File.java revision 12745:f068a4ffddd2
1/* 2 * Copyright (c) 1994, 2013, 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 26package java.io; 27 28import java.net.URI; 29import java.net.URL; 30import java.net.MalformedURLException; 31import java.net.URISyntaxException; 32import java.util.List; 33import java.util.ArrayList; 34import java.security.AccessController; 35import java.security.SecureRandom; 36import java.nio.file.Path; 37import java.nio.file.FileSystems; 38import sun.security.action.GetPropertyAction; 39 40/** 41 * An abstract representation of file and directory pathnames. 42 * 43 * <p> User interfaces and operating systems use system-dependent <em>pathname 44 * strings</em> to name files and directories. This class presents an 45 * abstract, system-independent view of hierarchical pathnames. An 46 * <em>abstract pathname</em> has two components: 47 * 48 * <ol> 49 * <li> An optional system-dependent <em>prefix</em> string, 50 * such as a disk-drive specifier, <code>"/"</code> for the UNIX root 51 * directory, or <code>"\\\\"</code> for a Microsoft Windows UNC pathname, and 52 * <li> A sequence of zero or more string <em>names</em>. 53 * </ol> 54 * 55 * The first name in an abstract pathname may be a directory name or, in the 56 * case of Microsoft Windows UNC pathnames, a hostname. Each subsequent name 57 * in an abstract pathname denotes a directory; the last name may denote 58 * either a directory or a file. The <em>empty</em> abstract pathname has no 59 * prefix and an empty name sequence. 60 * 61 * <p> The conversion of a pathname string to or from an abstract pathname is 62 * inherently system-dependent. When an abstract pathname is converted into a 63 * pathname string, each name is separated from the next by a single copy of 64 * the default <em>separator character</em>. The default name-separator 65 * character is defined by the system property <code>file.separator</code>, and 66 * is made available in the public static fields {@link 67 * #separator} and {@link #separatorChar} of this class. 68 * When a pathname string is converted into an abstract pathname, the names 69 * within it may be separated by the default name-separator character or by any 70 * other name-separator character that is supported by the underlying system. 71 * 72 * <p> A pathname, whether abstract or in string form, may be either 73 * <em>absolute</em> or <em>relative</em>. An absolute pathname is complete in 74 * that no other information is required in order to locate the file that it 75 * denotes. A relative pathname, in contrast, must be interpreted in terms of 76 * information taken from some other pathname. By default the classes in the 77 * <code>java.io</code> package always resolve relative pathnames against the 78 * current user directory. This directory is named by the system property 79 * <code>user.dir</code>, and is typically the directory in which the Java 80 * virtual machine was invoked. 81 * 82 * <p> The <em>parent</em> of an abstract pathname may be obtained by invoking 83 * the {@link #getParent} method of this class and consists of the pathname's 84 * prefix and each name in the pathname's name sequence except for the last. 85 * Each directory's absolute pathname is an ancestor of any {@code File} 86 * object with an absolute abstract pathname which begins with the directory's 87 * absolute pathname. For example, the directory denoted by the abstract 88 * pathname {@code "/usr"} is an ancestor of the directory denoted by the 89 * pathname {@code "/usr/local/bin"}. 90 * 91 * <p> The prefix concept is used to handle root directories on UNIX platforms, 92 * and drive specifiers, root directories and UNC pathnames on Microsoft Windows platforms, 93 * as follows: 94 * 95 * <ul> 96 * 97 * <li> For UNIX platforms, the prefix of an absolute pathname is always 98 * <code>"/"</code>. Relative pathnames have no prefix. The abstract pathname 99 * denoting the root directory has the prefix <code>"/"</code> and an empty 100 * name sequence. 101 * 102 * <li> For Microsoft Windows platforms, the prefix of a pathname that contains a drive 103 * specifier consists of the drive letter followed by <code>":"</code> and 104 * possibly followed by <code>"\\"</code> if the pathname is absolute. The 105 * prefix of a UNC pathname is <code>"\\\\"</code>; the hostname and the share 106 * name are the first two names in the name sequence. A relative pathname that 107 * does not specify a drive has no prefix. 108 * 109 * </ul> 110 * 111 * <p> Instances of this class may or may not denote an actual file-system 112 * object such as a file or a directory. If it does denote such an object 113 * then that object resides in a <i>partition</i>. A partition is an 114 * operating system-specific portion of storage for a file system. A single 115 * storage device (e.g. a physical disk-drive, flash memory, CD-ROM) may 116 * contain multiple partitions. The object, if any, will reside on the 117 * partition <a name="partName">named</a> by some ancestor of the absolute 118 * form of this pathname. 119 * 120 * <p> A file system may implement restrictions to certain operations on the 121 * actual file-system object, such as reading, writing, and executing. These 122 * restrictions are collectively known as <i>access permissions</i>. The file 123 * system may have multiple sets of access permissions on a single object. 124 * For example, one set may apply to the object's <i>owner</i>, and another 125 * may apply to all other users. The access permissions on an object may 126 * cause some methods in this class to fail. 127 * 128 * <p> Instances of the <code>File</code> class are immutable; that is, once 129 * created, the abstract pathname represented by a <code>File</code> object 130 * will never change. 131 * 132 * <h3>Interoperability with {@code java.nio.file} package</h3> 133 * 134 * <p> The <a href="../../java/nio/file/package-summary.html">{@code java.nio.file}</a> 135 * package defines interfaces and classes for the Java virtual machine to access 136 * files, file attributes, and file systems. This API may be used to overcome 137 * many of the limitations of the {@code java.io.File} class. 138 * The {@link #toPath toPath} method may be used to obtain a {@link 139 * Path} that uses the abstract path represented by a {@code File} object to 140 * locate a file. The resulting {@code Path} may be used with the {@link 141 * java.nio.file.Files} class to provide more efficient and extensive access to 142 * additional file operations, file attributes, and I/O exceptions to help 143 * diagnose errors when an operation on a file fails. 144 * 145 * @author unascribed 146 * @since 1.0 147 */ 148 149public class File 150 implements Serializable, Comparable<File> 151{ 152 153 /** 154 * The FileSystem object representing the platform's local file system. 155 */ 156 private static final FileSystem fs = DefaultFileSystem.getFileSystem(); 157 158 /** 159 * This abstract pathname's normalized pathname string. A normalized 160 * pathname string uses the default name-separator character and does not 161 * contain any duplicate or redundant separators. 162 * 163 * @serial 164 */ 165 private final String path; 166 167 /** 168 * Enum type that indicates the status of a file path. 169 */ 170 private static enum PathStatus { INVALID, CHECKED }; 171 172 /** 173 * The flag indicating whether the file path is invalid. 174 */ 175 private transient PathStatus status = null; 176 177 /** 178 * Check if the file has an invalid path. Currently, the inspection of 179 * a file path is very limited, and it only covers Nul character check. 180 * Returning true means the path is definitely invalid/garbage. But 181 * returning false does not guarantee that the path is valid. 182 * 183 * @return true if the file path is invalid. 184 */ 185 final boolean isInvalid() { 186 if (status == null) { 187 status = (this.path.indexOf('\u0000') < 0) ? PathStatus.CHECKED 188 : PathStatus.INVALID; 189 } 190 return status == PathStatus.INVALID; 191 } 192 193 /** 194 * The length of this abstract pathname's prefix, or zero if it has no 195 * prefix. 196 */ 197 private final transient int prefixLength; 198 199 /** 200 * Returns the length of this abstract pathname's prefix. 201 * For use by FileSystem classes. 202 */ 203 int getPrefixLength() { 204 return prefixLength; 205 } 206 207 /** 208 * The system-dependent default name-separator character. This field is 209 * initialized to contain the first character of the value of the system 210 * property <code>file.separator</code>. On UNIX systems the value of this 211 * field is <code>'/'</code>; on Microsoft Windows systems it is <code>'\\'</code>. 212 * 213 * @see java.lang.System#getProperty(java.lang.String) 214 */ 215 public static final char separatorChar = fs.getSeparator(); 216 217 /** 218 * The system-dependent default name-separator character, represented as a 219 * string for convenience. This string contains a single character, namely 220 * {@link #separatorChar}. 221 */ 222 public static final String separator = "" + separatorChar; 223 224 /** 225 * The system-dependent path-separator character. This field is 226 * initialized to contain the first character of the value of the system 227 * property <code>path.separator</code>. This character is used to 228 * separate filenames in a sequence of files given as a <em>path list</em>. 229 * On UNIX systems, this character is <code>':'</code>; on Microsoft Windows systems it 230 * is <code>';'</code>. 231 * 232 * @see java.lang.System#getProperty(java.lang.String) 233 */ 234 public static final char pathSeparatorChar = fs.getPathSeparator(); 235 236 /** 237 * The system-dependent path-separator character, represented as a string 238 * for convenience. This string contains a single character, namely 239 * {@link #pathSeparatorChar}. 240 */ 241 public static final String pathSeparator = "" + pathSeparatorChar; 242 243 244 /* -- Constructors -- */ 245 246 /** 247 * Internal constructor for already-normalized pathname strings. 248 */ 249 private File(String pathname, int prefixLength) { 250 this.path = pathname; 251 this.prefixLength = prefixLength; 252 } 253 254 /** 255 * Internal constructor for already-normalized pathname strings. 256 * The parameter order is used to disambiguate this method from the 257 * public(File, String) constructor. 258 */ 259 private File(String child, File parent) { 260 assert parent.path != null; 261 assert (!parent.path.equals("")); 262 this.path = fs.resolve(parent.path, child); 263 this.prefixLength = parent.prefixLength; 264 } 265 266 /** 267 * Creates a new <code>File</code> instance by converting the given 268 * pathname string into an abstract pathname. If the given string is 269 * the empty string, then the result is the empty abstract pathname. 270 * 271 * @param pathname A pathname string 272 * @throws NullPointerException 273 * If the <code>pathname</code> argument is <code>null</code> 274 */ 275 public File(String pathname) { 276 if (pathname == null) { 277 throw new NullPointerException(); 278 } 279 this.path = fs.normalize(pathname); 280 this.prefixLength = fs.prefixLength(this.path); 281 } 282 283 /* Note: The two-argument File constructors do not interpret an empty 284 parent abstract pathname as the current user directory. An empty parent 285 instead causes the child to be resolved against the system-dependent 286 directory defined by the FileSystem.getDefaultParent method. On Unix 287 this default is "/", while on Microsoft Windows it is "\\". This is required for 288 compatibility with the original behavior of this class. */ 289 290 /** 291 * Creates a new <code>File</code> instance from a parent pathname string 292 * and a child pathname string. 293 * 294 * <p> If <code>parent</code> is <code>null</code> then the new 295 * <code>File</code> instance is created as if by invoking the 296 * single-argument <code>File</code> constructor on the given 297 * <code>child</code> pathname string. 298 * 299 * <p> Otherwise the <code>parent</code> pathname string is taken to denote 300 * a directory, and the <code>child</code> pathname string is taken to 301 * denote either a directory or a file. If the <code>child</code> pathname 302 * string is absolute then it is converted into a relative pathname in a 303 * system-dependent way. If <code>parent</code> is the empty string then 304 * the new <code>File</code> instance is created by converting 305 * <code>child</code> into an abstract pathname and resolving the result 306 * against a system-dependent default directory. Otherwise each pathname 307 * string is converted into an abstract pathname and the child abstract 308 * pathname is resolved against the parent. 309 * 310 * @param parent The parent pathname string 311 * @param child The child pathname string 312 * @throws NullPointerException 313 * If <code>child</code> is <code>null</code> 314 */ 315 public File(String parent, String child) { 316 if (child == null) { 317 throw new NullPointerException(); 318 } 319 if (parent != null) { 320 if (parent.equals("")) { 321 this.path = fs.resolve(fs.getDefaultParent(), 322 fs.normalize(child)); 323 } else { 324 this.path = fs.resolve(fs.normalize(parent), 325 fs.normalize(child)); 326 } 327 } else { 328 this.path = fs.normalize(child); 329 } 330 this.prefixLength = fs.prefixLength(this.path); 331 } 332 333 /** 334 * Creates a new <code>File</code> instance from a parent abstract 335 * pathname and a child pathname string. 336 * 337 * <p> If <code>parent</code> is <code>null</code> then the new 338 * <code>File</code> instance is created as if by invoking the 339 * single-argument <code>File</code> constructor on the given 340 * <code>child</code> pathname string. 341 * 342 * <p> Otherwise the <code>parent</code> abstract pathname is taken to 343 * denote a directory, and the <code>child</code> pathname string is taken 344 * to denote either a directory or a file. If the <code>child</code> 345 * pathname string is absolute then it is converted into a relative 346 * pathname in a system-dependent way. If <code>parent</code> is the empty 347 * abstract pathname then the new <code>File</code> instance is created by 348 * converting <code>child</code> into an abstract pathname and resolving 349 * the result against a system-dependent default directory. Otherwise each 350 * pathname string is converted into an abstract pathname and the child 351 * abstract pathname is resolved against the parent. 352 * 353 * @param parent The parent abstract pathname 354 * @param child The child pathname string 355 * @throws NullPointerException 356 * If <code>child</code> is <code>null</code> 357 */ 358 public File(File parent, String child) { 359 if (child == null) { 360 throw new NullPointerException(); 361 } 362 if (parent != null) { 363 if (parent.path.equals("")) { 364 this.path = fs.resolve(fs.getDefaultParent(), 365 fs.normalize(child)); 366 } else { 367 this.path = fs.resolve(parent.path, 368 fs.normalize(child)); 369 } 370 } else { 371 this.path = fs.normalize(child); 372 } 373 this.prefixLength = fs.prefixLength(this.path); 374 } 375 376 /** 377 * Creates a new {@code File} instance by converting the given 378 * {@code file:} URI into an abstract pathname. 379 * 380 * <p> The exact form of a {@code file:} URI is system-dependent, hence 381 * the transformation performed by this constructor is also 382 * system-dependent. 383 * 384 * <p> For a given abstract pathname <i>f</i> it is guaranteed that 385 * 386 * <blockquote><code> 387 * new File(</code><i> f</i><code>.{@link #toURI() 388 * toURI}()).equals(</code><i> f</i><code>.{@link #getAbsoluteFile() getAbsoluteFile}()) 389 * </code></blockquote> 390 * 391 * so long as the original abstract pathname, the URI, and the new abstract 392 * pathname are all created in (possibly different invocations of) the same 393 * Java virtual machine. This relationship typically does not hold, 394 * however, when a {@code file:} URI that is created in a virtual machine 395 * on one operating system is converted into an abstract pathname in a 396 * virtual machine on a different operating system. 397 * 398 * @param uri 399 * An absolute, hierarchical URI with a scheme equal to 400 * {@code "file"}, a non-empty path component, and undefined 401 * authority, query, and fragment components 402 * 403 * @throws NullPointerException 404 * If {@code uri} is {@code null} 405 * 406 * @throws IllegalArgumentException 407 * If the preconditions on the parameter do not hold 408 * 409 * @see #toURI() 410 * @see java.net.URI 411 * @since 1.4 412 */ 413 public File(URI uri) { 414 415 // Check our many preconditions 416 if (!uri.isAbsolute()) 417 throw new IllegalArgumentException("URI is not absolute"); 418 if (uri.isOpaque()) 419 throw new IllegalArgumentException("URI is not hierarchical"); 420 String scheme = uri.getScheme(); 421 if ((scheme == null) || !scheme.equalsIgnoreCase("file")) 422 throw new IllegalArgumentException("URI scheme is not \"file\""); 423 if (uri.getAuthority() != null) 424 throw new IllegalArgumentException("URI has an authority component"); 425 if (uri.getFragment() != null) 426 throw new IllegalArgumentException("URI has a fragment component"); 427 if (uri.getQuery() != null) 428 throw new IllegalArgumentException("URI has a query component"); 429 String p = uri.getPath(); 430 if (p.equals("")) 431 throw new IllegalArgumentException("URI path component is empty"); 432 433 // Okay, now initialize 434 p = fs.fromURIPath(p); 435 if (File.separatorChar != '/') 436 p = p.replace('/', File.separatorChar); 437 this.path = fs.normalize(p); 438 this.prefixLength = fs.prefixLength(this.path); 439 } 440 441 442 /* -- Path-component accessors -- */ 443 444 /** 445 * Returns the name of the file or directory denoted by this abstract 446 * pathname. This is just the last name in the pathname's name 447 * sequence. If the pathname's name sequence is empty, then the empty 448 * string is returned. 449 * 450 * @return The name of the file or directory denoted by this abstract 451 * pathname, or the empty string if this pathname's name sequence 452 * is empty 453 */ 454 public String getName() { 455 int index = path.lastIndexOf(separatorChar); 456 if (index < prefixLength) return path.substring(prefixLength); 457 return path.substring(index + 1); 458 } 459 460 /** 461 * Returns the pathname string of this abstract pathname's parent, or 462 * <code>null</code> if this pathname does not name a parent directory. 463 * 464 * <p> The <em>parent</em> of an abstract pathname consists of the 465 * pathname's prefix, if any, and each name in the pathname's name 466 * sequence except for the last. If the name sequence is empty then 467 * the pathname does not name a parent directory. 468 * 469 * @return The pathname string of the parent directory named by this 470 * abstract pathname, or <code>null</code> if this pathname 471 * does not name a parent 472 */ 473 public String getParent() { 474 int index = path.lastIndexOf(separatorChar); 475 if (index < prefixLength) { 476 if ((prefixLength > 0) && (path.length() > prefixLength)) 477 return path.substring(0, prefixLength); 478 return null; 479 } 480 return path.substring(0, index); 481 } 482 483 /** 484 * Returns the abstract pathname of this abstract pathname's parent, 485 * or <code>null</code> if this pathname does not name a parent 486 * directory. 487 * 488 * <p> The <em>parent</em> of an abstract pathname consists of the 489 * pathname's prefix, if any, and each name in the pathname's name 490 * sequence except for the last. If the name sequence is empty then 491 * the pathname does not name a parent directory. 492 * 493 * @return The abstract pathname of the parent directory named by this 494 * abstract pathname, or <code>null</code> if this pathname 495 * does not name a parent 496 * 497 * @since 1.2 498 */ 499 public File getParentFile() { 500 String p = this.getParent(); 501 if (p == null) return null; 502 return new File(p, this.prefixLength); 503 } 504 505 /** 506 * Converts this abstract pathname into a pathname string. The resulting 507 * string uses the {@link #separator default name-separator character} to 508 * separate the names in the name sequence. 509 * 510 * @return The string form of this abstract pathname 511 */ 512 public String getPath() { 513 return path; 514 } 515 516 517 /* -- Path operations -- */ 518 519 /** 520 * Tests whether this abstract pathname is absolute. The definition of 521 * absolute pathname is system dependent. On UNIX systems, a pathname is 522 * absolute if its prefix is <code>"/"</code>. On Microsoft Windows systems, a 523 * pathname is absolute if its prefix is a drive specifier followed by 524 * <code>"\\"</code>, or if its prefix is <code>"\\\\"</code>. 525 * 526 * @return <code>true</code> if this abstract pathname is absolute, 527 * <code>false</code> otherwise 528 */ 529 public boolean isAbsolute() { 530 return fs.isAbsolute(this); 531 } 532 533 /** 534 * Returns the absolute pathname string of this abstract pathname. 535 * 536 * <p> If this abstract pathname is already absolute, then the pathname 537 * string is simply returned as if by the {@link #getPath} 538 * method. If this abstract pathname is the empty abstract pathname then 539 * the pathname string of the current user directory, which is named by the 540 * system property <code>user.dir</code>, is returned. Otherwise this 541 * pathname is resolved in a system-dependent way. On UNIX systems, a 542 * relative pathname is made absolute by resolving it against the current 543 * user directory. On Microsoft Windows systems, a relative pathname is made absolute 544 * by resolving it against the current directory of the drive named by the 545 * pathname, if any; if not, it is resolved against the current user 546 * directory. 547 * 548 * @return The absolute pathname string denoting the same file or 549 * directory as this abstract pathname 550 * 551 * @throws SecurityException 552 * If a required system property value cannot be accessed. 553 * 554 * @see java.io.File#isAbsolute() 555 */ 556 public String getAbsolutePath() { 557 return fs.resolve(this); 558 } 559 560 /** 561 * Returns the absolute form of this abstract pathname. Equivalent to 562 * <code>new File(this.{@link #getAbsolutePath})</code>. 563 * 564 * @return The absolute abstract pathname denoting the same file or 565 * directory as this abstract pathname 566 * 567 * @throws SecurityException 568 * If a required system property value cannot be accessed. 569 * 570 * @since 1.2 571 */ 572 public File getAbsoluteFile() { 573 String absPath = getAbsolutePath(); 574 return new File(absPath, fs.prefixLength(absPath)); 575 } 576 577 /** 578 * Returns the canonical pathname string of this abstract pathname. 579 * 580 * <p> A canonical pathname is both absolute and unique. The precise 581 * definition of canonical form is system-dependent. This method first 582 * converts this pathname to absolute form if necessary, as if by invoking the 583 * {@link #getAbsolutePath} method, and then maps it to its unique form in a 584 * system-dependent way. This typically involves removing redundant names 585 * such as {@code "."} and {@code ".."} from the pathname, resolving 586 * symbolic links (on UNIX platforms), and converting drive letters to a 587 * standard case (on Microsoft Windows platforms). 588 * 589 * <p> Every pathname that denotes an existing file or directory has a 590 * unique canonical form. Every pathname that denotes a nonexistent file 591 * or directory also has a unique canonical form. The canonical form of 592 * the pathname of a nonexistent file or directory may be different from 593 * the canonical form of the same pathname after the file or directory is 594 * created. Similarly, the canonical form of the pathname of an existing 595 * file or directory may be different from the canonical form of the same 596 * pathname after the file or directory is deleted. 597 * 598 * @return The canonical pathname string denoting the same file or 599 * directory as this abstract pathname 600 * 601 * @throws IOException 602 * If an I/O error occurs, which is possible because the 603 * construction of the canonical pathname may require 604 * filesystem queries 605 * 606 * @throws SecurityException 607 * If a required system property value cannot be accessed, or 608 * if a security manager exists and its {@link 609 * java.lang.SecurityManager#checkRead} method denies 610 * read access to the file 611 * 612 * @since 1.1 613 * @see Path#toRealPath 614 */ 615 public String getCanonicalPath() throws IOException { 616 if (isInvalid()) { 617 throw new IOException("Invalid file path"); 618 } 619 return fs.canonicalize(fs.resolve(this)); 620 } 621 622 /** 623 * Returns the canonical form of this abstract pathname. Equivalent to 624 * <code>new File(this.{@link #getCanonicalPath})</code>. 625 * 626 * @return The canonical pathname string denoting the same file or 627 * directory as this abstract pathname 628 * 629 * @throws IOException 630 * If an I/O error occurs, which is possible because the 631 * construction of the canonical pathname may require 632 * filesystem queries 633 * 634 * @throws SecurityException 635 * If a required system property value cannot be accessed, or 636 * if a security manager exists and its {@link 637 * java.lang.SecurityManager#checkRead} method denies 638 * read access to the file 639 * 640 * @since 1.2 641 * @see Path#toRealPath 642 */ 643 public File getCanonicalFile() throws IOException { 644 String canonPath = getCanonicalPath(); 645 return new File(canonPath, fs.prefixLength(canonPath)); 646 } 647 648 private static String slashify(String path, boolean isDirectory) { 649 String p = path; 650 if (File.separatorChar != '/') 651 p = p.replace(File.separatorChar, '/'); 652 if (!p.startsWith("/")) 653 p = "/" + p; 654 if (!p.endsWith("/") && isDirectory) 655 p = p + "/"; 656 return p; 657 } 658 659 /** 660 * Converts this abstract pathname into a <code>file:</code> URL. The 661 * exact form of the URL is system-dependent. If it can be determined that 662 * the file denoted by this abstract pathname is a directory, then the 663 * resulting URL will end with a slash. 664 * 665 * @return A URL object representing the equivalent file URL 666 * 667 * @throws MalformedURLException 668 * If the path cannot be parsed as a URL 669 * 670 * @see #toURI() 671 * @see java.net.URI 672 * @see java.net.URI#toURL() 673 * @see java.net.URL 674 * @since 1.2 675 * 676 * @deprecated This method does not automatically escape characters that 677 * are illegal in URLs. It is recommended that new code convert an 678 * abstract pathname into a URL by first converting it into a URI, via the 679 * {@link #toURI() toURI} method, and then converting the URI into a URL 680 * via the {@link java.net.URI#toURL() URI.toURL} method. 681 */ 682 @Deprecated 683 public URL toURL() throws MalformedURLException { 684 if (isInvalid()) { 685 throw new MalformedURLException("Invalid file path"); 686 } 687 return new URL("file", "", slashify(getAbsolutePath(), isDirectory())); 688 } 689 690 /** 691 * Constructs a {@code file:} URI that represents this abstract pathname. 692 * 693 * <p> The exact form of the URI is system-dependent. If it can be 694 * determined that the file denoted by this abstract pathname is a 695 * directory, then the resulting URI will end with a slash. 696 * 697 * <p> For a given abstract pathname <i>f</i>, it is guaranteed that 698 * 699 * <blockquote><code> 700 * new {@link #File(java.net.URI) File}(</code><i> f</i><code>.toURI()).equals( 701 * </code><i> f</i><code>.{@link #getAbsoluteFile() getAbsoluteFile}()) 702 * </code></blockquote> 703 * 704 * so long as the original abstract pathname, the URI, and the new abstract 705 * pathname are all created in (possibly different invocations of) the same 706 * Java virtual machine. Due to the system-dependent nature of abstract 707 * pathnames, however, this relationship typically does not hold when a 708 * {@code file:} URI that is created in a virtual machine on one operating 709 * system is converted into an abstract pathname in a virtual machine on a 710 * different operating system. 711 * 712 * <p> Note that when this abstract pathname represents a UNC pathname then 713 * all components of the UNC (including the server name component) are encoded 714 * in the {@code URI} path. The authority component is undefined, meaning 715 * that it is represented as {@code null}. The {@link Path} class defines the 716 * {@link Path#toUri toUri} method to encode the server name in the authority 717 * component of the resulting {@code URI}. The {@link #toPath toPath} method 718 * may be used to obtain a {@code Path} representing this abstract pathname. 719 * 720 * @return An absolute, hierarchical URI with a scheme equal to 721 * {@code "file"}, a path representing this abstract pathname, 722 * and undefined authority, query, and fragment components 723 * @throws SecurityException If a required system property value cannot 724 * be accessed. 725 * 726 * @see #File(java.net.URI) 727 * @see java.net.URI 728 * @see java.net.URI#toURL() 729 * @since 1.4 730 */ 731 public URI toURI() { 732 try { 733 File f = getAbsoluteFile(); 734 String sp = slashify(f.getPath(), f.isDirectory()); 735 if (sp.startsWith("//")) 736 sp = "//" + sp; 737 return new URI("file", null, sp, null); 738 } catch (URISyntaxException x) { 739 throw new Error(x); // Can't happen 740 } 741 } 742 743 744 /* -- Attribute accessors -- */ 745 746 /** 747 * Tests whether the application can read the file denoted by this 748 * abstract pathname. On some platforms it may be possible to start the 749 * Java virtual machine with special privileges that allow it to read 750 * files that are marked as unreadable. Consequently this method may return 751 * {@code true} even though the file does not have read permissions. 752 * 753 * @return <code>true</code> if and only if the file specified by this 754 * abstract pathname exists <em>and</em> can be read by the 755 * application; <code>false</code> otherwise 756 * 757 * @throws SecurityException 758 * If a security manager exists and its {@link 759 * java.lang.SecurityManager#checkRead(java.lang.String)} 760 * method denies read access to the file 761 */ 762 public boolean canRead() { 763 SecurityManager security = System.getSecurityManager(); 764 if (security != null) { 765 security.checkRead(path); 766 } 767 if (isInvalid()) { 768 return false; 769 } 770 return fs.checkAccess(this, FileSystem.ACCESS_READ); 771 } 772 773 /** 774 * Tests whether the application can modify the file denoted by this 775 * abstract pathname. On some platforms it may be possible to start the 776 * Java virtual machine with special privileges that allow it to modify 777 * files that are marked read-only. Consequently this method may return 778 * {@code true} even though the file is marked read-only. 779 * 780 * @return <code>true</code> if and only if the file system actually 781 * contains a file denoted by this abstract pathname <em>and</em> 782 * the application is allowed to write to the file; 783 * <code>false</code> otherwise. 784 * 785 * @throws SecurityException 786 * If a security manager exists and its {@link 787 * java.lang.SecurityManager#checkWrite(java.lang.String)} 788 * method denies write access to the file 789 */ 790 public boolean canWrite() { 791 SecurityManager security = System.getSecurityManager(); 792 if (security != null) { 793 security.checkWrite(path); 794 } 795 if (isInvalid()) { 796 return false; 797 } 798 return fs.checkAccess(this, FileSystem.ACCESS_WRITE); 799 } 800 801 /** 802 * Tests whether the file or directory denoted by this abstract pathname 803 * exists. 804 * 805 * @return <code>true</code> if and only if the file or directory denoted 806 * by this abstract pathname exists; <code>false</code> otherwise 807 * 808 * @throws SecurityException 809 * If a security manager exists and its {@link 810 * java.lang.SecurityManager#checkRead(java.lang.String)} 811 * method denies read access to the file or directory 812 */ 813 public boolean exists() { 814 SecurityManager security = System.getSecurityManager(); 815 if (security != null) { 816 security.checkRead(path); 817 } 818 if (isInvalid()) { 819 return false; 820 } 821 return ((fs.getBooleanAttributes(this) & FileSystem.BA_EXISTS) != 0); 822 } 823 824 /** 825 * Tests whether the file denoted by this abstract pathname is a 826 * directory. 827 * 828 * <p> Where it is required to distinguish an I/O exception from the case 829 * that the file is not a directory, or where several attributes of the 830 * same file are required at the same time, then the {@link 831 * java.nio.file.Files#readAttributes(Path,Class,LinkOption[]) 832 * Files.readAttributes} method may be used. 833 * 834 * @return <code>true</code> if and only if the file denoted by this 835 * abstract pathname exists <em>and</em> is a directory; 836 * <code>false</code> otherwise 837 * 838 * @throws SecurityException 839 * If a security manager exists and its {@link 840 * java.lang.SecurityManager#checkRead(java.lang.String)} 841 * method denies read access to the file 842 */ 843 public boolean isDirectory() { 844 SecurityManager security = System.getSecurityManager(); 845 if (security != null) { 846 security.checkRead(path); 847 } 848 if (isInvalid()) { 849 return false; 850 } 851 return ((fs.getBooleanAttributes(this) & FileSystem.BA_DIRECTORY) 852 != 0); 853 } 854 855 /** 856 * Tests whether the file denoted by this abstract pathname is a normal 857 * file. A file is <em>normal</em> if it is not a directory and, in 858 * addition, satisfies other system-dependent criteria. Any non-directory 859 * file created by a Java application is guaranteed to be a normal file. 860 * 861 * <p> Where it is required to distinguish an I/O exception from the case 862 * that the file is not a normal file, or where several attributes of the 863 * same file are required at the same time, then the {@link 864 * java.nio.file.Files#readAttributes(Path,Class,LinkOption[]) 865 * Files.readAttributes} method may be used. 866 * 867 * @return <code>true</code> if and only if the file denoted by this 868 * abstract pathname exists <em>and</em> is a normal file; 869 * <code>false</code> otherwise 870 * 871 * @throws SecurityException 872 * If a security manager exists and its {@link 873 * java.lang.SecurityManager#checkRead(java.lang.String)} 874 * method denies read access to the file 875 */ 876 public boolean isFile() { 877 SecurityManager security = System.getSecurityManager(); 878 if (security != null) { 879 security.checkRead(path); 880 } 881 if (isInvalid()) { 882 return false; 883 } 884 return ((fs.getBooleanAttributes(this) & FileSystem.BA_REGULAR) != 0); 885 } 886 887 /** 888 * Tests whether the file named by this abstract pathname is a hidden 889 * file. The exact definition of <em>hidden</em> is system-dependent. On 890 * UNIX systems, a file is considered to be hidden if its name begins with 891 * a period character (<code>'.'</code>). On Microsoft Windows systems, a file is 892 * considered to be hidden if it has been marked as such in the filesystem. 893 * 894 * @return <code>true</code> if and only if the file denoted by this 895 * abstract pathname is hidden according to the conventions of the 896 * underlying platform 897 * 898 * @throws SecurityException 899 * If a security manager exists and its {@link 900 * java.lang.SecurityManager#checkRead(java.lang.String)} 901 * method denies read access to the file 902 * 903 * @since 1.2 904 */ 905 public boolean isHidden() { 906 SecurityManager security = System.getSecurityManager(); 907 if (security != null) { 908 security.checkRead(path); 909 } 910 if (isInvalid()) { 911 return false; 912 } 913 return ((fs.getBooleanAttributes(this) & FileSystem.BA_HIDDEN) != 0); 914 } 915 916 /** 917 * Returns the time that the file denoted by this abstract pathname was 918 * last modified. 919 * 920 * <p> Where it is required to distinguish an I/O exception from the case 921 * where {@code 0L} is returned, or where several attributes of the 922 * same file are required at the same time, or where the time of last 923 * access or the creation time are required, then the {@link 924 * java.nio.file.Files#readAttributes(Path,Class,LinkOption[]) 925 * Files.readAttributes} method may be used. 926 * 927 * @return A <code>long</code> value representing the time the file was 928 * last modified, measured in milliseconds since the epoch 929 * (00:00:00 GMT, January 1, 1970), or <code>0L</code> if the 930 * file does not exist or if an I/O error occurs 931 * 932 * @throws SecurityException 933 * If a security manager exists and its {@link 934 * java.lang.SecurityManager#checkRead(java.lang.String)} 935 * method denies read access to the file 936 */ 937 public long lastModified() { 938 SecurityManager security = System.getSecurityManager(); 939 if (security != null) { 940 security.checkRead(path); 941 } 942 if (isInvalid()) { 943 return 0L; 944 } 945 return fs.getLastModifiedTime(this); 946 } 947 948 /** 949 * Returns the length of the file denoted by this abstract pathname. 950 * The return value is unspecified if this pathname denotes a directory. 951 * 952 * <p> Where it is required to distinguish an I/O exception from the case 953 * that {@code 0L} is returned, or where several attributes of the same file 954 * are required at the same time, then the {@link 955 * java.nio.file.Files#readAttributes(Path,Class,LinkOption[]) 956 * Files.readAttributes} method may be used. 957 * 958 * @return The length, in bytes, of the file denoted by this abstract 959 * pathname, or <code>0L</code> if the file does not exist. Some 960 * operating systems may return <code>0L</code> for pathnames 961 * denoting system-dependent entities such as devices or pipes. 962 * 963 * @throws SecurityException 964 * If a security manager exists and its {@link 965 * java.lang.SecurityManager#checkRead(java.lang.String)} 966 * method denies read access to the file 967 */ 968 public long length() { 969 SecurityManager security = System.getSecurityManager(); 970 if (security != null) { 971 security.checkRead(path); 972 } 973 if (isInvalid()) { 974 return 0L; 975 } 976 return fs.getLength(this); 977 } 978 979 980 /* -- File operations -- */ 981 982 /** 983 * Atomically creates a new, empty file named by this abstract pathname if 984 * and only if a file with this name does not yet exist. The check for the 985 * existence of the file and the creation of the file if it does not exist 986 * are a single operation that is atomic with respect to all other 987 * filesystem activities that might affect the file. 988 * <P> 989 * Note: this method should <i>not</i> be used for file-locking, as 990 * the resulting protocol cannot be made to work reliably. The 991 * {@link java.nio.channels.FileLock FileLock} 992 * facility should be used instead. 993 * 994 * @return <code>true</code> if the named file does not exist and was 995 * successfully created; <code>false</code> if the named file 996 * already exists 997 * 998 * @throws IOException 999 * If an I/O error occurred 1000 * 1001 * @throws SecurityException 1002 * If a security manager exists and its {@link 1003 * java.lang.SecurityManager#checkWrite(java.lang.String)} 1004 * method denies write access to the file 1005 * 1006 * @since 1.2 1007 */ 1008 public boolean createNewFile() throws IOException { 1009 SecurityManager security = System.getSecurityManager(); 1010 if (security != null) security.checkWrite(path); 1011 if (isInvalid()) { 1012 throw new IOException("Invalid file path"); 1013 } 1014 return fs.createFileExclusively(path); 1015 } 1016 1017 /** 1018 * Deletes the file or directory denoted by this abstract pathname. If 1019 * this pathname denotes a directory, then the directory must be empty in 1020 * order to be deleted. 1021 * 1022 * <p> Note that the {@link java.nio.file.Files} class defines the {@link 1023 * java.nio.file.Files#delete(Path) delete} method to throw an {@link IOException} 1024 * when a file cannot be deleted. This is useful for error reporting and to 1025 * diagnose why a file cannot be deleted. 1026 * 1027 * @return <code>true</code> if and only if the file or directory is 1028 * successfully deleted; <code>false</code> otherwise 1029 * 1030 * @throws SecurityException 1031 * If a security manager exists and its {@link 1032 * java.lang.SecurityManager#checkDelete} method denies 1033 * delete access to the file 1034 */ 1035 public boolean delete() { 1036 SecurityManager security = System.getSecurityManager(); 1037 if (security != null) { 1038 security.checkDelete(path); 1039 } 1040 if (isInvalid()) { 1041 return false; 1042 } 1043 return fs.delete(this); 1044 } 1045 1046 /** 1047 * Requests that the file or directory denoted by this abstract 1048 * pathname be deleted when the virtual machine terminates. 1049 * Files (or directories) are deleted in the reverse order that 1050 * they are registered. Invoking this method to delete a file or 1051 * directory that is already registered for deletion has no effect. 1052 * Deletion will be attempted only for normal termination of the 1053 * virtual machine, as defined by the Java Language Specification. 1054 * 1055 * <p> Once deletion has been requested, it is not possible to cancel the 1056 * request. This method should therefore be used with care. 1057 * 1058 * <P> 1059 * Note: this method should <i>not</i> be used for file-locking, as 1060 * the resulting protocol cannot be made to work reliably. The 1061 * {@link java.nio.channels.FileLock FileLock} 1062 * facility should be used instead. 1063 * 1064 * @throws SecurityException 1065 * If a security manager exists and its {@link 1066 * java.lang.SecurityManager#checkDelete} method denies 1067 * delete access to the file 1068 * 1069 * @see #delete 1070 * 1071 * @since 1.2 1072 */ 1073 public void deleteOnExit() { 1074 SecurityManager security = System.getSecurityManager(); 1075 if (security != null) { 1076 security.checkDelete(path); 1077 } 1078 if (isInvalid()) { 1079 return; 1080 } 1081 DeleteOnExitHook.add(path); 1082 } 1083 1084 /** 1085 * Returns an array of strings naming the files and directories in the 1086 * directory denoted by this abstract pathname. 1087 * 1088 * <p> If this abstract pathname does not denote a directory, then this 1089 * method returns {@code null}. Otherwise an array of strings is 1090 * returned, one for each file or directory in the directory. Names 1091 * denoting the directory itself and the directory's parent directory are 1092 * not included in the result. Each string is a file name rather than a 1093 * complete path. 1094 * 1095 * <p> There is no guarantee that the name strings in the resulting array 1096 * will appear in any specific order; they are not, in particular, 1097 * guaranteed to appear in alphabetical order. 1098 * 1099 * <p> Note that the {@link java.nio.file.Files} class defines the {@link 1100 * java.nio.file.Files#newDirectoryStream(Path) newDirectoryStream} method to 1101 * open a directory and iterate over the names of the files in the directory. 1102 * This may use less resources when working with very large directories, and 1103 * may be more responsive when working with remote directories. 1104 * 1105 * @return An array of strings naming the files and directories in the 1106 * directory denoted by this abstract pathname. The array will be 1107 * empty if the directory is empty. Returns {@code null} if 1108 * this abstract pathname does not denote a directory, or if an 1109 * I/O error occurs. 1110 * 1111 * @throws SecurityException 1112 * If a security manager exists and its {@link 1113 * SecurityManager#checkRead(String)} method denies read access to 1114 * the directory 1115 */ 1116 public String[] list() { 1117 SecurityManager security = System.getSecurityManager(); 1118 if (security != null) { 1119 security.checkRead(path); 1120 } 1121 if (isInvalid()) { 1122 return null; 1123 } 1124 return fs.list(this); 1125 } 1126 1127 /** 1128 * Returns an array of strings naming the files and directories in the 1129 * directory denoted by this abstract pathname that satisfy the specified 1130 * filter. The behavior of this method is the same as that of the 1131 * {@link #list()} method, except that the strings in the returned array 1132 * must satisfy the filter. If the given {@code filter} is {@code null} 1133 * then all names are accepted. Otherwise, a name satisfies the filter if 1134 * and only if the value {@code true} results when the {@link 1135 * FilenameFilter#accept FilenameFilter.accept(File, String)} method 1136 * of the filter is invoked on this abstract pathname and the name of a 1137 * file or directory in the directory that it denotes. 1138 * 1139 * @param filter 1140 * A filename filter 1141 * 1142 * @return An array of strings naming the files and directories in the 1143 * directory denoted by this abstract pathname that were accepted 1144 * by the given {@code filter}. The array will be empty if the 1145 * directory is empty or if no names were accepted by the filter. 1146 * Returns {@code null} if this abstract pathname does not denote 1147 * a directory, or if an I/O error occurs. 1148 * 1149 * @throws SecurityException 1150 * If a security manager exists and its {@link 1151 * SecurityManager#checkRead(String)} method denies read access to 1152 * the directory 1153 * 1154 * @see java.nio.file.Files#newDirectoryStream(Path,String) 1155 */ 1156 public String[] list(FilenameFilter filter) { 1157 String names[] = list(); 1158 if ((names == null) || (filter == null)) { 1159 return names; 1160 } 1161 List<String> v = new ArrayList<>(); 1162 for (int i = 0 ; i < names.length ; i++) { 1163 if (filter.accept(this, names[i])) { 1164 v.add(names[i]); 1165 } 1166 } 1167 return v.toArray(new String[v.size()]); 1168 } 1169 1170 /** 1171 * Returns an array of abstract pathnames denoting the files in the 1172 * directory denoted by this abstract pathname. 1173 * 1174 * <p> If this abstract pathname does not denote a directory, then this 1175 * method returns {@code null}. Otherwise an array of {@code File} objects 1176 * is returned, one for each file or directory in the directory. Pathnames 1177 * denoting the directory itself and the directory's parent directory are 1178 * not included in the result. Each resulting abstract pathname is 1179 * constructed from this abstract pathname using the {@link #File(File, 1180 * String) File(File, String)} constructor. Therefore if this 1181 * pathname is absolute then each resulting pathname is absolute; if this 1182 * pathname is relative then each resulting pathname will be relative to 1183 * the same directory. 1184 * 1185 * <p> There is no guarantee that the name strings in the resulting array 1186 * will appear in any specific order; they are not, in particular, 1187 * guaranteed to appear in alphabetical order. 1188 * 1189 * <p> Note that the {@link java.nio.file.Files} class defines the {@link 1190 * java.nio.file.Files#newDirectoryStream(Path) newDirectoryStream} method 1191 * to open a directory and iterate over the names of the files in the 1192 * directory. This may use less resources when working with very large 1193 * directories. 1194 * 1195 * @return An array of abstract pathnames denoting the files and 1196 * directories in the directory denoted by this abstract pathname. 1197 * The array will be empty if the directory is empty. Returns 1198 * {@code null} if this abstract pathname does not denote a 1199 * directory, or if an I/O error occurs. 1200 * 1201 * @throws SecurityException 1202 * If a security manager exists and its {@link 1203 * SecurityManager#checkRead(String)} method denies read access to 1204 * the directory 1205 * 1206 * @since 1.2 1207 */ 1208 public File[] listFiles() { 1209 String[] ss = list(); 1210 if (ss == null) return null; 1211 int n = ss.length; 1212 File[] fs = new File[n]; 1213 for (int i = 0; i < n; i++) { 1214 fs[i] = new File(ss[i], this); 1215 } 1216 return fs; 1217 } 1218 1219 /** 1220 * Returns an array of abstract pathnames denoting the files and 1221 * directories in the directory denoted by this abstract pathname that 1222 * satisfy the specified filter. The behavior of this method is the same 1223 * as that of the {@link #listFiles()} method, except that the pathnames in 1224 * the returned array must satisfy the filter. If the given {@code filter} 1225 * is {@code null} then all pathnames are accepted. Otherwise, a pathname 1226 * satisfies the filter if and only if the value {@code true} results when 1227 * the {@link FilenameFilter#accept 1228 * FilenameFilter.accept(File, String)} method of the filter is 1229 * invoked on this abstract pathname and the name of a file or directory in 1230 * the directory that it denotes. 1231 * 1232 * @param filter 1233 * A filename filter 1234 * 1235 * @return An array of abstract pathnames denoting the files and 1236 * directories in the directory denoted by this abstract pathname. 1237 * The array will be empty if the directory is empty. Returns 1238 * {@code null} if this abstract pathname does not denote a 1239 * directory, or if an I/O error occurs. 1240 * 1241 * @throws SecurityException 1242 * If a security manager exists and its {@link 1243 * SecurityManager#checkRead(String)} method denies read access to 1244 * the directory 1245 * 1246 * @since 1.2 1247 * @see java.nio.file.Files#newDirectoryStream(Path,String) 1248 */ 1249 public File[] listFiles(FilenameFilter filter) { 1250 String ss[] = list(); 1251 if (ss == null) return null; 1252 ArrayList<File> files = new ArrayList<>(); 1253 for (String s : ss) 1254 if ((filter == null) || filter.accept(this, s)) 1255 files.add(new File(s, this)); 1256 return files.toArray(new File[files.size()]); 1257 } 1258 1259 /** 1260 * Returns an array of abstract pathnames denoting the files and 1261 * directories in the directory denoted by this abstract pathname that 1262 * satisfy the specified filter. The behavior of this method is the same 1263 * as that of the {@link #listFiles()} method, except that the pathnames in 1264 * the returned array must satisfy the filter. If the given {@code filter} 1265 * is {@code null} then all pathnames are accepted. Otherwise, a pathname 1266 * satisfies the filter if and only if the value {@code true} results when 1267 * the {@link FileFilter#accept FileFilter.accept(File)} method of the 1268 * filter is invoked on the pathname. 1269 * 1270 * @param filter 1271 * A file filter 1272 * 1273 * @return An array of abstract pathnames denoting the files and 1274 * directories in the directory denoted by this abstract pathname. 1275 * The array will be empty if the directory is empty. Returns 1276 * {@code null} if this abstract pathname does not denote a 1277 * directory, or if an I/O error occurs. 1278 * 1279 * @throws SecurityException 1280 * If a security manager exists and its {@link 1281 * SecurityManager#checkRead(String)} method denies read access to 1282 * the directory 1283 * 1284 * @since 1.2 1285 * @see java.nio.file.Files#newDirectoryStream(Path,java.nio.file.DirectoryStream.Filter) 1286 */ 1287 public File[] listFiles(FileFilter filter) { 1288 String ss[] = list(); 1289 if (ss == null) return null; 1290 ArrayList<File> files = new ArrayList<>(); 1291 for (String s : ss) { 1292 File f = new File(s, this); 1293 if ((filter == null) || filter.accept(f)) 1294 files.add(f); 1295 } 1296 return files.toArray(new File[files.size()]); 1297 } 1298 1299 /** 1300 * Creates the directory named by this abstract pathname. 1301 * 1302 * @return <code>true</code> if and only if the directory was 1303 * created; <code>false</code> otherwise 1304 * 1305 * @throws SecurityException 1306 * If a security manager exists and its {@link 1307 * java.lang.SecurityManager#checkWrite(java.lang.String)} 1308 * method does not permit the named directory to be created 1309 */ 1310 public boolean mkdir() { 1311 SecurityManager security = System.getSecurityManager(); 1312 if (security != null) { 1313 security.checkWrite(path); 1314 } 1315 if (isInvalid()) { 1316 return false; 1317 } 1318 return fs.createDirectory(this); 1319 } 1320 1321 /** 1322 * Creates the directory named by this abstract pathname, including any 1323 * necessary but nonexistent parent directories. Note that if this 1324 * operation fails it may have succeeded in creating some of the necessary 1325 * parent directories. 1326 * 1327 * @return <code>true</code> if and only if the directory was created, 1328 * along with all necessary parent directories; <code>false</code> 1329 * otherwise 1330 * 1331 * @throws SecurityException 1332 * If a security manager exists and its {@link 1333 * java.lang.SecurityManager#checkRead(java.lang.String)} 1334 * method does not permit verification of the existence of the 1335 * named directory and all necessary parent directories; or if 1336 * the {@link 1337 * java.lang.SecurityManager#checkWrite(java.lang.String)} 1338 * method does not permit the named directory and all necessary 1339 * parent directories to be created 1340 */ 1341 public boolean mkdirs() { 1342 if (exists()) { 1343 return false; 1344 } 1345 if (mkdir()) { 1346 return true; 1347 } 1348 File canonFile = null; 1349 try { 1350 canonFile = getCanonicalFile(); 1351 } catch (IOException e) { 1352 return false; 1353 } 1354 1355 File parent = canonFile.getParentFile(); 1356 return (parent != null && (parent.mkdirs() || parent.exists()) && 1357 canonFile.mkdir()); 1358 } 1359 1360 /** 1361 * Renames the file denoted by this abstract pathname. 1362 * 1363 * <p> Many aspects of the behavior of this method are inherently 1364 * platform-dependent: The rename operation might not be able to move a 1365 * file from one filesystem to another, it might not be atomic, and it 1366 * might not succeed if a file with the destination abstract pathname 1367 * already exists. The return value should always be checked to make sure 1368 * that the rename operation was successful. 1369 * 1370 * <p> Note that the {@link java.nio.file.Files} class defines the {@link 1371 * java.nio.file.Files#move move} method to move or rename a file in a 1372 * platform independent manner. 1373 * 1374 * @param dest The new abstract pathname for the named file 1375 * 1376 * @return <code>true</code> if and only if the renaming succeeded; 1377 * <code>false</code> otherwise 1378 * 1379 * @throws SecurityException 1380 * If a security manager exists and its {@link 1381 * java.lang.SecurityManager#checkWrite(java.lang.String)} 1382 * method denies write access to either the old or new pathnames 1383 * 1384 * @throws NullPointerException 1385 * If parameter <code>dest</code> is <code>null</code> 1386 */ 1387 public boolean renameTo(File dest) { 1388 SecurityManager security = System.getSecurityManager(); 1389 if (security != null) { 1390 security.checkWrite(path); 1391 security.checkWrite(dest.path); 1392 } 1393 if (dest == null) { 1394 throw new NullPointerException(); 1395 } 1396 if (this.isInvalid() || dest.isInvalid()) { 1397 return false; 1398 } 1399 return fs.rename(this, dest); 1400 } 1401 1402 /** 1403 * Sets the last-modified time of the file or directory named by this 1404 * abstract pathname. 1405 * 1406 * <p> All platforms support file-modification times to the nearest second, 1407 * but some provide more precision. The argument will be truncated to fit 1408 * the supported precision. If the operation succeeds and no intervening 1409 * operations on the file take place, then the next invocation of the 1410 * {@link #lastModified} method will return the (possibly 1411 * truncated) <code>time</code> argument that was passed to this method. 1412 * 1413 * @param time The new last-modified time, measured in milliseconds since 1414 * the epoch (00:00:00 GMT, January 1, 1970) 1415 * 1416 * @return <code>true</code> if and only if the operation succeeded; 1417 * <code>false</code> otherwise 1418 * 1419 * @throws IllegalArgumentException If the argument is negative 1420 * 1421 * @throws SecurityException 1422 * If a security manager exists and its {@link 1423 * java.lang.SecurityManager#checkWrite(java.lang.String)} 1424 * method denies write access to the named file 1425 * 1426 * @since 1.2 1427 */ 1428 public boolean setLastModified(long time) { 1429 if (time < 0) throw new IllegalArgumentException("Negative time"); 1430 SecurityManager security = System.getSecurityManager(); 1431 if (security != null) { 1432 security.checkWrite(path); 1433 } 1434 if (isInvalid()) { 1435 return false; 1436 } 1437 return fs.setLastModifiedTime(this, time); 1438 } 1439 1440 /** 1441 * Marks the file or directory named by this abstract pathname so that 1442 * only read operations are allowed. After invoking this method the file 1443 * or directory will not change until it is either deleted or marked 1444 * to allow write access. On some platforms it may be possible to start the 1445 * Java virtual machine with special privileges that allow it to modify 1446 * files that are marked read-only. Whether or not a read-only file or 1447 * directory may be deleted depends upon the underlying system. 1448 * 1449 * @return <code>true</code> if and only if the operation succeeded; 1450 * <code>false</code> otherwise 1451 * 1452 * @throws SecurityException 1453 * If a security manager exists and its {@link 1454 * java.lang.SecurityManager#checkWrite(java.lang.String)} 1455 * method denies write access to the named file 1456 * 1457 * @since 1.2 1458 */ 1459 public boolean setReadOnly() { 1460 SecurityManager security = System.getSecurityManager(); 1461 if (security != null) { 1462 security.checkWrite(path); 1463 } 1464 if (isInvalid()) { 1465 return false; 1466 } 1467 return fs.setReadOnly(this); 1468 } 1469 1470 /** 1471 * Sets the owner's or everybody's write permission for this abstract 1472 * pathname. On some platforms it may be possible to start the Java virtual 1473 * machine with special privileges that allow it to modify files that 1474 * disallow write operations. 1475 * 1476 * <p> The {@link java.nio.file.Files} class defines methods that operate on 1477 * file attributes including file permissions. This may be used when finer 1478 * manipulation of file permissions is required. 1479 * 1480 * @param writable 1481 * If <code>true</code>, sets the access permission to allow write 1482 * operations; if <code>false</code> to disallow write operations 1483 * 1484 * @param ownerOnly 1485 * If <code>true</code>, the write permission applies only to the 1486 * owner's write permission; otherwise, it applies to everybody. If 1487 * the underlying file system can not distinguish the owner's write 1488 * permission from that of others, then the permission will apply to 1489 * everybody, regardless of this value. 1490 * 1491 * @return <code>true</code> if and only if the operation succeeded. The 1492 * operation will fail if the user does not have permission to change 1493 * the access permissions of this abstract pathname. 1494 * 1495 * @throws SecurityException 1496 * If a security manager exists and its {@link 1497 * java.lang.SecurityManager#checkWrite(java.lang.String)} 1498 * method denies write access to the named file 1499 * 1500 * @since 1.6 1501 */ 1502 public boolean setWritable(boolean writable, boolean ownerOnly) { 1503 SecurityManager security = System.getSecurityManager(); 1504 if (security != null) { 1505 security.checkWrite(path); 1506 } 1507 if (isInvalid()) { 1508 return false; 1509 } 1510 return fs.setPermission(this, FileSystem.ACCESS_WRITE, writable, ownerOnly); 1511 } 1512 1513 /** 1514 * A convenience method to set the owner's write permission for this abstract 1515 * pathname. On some platforms it may be possible to start the Java virtual 1516 * machine with special privileges that allow it to modify files that 1517 * disallow write operations. 1518 * 1519 * <p> An invocation of this method of the form {@code file.setWritable(arg)} 1520 * behaves in exactly the same way as the invocation 1521 * 1522 * <pre>{@code 1523 * file.setWritable(arg, true) 1524 * }</pre> 1525 * 1526 * @param writable 1527 * If <code>true</code>, sets the access permission to allow write 1528 * operations; if <code>false</code> to disallow write operations 1529 * 1530 * @return <code>true</code> if and only if the operation succeeded. The 1531 * operation will fail if the user does not have permission to 1532 * change the access permissions of this abstract pathname. 1533 * 1534 * @throws SecurityException 1535 * If a security manager exists and its {@link 1536 * java.lang.SecurityManager#checkWrite(java.lang.String)} 1537 * method denies write access to the file 1538 * 1539 * @since 1.6 1540 */ 1541 public boolean setWritable(boolean writable) { 1542 return setWritable(writable, true); 1543 } 1544 1545 /** 1546 * Sets the owner's or everybody's read permission for this abstract 1547 * pathname. On some platforms it may be possible to start the Java virtual 1548 * machine with special privileges that allow it to read files that are 1549 * marked as unreadable. 1550 * 1551 * <p> The {@link java.nio.file.Files} class defines methods that operate on 1552 * file attributes including file permissions. This may be used when finer 1553 * manipulation of file permissions is required. 1554 * 1555 * @param readable 1556 * If <code>true</code>, sets the access permission to allow read 1557 * operations; if <code>false</code> to disallow read operations 1558 * 1559 * @param ownerOnly 1560 * If <code>true</code>, the read permission applies only to the 1561 * owner's read permission; otherwise, it applies to everybody. If 1562 * the underlying file system can not distinguish the owner's read 1563 * permission from that of others, then the permission will apply to 1564 * everybody, regardless of this value. 1565 * 1566 * @return <code>true</code> if and only if the operation succeeded. The 1567 * operation will fail if the user does not have permission to 1568 * change the access permissions of this abstract pathname. If 1569 * <code>readable</code> is <code>false</code> and the underlying 1570 * file system does not implement a read permission, then the 1571 * operation will fail. 1572 * 1573 * @throws SecurityException 1574 * If a security manager exists and its {@link 1575 * java.lang.SecurityManager#checkWrite(java.lang.String)} 1576 * method denies write access to the file 1577 * 1578 * @since 1.6 1579 */ 1580 public boolean setReadable(boolean readable, boolean ownerOnly) { 1581 SecurityManager security = System.getSecurityManager(); 1582 if (security != null) { 1583 security.checkWrite(path); 1584 } 1585 if (isInvalid()) { 1586 return false; 1587 } 1588 return fs.setPermission(this, FileSystem.ACCESS_READ, readable, ownerOnly); 1589 } 1590 1591 /** 1592 * A convenience method to set the owner's read permission for this abstract 1593 * pathname. On some platforms it may be possible to start the Java virtual 1594 * machine with special privileges that allow it to read files that are 1595 * marked as unreadable. 1596 * 1597 * <p>An invocation of this method of the form {@code file.setReadable(arg)} 1598 * behaves in exactly the same way as the invocation 1599 * 1600 * <pre>{@code 1601 * file.setReadable(arg, true) 1602 * }</pre> 1603 * 1604 * @param readable 1605 * If <code>true</code>, sets the access permission to allow read 1606 * operations; if <code>false</code> to disallow read operations 1607 * 1608 * @return <code>true</code> if and only if the operation succeeded. The 1609 * operation will fail if the user does not have permission to 1610 * change the access permissions of this abstract pathname. If 1611 * <code>readable</code> is <code>false</code> and the underlying 1612 * file system does not implement a read permission, then the 1613 * operation will fail. 1614 * 1615 * @throws SecurityException 1616 * If a security manager exists and its {@link 1617 * java.lang.SecurityManager#checkWrite(java.lang.String)} 1618 * method denies write access to the file 1619 * 1620 * @since 1.6 1621 */ 1622 public boolean setReadable(boolean readable) { 1623 return setReadable(readable, true); 1624 } 1625 1626 /** 1627 * Sets the owner's or everybody's execute permission for this abstract 1628 * pathname. On some platforms it may be possible to start the Java virtual 1629 * machine with special privileges that allow it to execute files that are 1630 * not marked executable. 1631 * 1632 * <p> The {@link java.nio.file.Files} class defines methods that operate on 1633 * file attributes including file permissions. This may be used when finer 1634 * manipulation of file permissions is required. 1635 * 1636 * @param executable 1637 * If <code>true</code>, sets the access permission to allow execute 1638 * operations; if <code>false</code> to disallow execute operations 1639 * 1640 * @param ownerOnly 1641 * If <code>true</code>, the execute permission applies only to the 1642 * owner's execute permission; otherwise, it applies to everybody. 1643 * If the underlying file system can not distinguish the owner's 1644 * execute permission from that of others, then the permission will 1645 * apply to everybody, regardless of this value. 1646 * 1647 * @return <code>true</code> if and only if the operation succeeded. The 1648 * operation will fail if the user does not have permission to 1649 * change the access permissions of this abstract pathname. If 1650 * <code>executable</code> is <code>false</code> and the underlying 1651 * file system does not implement an execute permission, then the 1652 * operation will fail. 1653 * 1654 * @throws SecurityException 1655 * If a security manager exists and its {@link 1656 * java.lang.SecurityManager#checkWrite(java.lang.String)} 1657 * method denies write access to the file 1658 * 1659 * @since 1.6 1660 */ 1661 public boolean setExecutable(boolean executable, boolean ownerOnly) { 1662 SecurityManager security = System.getSecurityManager(); 1663 if (security != null) { 1664 security.checkWrite(path); 1665 } 1666 if (isInvalid()) { 1667 return false; 1668 } 1669 return fs.setPermission(this, FileSystem.ACCESS_EXECUTE, executable, ownerOnly); 1670 } 1671 1672 /** 1673 * A convenience method to set the owner's execute permission for this 1674 * abstract pathname. On some platforms it may be possible to start the Java 1675 * virtual machine with special privileges that allow it to execute files 1676 * that are not marked executable. 1677 * 1678 * <p>An invocation of this method of the form {@code file.setExcutable(arg)} 1679 * behaves in exactly the same way as the invocation 1680 * 1681 * <pre>{@code 1682 * file.setExecutable(arg, true) 1683 * }</pre> 1684 * 1685 * @param executable 1686 * If <code>true</code>, sets the access permission to allow execute 1687 * operations; if <code>false</code> to disallow execute operations 1688 * 1689 * @return <code>true</code> if and only if the operation succeeded. The 1690 * operation will fail if the user does not have permission to 1691 * change the access permissions of this abstract pathname. If 1692 * <code>executable</code> is <code>false</code> and the underlying 1693 * file system does not implement an execute permission, then the 1694 * operation will fail. 1695 * 1696 * @throws SecurityException 1697 * If a security manager exists and its {@link 1698 * java.lang.SecurityManager#checkWrite(java.lang.String)} 1699 * method denies write access to the file 1700 * 1701 * @since 1.6 1702 */ 1703 public boolean setExecutable(boolean executable) { 1704 return setExecutable(executable, true); 1705 } 1706 1707 /** 1708 * Tests whether the application can execute the file denoted by this 1709 * abstract pathname. On some platforms it may be possible to start the 1710 * Java virtual machine with special privileges that allow it to execute 1711 * files that are not marked executable. Consequently this method may return 1712 * {@code true} even though the file does not have execute permissions. 1713 * 1714 * @return <code>true</code> if and only if the abstract pathname exists 1715 * <em>and</em> the application is allowed to execute the file 1716 * 1717 * @throws SecurityException 1718 * If a security manager exists and its {@link 1719 * java.lang.SecurityManager#checkExec(java.lang.String)} 1720 * method denies execute access to the file 1721 * 1722 * @since 1.6 1723 */ 1724 public boolean canExecute() { 1725 SecurityManager security = System.getSecurityManager(); 1726 if (security != null) { 1727 security.checkExec(path); 1728 } 1729 if (isInvalid()) { 1730 return false; 1731 } 1732 return fs.checkAccess(this, FileSystem.ACCESS_EXECUTE); 1733 } 1734 1735 1736 /* -- Filesystem interface -- */ 1737 1738 /** 1739 * List the available filesystem roots. 1740 * 1741 * <p> A particular Java platform may support zero or more 1742 * hierarchically-organized file systems. Each file system has a 1743 * {@code root} directory from which all other files in that file system 1744 * can be reached. Windows platforms, for example, have a root directory 1745 * for each active drive; UNIX platforms have a single root directory, 1746 * namely {@code "/"}. The set of available filesystem roots is affected 1747 * by various system-level operations such as the insertion or ejection of 1748 * removable media and the disconnecting or unmounting of physical or 1749 * virtual disk drives. 1750 * 1751 * <p> This method returns an array of {@code File} objects that denote the 1752 * root directories of the available filesystem roots. It is guaranteed 1753 * that the canonical pathname of any file physically present on the local 1754 * machine will begin with one of the roots returned by this method. 1755 * 1756 * <p> The canonical pathname of a file that resides on some other machine 1757 * and is accessed via a remote-filesystem protocol such as SMB or NFS may 1758 * or may not begin with one of the roots returned by this method. If the 1759 * pathname of a remote file is syntactically indistinguishable from the 1760 * pathname of a local file then it will begin with one of the roots 1761 * returned by this method. Thus, for example, {@code File} objects 1762 * denoting the root directories of the mapped network drives of a Windows 1763 * platform will be returned by this method, while {@code File} objects 1764 * containing UNC pathnames will not be returned by this method. 1765 * 1766 * <p> Unlike most methods in this class, this method does not throw 1767 * security exceptions. If a security manager exists and its {@link 1768 * SecurityManager#checkRead(String)} method denies read access to a 1769 * particular root directory, then that directory will not appear in the 1770 * result. 1771 * 1772 * @return An array of {@code File} objects denoting the available 1773 * filesystem roots, or {@code null} if the set of roots could not 1774 * be determined. The array will be empty if there are no 1775 * filesystem roots. 1776 * 1777 * @since 1.2 1778 * @see java.nio.file.FileStore 1779 */ 1780 public static File[] listRoots() { 1781 return fs.listRoots(); 1782 } 1783 1784 1785 /* -- Disk usage -- */ 1786 1787 /** 1788 * Returns the size of the partition <a href="#partName">named</a> by this 1789 * abstract pathname. 1790 * 1791 * @return The size, in bytes, of the partition or {@code 0L} if this 1792 * abstract pathname does not name a partition 1793 * 1794 * @throws SecurityException 1795 * If a security manager has been installed and it denies 1796 * {@link RuntimePermission}{@code ("getFileSystemAttributes")} 1797 * or its {@link SecurityManager#checkRead(String)} method denies 1798 * read access to the file named by this abstract pathname 1799 * 1800 * @since 1.6 1801 */ 1802 public long getTotalSpace() { 1803 SecurityManager sm = System.getSecurityManager(); 1804 if (sm != null) { 1805 sm.checkPermission(new RuntimePermission("getFileSystemAttributes")); 1806 sm.checkRead(path); 1807 } 1808 if (isInvalid()) { 1809 return 0L; 1810 } 1811 return fs.getSpace(this, FileSystem.SPACE_TOTAL); 1812 } 1813 1814 /** 1815 * Returns the number of unallocated bytes in the partition <a 1816 * href="#partName">named</a> by this abstract path name. 1817 * 1818 * <p> The returned number of unallocated bytes is a hint, but not 1819 * a guarantee, that it is possible to use most or any of these 1820 * bytes. The number of unallocated bytes is most likely to be 1821 * accurate immediately after this call. It is likely to be made 1822 * inaccurate by any external I/O operations including those made 1823 * on the system outside of this virtual machine. This method 1824 * makes no guarantee that write operations to this file system 1825 * will succeed. 1826 * 1827 * @return The number of unallocated bytes on the partition or {@code 0L} 1828 * if the abstract pathname does not name a partition. This 1829 * value will be less than or equal to the total file system size 1830 * returned by {@link #getTotalSpace}. 1831 * 1832 * @throws SecurityException 1833 * If a security manager has been installed and it denies 1834 * {@link RuntimePermission}{@code ("getFileSystemAttributes")} 1835 * or its {@link SecurityManager#checkRead(String)} method denies 1836 * read access to the file named by this abstract pathname 1837 * 1838 * @since 1.6 1839 */ 1840 public long getFreeSpace() { 1841 SecurityManager sm = System.getSecurityManager(); 1842 if (sm != null) { 1843 sm.checkPermission(new RuntimePermission("getFileSystemAttributes")); 1844 sm.checkRead(path); 1845 } 1846 if (isInvalid()) { 1847 return 0L; 1848 } 1849 return fs.getSpace(this, FileSystem.SPACE_FREE); 1850 } 1851 1852 /** 1853 * Returns the number of bytes available to this virtual machine on the 1854 * partition <a href="#partName">named</a> by this abstract pathname. When 1855 * possible, this method checks for write permissions and other operating 1856 * system restrictions and will therefore usually provide a more accurate 1857 * estimate of how much new data can actually be written than {@link 1858 * #getFreeSpace}. 1859 * 1860 * <p> The returned number of available bytes is a hint, but not a 1861 * guarantee, that it is possible to use most or any of these bytes. The 1862 * number of unallocated bytes is most likely to be accurate immediately 1863 * after this call. It is likely to be made inaccurate by any external 1864 * I/O operations including those made on the system outside of this 1865 * virtual machine. This method makes no guarantee that write operations 1866 * to this file system will succeed. 1867 * 1868 * @return The number of available bytes on the partition or {@code 0L} 1869 * if the abstract pathname does not name a partition. On 1870 * systems where this information is not available, this method 1871 * will be equivalent to a call to {@link #getFreeSpace}. 1872 * 1873 * @throws SecurityException 1874 * If a security manager has been installed and it denies 1875 * {@link RuntimePermission}{@code ("getFileSystemAttributes")} 1876 * or its {@link SecurityManager#checkRead(String)} method denies 1877 * read access to the file named by this abstract pathname 1878 * 1879 * @since 1.6 1880 */ 1881 public long getUsableSpace() { 1882 SecurityManager sm = System.getSecurityManager(); 1883 if (sm != null) { 1884 sm.checkPermission(new RuntimePermission("getFileSystemAttributes")); 1885 sm.checkRead(path); 1886 } 1887 if (isInvalid()) { 1888 return 0L; 1889 } 1890 return fs.getSpace(this, FileSystem.SPACE_USABLE); 1891 } 1892 1893 /* -- Temporary files -- */ 1894 1895 private static class TempDirectory { 1896 private TempDirectory() { } 1897 1898 // temporary directory location 1899 private static final File tmpdir = new File(AccessController 1900 .doPrivileged(new GetPropertyAction("java.io.tmpdir"))); 1901 static File location() { 1902 return tmpdir; 1903 } 1904 1905 // file name generation 1906 private static final SecureRandom random = new SecureRandom(); 1907 static File generateFile(String prefix, String suffix, File dir) 1908 throws IOException 1909 { 1910 long n = random.nextLong(); 1911 if (n == Long.MIN_VALUE) { 1912 n = 0; // corner case 1913 } else { 1914 n = Math.abs(n); 1915 } 1916 1917 // Use only the file name from the supplied prefix 1918 prefix = (new File(prefix)).getName(); 1919 1920 String name = prefix + Long.toString(n) + suffix; 1921 File f = new File(dir, name); 1922 if (!name.equals(f.getName()) || f.isInvalid()) { 1923 if (System.getSecurityManager() != null) 1924 throw new IOException("Unable to create temporary file"); 1925 else 1926 throw new IOException("Unable to create temporary file, " + f); 1927 } 1928 return f; 1929 } 1930 } 1931 1932 /** 1933 * <p> Creates a new empty file in the specified directory, using the 1934 * given prefix and suffix strings to generate its name. If this method 1935 * returns successfully then it is guaranteed that: 1936 * 1937 * <ol> 1938 * <li> The file denoted by the returned abstract pathname did not exist 1939 * before this method was invoked, and 1940 * <li> Neither this method nor any of its variants will return the same 1941 * abstract pathname again in the current invocation of the virtual 1942 * machine. 1943 * </ol> 1944 * 1945 * This method provides only part of a temporary-file facility. To arrange 1946 * for a file created by this method to be deleted automatically, use the 1947 * {@link #deleteOnExit} method. 1948 * 1949 * <p> The <code>prefix</code> argument must be at least three characters 1950 * long. It is recommended that the prefix be a short, meaningful string 1951 * such as <code>"hjb"</code> or <code>"mail"</code>. The 1952 * <code>suffix</code> argument may be <code>null</code>, in which case the 1953 * suffix <code>".tmp"</code> will be used. 1954 * 1955 * <p> To create the new file, the prefix and the suffix may first be 1956 * adjusted to fit the limitations of the underlying platform. If the 1957 * prefix is too long then it will be truncated, but its first three 1958 * characters will always be preserved. If the suffix is too long then it 1959 * too will be truncated, but if it begins with a period character 1960 * (<code>'.'</code>) then the period and the first three characters 1961 * following it will always be preserved. Once these adjustments have been 1962 * made the name of the new file will be generated by concatenating the 1963 * prefix, five or more internally-generated characters, and the suffix. 1964 * 1965 * <p> If the <code>directory</code> argument is <code>null</code> then the 1966 * system-dependent default temporary-file directory will be used. The 1967 * default temporary-file directory is specified by the system property 1968 * <code>java.io.tmpdir</code>. On UNIX systems the default value of this 1969 * property is typically <code>"/tmp"</code> or <code>"/var/tmp"</code>; on 1970 * Microsoft Windows systems it is typically <code>"C:\\WINNT\\TEMP"</code>. A different 1971 * value may be given to this system property when the Java virtual machine 1972 * is invoked, but programmatic changes to this property are not guaranteed 1973 * to have any effect upon the temporary directory used by this method. 1974 * 1975 * @param prefix The prefix string to be used in generating the file's 1976 * name; must be at least three characters long 1977 * 1978 * @param suffix The suffix string to be used in generating the file's 1979 * name; may be <code>null</code>, in which case the 1980 * suffix <code>".tmp"</code> will be used 1981 * 1982 * @param directory The directory in which the file is to be created, or 1983 * <code>null</code> if the default temporary-file 1984 * directory is to be used 1985 * 1986 * @return An abstract pathname denoting a newly-created empty file 1987 * 1988 * @throws IllegalArgumentException 1989 * If the <code>prefix</code> argument contains fewer than three 1990 * characters 1991 * 1992 * @throws IOException If a file could not be created 1993 * 1994 * @throws SecurityException 1995 * If a security manager exists and its {@link 1996 * java.lang.SecurityManager#checkWrite(java.lang.String)} 1997 * method does not allow a file to be created 1998 * 1999 * @since 1.2 2000 */ 2001 public static File createTempFile(String prefix, String suffix, 2002 File directory) 2003 throws IOException 2004 { 2005 if (prefix.length() < 3) { 2006 throw new IllegalArgumentException("Prefix string \"" + prefix + 2007 "\" too short: length must be at least 3"); 2008 } 2009 if (suffix == null) 2010 suffix = ".tmp"; 2011 2012 File tmpdir = (directory != null) ? directory 2013 : TempDirectory.location(); 2014 SecurityManager sm = System.getSecurityManager(); 2015 File f; 2016 do { 2017 f = TempDirectory.generateFile(prefix, suffix, tmpdir); 2018 2019 if (sm != null) { 2020 try { 2021 sm.checkWrite(f.getPath()); 2022 } catch (SecurityException se) { 2023 // don't reveal temporary directory location 2024 if (directory == null) 2025 throw new SecurityException("Unable to create temporary file"); 2026 throw se; 2027 } 2028 } 2029 } while ((fs.getBooleanAttributes(f) & FileSystem.BA_EXISTS) != 0); 2030 2031 if (!fs.createFileExclusively(f.getPath())) 2032 throw new IOException("Unable to create temporary file"); 2033 2034 return f; 2035 } 2036 2037 /** 2038 * Creates an empty file in the default temporary-file directory, using 2039 * the given prefix and suffix to generate its name. Invoking this method 2040 * is equivalent to invoking {@link #createTempFile(java.lang.String, 2041 * java.lang.String, java.io.File) 2042 * createTempFile(prefix, suffix, null)}. 2043 * 2044 * <p> The {@link 2045 * java.nio.file.Files#createTempFile(String,String,java.nio.file.attribute.FileAttribute[]) 2046 * Files.createTempFile} method provides an alternative method to create an 2047 * empty file in the temporary-file directory. Files created by that method 2048 * may have more restrictive access permissions to files created by this 2049 * method and so may be more suited to security-sensitive applications. 2050 * 2051 * @param prefix The prefix string to be used in generating the file's 2052 * name; must be at least three characters long 2053 * 2054 * @param suffix The suffix string to be used in generating the file's 2055 * name; may be <code>null</code>, in which case the 2056 * suffix <code>".tmp"</code> will be used 2057 * 2058 * @return An abstract pathname denoting a newly-created empty file 2059 * 2060 * @throws IllegalArgumentException 2061 * If the <code>prefix</code> argument contains fewer than three 2062 * characters 2063 * 2064 * @throws IOException If a file could not be created 2065 * 2066 * @throws SecurityException 2067 * If a security manager exists and its {@link 2068 * java.lang.SecurityManager#checkWrite(java.lang.String)} 2069 * method does not allow a file to be created 2070 * 2071 * @since 1.2 2072 * @see java.nio.file.Files#createTempDirectory(String,FileAttribute[]) 2073 */ 2074 public static File createTempFile(String prefix, String suffix) 2075 throws IOException 2076 { 2077 return createTempFile(prefix, suffix, null); 2078 } 2079 2080 /* -- Basic infrastructure -- */ 2081 2082 /** 2083 * Compares two abstract pathnames lexicographically. The ordering 2084 * defined by this method depends upon the underlying system. On UNIX 2085 * systems, alphabetic case is significant in comparing pathnames; on Microsoft Windows 2086 * systems it is not. 2087 * 2088 * @param pathname The abstract pathname to be compared to this abstract 2089 * pathname 2090 * 2091 * @return Zero if the argument is equal to this abstract pathname, a 2092 * value less than zero if this abstract pathname is 2093 * lexicographically less than the argument, or a value greater 2094 * than zero if this abstract pathname is lexicographically 2095 * greater than the argument 2096 * 2097 * @since 1.2 2098 */ 2099 public int compareTo(File pathname) { 2100 return fs.compare(this, pathname); 2101 } 2102 2103 /** 2104 * Tests this abstract pathname for equality with the given object. 2105 * Returns <code>true</code> if and only if the argument is not 2106 * <code>null</code> and is an abstract pathname that denotes the same file 2107 * or directory as this abstract pathname. Whether or not two abstract 2108 * pathnames are equal depends upon the underlying system. On UNIX 2109 * systems, alphabetic case is significant in comparing pathnames; on Microsoft Windows 2110 * systems it is not. 2111 * 2112 * @param obj The object to be compared with this abstract pathname 2113 * 2114 * @return <code>true</code> if and only if the objects are the same; 2115 * <code>false</code> otherwise 2116 */ 2117 public boolean equals(Object obj) { 2118 if ((obj != null) && (obj instanceof File)) { 2119 return compareTo((File)obj) == 0; 2120 } 2121 return false; 2122 } 2123 2124 /** 2125 * Computes a hash code for this abstract pathname. Because equality of 2126 * abstract pathnames is inherently system-dependent, so is the computation 2127 * of their hash codes. On UNIX systems, the hash code of an abstract 2128 * pathname is equal to the exclusive <em>or</em> of the hash code 2129 * of its pathname string and the decimal value 2130 * <code>1234321</code>. On Microsoft Windows systems, the hash 2131 * code is equal to the exclusive <em>or</em> of the hash code of 2132 * its pathname string converted to lower case and the decimal 2133 * value <code>1234321</code>. Locale is not taken into account on 2134 * lowercasing the pathname string. 2135 * 2136 * @return A hash code for this abstract pathname 2137 */ 2138 public int hashCode() { 2139 return fs.hashCode(this); 2140 } 2141 2142 /** 2143 * Returns the pathname string of this abstract pathname. This is just the 2144 * string returned by the {@link #getPath} method. 2145 * 2146 * @return The string form of this abstract pathname 2147 */ 2148 public String toString() { 2149 return getPath(); 2150 } 2151 2152 /** 2153 * WriteObject is called to save this filename. 2154 * The separator character is saved also so it can be replaced 2155 * in case the path is reconstituted on a different host type. 2156 * 2157 * @serialData Default fields followed by separator character. 2158 */ 2159 private synchronized void writeObject(java.io.ObjectOutputStream s) 2160 throws IOException 2161 { 2162 s.defaultWriteObject(); 2163 s.writeChar(separatorChar); // Add the separator character 2164 } 2165 2166 /** 2167 * readObject is called to restore this filename. 2168 * The original separator character is read. If it is different 2169 * than the separator character on this system, then the old separator 2170 * is replaced by the local separator. 2171 */ 2172 private synchronized void readObject(java.io.ObjectInputStream s) 2173 throws IOException, ClassNotFoundException 2174 { 2175 ObjectInputStream.GetField fields = s.readFields(); 2176 String pathField = (String)fields.get("path", null); 2177 char sep = s.readChar(); // read the previous separator char 2178 if (sep != separatorChar) 2179 pathField = pathField.replace(sep, separatorChar); 2180 String path = fs.normalize(pathField); 2181 UNSAFE.putObject(this, PATH_OFFSET, path); 2182 UNSAFE.putIntVolatile(this, PREFIX_LENGTH_OFFSET, fs.prefixLength(path)); 2183 } 2184 2185 private static final long PATH_OFFSET; 2186 private static final long PREFIX_LENGTH_OFFSET; 2187 private static final sun.misc.Unsafe UNSAFE; 2188 static { 2189 try { 2190 sun.misc.Unsafe unsafe = sun.misc.Unsafe.getUnsafe(); 2191 PATH_OFFSET = unsafe.objectFieldOffset( 2192 File.class.getDeclaredField("path")); 2193 PREFIX_LENGTH_OFFSET = unsafe.objectFieldOffset( 2194 File.class.getDeclaredField("prefixLength")); 2195 UNSAFE = unsafe; 2196 } catch (ReflectiveOperationException e) { 2197 throw new Error(e); 2198 } 2199 } 2200 2201 2202 /** use serialVersionUID from JDK 1.0.2 for interoperability */ 2203 private static final long serialVersionUID = 301077366599181567L; 2204 2205 // -- Integration with java.nio.file -- 2206 2207 private transient volatile Path filePath; 2208 2209 /** 2210 * Returns a {@link Path java.nio.file.Path} object constructed from the 2211 * this abstract path. The resulting {@code Path} is associated with the 2212 * {@link java.nio.file.FileSystems#getDefault default-filesystem}. 2213 * 2214 * <p> The first invocation of this method works as if invoking it were 2215 * equivalent to evaluating the expression: 2216 * <blockquote><pre> 2217 * {@link java.nio.file.FileSystems#getDefault FileSystems.getDefault}().{@link 2218 * java.nio.file.FileSystem#getPath getPath}(this.{@link #getPath getPath}()); 2219 * </pre></blockquote> 2220 * Subsequent invocations of this method return the same {@code Path}. 2221 * 2222 * <p> If this abstract pathname is the empty abstract pathname then this 2223 * method returns a {@code Path} that may be used to access the current 2224 * user directory. 2225 * 2226 * @return a {@code Path} constructed from this abstract path 2227 * 2228 * @throws java.nio.file.InvalidPathException 2229 * if a {@code Path} object cannot be constructed from the abstract 2230 * path (see {@link java.nio.file.FileSystem#getPath FileSystem.getPath}) 2231 * 2232 * @since 1.7 2233 * @see Path#toFile 2234 */ 2235 public Path toPath() { 2236 Path result = filePath; 2237 if (result == null) { 2238 synchronized (this) { 2239 result = filePath; 2240 if (result == null) { 2241 result = FileSystems.getDefault().getPath(path); 2242 filePath = result; 2243 } 2244 } 2245 } 2246 return result; 2247 } 2248} 2249