1 /* 2 * Copyright (c) 1994, 2017, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package java.io; 27 28 import java.net.URI; 29 import java.net.URL; 30 import java.net.MalformedURLException; 31 import java.net.URISyntaxException; 32 import java.util.List; 33 import java.util.ArrayList; 34 import java.security.SecureRandom; 35 import java.nio.file.Path; 36 import java.nio.file.FileSystems; 37 import sun.security.action.GetPropertyAction; 38 39 /** 40 * An abstract representation of file and directory pathnames. 41 * 42 * <p> User interfaces and operating systems use system-dependent <em>pathname 43 * strings</em> to name files and directories. This class presents an 44 * abstract, system-independent view of hierarchical pathnames. An 45 * <em>abstract pathname</em> has two components: 46 * 47 * <ol> 48 * <li> An optional system-dependent <em>prefix</em> string, 49 * such as a disk-drive specifier, <code>"/"</code> for the UNIX root 50 * directory, or <code>"\\\\"</code> for a Microsoft Windows UNC pathname, and 51 * <li> A sequence of zero or more string <em>names</em>. 52 * </ol> 53 * 54 * The first name in an abstract pathname may be a directory name or, in the 55 * case of Microsoft Windows UNC pathnames, a hostname. Each subsequent name 56 * in an abstract pathname denotes a directory; the last name may denote 57 * either a directory or a file. The <em>empty</em> abstract pathname has no 58 * prefix and an empty name sequence. 59 * 60 * <p> The conversion of a pathname string to or from an abstract pathname is 61 * inherently system-dependent. When an abstract pathname is converted into a 62 * pathname string, each name is separated from the next by a single copy of 63 * the default <em>separator character</em>. The default name-separator 64 * character is defined by the system property <code>file.separator</code>, and 65 * is made available in the public static fields {@link 66 * #separator} and {@link #separatorChar} of this class. 67 * When a pathname string is converted into an abstract pathname, the names 68 * within it may be separated by the default name-separator character or by any 69 * other name-separator character that is supported by the underlying system. 70 * 71 * <p> A pathname, whether abstract or in string form, may be either 72 * <em>absolute</em> or <em>relative</em>. An absolute pathname is complete in 73 * that no other information is required in order to locate the file that it 74 * denotes. A relative pathname, in contrast, must be interpreted in terms of 75 * information taken from some other pathname. By default the classes in the 76 * <code>java.io</code> package always resolve relative pathnames against the 77 * current user directory. This directory is named by the system property 78 * <code>user.dir</code>, and is typically the directory in which the Java 79 * virtual machine was invoked. 80 * 81 * <p> The <em>parent</em> of an abstract pathname may be obtained by invoking 82 * the {@link #getParent} method of this class and consists of the pathname's 83 * prefix and each name in the pathname's name sequence except for the last. 84 * Each directory's absolute pathname is an ancestor of any {@code File} 85 * object with an absolute abstract pathname which begins with the directory's 86 * absolute pathname. For example, the directory denoted by the abstract 87 * pathname {@code "/usr"} is an ancestor of the directory denoted by the 88 * pathname {@code "/usr/local/bin"}. 89 * 90 * <p> The prefix concept is used to handle root directories on UNIX platforms, 91 * and drive specifiers, root directories and UNC pathnames on Microsoft Windows platforms, 92 * as follows: 93 * 94 * <ul> 95 * 96 * <li> For UNIX platforms, the prefix of an absolute pathname is always 97 * <code>"/"</code>. Relative pathnames have no prefix. The abstract pathname 98 * denoting the root directory has the prefix <code>"/"</code> and an empty 99 * name sequence. 100 * 101 * <li> For Microsoft Windows platforms, the prefix of a pathname that contains a drive 102 * specifier consists of the drive letter followed by <code>":"</code> and 103 * possibly followed by <code>"\\"</code> if the pathname is absolute. The 104 * prefix of a UNC pathname is <code>"\\\\"</code>; the hostname and the share 105 * name are the first two names in the name sequence. A relative pathname that 106 * does not specify a drive has no prefix. 107 * 108 * </ul> 109 * 110 * <p> Instances of this class may or may not denote an actual file-system 111 * object such as a file or a directory. If it does denote such an object 112 * then that object resides in a <i>partition</i>. A partition is an 113 * operating system-specific portion of storage for a file system. A single 114 * storage device (e.g. a physical disk-drive, flash memory, CD-ROM) may 115 * contain multiple partitions. The object, if any, will reside on the 116 * partition <a id="partName">named</a> by some ancestor of the absolute 117 * form of this pathname. 118 * 119 * <p> A file system may implement restrictions to certain operations on the 120 * actual file-system object, such as reading, writing, and executing. These 121 * restrictions are collectively known as <i>access permissions</i>. The file 122 * system may have multiple sets of access permissions on a single object. 123 * For example, one set may apply to the object's <i>owner</i>, and another 124 * may apply to all other users. The access permissions on an object may 125 * cause some methods in this class to fail. 126 * 127 * <p> Instances of the <code>File</code> class are immutable; that is, once 128 * created, the abstract pathname represented by a <code>File</code> object 129 * will never change. 130 * 131 * <h3>Interoperability with {@code java.nio.file} package</h3> 132 * 133 * <p> The <a href="../../java/nio/file/package-summary.html">{@code java.nio.file}</a> 134 * package defines interfaces and classes for the Java virtual machine to access 135 * files, file attributes, and file systems. This API may be used to overcome 136 * many of the limitations of the {@code java.io.File} class. 137 * The {@link #toPath toPath} method may be used to obtain a {@link 138 * Path} that uses the abstract path represented by a {@code File} object to 139 * locate a file. The resulting {@code Path} may be used with the {@link 140 * java.nio.file.Files} class to provide more efficient and extensive access to 141 * additional file operations, file attributes, and I/O exceptions to help 142 * diagnose errors when an operation on a file fails. 143 * 144 * @author unascribed 145 * @since 1.0 146 */ 147 148 public class File 149 implements Serializable, Comparable<File> 150 { 151 152 /** 153 * The FileSystem object representing the platform's local file system. 154 */ 155 private static final FileSystem fs = DefaultFileSystem.getFileSystem(); 156 157 /** 158 * This abstract pathname's normalized pathname string. A normalized 159 * pathname string uses the default name-separator character and does not 160 * contain any duplicate or redundant separators. 161 * 162 * @serial 163 */ 164 private final String path; 165 166 /** 167 * Enum type that indicates the status of a file path. 168 */ 169 private static enum PathStatus { INVALID, CHECKED }; 170 171 /** 172 * The flag indicating whether the file path is invalid. 173 */ 174 private transient PathStatus status = null; 175 176 /** 177 * Check if the file has an invalid path. Currently, the inspection of 178 * a file path is very limited, and it only covers Nul character check. 179 * Returning true means the path is definitely invalid/garbage. But 180 * returning false does not guarantee that the path is valid. 181 * 182 * @return true if the file path is invalid. 183 */ 184 final boolean isInvalid() { 185 if (status == null) { 186 status = (this.path.indexOf('\u0000') < 0) ? PathStatus.CHECKED 187 : PathStatus.INVALID; 188 } 189 return status == PathStatus.INVALID; 190 } 191 192 /** 193 * The length of this abstract pathname's prefix, or zero if it has no 194 * prefix. 195 */ 196 private final transient int prefixLength; 197 198 /** 199 * Returns the length of this abstract pathname's prefix. 200 * For use by FileSystem classes. 201 */ 202 int getPrefixLength() { 203 return prefixLength; 204 } 205 206 /** 207 * The system-dependent default name-separator character. This field is 208 * initialized to contain the first character of the value of the system 209 * property <code>file.separator</code>. On UNIX systems the value of this 210 * field is <code>'/'</code>; on Microsoft Windows systems it is <code>'\\'</code>. 211 * 212 * @see java.lang.System#getProperty(java.lang.String) 213 */ 214 public static final char separatorChar = fs.getSeparator(); 215 216 /** 217 * The system-dependent default name-separator character, represented as a 218 * string for convenience. This string contains a single character, namely 219 * {@link #separatorChar}. 220 */ 221 public static final String separator = "" + separatorChar; 222 223 /** 224 * The system-dependent path-separator character. This field is 225 * initialized to contain the first character of the value of the system 226 * property <code>path.separator</code>. This character is used to 227 * separate filenames in a sequence of files given as a <em>path list</em>. 228 * On UNIX systems, this character is <code>':'</code>; on Microsoft Windows systems it 229 * is <code>';'</code>. 230 * 231 * @see java.lang.System#getProperty(java.lang.String) 232 */ 233 public static final char pathSeparatorChar = fs.getPathSeparator(); 234 235 /** 236 * The system-dependent path-separator character, represented as a string 237 * for convenience. This string contains a single character, namely 238 * {@link #pathSeparatorChar}. 239 */ 240 public static final String pathSeparator = "" + pathSeparatorChar; 241 242 243 /* -- Constructors -- */ 244 245 /** 246 * Internal constructor for already-normalized pathname strings. 247 */ 248 private File(String pathname, int prefixLength) { 249 this.path = pathname; 250 this.prefixLength = prefixLength; 251 } 252 253 /** 254 * Internal constructor for already-normalized pathname strings. 255 * The parameter order is used to disambiguate this method from the 256 * public(File, String) constructor. 257 */ 258 private File(String child, File parent) { 259 assert parent.path != null; 260 assert (!parent.path.equals("")); 261 this.path = fs.resolve(parent.path, child); 262 this.prefixLength = parent.prefixLength; 263 } 264 265 /** 266 * Creates a new <code>File</code> instance by converting the given 267 * pathname string into an abstract pathname. If the given string is 268 * the empty string, then the result is the empty abstract pathname. 269 * 270 * @param pathname A pathname string 271 * @throws NullPointerException 272 * If the <code>pathname</code> argument is <code>null</code> 273 */ 274 public File(String pathname) { 275 if (pathname == null) { 276 throw new NullPointerException(); 277 } 278 this.path = fs.normalize(pathname); 279 this.prefixLength = fs.prefixLength(this.path); 280 } 281 282 /* Note: The two-argument File constructors do not interpret an empty 283 parent abstract pathname as the current user directory. An empty parent 284 instead causes the child to be resolved against the system-dependent 285 directory defined by the FileSystem.getDefaultParent method. On Unix 286 this default is "/", while on Microsoft Windows it is "\\". This is required for 287 compatibility with the original behavior of this class. */ 288 289 /** 290 * Creates a new <code>File</code> instance from a parent pathname string 291 * and a child pathname string. 292 * 293 * <p> If <code>parent</code> is <code>null</code> then the new 294 * <code>File</code> instance is created as if by invoking the 295 * single-argument <code>File</code> constructor on the given 296 * <code>child</code> pathname string. 297 * 298 * <p> Otherwise the <code>parent</code> pathname string is taken to denote 299 * a directory, and the <code>child</code> pathname string is taken to 300 * denote either a directory or a file. If the <code>child</code> pathname 301 * string is absolute then it is converted into a relative pathname in a 302 * system-dependent way. If <code>parent</code> is the empty string then 303 * the new <code>File</code> instance is created by converting 304 * <code>child</code> into an abstract pathname and resolving the result 305 * against a system-dependent default directory. Otherwise each pathname 306 * string is converted into an abstract pathname and the child abstract 307 * pathname is resolved against the parent. 308 * 309 * @param parent The parent pathname string 310 * @param child The child pathname string 311 * @throws NullPointerException 312 * If <code>child</code> is <code>null</code> 313 */ 314 public File(String parent, String child) { 315 if (child == null) { 316 throw new NullPointerException(); 317 } 318 if (parent != null) { 319 if (parent.equals("")) { 320 this.path = fs.resolve(fs.getDefaultParent(), 321 fs.normalize(child)); 322 } else { 323 this.path = fs.resolve(fs.normalize(parent), 324 fs.normalize(child)); 325 } 326 } else { 327 this.path = fs.normalize(child); 328 } 329 this.prefixLength = fs.prefixLength(this.path); 330 } 331 332 /** 333 * Creates a new <code>File</code> instance from a parent abstract 334 * pathname and a child pathname string. 335 * 336 * <p> If <code>parent</code> is <code>null</code> then the new 337 * <code>File</code> instance is created as if by invoking the 338 * single-argument <code>File</code> constructor on the given 339 * <code>child</code> pathname string. 340 * 341 * <p> Otherwise the <code>parent</code> abstract pathname is taken to 342 * denote a directory, and the <code>child</code> pathname string is taken 343 * to denote either a directory or a file. If the <code>child</code> 344 * pathname string is absolute then it is converted into a relative 345 * pathname in a system-dependent way. If <code>parent</code> is the empty 346 * abstract pathname then the new <code>File</code> instance is created by 347 * converting <code>child</code> into an abstract pathname and resolving 348 * the result against a system-dependent default directory. Otherwise each 349 * pathname string is converted into an abstract pathname and the child 350 * abstract pathname is resolved against the parent. 351 * 352 * @param parent The parent abstract pathname 353 * @param child The child pathname string 354 * @throws NullPointerException 355 * If <code>child</code> is <code>null</code> 356 */ 357 public File(File parent, String child) { 358 if (child == null) { 359 throw new NullPointerException(); 360 } 361 if (parent != null) { 362 if (parent.path.equals("")) { 363 this.path = fs.resolve(fs.getDefaultParent(), 364 fs.normalize(child)); 365 } else { 366 this.path = fs.resolve(parent.path, 367 fs.normalize(child)); 368 } 369 } else { 370 this.path = fs.normalize(child); 371 } 372 this.prefixLength = fs.prefixLength(this.path); 373 } 374 375 /** 376 * Creates a new {@code File} instance by converting the given 377 * {@code file:} URI into an abstract pathname. 378 * 379 * <p> The exact form of a {@code file:} URI is system-dependent, hence 380 * the transformation performed by this constructor is also 381 * system-dependent. 382 * 383 * <p> For a given abstract pathname <i>f</i> it is guaranteed that 384 * 385 * <blockquote><code> 386 * new File(</code><i> f</i><code>.{@link #toURI() 387 * toURI}()).equals(</code><i> f</i><code>.{@link #getAbsoluteFile() getAbsoluteFile}()) 388 * </code></blockquote> 389 * 390 * so long as the original abstract pathname, the URI, and the new abstract 391 * pathname are all created in (possibly different invocations of) the same 392 * Java virtual machine. This relationship typically does not hold, 393 * however, when a {@code file:} URI that is created in a virtual machine 394 * on one operating system is converted into an abstract pathname in a 395 * virtual machine on a different operating system. 396 * 397 * @param uri 398 * An absolute, hierarchical URI with a scheme equal to 399 * {@code "file"}, a non-empty path component, and undefined 400 * authority, query, and fragment components 401 * 402 * @throws NullPointerException 403 * If {@code uri} is {@code null} 404 * 405 * @throws IllegalArgumentException 406 * If the preconditions on the parameter do not hold 407 * 408 * @see #toURI() 409 * @see java.net.URI 410 * @since 1.4 411 */ 412 public File(URI uri) { 413 414 // Check our many preconditions 415 if (!uri.isAbsolute()) 416 throw new IllegalArgumentException("URI is not absolute"); 417 if (uri.isOpaque()) 418 throw new IllegalArgumentException("URI is not hierarchical"); 419 String scheme = uri.getScheme(); 420 if ((scheme == null) || !scheme.equalsIgnoreCase("file")) 421 throw new IllegalArgumentException("URI scheme is not \"file\""); 422 if (uri.getRawAuthority() != null) 423 throw new IllegalArgumentException("URI has an authority component"); 424 if (uri.getRawFragment() != null) 425 throw new IllegalArgumentException("URI has a fragment component"); 426 if (uri.getRawQuery() != null) 427 throw new IllegalArgumentException("URI has a query component"); 428 String p = uri.getPath(); 429 if (p.equals("")) 430 throw new IllegalArgumentException("URI path component is empty"); 431 432 // Okay, now initialize 433 p = fs.fromURIPath(p); 434 if (File.separatorChar != '/') 435 p = p.replace('/', File.separatorChar); 436 this.path = fs.normalize(p); 437 this.prefixLength = fs.prefixLength(this.path); 438 } 439 440 441 /* -- Path-component accessors -- */ 442 443 /** 444 * Returns the name of the file or directory denoted by this abstract 445 * pathname. This is just the last name in the pathname's name 446 * sequence. If the pathname's name sequence is empty, then the empty 447 * string is returned. 448 * 449 * @return The name of the file or directory denoted by this abstract 450 * pathname, or the empty string if this pathname's name sequence 451 * is empty 452 */ 453 public String getName() { 454 int index = path.lastIndexOf(separatorChar); 455 if (index < prefixLength) return path.substring(prefixLength); 456 return path.substring(index + 1); 457 } 458 459 /** 460 * Returns the pathname string of this abstract pathname's parent, or 461 * <code>null</code> if this pathname does not name a parent directory. 462 * 463 * <p> The <em>parent</em> of an abstract pathname consists of the 464 * pathname's prefix, if any, and each name in the pathname's name 465 * sequence except for the last. If the name sequence is empty then 466 * the pathname does not name a parent directory. 467 * 468 * @return The pathname string of the parent directory named by this 469 * abstract pathname, or <code>null</code> if this pathname 470 * does not name a parent 471 */ 472 public String getParent() { 473 int index = path.lastIndexOf(separatorChar); 474 if (index < prefixLength) { 475 if ((prefixLength > 0) && (path.length() > prefixLength)) 476 return path.substring(0, prefixLength); 477 return null; 478 } 479 return path.substring(0, index); 480 } 481 482 /** 483 * Returns the abstract pathname of this abstract pathname's parent, 484 * or <code>null</code> if this pathname does not name a parent 485 * directory. 486 * 487 * <p> The <em>parent</em> of an abstract pathname consists of the 488 * pathname's prefix, if any, and each name in the pathname's name 489 * sequence except for the last. If the name sequence is empty then 490 * the pathname does not name a parent directory. 491 * 492 * @return The abstract pathname of the parent directory named by this 493 * abstract pathname, or <code>null</code> if this pathname 494 * does not name a parent 495 * 496 * @since 1.2 497 */ 498 public File getParentFile() { 499 String p = this.getParent(); 500 if (p == null) return null; 501 return new File(p, this.prefixLength); 502 } 503 504 /** 505 * Converts this abstract pathname into a pathname string. The resulting 506 * string uses the {@link #separator default name-separator character} to 507 * separate the names in the name sequence. 508 * 509 * @return The string form of this abstract pathname 510 */ 511 public String getPath() { 512 return path; 513 } 514 515 516 /* -- Path operations -- */ 517 518 /** 519 * Tests whether this abstract pathname is absolute. The definition of 520 * absolute pathname is system dependent. On UNIX systems, a pathname is 521 * absolute if its prefix is <code>"/"</code>. On Microsoft Windows systems, a 522 * pathname is absolute if its prefix is a drive specifier followed by 523 * <code>"\\"</code>, or if its prefix is <code>"\\\\"</code>. 524 * 525 * @return <code>true</code> if this abstract pathname is absolute, 526 * <code>false</code> otherwise 527 */ 528 public boolean isAbsolute() { 529 return fs.isAbsolute(this); 530 } 531 532 /** 533 * Returns the absolute pathname string of this abstract pathname. 534 * 535 * <p> If this abstract pathname is already absolute, then the pathname 536 * string is simply returned as if by the {@link #getPath} 537 * method. If this abstract pathname is the empty abstract pathname then 538 * the pathname string of the current user directory, which is named by the 539 * system property <code>user.dir</code>, is returned. Otherwise this 540 * pathname is resolved in a system-dependent way. On UNIX systems, a 541 * relative pathname is made absolute by resolving it against the current 542 * user directory. On Microsoft Windows systems, a relative pathname is made absolute 543 * by resolving it against the current directory of the drive named by the 544 * pathname, if any; if not, it is resolved against the current user 545 * directory. 546 * 547 * @return The absolute pathname string denoting the same file or 548 * directory as this abstract pathname 549 * 550 * @throws SecurityException 551 * If a required system property value cannot be accessed. 552 * 553 * @see java.io.File#isAbsolute() 554 */ 555 public String getAbsolutePath() { 556 return fs.resolve(this); 557 } 558 559 /** 560 * Returns the absolute form of this abstract pathname. Equivalent to 561 * <code>new File(this.{@link #getAbsolutePath})</code>. 562 * 563 * @return The absolute abstract pathname denoting the same file or 564 * directory as this abstract pathname 565 * 566 * @throws SecurityException 567 * If a required system property value cannot be accessed. 568 * 569 * @since 1.2 570 */ 571 public File getAbsoluteFile() { 572 String absPath = getAbsolutePath(); 573 return new File(absPath, fs.prefixLength(absPath)); 574 } 575 576 /** 577 * Returns the canonical pathname string of this abstract pathname. 578 * 579 * <p> A canonical pathname is both absolute and unique. The precise 580 * definition of canonical form is system-dependent. This method first 581 * converts this pathname to absolute form if necessary, as if by invoking the 582 * {@link #getAbsolutePath} method, and then maps it to its unique form in a 583 * system-dependent way. This typically involves removing redundant names 584 * such as {@code "."} and {@code ".."} from the pathname, resolving 585 * symbolic links (on UNIX platforms), and converting drive letters to a 586 * standard case (on Microsoft Windows platforms). 587 * 588 * <p> Every pathname that denotes an existing file or directory has a 589 * unique canonical form. Every pathname that denotes a nonexistent file 590 * or directory also has a unique canonical form. The canonical form of 591 * the pathname of a nonexistent file or directory may be different from 592 * the canonical form of the same pathname after the file or directory is 593 * created. Similarly, the canonical form of the pathname of an existing 594 * file or directory may be different from the canonical form of the same 595 * pathname after the file or directory is deleted. 596 * 597 * @return The canonical pathname string denoting the same file or 598 * directory as this abstract pathname 599 * 600 * @throws IOException 601 * If an I/O error occurs, which is possible because the 602 * construction of the canonical pathname may require 603 * filesystem queries 604 * 605 * @throws SecurityException 606 * If a required system property value cannot be accessed, or 607 * if a security manager exists and its {@link 608 * java.lang.SecurityManager#checkRead} method denies 609 * read access to the file 610 * 611 * @since 1.1 612 * @see Path#toRealPath 613 */ 614 public String getCanonicalPath() throws IOException { 615 if (isInvalid()) { 616 throw new IOException("Invalid file path"); 617 } 618 return fs.canonicalize(fs.resolve(this)); 619 } 620 621 /** 622 * Returns the canonical form of this abstract pathname. Equivalent to 623 * <code>new File(this.{@link #getCanonicalPath})</code>. 624 * 625 * @return The canonical pathname string denoting the same file or 626 * directory as this abstract pathname 627 * 628 * @throws IOException 629 * If an I/O error occurs, which is possible because the 630 * construction of the canonical pathname may require 631 * filesystem queries 632 * 633 * @throws SecurityException 634 * If a required system property value cannot be accessed, or 635 * if a security manager exists and its {@link 636 * java.lang.SecurityManager#checkRead} method denies 637 * read access to the file 638 * 639 * @since 1.2 640 * @see Path#toRealPath 641 */ 642 public File getCanonicalFile() throws IOException { 643 String canonPath = getCanonicalPath(); 644 return new File(canonPath, fs.prefixLength(canonPath)); 645 } 646 647 private static String slashify(String path, boolean isDirectory) { 648 String p = path; 649 if (File.separatorChar != '/') 650 p = p.replace(File.separatorChar, '/'); 651 if (!p.startsWith("/")) 652 p = "/" + p; 653 if (!p.endsWith("/") && isDirectory) 654 p = p + "/"; 655 return p; 656 } 657 658 /** 659 * Converts this abstract pathname into a <code>file:</code> URL. The 660 * exact form of the URL is system-dependent. If it can be determined that 661 * the file denoted by this abstract pathname is a directory, then the 662 * resulting URL will end with a slash. 663 * 664 * @return A URL object representing the equivalent file URL 665 * 666 * @throws MalformedURLException 667 * If the path cannot be parsed as a URL 668 * 669 * @see #toURI() 670 * @see java.net.URI 671 * @see java.net.URI#toURL() 672 * @see java.net.URL 673 * @since 1.2 674 * 675 * @deprecated This method does not automatically escape characters that 676 * are illegal in URLs. It is recommended that new code convert an 677 * abstract pathname into a URL by first converting it into a URI, via the 678 * {@link #toURI() toURI} method, and then converting the URI into a URL 679 * via the {@link java.net.URI#toURL() URI.toURL} method. 680 */ 681 @Deprecated 682 public URL toURL() throws MalformedURLException { 683 if (isInvalid()) { 684 throw new MalformedURLException("Invalid file path"); 685 } 686 return new URL("file", "", slashify(getAbsolutePath(), isDirectory())); 687 } 688 689 /** 690 * Constructs a {@code file:} URI that represents this abstract pathname. 691 * 692 * <p> The exact form of the URI is system-dependent. If it can be 693 * determined that the file denoted by this abstract pathname is a 694 * directory, then the resulting URI will end with a slash. 695 * 696 * <p> For a given abstract pathname <i>f</i>, it is guaranteed that 697 * 698 * <blockquote><code> 699 * new {@link #File(java.net.URI) File}(</code><i> f</i><code>.toURI()).equals( 700 * </code><i> f</i><code>.{@link #getAbsoluteFile() getAbsoluteFile}()) 701 * </code></blockquote> 702 * 703 * so long as the original abstract pathname, the URI, and the new abstract 704 * pathname are all created in (possibly different invocations of) the same 705 * Java virtual machine. Due to the system-dependent nature of abstract 706 * pathnames, however, this relationship typically does not hold when a 707 * {@code file:} URI that is created in a virtual machine on one operating 708 * system is converted into an abstract pathname in a virtual machine on a 709 * different operating system. 710 * 711 * <p> Note that when this abstract pathname represents a UNC pathname then 712 * all components of the UNC (including the server name component) are encoded 713 * in the {@code URI} path. The authority component is undefined, meaning 714 * that it is represented as {@code null}. The {@link Path} class defines the 715 * {@link Path#toUri toUri} method to encode the server name in the authority 716 * component of the resulting {@code URI}. The {@link #toPath toPath} method 717 * may be used to obtain a {@code Path} representing this abstract pathname. 718 * 719 * @return An absolute, hierarchical URI with a scheme equal to 720 * {@code "file"}, a path representing this abstract pathname, 721 * and undefined authority, query, and fragment components 722 * @throws SecurityException If a required system property value cannot 723 * be accessed. 724 * 725 * @see #File(java.net.URI) 726 * @see java.net.URI 727 * @see java.net.URI#toURL() 728 * @since 1.4 729 */ 730 public URI toURI() { 731 try { 732 File f = getAbsoluteFile(); 733 String sp = slashify(f.getPath(), f.isDirectory()); 734 if (sp.startsWith("//")) 735 sp = "//" + sp; 736 return new URI("file", null, sp, null); 737 } catch (URISyntaxException x) { 738 throw new Error(x); // Can't happen 739 } 740 } 741 742 743 /* -- Attribute accessors -- */ 744 745 /** 746 * Tests whether the application can read the file denoted by this 747 * abstract pathname. On some platforms it may be possible to start the 748 * Java virtual machine with special privileges that allow it to read 749 * files that are marked as unreadable. Consequently this method may return 750 * {@code true} even though the file does not have read permissions. 751 * 752 * @return <code>true</code> if and only if the file specified by this 753 * abstract pathname exists <em>and</em> can be read by the 754 * application; <code>false</code> otherwise 755 * 756 * @throws SecurityException 757 * If a security manager exists and its {@link 758 * java.lang.SecurityManager#checkRead(java.lang.String)} 759 * method denies read access to the file 760 */ 761 public boolean canRead() { 762 SecurityManager security = System.getSecurityManager(); 763 if (security != null) { 764 security.checkRead(path); 765 } 766 if (isInvalid()) { 767 return false; 768 } 769 return fs.checkAccess(this, FileSystem.ACCESS_READ); 770 } 771 772 /** 773 * Tests whether the application can modify the file denoted by this 774 * abstract pathname. On some platforms it may be possible to start the 775 * Java virtual machine with special privileges that allow it to modify 776 * files that are marked read-only. Consequently this method may return 777 * {@code true} even though the file is marked read-only. 778 * 779 * @return <code>true</code> if and only if the file system actually 780 * contains a file denoted by this abstract pathname <em>and</em> 781 * the application is allowed to write to the file; 782 * <code>false</code> otherwise. 783 * 784 * @throws SecurityException 785 * If a security manager exists and its {@link 786 * java.lang.SecurityManager#checkWrite(java.lang.String)} 787 * method denies write access to the file 788 */ 789 public boolean canWrite() { 790 SecurityManager security = System.getSecurityManager(); 791 if (security != null) { 792 security.checkWrite(path); 793 } 794 if (isInvalid()) { 795 return false; 796 } 797 return fs.checkAccess(this, FileSystem.ACCESS_WRITE); 798 } 799 800 /** 801 * Tests whether the file or directory denoted by this abstract pathname 802 * exists. 803 * 804 * @return <code>true</code> if and only if the file or directory denoted 805 * by this abstract pathname exists; <code>false</code> otherwise 806 * 807 * @throws SecurityException 808 * If a security manager exists and its {@link 809 * java.lang.SecurityManager#checkRead(java.lang.String)} 810 * method denies read access to the file or directory 811 */ 812 public boolean exists() { 813 SecurityManager security = System.getSecurityManager(); 814 if (security != null) { 815 security.checkRead(path); 816 } 817 if (isInvalid()) { 818 return false; 819 } 820 return ((fs.getBooleanAttributes(this) & FileSystem.BA_EXISTS) != 0); 821 } 822 823 /** 824 * Tests whether the file denoted by this abstract pathname is a 825 * directory. 826 * 827 * <p> Where it is required to distinguish an I/O exception from the case 828 * that the file is not a directory, or where several attributes of the 829 * same file are required at the same time, then the {@link 830 * java.nio.file.Files#readAttributes(Path,Class,LinkOption[]) 831 * Files.readAttributes} method may be used. 832 * 833 * @return <code>true</code> if and only if the file denoted by this 834 * abstract pathname exists <em>and</em> is a directory; 835 * <code>false</code> otherwise 836 * 837 * @throws SecurityException 838 * If a security manager exists and its {@link 839 * java.lang.SecurityManager#checkRead(java.lang.String)} 840 * method denies read access to the file 841 */ 842 public boolean isDirectory() { 843 SecurityManager security = System.getSecurityManager(); 844 if (security != null) { 845 security.checkRead(path); 846 } 847 if (isInvalid()) { 848 return false; 849 } 850 return ((fs.getBooleanAttributes(this) & FileSystem.BA_DIRECTORY) 851 != 0); 852 } 853 854 /** 855 * Tests whether the file denoted by this abstract pathname is a normal 856 * file. A file is <em>normal</em> if it is not a directory and, in 857 * addition, satisfies other system-dependent criteria. Any non-directory 858 * file created by a Java application is guaranteed to be a normal file. 859 * 860 * <p> Where it is required to distinguish an I/O exception from the case 861 * that the file is not a normal file, or where several attributes of the 862 * same file are required at the same time, then the {@link 863 * java.nio.file.Files#readAttributes(Path,Class,LinkOption[]) 864 * Files.readAttributes} method may be used. 865 * 866 * @return <code>true</code> if and only if the file denoted by this 867 * abstract pathname exists <em>and</em> is a normal file; 868 * <code>false</code> otherwise 869 * 870 * @throws SecurityException 871 * If a security manager exists and its {@link 872 * java.lang.SecurityManager#checkRead(java.lang.String)} 873 * method denies read access to the file 874 */ 875 public boolean isFile() { 876 SecurityManager security = System.getSecurityManager(); 877 if (security != null) { 878 security.checkRead(path); 879 } 880 if (isInvalid()) { 881 return false; 882 } 883 return ((fs.getBooleanAttributes(this) & FileSystem.BA_REGULAR) != 0); 884 } 885 886 /** 887 * Tests whether the file named by this abstract pathname is a hidden 888 * file. The exact definition of <em>hidden</em> is system-dependent. On 889 * UNIX systems, a file is considered to be hidden if its name begins with 890 * a period character (<code>'.'</code>). On Microsoft Windows systems, a file is 891 * considered to be hidden if it has been marked as such in the filesystem. 892 * 893 * @return <code>true</code> if and only if the file denoted by this 894 * abstract pathname is hidden according to the conventions of the 895 * underlying platform 896 * 897 * @throws SecurityException 898 * If a security manager exists and its {@link 899 * java.lang.SecurityManager#checkRead(java.lang.String)} 900 * method denies read access to the file 901 * 902 * @since 1.2 903 */ 904 public boolean isHidden() { 905 SecurityManager security = System.getSecurityManager(); 906 if (security != null) { 907 security.checkRead(path); 908 } 909 if (isInvalid()) { 910 return false; 911 } 912 return ((fs.getBooleanAttributes(this) & FileSystem.BA_HIDDEN) != 0); 913 } 914 915 /** 916 * Returns the time that the file denoted by this abstract pathname was 917 * last modified. 918 * 919 * <p> Where it is required to distinguish an I/O exception from the case 920 * where {@code 0L} is returned, or where several attributes of the 921 * same file are required at the same time, or where the time of last 922 * access or the creation time are required, then the {@link 923 * java.nio.file.Files#readAttributes(Path,Class,LinkOption[]) 924 * Files.readAttributes} method may be used. 925 * 926 * @apiNote 927 * While the unit of time of the return value is milliseconds, 928 * the granularity of the value depends on the underlying 929 * file system and may be larger. For example, some 930 * file systems use time stamps in units of seconds. 931 * 932 * @return A <code>long</code> value representing the time the file was 933 * last modified, measured in milliseconds since the epoch 934 * (00:00:00 GMT, January 1, 1970), or <code>0L</code> if the 935 * file does not exist or if an I/O error occurs 936 * 937 * @throws SecurityException 938 * If a security manager exists and its {@link 939 * java.lang.SecurityManager#checkRead(java.lang.String)} 940 * method denies read access to the file 941 */ 942 public long lastModified() { 943 SecurityManager security = System.getSecurityManager(); 944 if (security != null) { 945 security.checkRead(path); 946 } 947 if (isInvalid()) { 948 return 0L; 949 } 950 return fs.getLastModifiedTime(this); 951 } 952 953 /** 954 * Returns the length of the file denoted by this abstract pathname. 955 * The return value is unspecified if this pathname denotes a directory. 956 * 957 * <p> Where it is required to distinguish an I/O exception from the case 958 * that {@code 0L} is returned, or where several attributes of the same file 959 * are required at the same time, then the {@link 960 * java.nio.file.Files#readAttributes(Path,Class,LinkOption[]) 961 * Files.readAttributes} method may be used. 962 * 963 * @return The length, in bytes, of the file denoted by this abstract 964 * pathname, or <code>0L</code> if the file does not exist. Some 965 * operating systems may return <code>0L</code> for pathnames 966 * denoting system-dependent entities such as devices or pipes. 967 * 968 * @throws SecurityException 969 * If a security manager exists and its {@link 970 * java.lang.SecurityManager#checkRead(java.lang.String)} 971 * method denies read access to the file 972 */ 973 public long length() { 974 SecurityManager security = System.getSecurityManager(); 975 if (security != null) { 976 security.checkRead(path); 977 } 978 if (isInvalid()) { 979 return 0L; 980 } 981 return fs.getLength(this); 982 } 983 984 985 /* -- File operations -- */ 986 987 /** 988 * Atomically creates a new, empty file named by this abstract pathname if 989 * and only if a file with this name does not yet exist. The check for the 990 * existence of the file and the creation of the file if it does not exist 991 * are a single operation that is atomic with respect to all other 992 * filesystem activities that might affect the file. 993 * <P> 994 * Note: this method should <i>not</i> be used for file-locking, as 995 * the resulting protocol cannot be made to work reliably. The 996 * {@link java.nio.channels.FileLock FileLock} 997 * facility should be used instead. 998 * 999 * @return <code>true</code> if the named file does not exist and was 1000 * successfully created; <code>false</code> if the named file 1001 * already exists 1002 * 1003 * @throws IOException 1004 * If an I/O error occurred 1005 * 1006 * @throws SecurityException 1007 * If a security manager exists and its {@link 1008 * java.lang.SecurityManager#checkWrite(java.lang.String)} 1009 * method denies write access to the file 1010 * 1011 * @since 1.2 1012 */ 1013 public boolean createNewFile() throws IOException { 1014 SecurityManager security = System.getSecurityManager(); 1015 if (security != null) security.checkWrite(path); 1016 if (isInvalid()) { 1017 throw new IOException("Invalid file path"); 1018 } 1019 return fs.createFileExclusively(path); 1020 } 1021 1022 /** 1023 * Deletes the file or directory denoted by this abstract pathname. If 1024 * this pathname denotes a directory, then the directory must be empty in 1025 * order to be deleted. 1026 * 1027 * <p> Note that the {@link java.nio.file.Files} class defines the {@link 1028 * java.nio.file.Files#delete(Path) delete} method to throw an {@link IOException} 1029 * when a file cannot be deleted. This is useful for error reporting and to 1030 * diagnose why a file cannot be deleted. 1031 * 1032 * @return <code>true</code> if and only if the file or directory is 1033 * successfully deleted; <code>false</code> otherwise 1034 * 1035 * @throws SecurityException 1036 * If a security manager exists and its {@link 1037 * java.lang.SecurityManager#checkDelete} method denies 1038 * delete access to the file 1039 */ 1040 public boolean delete() { 1041 SecurityManager security = System.getSecurityManager(); 1042 if (security != null) { 1043 security.checkDelete(path); 1044 } 1045 if (isInvalid()) { 1046 return false; 1047 } 1048 return fs.delete(this); 1049 } 1050 1051 /** 1052 * Requests that the file or directory denoted by this abstract 1053 * pathname be deleted when the virtual machine terminates. 1054 * Files (or directories) are deleted in the reverse order that 1055 * they are registered. Invoking this method to delete a file or 1056 * directory that is already registered for deletion has no effect. 1057 * Deletion will be attempted only for normal termination of the 1058 * virtual machine, as defined by the Java Language Specification. 1059 * 1060 * <p> Once deletion has been requested, it is not possible to cancel the 1061 * request. This method should therefore be used with care. 1062 * 1063 * <P> 1064 * Note: this method should <i>not</i> be used for file-locking, as 1065 * the resulting protocol cannot be made to work reliably. The 1066 * {@link java.nio.channels.FileLock FileLock} 1067 * facility should be used instead. 1068 * 1069 * @throws SecurityException 1070 * If a security manager exists and its {@link 1071 * java.lang.SecurityManager#checkDelete} method denies 1072 * delete access to the file 1073 * 1074 * @see #delete 1075 * 1076 * @since 1.2 1077 */ 1078 public void deleteOnExit() { 1079 SecurityManager security = System.getSecurityManager(); 1080 if (security != null) { 1081 security.checkDelete(path); 1082 } 1083 if (isInvalid()) { 1084 return; 1085 } 1086 DeleteOnExitHook.add(path); 1087 } 1088 1089 /** 1090 * Returns an array of strings naming the files and directories in the 1091 * directory denoted by this abstract pathname. 1092 * 1093 * <p> If this abstract pathname does not denote a directory, then this 1094 * method returns {@code null}. Otherwise an array of strings is 1095 * returned, one for each file or directory in the directory. Names 1096 * denoting the directory itself and the directory's parent directory are 1097 * not included in the result. Each string is a file name rather than a 1098 * complete path. 1099 * 1100 * <p> There is no guarantee that the name strings in the resulting array 1101 * will appear in any specific order; they are not, in particular, 1102 * guaranteed to appear in alphabetical order. 1103 * 1104 * <p> Note that the {@link java.nio.file.Files} class defines the {@link 1105 * java.nio.file.Files#newDirectoryStream(Path) newDirectoryStream} method to 1106 * open a directory and iterate over the names of the files in the directory. 1107 * This may use less resources when working with very large directories, and 1108 * may be more responsive when working with remote directories. 1109 * 1110 * @return An array of strings naming the files and directories in the 1111 * directory denoted by this abstract pathname. The array will be 1112 * empty if the directory is empty. Returns {@code null} if 1113 * this abstract pathname does not denote a directory, or if an 1114 * I/O error occurs. 1115 * 1116 * @throws SecurityException 1117 * If a security manager exists and its {@link 1118 * SecurityManager#checkRead(String)} method denies read access to 1119 * the directory 1120 */ 1121 public String[] list() { 1122 SecurityManager security = System.getSecurityManager(); 1123 if (security != null) { 1124 security.checkRead(path); 1125 } 1126 if (isInvalid()) { 1127 return null; 1128 } 1129 return fs.list(this); 1130 } 1131 1132 /** 1133 * Returns an array of strings naming the files and directories in the 1134 * directory denoted by this abstract pathname that satisfy the specified 1135 * filter. The behavior of this method is the same as that of the 1136 * {@link #list()} method, except that the strings in the returned array 1137 * must satisfy the filter. If the given {@code filter} is {@code null} 1138 * then all names are accepted. Otherwise, a name satisfies the filter if 1139 * and only if the value {@code true} results when the {@link 1140 * FilenameFilter#accept FilenameFilter.accept(File, String)} method 1141 * of the filter is invoked on this abstract pathname and the name of a 1142 * file or directory in the directory that it denotes. 1143 * 1144 * @param filter 1145 * A filename filter 1146 * 1147 * @return An array of strings naming the files and directories in the 1148 * directory denoted by this abstract pathname that were accepted 1149 * by the given {@code filter}. The array will be empty if the 1150 * directory is empty or if no names were accepted by the filter. 1151 * Returns {@code null} if this abstract pathname does not denote 1152 * a directory, or if an I/O error occurs. 1153 * 1154 * @throws SecurityException 1155 * If a security manager exists and its {@link 1156 * SecurityManager#checkRead(String)} method denies read access to 1157 * the directory 1158 * 1159 * @see java.nio.file.Files#newDirectoryStream(Path,String) 1160 */ 1161 public String[] list(FilenameFilter filter) { 1162 String names[] = list(); 1163 if ((names == null) || (filter == null)) { 1164 return names; 1165 } 1166 List<String> v = new ArrayList<>(); 1167 for (int i = 0 ; i < names.length ; i++) { 1168 if (filter.accept(this, names[i])) { 1169 v.add(names[i]); 1170 } 1171 } 1172 return v.toArray(new String[v.size()]); 1173 } 1174 1175 /** 1176 * Returns an array of abstract pathnames denoting the files in the 1177 * directory denoted by this abstract pathname. 1178 * 1179 * <p> If this abstract pathname does not denote a directory, then this 1180 * method returns {@code null}. Otherwise an array of {@code File} objects 1181 * is returned, one for each file or directory in the directory. Pathnames 1182 * denoting the directory itself and the directory's parent directory are 1183 * not included in the result. Each resulting abstract pathname is 1184 * constructed from this abstract pathname using the {@link #File(File, 1185 * String) File(File, String)} constructor. Therefore if this 1186 * pathname is absolute then each resulting pathname is absolute; if this 1187 * pathname is relative then each resulting pathname will be relative to 1188 * the same directory. 1189 * 1190 * <p> There is no guarantee that the name strings in the resulting array 1191 * will appear in any specific order; they are not, in particular, 1192 * guaranteed to appear in alphabetical order. 1193 * 1194 * <p> Note that the {@link java.nio.file.Files} class defines the {@link 1195 * java.nio.file.Files#newDirectoryStream(Path) newDirectoryStream} method 1196 * to open a directory and iterate over the names of the files in the 1197 * directory. This may use less resources when working with very large 1198 * directories. 1199 * 1200 * @return An array of abstract pathnames denoting the files and 1201 * directories in the directory denoted by this abstract pathname. 1202 * The array will be empty if the directory is empty. Returns 1203 * {@code null} if this abstract pathname does not denote a 1204 * directory, or if an I/O error occurs. 1205 * 1206 * @throws SecurityException 1207 * If a security manager exists and its {@link 1208 * SecurityManager#checkRead(String)} method denies read access to 1209 * the directory 1210 * 1211 * @since 1.2 1212 */ 1213 public File[] listFiles() { 1214 String[] ss = list(); 1215 if (ss == null) return null; 1216 int n = ss.length; 1217 File[] fs = new File[n]; 1218 for (int i = 0; i < n; i++) { 1219 fs[i] = new File(ss[i], this); 1220 } 1221 return fs; 1222 } 1223 1224 /** 1225 * Returns an array of abstract pathnames denoting the files and 1226 * directories in the directory denoted by this abstract pathname that 1227 * satisfy the specified filter. The behavior of this method is the same 1228 * as that of the {@link #listFiles()} method, except that the pathnames in 1229 * the returned array must satisfy the filter. If the given {@code filter} 1230 * is {@code null} then all pathnames are accepted. Otherwise, a pathname 1231 * satisfies the filter if and only if the value {@code true} results when 1232 * the {@link FilenameFilter#accept 1233 * FilenameFilter.accept(File, String)} method of the filter is 1234 * invoked on this abstract pathname and the name of a file or directory in 1235 * the directory that it denotes. 1236 * 1237 * @param filter 1238 * A filename filter 1239 * 1240 * @return An array of abstract pathnames denoting the files and 1241 * directories in the directory denoted by this abstract pathname. 1242 * The array will be empty if the directory is empty. Returns 1243 * {@code null} if this abstract pathname does not denote a 1244 * directory, or if an I/O error occurs. 1245 * 1246 * @throws SecurityException 1247 * If a security manager exists and its {@link 1248 * SecurityManager#checkRead(String)} method denies read access to 1249 * the directory 1250 * 1251 * @since 1.2 1252 * @see java.nio.file.Files#newDirectoryStream(Path,String) 1253 */ 1254 public File[] listFiles(FilenameFilter filter) { 1255 String ss[] = list(); 1256 if (ss == null) return null; 1257 ArrayList<File> files = new ArrayList<>(); 1258 for (String s : ss) 1259 if ((filter == null) || filter.accept(this, s)) 1260 files.add(new File(s, this)); 1261 return files.toArray(new File[files.size()]); 1262 } 1263 1264 /** 1265 * Returns an array of abstract pathnames denoting the files and 1266 * directories in the directory denoted by this abstract pathname that 1267 * satisfy the specified filter. The behavior of this method is the same 1268 * as that of the {@link #listFiles()} method, except that the pathnames in 1269 * the returned array must satisfy the filter. If the given {@code filter} 1270 * is {@code null} then all pathnames are accepted. Otherwise, a pathname 1271 * satisfies the filter if and only if the value {@code true} results when 1272 * the {@link FileFilter#accept FileFilter.accept(File)} method of the 1273 * filter is invoked on the pathname. 1274 * 1275 * @param filter 1276 * A file filter 1277 * 1278 * @return An array of abstract pathnames denoting the files and 1279 * directories in the directory denoted by this abstract pathname. 1280 * The array will be empty if the directory is empty. Returns 1281 * {@code null} if this abstract pathname does not denote a 1282 * directory, or if an I/O error occurs. 1283 * 1284 * @throws SecurityException 1285 * If a security manager exists and its {@link 1286 * SecurityManager#checkRead(String)} method denies read access to 1287 * the directory 1288 * 1289 * @since 1.2 1290 * @see java.nio.file.Files#newDirectoryStream(Path,java.nio.file.DirectoryStream.Filter) 1291 */ 1292 public File[] listFiles(FileFilter filter) { 1293 String ss[] = list(); 1294 if (ss == null) return null; 1295 ArrayList<File> files = new ArrayList<>(); 1296 for (String s : ss) { 1297 File f = new File(s, this); 1298 if ((filter == null) || filter.accept(f)) 1299 files.add(f); 1300 } 1301 return files.toArray(new File[files.size()]); 1302 } 1303 1304 /** 1305 * Creates the directory named by this abstract pathname. 1306 * 1307 * @return <code>true</code> if and only if the directory was 1308 * created; <code>false</code> otherwise 1309 * 1310 * @throws SecurityException 1311 * If a security manager exists and its {@link 1312 * java.lang.SecurityManager#checkWrite(java.lang.String)} 1313 * method does not permit the named directory to be created 1314 */ 1315 public boolean mkdir() { 1316 SecurityManager security = System.getSecurityManager(); 1317 if (security != null) { 1318 security.checkWrite(path); 1319 } 1320 if (isInvalid()) { 1321 return false; 1322 } 1323 return fs.createDirectory(this); 1324 } 1325 1326 /** 1327 * Creates the directory named by this abstract pathname, including any 1328 * necessary but nonexistent parent directories. Note that if this 1329 * operation fails it may have succeeded in creating some of the necessary 1330 * parent directories. 1331 * 1332 * @return <code>true</code> if and only if the directory was created, 1333 * along with all necessary parent directories; <code>false</code> 1334 * otherwise 1335 * 1336 * @throws SecurityException 1337 * If a security manager exists and its {@link 1338 * java.lang.SecurityManager#checkRead(java.lang.String)} 1339 * method does not permit verification of the existence of the 1340 * named directory and all necessary parent directories; or if 1341 * the {@link 1342 * java.lang.SecurityManager#checkWrite(java.lang.String)} 1343 * method does not permit the named directory and all necessary 1344 * parent directories to be created 1345 */ 1346 public boolean mkdirs() { 1347 if (exists()) { 1348 return false; 1349 } 1350 if (mkdir()) { 1351 return true; 1352 } 1353 File canonFile = null; 1354 try { 1355 canonFile = getCanonicalFile(); 1356 } catch (IOException e) { 1357 return false; 1358 } 1359 1360 File parent = canonFile.getParentFile(); 1361 return (parent != null && (parent.mkdirs() || parent.exists()) && 1362 canonFile.mkdir()); 1363 } 1364 1365 /** 1366 * Renames the file denoted by this abstract pathname. 1367 * 1368 * <p> Many aspects of the behavior of this method are inherently 1369 * platform-dependent: The rename operation might not be able to move a 1370 * file from one filesystem to another, it might not be atomic, and it 1371 * might not succeed if a file with the destination abstract pathname 1372 * already exists. The return value should always be checked to make sure 1373 * that the rename operation was successful. 1374 * 1375 * <p> Note that the {@link java.nio.file.Files} class defines the {@link 1376 * java.nio.file.Files#move move} method to move or rename a file in a 1377 * platform independent manner. 1378 * 1379 * @param dest The new abstract pathname for the named file 1380 * 1381 * @return <code>true</code> if and only if the renaming succeeded; 1382 * <code>false</code> otherwise 1383 * 1384 * @throws SecurityException 1385 * If a security manager exists and its {@link 1386 * java.lang.SecurityManager#checkWrite(java.lang.String)} 1387 * method denies write access to either the old or new pathnames 1388 * 1389 * @throws NullPointerException 1390 * If parameter <code>dest</code> is <code>null</code> 1391 */ 1392 public boolean renameTo(File dest) { 1393 SecurityManager security = System.getSecurityManager(); 1394 if (security != null) { 1395 security.checkWrite(path); 1396 security.checkWrite(dest.path); 1397 } 1398 if (dest == null) { 1399 throw new NullPointerException(); 1400 } 1401 if (this.isInvalid() || dest.isInvalid()) { 1402 return false; 1403 } 1404 return fs.rename(this, dest); 1405 } 1406 1407 /** 1408 * Sets the last-modified time of the file or directory named by this 1409 * abstract pathname. 1410 * 1411 * <p> All platforms support file-modification times to the nearest second, 1412 * but some provide more precision. The argument will be truncated to fit 1413 * the supported precision. If the operation succeeds and no intervening 1414 * operations on the file take place, then the next invocation of the 1415 * {@link #lastModified} method will return the (possibly 1416 * truncated) <code>time</code> argument that was passed to this method. 1417 * 1418 * @param time The new last-modified time, measured in milliseconds since 1419 * the epoch (00:00:00 GMT, January 1, 1970) 1420 * 1421 * @return <code>true</code> if and only if the operation succeeded; 1422 * <code>false</code> otherwise 1423 * 1424 * @throws IllegalArgumentException If the argument is negative 1425 * 1426 * @throws SecurityException 1427 * If a security manager exists and its {@link 1428 * java.lang.SecurityManager#checkWrite(java.lang.String)} 1429 * method denies write access to the named file 1430 * 1431 * @since 1.2 1432 */ 1433 public boolean setLastModified(long time) { 1434 if (time < 0) throw new IllegalArgumentException("Negative time"); 1435 SecurityManager security = System.getSecurityManager(); 1436 if (security != null) { 1437 security.checkWrite(path); 1438 } 1439 if (isInvalid()) { 1440 return false; 1441 } 1442 return fs.setLastModifiedTime(this, time); 1443 } 1444 1445 /** 1446 * Marks the file or directory named by this abstract pathname so that 1447 * only read operations are allowed. After invoking this method the file 1448 * or directory will not change until it is either deleted or marked 1449 * to allow write access. On some platforms it may be possible to start the 1450 * Java virtual machine with special privileges that allow it to modify 1451 * files that are marked read-only. Whether or not a read-only file or 1452 * directory may be deleted depends upon the underlying system. 1453 * 1454 * @return <code>true</code> if and only if the operation succeeded; 1455 * <code>false</code> otherwise 1456 * 1457 * @throws SecurityException 1458 * If a security manager exists and its {@link 1459 * java.lang.SecurityManager#checkWrite(java.lang.String)} 1460 * method denies write access to the named file 1461 * 1462 * @since 1.2 1463 */ 1464 public boolean setReadOnly() { 1465 SecurityManager security = System.getSecurityManager(); 1466 if (security != null) { 1467 security.checkWrite(path); 1468 } 1469 if (isInvalid()) { 1470 return false; 1471 } 1472 return fs.setReadOnly(this); 1473 } 1474 1475 /** 1476 * Sets the owner's or everybody's write permission for this abstract 1477 * pathname. On some platforms it may be possible to start the Java virtual 1478 * machine with special privileges that allow it to modify files that 1479 * disallow write operations. 1480 * 1481 * <p> The {@link java.nio.file.Files} class defines methods that operate on 1482 * file attributes including file permissions. This may be used when finer 1483 * manipulation of file permissions is required. 1484 * 1485 * @param writable 1486 * If <code>true</code>, sets the access permission to allow write 1487 * operations; if <code>false</code> to disallow write operations 1488 * 1489 * @param ownerOnly 1490 * If <code>true</code>, the write permission applies only to the 1491 * owner's write permission; otherwise, it applies to everybody. If 1492 * the underlying file system can not distinguish the owner's write 1493 * permission from that of others, then the permission will apply to 1494 * everybody, regardless of this value. 1495 * 1496 * @return <code>true</code> if and only if the operation succeeded. The 1497 * operation will fail if the user does not have permission to change 1498 * the access permissions of this abstract pathname. 1499 * 1500 * @throws SecurityException 1501 * If a security manager exists and its {@link 1502 * java.lang.SecurityManager#checkWrite(java.lang.String)} 1503 * method denies write access to the named file 1504 * 1505 * @since 1.6 1506 */ 1507 public boolean setWritable(boolean writable, boolean ownerOnly) { 1508 SecurityManager security = System.getSecurityManager(); 1509 if (security != null) { 1510 security.checkWrite(path); 1511 } 1512 if (isInvalid()) { 1513 return false; 1514 } 1515 return fs.setPermission(this, FileSystem.ACCESS_WRITE, writable, ownerOnly); 1516 } 1517 1518 /** 1519 * A convenience method to set the owner's write permission for this abstract 1520 * pathname. On some platforms it may be possible to start the Java virtual 1521 * machine with special privileges that allow it to modify files that 1522 * disallow write operations. 1523 * 1524 * <p> An invocation of this method of the form {@code file.setWritable(arg)} 1525 * behaves in exactly the same way as the invocation 1526 * 1527 * <pre>{@code 1528 * file.setWritable(arg, true) 1529 * }</pre> 1530 * 1531 * @param writable 1532 * If <code>true</code>, sets the access permission to allow write 1533 * operations; if <code>false</code> to disallow write operations 1534 * 1535 * @return <code>true</code> if and only if the operation succeeded. The 1536 * operation will fail if the user does not have permission to 1537 * change the access permissions of this abstract pathname. 1538 * 1539 * @throws SecurityException 1540 * If a security manager exists and its {@link 1541 * java.lang.SecurityManager#checkWrite(java.lang.String)} 1542 * method denies write access to the file 1543 * 1544 * @since 1.6 1545 */ 1546 public boolean setWritable(boolean writable) { 1547 return setWritable(writable, true); 1548 } 1549 1550 /** 1551 * Sets the owner's or everybody's read permission for this abstract 1552 * pathname. On some platforms it may be possible to start the Java virtual 1553 * machine with special privileges that allow it to read files that are 1554 * marked as unreadable. 1555 * 1556 * <p> The {@link java.nio.file.Files} class defines methods that operate on 1557 * file attributes including file permissions. This may be used when finer 1558 * manipulation of file permissions is required. 1559 * 1560 * @param readable 1561 * If <code>true</code>, sets the access permission to allow read 1562 * operations; if <code>false</code> to disallow read operations 1563 * 1564 * @param ownerOnly 1565 * If <code>true</code>, the read permission applies only to the 1566 * owner's read permission; otherwise, it applies to everybody. If 1567 * the underlying file system can not distinguish the owner's read 1568 * permission from that of others, then the permission will apply to 1569 * everybody, regardless of this value. 1570 * 1571 * @return <code>true</code> if and only if the operation succeeded. The 1572 * operation will fail if the user does not have permission to 1573 * change the access permissions of this abstract pathname. If 1574 * <code>readable</code> is <code>false</code> and the underlying 1575 * file system does not implement a read permission, then the 1576 * operation will fail. 1577 * 1578 * @throws SecurityException 1579 * If a security manager exists and its {@link 1580 * java.lang.SecurityManager#checkWrite(java.lang.String)} 1581 * method denies write access to the file 1582 * 1583 * @since 1.6 1584 */ 1585 public boolean setReadable(boolean readable, boolean ownerOnly) { 1586 SecurityManager security = System.getSecurityManager(); 1587 if (security != null) { 1588 security.checkWrite(path); 1589 } 1590 if (isInvalid()) { 1591 return false; 1592 } 1593 return fs.setPermission(this, FileSystem.ACCESS_READ, readable, ownerOnly); 1594 } 1595 1596 /** 1597 * A convenience method to set the owner's read permission for this abstract 1598 * pathname. On some platforms it may be possible to start the Java virtual 1599 * machine with special privileges that allow it to read files that are 1600 * marked as unreadable. 1601 * 1602 * <p>An invocation of this method of the form {@code file.setReadable(arg)} 1603 * behaves in exactly the same way as the invocation 1604 * 1605 * <pre>{@code 1606 * file.setReadable(arg, true) 1607 * }</pre> 1608 * 1609 * @param readable 1610 * If <code>true</code>, sets the access permission to allow read 1611 * operations; if <code>false</code> to disallow read operations 1612 * 1613 * @return <code>true</code> if and only if the operation succeeded. The 1614 * operation will fail if the user does not have permission to 1615 * change the access permissions of this abstract pathname. If 1616 * <code>readable</code> is <code>false</code> and the underlying 1617 * file system does not implement a read permission, then the 1618 * operation will fail. 1619 * 1620 * @throws SecurityException 1621 * If a security manager exists and its {@link 1622 * java.lang.SecurityManager#checkWrite(java.lang.String)} 1623 * method denies write access to the file 1624 * 1625 * @since 1.6 1626 */ 1627 public boolean setReadable(boolean readable) { 1628 return setReadable(readable, true); 1629 } 1630 1631 /** 1632 * Sets the owner's or everybody's execute permission for this abstract 1633 * pathname. On some platforms it may be possible to start the Java virtual 1634 * machine with special privileges that allow it to execute files that are 1635 * not marked executable. 1636 * 1637 * <p> The {@link java.nio.file.Files} class defines methods that operate on 1638 * file attributes including file permissions. This may be used when finer 1639 * manipulation of file permissions is required. 1640 * 1641 * @param executable 1642 * If <code>true</code>, sets the access permission to allow execute 1643 * operations; if <code>false</code> to disallow execute operations 1644 * 1645 * @param ownerOnly 1646 * If <code>true</code>, the execute permission applies only to the 1647 * owner's execute permission; otherwise, it applies to everybody. 1648 * If the underlying file system can not distinguish the owner's 1649 * execute permission from that of others, then the permission will 1650 * apply to everybody, regardless of this value. 1651 * 1652 * @return <code>true</code> if and only if the operation succeeded. The 1653 * operation will fail if the user does not have permission to 1654 * change the access permissions of this abstract pathname. If 1655 * <code>executable</code> is <code>false</code> and the underlying 1656 * file system does not implement an execute permission, then the 1657 * operation will fail. 1658 * 1659 * @throws SecurityException 1660 * If a security manager exists and its {@link 1661 * java.lang.SecurityManager#checkWrite(java.lang.String)} 1662 * method denies write access to the file 1663 * 1664 * @since 1.6 1665 */ 1666 public boolean setExecutable(boolean executable, boolean ownerOnly) { 1667 SecurityManager security = System.getSecurityManager(); 1668 if (security != null) { 1669 security.checkWrite(path); 1670 } 1671 if (isInvalid()) { 1672 return false; 1673 } 1674 return fs.setPermission(this, FileSystem.ACCESS_EXECUTE, executable, ownerOnly); 1675 } 1676 1677 /** 1678 * A convenience method to set the owner's execute permission for this 1679 * abstract pathname. On some platforms it may be possible to start the Java 1680 * virtual machine with special privileges that allow it to execute files 1681 * that are not marked executable. 1682 * 1683 * <p>An invocation of this method of the form {@code file.setExcutable(arg)} 1684 * behaves in exactly the same way as the invocation 1685 * 1686 * <pre>{@code 1687 * file.setExecutable(arg, true) 1688 * }</pre> 1689 * 1690 * @param executable 1691 * If <code>true</code>, sets the access permission to allow execute 1692 * operations; if <code>false</code> to disallow execute operations 1693 * 1694 * @return <code>true</code> if and only if the operation succeeded. The 1695 * operation will fail if the user does not have permission to 1696 * change the access permissions of this abstract pathname. If 1697 * <code>executable</code> is <code>false</code> and the underlying 1698 * file system does not implement an execute permission, then the 1699 * operation will fail. 1700 * 1701 * @throws SecurityException 1702 * If a security manager exists and its {@link 1703 * java.lang.SecurityManager#checkWrite(java.lang.String)} 1704 * method denies write access to the file 1705 * 1706 * @since 1.6 1707 */ 1708 public boolean setExecutable(boolean executable) { 1709 return setExecutable(executable, true); 1710 } 1711 1712 /** 1713 * Tests whether the application can execute the file denoted by this 1714 * abstract pathname. On some platforms it may be possible to start the 1715 * Java virtual machine with special privileges that allow it to execute 1716 * files that are not marked executable. Consequently this method may return 1717 * {@code true} even though the file does not have execute permissions. 1718 * 1719 * @return <code>true</code> if and only if the abstract pathname exists 1720 * <em>and</em> the application is allowed to execute the file 1721 * 1722 * @throws SecurityException 1723 * If a security manager exists and its {@link 1724 * java.lang.SecurityManager#checkExec(java.lang.String)} 1725 * method denies execute access to the file 1726 * 1727 * @since 1.6 1728 */ 1729 public boolean canExecute() { 1730 SecurityManager security = System.getSecurityManager(); 1731 if (security != null) { 1732 security.checkExec(path); 1733 } 1734 if (isInvalid()) { 1735 return false; 1736 } 1737 return fs.checkAccess(this, FileSystem.ACCESS_EXECUTE); 1738 } 1739 1740 1741 /* -- Filesystem interface -- */ 1742 1743 /** 1744 * List the available filesystem roots. 1745 * 1746 * <p> A particular Java platform may support zero or more 1747 * hierarchically-organized file systems. Each file system has a 1748 * {@code root} directory from which all other files in that file system 1749 * can be reached. Windows platforms, for example, have a root directory 1750 * for each active drive; UNIX platforms have a single root directory, 1751 * namely {@code "/"}. The set of available filesystem roots is affected 1752 * by various system-level operations such as the insertion or ejection of 1753 * removable media and the disconnecting or unmounting of physical or 1754 * virtual disk drives. 1755 * 1756 * <p> This method returns an array of {@code File} objects that denote the 1757 * root directories of the available filesystem roots. It is guaranteed 1758 * that the canonical pathname of any file physically present on the local 1759 * machine will begin with one of the roots returned by this method. 1760 * 1761 * <p> The canonical pathname of a file that resides on some other machine 1762 * and is accessed via a remote-filesystem protocol such as SMB or NFS may 1763 * or may not begin with one of the roots returned by this method. If the 1764 * pathname of a remote file is syntactically indistinguishable from the 1765 * pathname of a local file then it will begin with one of the roots 1766 * returned by this method. Thus, for example, {@code File} objects 1767 * denoting the root directories of the mapped network drives of a Windows 1768 * platform will be returned by this method, while {@code File} objects 1769 * containing UNC pathnames will not be returned by this method. 1770 * 1771 * <p> Unlike most methods in this class, this method does not throw 1772 * security exceptions. If a security manager exists and its {@link 1773 * SecurityManager#checkRead(String)} method denies read access to a 1774 * particular root directory, then that directory will not appear in the 1775 * result. 1776 * 1777 * @return An array of {@code File} objects denoting the available 1778 * filesystem roots, or {@code null} if the set of roots could not 1779 * be determined. The array will be empty if there are no 1780 * filesystem roots. 1781 * 1782 * @since 1.2 1783 * @see java.nio.file.FileStore 1784 */ 1785 public static File[] listRoots() { 1786 return fs.listRoots(); 1787 } 1788 1789 1790 /* -- Disk usage -- */ 1791 1792 /** 1793 * Returns the size of the partition <a href="#partName">named</a> by this 1794 * abstract pathname. 1795 * 1796 * @return The size, in bytes, of the partition or {@code 0L} if this 1797 * abstract pathname does not name a partition 1798 * 1799 * @throws SecurityException 1800 * If a security manager has been installed and it denies 1801 * {@link RuntimePermission}{@code ("getFileSystemAttributes")} 1802 * or its {@link SecurityManager#checkRead(String)} method denies 1803 * read access to the file named by this abstract pathname 1804 * 1805 * @since 1.6 1806 */ 1807 public long getTotalSpace() { 1808 SecurityManager sm = System.getSecurityManager(); 1809 if (sm != null) { 1810 sm.checkPermission(new RuntimePermission("getFileSystemAttributes")); 1811 sm.checkRead(path); 1812 } 1813 if (isInvalid()) { 1814 return 0L; 1815 } 1816 return fs.getSpace(this, FileSystem.SPACE_TOTAL); 1817 } 1818 1819 /** 1820 * Returns the number of unallocated bytes in the partition <a 1821 * href="#partName">named</a> by this abstract path name. 1822 * 1823 * <p> The returned number of unallocated bytes is a hint, but not 1824 * a guarantee, that it is possible to use most or any of these 1825 * bytes. The number of unallocated bytes is most likely to be 1826 * accurate immediately after this call. It is likely to be made 1827 * inaccurate by any external I/O operations including those made 1828 * on the system outside of this virtual machine. This method 1829 * makes no guarantee that write operations to this file system 1830 * will succeed. 1831 * 1832 * @return The number of unallocated bytes on the partition or {@code 0L} 1833 * if the abstract pathname does not name a partition. This 1834 * value will be less than or equal to the total file system size 1835 * returned by {@link #getTotalSpace}. 1836 * 1837 * @throws SecurityException 1838 * If a security manager has been installed and it denies 1839 * {@link RuntimePermission}{@code ("getFileSystemAttributes")} 1840 * or its {@link SecurityManager#checkRead(String)} method denies 1841 * read access to the file named by this abstract pathname 1842 * 1843 * @since 1.6 1844 */ 1845 public long getFreeSpace() { 1846 SecurityManager sm = System.getSecurityManager(); 1847 if (sm != null) { 1848 sm.checkPermission(new RuntimePermission("getFileSystemAttributes")); 1849 sm.checkRead(path); 1850 } 1851 if (isInvalid()) { 1852 return 0L; 1853 } 1854 return fs.getSpace(this, FileSystem.SPACE_FREE); 1855 } 1856 1857 /** 1858 * Returns the number of bytes available to this virtual machine on the 1859 * partition <a href="#partName">named</a> by this abstract pathname. When 1860 * possible, this method checks for write permissions and other operating 1861 * system restrictions and will therefore usually provide a more accurate 1862 * estimate of how much new data can actually be written than {@link 1863 * #getFreeSpace}. 1864 * 1865 * <p> The returned number of available bytes is a hint, but not a 1866 * guarantee, that it is possible to use most or any of these bytes. The 1867 * number of unallocated bytes is most likely to be accurate immediately 1868 * after this call. It is likely to be made inaccurate by any external 1869 * I/O operations including those made on the system outside of this 1870 * virtual machine. This method makes no guarantee that write operations 1871 * to this file system will succeed. 1872 * 1873 * @return The number of available bytes on the partition or {@code 0L} 1874 * if the abstract pathname does not name a partition. On 1875 * systems where this information is not available, this method 1876 * will be equivalent to a call to {@link #getFreeSpace}. 1877 * 1878 * @throws SecurityException 1879 * If a security manager has been installed and it denies 1880 * {@link RuntimePermission}{@code ("getFileSystemAttributes")} 1881 * or its {@link SecurityManager#checkRead(String)} method denies 1882 * read access to the file named by this abstract pathname 1883 * 1884 * @since 1.6 1885 */ 1886 public long getUsableSpace() { 1887 SecurityManager sm = System.getSecurityManager(); 1888 if (sm != null) { 1889 sm.checkPermission(new RuntimePermission("getFileSystemAttributes")); 1890 sm.checkRead(path); 1891 } 1892 if (isInvalid()) { 1893 return 0L; 1894 } 1895 return fs.getSpace(this, FileSystem.SPACE_USABLE); 1896 } 1897 1898 /* -- Temporary files -- */ 1899 1900 private static class TempDirectory { 1901 private TempDirectory() { } 1902 1903 // temporary directory location 1904 private static final File tmpdir = new File( 1905 GetPropertyAction.privilegedGetProperty("java.io.tmpdir")); 1906 static File location() { 1907 return tmpdir; 1908 } 1909 1910 // file name generation 1911 private static final SecureRandom random = new SecureRandom(); 1912 private static int shortenSubName(int subNameLength, int excess, 1913 int nameMin) { 1914 int newLength = Math.max(nameMin, subNameLength - excess); 1915 if (newLength < subNameLength) { 1916 return newLength; 1917 } 1918 return subNameLength; 1919 } 1920 static File generateFile(String prefix, String suffix, File dir) 1921 throws IOException 1922 { 1923 long n = random.nextLong(); 1924 String nus = Long.toUnsignedString(n); 1925 1926 // Use only the file name from the supplied prefix 1927 prefix = (new File(prefix)).getName(); 1928 1929 int prefixLength = prefix.length(); 1930 int nusLength = nus.length(); 1931 int suffixLength = suffix.length();; 1932 1933 String name; 1934 int nameMax = fs.getNameMax(dir.getPath()); 1935 int excess = prefixLength + nusLength + suffixLength - nameMax; 1936 if (excess <= 0) { 1937 name = prefix + nus + suffix; 1938 } else { 1939 // Name exceeds the maximum path component length: shorten it 1940 1941 // Attempt to shorten the prefix length to no less then 3 1942 prefixLength = shortenSubName(prefixLength, excess, 3); 1943 excess = prefixLength + nusLength + suffixLength - nameMax; 1944 1945 if (excess > 0) { 1946 // Attempt to shorten the suffix length to no less than 1947 // 0 or 4 depending on whether it begins with a dot ('.') 1948 suffixLength = shortenSubName(suffixLength, excess, 1949 suffix.indexOf(".") == 0 ? 4 : 0); 1950 suffixLength = shortenSubName(suffixLength, excess, 3); 1951 excess = prefixLength + nusLength + suffixLength - nameMax; 1952 } 1953 1954 if (excess > 0 && excess <= nusLength - 5) { 1955 // Attempt to shorten the random character string length 1956 // to no less than 5 1957 nusLength = shortenSubName(nusLength, excess, 5); 1958 } 1959 1960 StringBuilder sb = 1961 new StringBuilder(prefixLength + nusLength + suffixLength); 1962 sb.append(prefixLength < prefix.length() ? 1963 prefix.substring(0, prefixLength) : prefix); 1964 sb.append(nusLength < nus.length() ? 1965 nus.substring(0, nusLength) : nus); 1966 sb.append(suffixLength < suffix.length() ? 1967 suffix.substring(0, suffixLength) : suffix); 1968 name = sb.toString(); 1969 } 1970 1971 // Normalize the path component 1972 name = fs.normalize(name); 1973 1974 File f = new File(dir, name); 1975 if (!name.equals(f.getName()) || f.isInvalid()) { 1976 if (System.getSecurityManager() != null) 1977 throw new IOException("Unable to create temporary file"); 1978 else 1979 throw new IOException("Unable to create temporary file, " 1980 + name); 1981 } 1982 return f; 1983 } 1984 } 1985 1986 /** 1987 * <p> Creates a new empty file in the specified directory, using the 1988 * given prefix and suffix strings to generate its name. If this method 1989 * returns successfully then it is guaranteed that: 1990 * 1991 * <ol> 1992 * <li> The file denoted by the returned abstract pathname did not exist 1993 * before this method was invoked, and 1994 * <li> Neither this method nor any of its variants will return the same 1995 * abstract pathname again in the current invocation of the virtual 1996 * machine. 1997 * </ol> 1998 * 1999 * This method provides only part of a temporary-file facility. To arrange 2000 * for a file created by this method to be deleted automatically, use the 2001 * {@link #deleteOnExit} method. 2002 * 2003 * <p> The <code>prefix</code> argument must be at least three characters 2004 * long. It is recommended that the prefix be a short, meaningful string 2005 * such as <code>"hjb"</code> or <code>"mail"</code>. The 2006 * <code>suffix</code> argument may be <code>null</code>, in which case the 2007 * suffix <code>".tmp"</code> will be used. 2008 * 2009 * <p> To create the new file, the prefix and the suffix may first be 2010 * adjusted to fit the limitations of the underlying platform. If the 2011 * prefix is too long then it will be truncated, but its first three 2012 * characters will always be preserved. If the suffix is too long then it 2013 * too will be truncated, but if it begins with a period character 2014 * (<code>'.'</code>) then the period and the first three characters 2015 * following it will always be preserved. Once these adjustments have been 2016 * made the name of the new file will be generated by concatenating the 2017 * prefix, five or more internally-generated characters, and the suffix. 2018 * 2019 * <p> If the <code>directory</code> argument is <code>null</code> then the 2020 * system-dependent default temporary-file directory will be used. The 2021 * default temporary-file directory is specified by the system property 2022 * <code>java.io.tmpdir</code>. On UNIX systems the default value of this 2023 * property is typically <code>"/tmp"</code> or <code>"/var/tmp"</code>; on 2024 * Microsoft Windows systems it is typically <code>"C:\\WINNT\\TEMP"</code>. A different 2025 * value may be given to this system property when the Java virtual machine 2026 * is invoked, but programmatic changes to this property are not guaranteed 2027 * to have any effect upon the temporary directory used by this method. 2028 * 2029 * @param prefix The prefix string to be used in generating the file's 2030 * name; must be at least three characters long 2031 * 2032 * @param suffix The suffix string to be used in generating the file's 2033 * name; may be <code>null</code>, in which case the 2034 * suffix <code>".tmp"</code> will be used 2035 * 2036 * @param directory The directory in which the file is to be created, or 2037 * <code>null</code> if the default temporary-file 2038 * directory is to be used 2039 * 2040 * @return An abstract pathname denoting a newly-created empty file 2041 * 2042 * @throws IllegalArgumentException 2043 * If the <code>prefix</code> argument contains fewer than three 2044 * characters 2045 * 2046 * @throws IOException If a file could not be created 2047 * 2048 * @throws SecurityException 2049 * If a security manager exists and its {@link 2050 * java.lang.SecurityManager#checkWrite(java.lang.String)} 2051 * method does not allow a file to be created 2052 * 2053 * @since 1.2 2054 */ 2055 public static File createTempFile(String prefix, String suffix, 2056 File directory) 2057 throws IOException 2058 { 2059 if (prefix.length() < 3) { 2060 throw new IllegalArgumentException("Prefix string \"" + prefix + 2061 "\" too short: length must be at least 3"); 2062 } 2063 if (suffix == null) 2064 suffix = ".tmp"; 2065 2066 File tmpdir = (directory != null) ? directory 2067 : TempDirectory.location(); 2068 SecurityManager sm = System.getSecurityManager(); 2069 File f; 2070 do { 2071 f = TempDirectory.generateFile(prefix, suffix, tmpdir); 2072 2073 if (sm != null) { 2074 try { 2075 sm.checkWrite(f.getPath()); 2076 } catch (SecurityException se) { 2077 // don't reveal temporary directory location 2078 if (directory == null) 2079 throw new SecurityException("Unable to create temporary file"); 2080 throw se; 2081 } 2082 } 2083 } while ((fs.getBooleanAttributes(f) & FileSystem.BA_EXISTS) != 0); 2084 2085 if (!fs.createFileExclusively(f.getPath())) 2086 throw new IOException("Unable to create temporary file"); 2087 2088 return f; 2089 } 2090 2091 /** 2092 * Creates an empty file in the default temporary-file directory, using 2093 * the given prefix and suffix to generate its name. Invoking this method 2094 * is equivalent to invoking {@link #createTempFile(java.lang.String, 2095 * java.lang.String, java.io.File) 2096 * createTempFile(prefix, suffix, null)}. 2097 * 2098 * <p> The {@link 2099 * java.nio.file.Files#createTempFile(String,String,java.nio.file.attribute.FileAttribute[]) 2100 * Files.createTempFile} method provides an alternative method to create an 2101 * empty file in the temporary-file directory. Files created by that method 2102 * may have more restrictive access permissions to files created by this 2103 * method and so may be more suited to security-sensitive applications. 2104 * 2105 * @param prefix The prefix string to be used in generating the file's 2106 * name; must be at least three characters long 2107 * 2108 * @param suffix The suffix string to be used in generating the file's 2109 * name; may be <code>null</code>, in which case the 2110 * suffix <code>".tmp"</code> will be used 2111 * 2112 * @return An abstract pathname denoting a newly-created empty file 2113 * 2114 * @throws IllegalArgumentException 2115 * If the <code>prefix</code> argument contains fewer than three 2116 * characters 2117 * 2118 * @throws IOException If a file could not be created 2119 * 2120 * @throws SecurityException 2121 * If a security manager exists and its {@link 2122 * java.lang.SecurityManager#checkWrite(java.lang.String)} 2123 * method does not allow a file to be created 2124 * 2125 * @since 1.2 2126 * @see java.nio.file.Files#createTempDirectory(String,FileAttribute[]) 2127 */ 2128 public static File createTempFile(String prefix, String suffix) 2129 throws IOException 2130 { 2131 return createTempFile(prefix, suffix, null); 2132 } 2133 2134 /* -- Basic infrastructure -- */ 2135 2136 /** 2137 * Compares two abstract pathnames lexicographically. The ordering 2138 * defined by this method depends upon the underlying system. On UNIX 2139 * systems, alphabetic case is significant in comparing pathnames; on Microsoft Windows 2140 * systems it is not. 2141 * 2142 * @param pathname The abstract pathname to be compared to this abstract 2143 * pathname 2144 * 2145 * @return Zero if the argument is equal to this abstract pathname, a 2146 * value less than zero if this abstract pathname is 2147 * lexicographically less than the argument, or a value greater 2148 * than zero if this abstract pathname is lexicographically 2149 * greater than the argument 2150 * 2151 * @since 1.2 2152 */ 2153 public int compareTo(File pathname) { 2154 return fs.compare(this, pathname); 2155 } 2156 2157 /** 2158 * Tests this abstract pathname for equality with the given object. 2159 * Returns <code>true</code> if and only if the argument is not 2160 * <code>null</code> and is an abstract pathname that denotes the same file 2161 * or directory as this abstract pathname. Whether or not two abstract 2162 * pathnames are equal depends upon the underlying system. On UNIX 2163 * systems, alphabetic case is significant in comparing pathnames; on Microsoft Windows 2164 * systems it is not. 2165 * 2166 * @param obj The object to be compared with this abstract pathname 2167 * 2168 * @return <code>true</code> if and only if the objects are the same; 2169 * <code>false</code> otherwise 2170 */ 2171 public boolean equals(Object obj) { 2172 if ((obj != null) && (obj instanceof File)) { 2173 return compareTo((File)obj) == 0; 2174 } 2175 return false; 2176 } 2177 2178 /** 2179 * Computes a hash code for this abstract pathname. Because equality of 2180 * abstract pathnames is inherently system-dependent, so is the computation 2181 * of their hash codes. On UNIX systems, the hash code of an abstract 2182 * pathname is equal to the exclusive <em>or</em> of the hash code 2183 * of its pathname string and the decimal value 2184 * <code>1234321</code>. On Microsoft Windows systems, the hash 2185 * code is equal to the exclusive <em>or</em> of the hash code of 2186 * its pathname string converted to lower case and the decimal 2187 * value <code>1234321</code>. Locale is not taken into account on 2188 * lowercasing the pathname string. 2189 * 2190 * @return A hash code for this abstract pathname 2191 */ 2192 public int hashCode() { 2193 return fs.hashCode(this); 2194 } 2195 2196 /** 2197 * Returns the pathname string of this abstract pathname. This is just the 2198 * string returned by the {@link #getPath} method. 2199 * 2200 * @return The string form of this abstract pathname 2201 */ 2202 public String toString() { 2203 return getPath(); 2204 } 2205 2206 /** 2207 * WriteObject is called to save this filename. 2208 * The separator character is saved also so it can be replaced 2209 * in case the path is reconstituted on a different host type. 2210 * 2211 * @serialData Default fields followed by separator character. 2212 */ 2213 private synchronized void writeObject(java.io.ObjectOutputStream s) 2214 throws IOException 2215 { 2216 s.defaultWriteObject(); 2217 s.writeChar(separatorChar); // Add the separator character 2218 } 2219 2220 /** 2221 * readObject is called to restore this filename. 2222 * The original separator character is read. If it is different 2223 * than the separator character on this system, then the old separator 2224 * is replaced by the local separator. 2225 */ 2226 private synchronized void readObject(java.io.ObjectInputStream s) 2227 throws IOException, ClassNotFoundException 2228 { 2229 ObjectInputStream.GetField fields = s.readFields(); 2230 String pathField = (String)fields.get("path", null); 2231 char sep = s.readChar(); // read the previous separator char 2232 if (sep != separatorChar) 2233 pathField = pathField.replace(sep, separatorChar); 2234 String path = fs.normalize(pathField); 2235 UNSAFE.putObject(this, PATH_OFFSET, path); 2236 UNSAFE.putIntVolatile(this, PREFIX_LENGTH_OFFSET, fs.prefixLength(path)); 2237 } 2238 2239 private static final long PATH_OFFSET; 2240 private static final long PREFIX_LENGTH_OFFSET; 2241 private static final jdk.internal.misc.Unsafe UNSAFE; 2242 static { 2243 try { 2244 jdk.internal.misc.Unsafe unsafe = jdk.internal.misc.Unsafe.getUnsafe(); 2245 PATH_OFFSET = unsafe.objectFieldOffset( 2246 File.class.getDeclaredField("path")); 2247 PREFIX_LENGTH_OFFSET = unsafe.objectFieldOffset( 2248 File.class.getDeclaredField("prefixLength")); 2249 UNSAFE = unsafe; 2250 } catch (ReflectiveOperationException e) { 2251 throw new Error(e); 2252 } 2253 } 2254 2255 2256 /** use serialVersionUID from JDK 1.0.2 for interoperability */ 2257 private static final long serialVersionUID = 301077366599181567L; 2258 2259 // -- Integration with java.nio.file -- 2260 2261 private transient volatile Path filePath; 2262 2263 /** 2264 * Returns a {@link Path java.nio.file.Path} object constructed from the 2265 * this abstract path. The resulting {@code Path} is associated with the 2266 * {@link java.nio.file.FileSystems#getDefault default-filesystem}. 2267 * 2268 * <p> The first invocation of this method works as if invoking it were 2269 * equivalent to evaluating the expression: 2270 * <blockquote><pre> 2271 * {@link java.nio.file.FileSystems#getDefault FileSystems.getDefault}().{@link 2272 * java.nio.file.FileSystem#getPath getPath}(this.{@link #getPath getPath}()); 2273 * </pre></blockquote> 2274 * Subsequent invocations of this method return the same {@code Path}. 2275 * 2276 * <p> If this abstract pathname is the empty abstract pathname then this 2277 * method returns a {@code Path} that may be used to access the current 2278 * user directory. 2279 * 2280 * @return a {@code Path} constructed from this abstract path 2281 * 2282 * @throws java.nio.file.InvalidPathException 2283 * if a {@code Path} object cannot be constructed from the abstract 2284 * path (see {@link java.nio.file.FileSystem#getPath FileSystem.getPath}) 2285 * 2286 * @since 1.7 2287 * @see Path#toFile 2288 */ 2289 public Path toPath() { 2290 Path result = filePath; 2291 if (result == null) { 2292 synchronized (this) { 2293 result = filePath; 2294 if (result == null) { 2295 result = FileSystems.getDefault().getPath(path); 2296 filePath = result; 2297 } 2298 } 2299 } 2300 return result; 2301 } 2302 }