method is invoked to check read access |
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187 * to each root directory. It is system dependent if the permission checks |
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188 * are done when the iterator is obtained or during iteration. |
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189 * |
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190 * @return An object to iterate over the root directories |
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191 */ |
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192 public abstract Iterable<Path> getRootDirectories(); |
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193 |
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194 /** |
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195 * Returns an object to iterate over the underlying file stores. |
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196 * |
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197 * <p> The elements of the returned iterator are the {@link |
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198 * FileStore FileStores} for this file system. The order of the elements is |
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199 * not defined and the file stores may change during the lifetime of the |
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200 * Java virtual machine. When an I/O error occurs, perhaps because a file |
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201 * store is not accessible, then it is not returned by the iterator. |
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202 * |
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203 * <p> In the case of the default provider, and a security manager is |
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204 * installed, the security manager is invoked to check {@link |
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205 * RuntimePermission}<tt>("getFileStoreAttributes")</tt>. If denied, then |
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206 * no file stores are returned by the iterator. In addition, the security |
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207 * manager's {@link SecurityManager#checkRead(String)} method is invoked to |
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208 * check read access to the file store's <em>top-most</em> directory. If |
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209 * denied, the file store is not returned by the iterator. It is system |
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210 * dependent if the permission checks are done when the iterator is obtained |
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211 * or during iteration. |
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212 * |
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213 * <p> <b>Usage Example:</b> |
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214 * Suppose we want to print the space usage for all file stores: |
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215 * <pre> |
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216 * for (FileStore store: FileSystems.getDefault().getFileStores()) { |
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217 * FileStoreSpaceAttributes attrs = Attributes.readFileStoreSpaceAttributes(store); |
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218 * long total = attrs.totalSpace() / 1024; |
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219 * long used = (attrs.totalSpace() - attrs.unallocatedSpace()) / 1024; |
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220 * long avail = attrs.usableSpace() / 1024; |
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221 * System.out.format("%-20s %12d %12d %12d%n", store, total, used, avail); |
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222 * } |
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223 * </pre> |
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224 * |
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225 * @return An object to iterate over the backing file stores |
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226 */ |
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227 public abstract Iterable<FileStore> getFileStores(); |
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228 |
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229 /** |
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230 * Returns the set of the {@link FileAttributeView#name names} of the file |
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231 * attribute views supported by this {@code FileSystem}. |
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232 * |
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233 * <p> The {@link BasicFileAttributeView} is required to be supported and |
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234 * therefore the set contains at least one element, "basic". |
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235 * |
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236 * <p> The {@link FileStore#supportsFileAttributeView(String) |
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237 * supportsFileAttributeView(String)} method may be used to test if an |
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238 * underlying {@link FileStore} supports the file attributes identified by a |
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239 * file attribute view. |
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240 * |
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241 * @return An unmodifiable set of the names of the supported file attribute |
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242 * views |
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243 */ |
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244 public abstract Set<String> supportedFileAttributeViews(); |
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245 |
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246 /** |
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247 * Converts a path string to a {@code Path}. |
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248 * |
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249 * <p> The parsing and conversion to a path object is inherently |
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250 * implementation dependent. In the simplest case, the path string is rejected, |
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251 * and {@link InvalidPathException} thrown, if the path string contains |
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252 * characters that cannot be converted to characters that are <em>legal</em> |
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253 * to the file store. For example, on UNIX systems, the NUL (\u0000) |
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254 * character is not allowed to be present in a path. An implementation may |
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255 * choose to reject path strings that contain names that are longer than those |
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256 * allowed by any file store, and where an implementation supports a complex |
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257 * path syntax, it may choose to reject path strings that are <em>badly |
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258 * formed</em>. |
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259 * |
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260 * <p> In the case of the default provider, path strings are parsed based |
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261 * on the definition of paths at the platform or virtual file system level. |
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262 * For example, an operating system may not allow specific characters to be |
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263 * present in a file name, but a specific underlying file store may impose |
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264 * different or additional restrictions on the set of legal |
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265 * characters. |
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266 * |
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267 * <p> This method throws {@link InvalidPathException} when the path string |
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268 * cannot be converted to a path. Where possible, and where applicable, |
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269 * the exception is created with an {@link InvalidPathException#getIndex |
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270 * index} value indicating the first position in the {@code path} parameter |
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271 * that caused the path string to be rejected. |
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272 * |
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273 * <p> Invoking this method with an empty path string throws |
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274 * {@code InvalidPathException}. |
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275 * |
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276 * @param path |
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277 * The path string |
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278 * |
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279 * @return A {@code Path} object |
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280 * |
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281 * @throws InvalidPathException |
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282 * If the path string cannot be converted |
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283 */ |
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284 public abstract Path getPath(String path); |
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285 |
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286 /** |
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287 * Returns a {@code PathMatcher} that performs match operations on the |
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288 * {@code String} representation of {@link Path} objects by interpreting a |
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289 * given pattern. |
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290 * |
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291 * The {@code syntaxAndPattern} parameter identifies the syntax and the |
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292 * pattern and takes the form: |
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293 * <blockquote> |
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294 * <i>syntax</i><b>:</b><i>pattern</i> |
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295 * </blockquote> |
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296 * where {@code ':'} stands for itself. |
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297 * |
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298 * <p> A {@code FileSystem} implementation supports the "{@code glob}" and |
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299 * "{@code regex}" syntaxes, and may support others. The value of the syntax |
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300 * component is compared without regard to case. |
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301 * |
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302 * <p> When the syntax is "{@code glob}" then the {@code String} |
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303 * representation of the path is matched using a limited pattern language |
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304 * that resembles regular expressions but with a simpler syntax. For example: |
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305 * |
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306 * <blockquote> |
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307 * <table border="0"> |
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308 * <tr> |
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309 * <td>{@code *.java}</td> |
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310 * <td>Matches a path that represents a file name ending in {@code .java}</td> |
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311 * </tr> |
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312 * <tr> |
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313 * <td>{@code *.*}</td> |
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314 * <td>Matches file names containing a dot</td> |
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315 * </tr> |
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316 * <tr> |
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317 * <tr> |
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318 * <td>{@code *.{java,class}}</td> |
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319 * <td>Matches file names ending with {@code .java} or {@code .class}</td> |
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320 * </tr> |
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321 * <tr> |
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322 * <td>{@code foo.?}</td> |
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323 * <td>Matches file names starting with {@code foo.} and a single |
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324 * character extension</td> |
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325 * </tr> |
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326 * <tr> |
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327 * <td><tt>/home/*/*</tt> |
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328 * <td>Matches <tt>/home/gus/data</tt> on UNIX platforms</td> |
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329 * </tr> |
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330 * <tr> |
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331 * <td><tt>/home/**</tt> |
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332 * <td>Matches <tt>/home/gus</tt> and |
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333 * <tt>/home/gus/data</tt> on UNIX platforms</td> |
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334 * </tr> |
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335 * <tr> |
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336 * <td><tt>C:\\*</tt> |
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337 * <td>Matches <tt>C:\foo</tt> and <tt>C:\bar</tt> on the Windows |
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338 * platform (note that the backslash is escaped; as a string literal in the |
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339 * Java Language the pattern would be <tt>"C:\\\\*"</tt>) </td> |
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340 * </tr> |
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341 * |
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342 * </table> |
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343 * </blockquote> |
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344 * |
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345 * <p> The following rules are used to interpret glob patterns: |
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346 * |
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347 * <p> <ul> |
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348 * <li><p> The {@code *} character matches zero or more {@link Character |
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349 * characters} of a {@link Path#getName(int) name} component without |
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350 * crossing directory boundaries. </p></li> |
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351 * |
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352 * <li><p> The {@code **} characters matches zero or more {@link Character |
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353 * characters} crossing directory boundaries. </p></li> |
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354 * |
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355 * <li><p> The {@code ?} character matches exactly one character of a |
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356 * name component.</p></li> |
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357 * |
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358 * <li><p> The backslash character ({@code \}) is used to escape characters |
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359 * that would otherwise be interpreted as special characters. The expression |
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360 * {@code \\} matches a single backslash and "\{" matches a left brace |
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361 * for example. </p></li> |
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362 * |
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363 * <li><p> The {@code [ ]} characters are a <i>bracket expression</i> that |
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364 * match a single character of a name component out of a set of characters. |
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365 * For example, {@code [abc]} matches {@code "a"}, {@code "b"}, or {@code "c"}. |
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366 * The hyphen ({@code -}) may be used to specify a range so {@code [a-z]} |
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367 * specifies a range that matches from {@code "a"} to {@code "z"} (inclusive). |
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368 * These forms can be mixed so [abce-g] matches {@code "a"}, {@code "b"}, |
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369 * {@code "c"}, {@code "e"}, {@code "f"} or {@code "g"}. If the character |
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370 * after the {@code [} is a {@code !} then it is used for negation so {@code |
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371 * [!a-c]} matches any character except {@code "a"}, {@code "b"}, or {@code |
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372 * "c"}. |
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373 * <p> Within a bracket expression the {@code *}, {@code ?} and {@code \} |
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374 * characters match themselves. The ({@code -}) character matches itself if |
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375 * it is the first character within the brackets, or the first character |
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376 * after the {@code !} if negating.</p></li> |
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377 * |
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378 * <li><p> The {@code { }} characters are a group of subpatterns, where |
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379 * the group matches if any subpattern in the group matches. The {@code ","} |
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380 * character is used to separate the subpatterns. Groups cannot be nested. |
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381 * </p></li> |
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382 * |
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383 * <li><p> All other characters match themselves in an implementation |
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384 * dependent manner. This includes characters representing any {@link |
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385 * FileSystem#getSeparator name-separators}. </p></li> |
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386 * |
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387 * <li><p> The matching of {@link Path#getRoot root} components is highly |
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388 * implementation-dependent and is not specified. </p></li> |
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389 * |
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390 * </ul> |
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391 * |
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392 * <p> When the syntax is "{@code regex}" then the pattern component is a |
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393 * regular expression as defined by the {@link java.util.regex.Pattern} |
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394 * class. |
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395 * |
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396 * <p> For both the glob and regex syntaxes, the matching details, such as |
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397 * whether the matching is case sensitive, are implementation-dependent |
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398 * and therefore not specified. |
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399 * |
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400 * @param syntaxAndPattern |
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401 * The syntax and pattern |
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402 * |
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403 * @return A path matcher that may be used to match paths against the pattern |
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404 * |
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405 * @throws IllegalArgumentException |
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406 * If the parameter does not take the form: {@code syntax:pattern} |
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407 * @throws java.util.regex.PatternSyntaxException |
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408 * If the pattern is invalid |
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409 * @throws UnsupportedOperationException |
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410 * If the pattern syntax is not known to the implementation |
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411 * |
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412 * @see Path#newDirectoryStream(String) |
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413 */ |
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414 public abstract PathMatcher getPathMatcher(String syntaxAndPattern); |
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415 |
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416 /** |
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417 * Returns the {@code UserPrincipalLookupService} for this file system |
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418 * <i>(optional operation)</i>. The resulting lookup service may be used to |
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419 * lookup user or group names. |
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420 * |
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421 * <p> <b>Usage Example:</b> |
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422 * Suppose we want to make "joe" the owner of a file: |
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423 * <pre> |
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424 * Path file = ... |
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425 * UserPrincipal joe = file.getFileSystem().getUserPrincipalLookupService() |
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426 * .lookupPrincipalByName("joe"); |
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427 * Attributes.setOwner(file, joe); |
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428 * </pre> |
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429 * |
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430 * @throws UnsupportedOperationException |
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431 * If this {@code FileSystem} does not does have a lookup service |
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432 * |
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433 * @return The {@code UserPrincipalLookupService} for this file system |
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434 */ |
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435 public abstract UserPrincipalLookupService getUserPrincipalLookupService(); |
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436 |
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437 /** |
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438 * Constructs a new {@link WatchService} <i>(optional operation)</i>. |
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439 * |
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440 * <p> This method constructs a new watch service that may be used to watch |
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441 * registered objects for changes and events. |
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442 * |
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443 * @return a new watch service |
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444 * |
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445 * @throws UnsupportedOperationException |
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446 * If this {@code FileSystem} does not support watching file system |
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447 * objects for changes and events. This exception is not thrown |
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448 * by {@code FileSystems} created by the default provider. |
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449 * @throws IOException |
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450 * If an I/O error occurs |
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451 */ |
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452 public abstract WatchService newWatchService() throws IOException; |
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453 } |