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; the value may
936 * be negative in which case its absolute value indicates the
937 * number of milliseconds before the epoch
938 *
939 * @throws SecurityException
940 * If a security manager exists and its {@link
941 * java.lang.SecurityManager#checkRead(java.lang.String)}
942 * method denies read access to the file
943 */
944 public long lastModified() {
945 SecurityManager security = System.getSecurityManager();
946 if (security != null) {
947 security.checkRead(path);
948 }
949 if (isInvalid()) {
950 return 0L;
951 }
952 return fs.getLastModifiedTime(this);
953 }
954
955 /**
956 * Returns the length of the file denoted by this abstract pathname.
957 * The return value is unspecified if this pathname denotes a directory.
958 *
959 * <p> Where it is required to distinguish an I/O exception from the case
960 * that {@code 0L} is returned, or where several attributes of the same file
961 * are required at the same time, then the {@link
962 * java.nio.file.Files#readAttributes(Path,Class,LinkOption[])
963 * Files.readAttributes} method may be used.
964 *
965 * @return The length, in bytes, of the file denoted by this abstract
966 * pathname, or <code>0L</code> if the file does not exist. Some
967 * operating systems may return <code>0L</code> for pathnames
968 * denoting system-dependent entities such as devices or pipes.
969 *
970 * @throws SecurityException
971 * If a security manager exists and its {@link
972 * java.lang.SecurityManager#checkRead(java.lang.String)}
973 * method denies read access to the file
974 */
975 public long length() {
976 SecurityManager security = System.getSecurityManager();
977 if (security != null) {
978 security.checkRead(path);
979 }
980 if (isInvalid()) {
981 return 0L;
982 }
983 return fs.getLength(this);
984 }
985
986
987 /* -- File operations -- */
988
989 /**
990 * Atomically creates a new, empty file named by this abstract pathname if
991 * and only if a file with this name does not yet exist. The check for the
992 * existence of the file and the creation of the file if it does not exist
993 * are a single operation that is atomic with respect to all other
994 * filesystem activities that might affect the file.
995 * <P>
996 * Note: this method should <i>not</i> be used for file-locking, as
997 * the resulting protocol cannot be made to work reliably. The
998 * {@link java.nio.channels.FileLock FileLock}
999 * facility should be used instead.
1000 *
1001 * @return <code>true</code> if the named file does not exist and was
1002 * successfully created; <code>false</code> if the named file
1003 * already exists
1004 *
1005 * @throws IOException
1006 * If an I/O error occurred
1007 *
1008 * @throws SecurityException
1009 * If a security manager exists and its {@link
1010 * java.lang.SecurityManager#checkWrite(java.lang.String)}
1011 * method denies write access to the file
1012 *
1013 * @since 1.2
1014 */
1015 public boolean createNewFile() throws IOException {
1016 SecurityManager security = System.getSecurityManager();
1017 if (security != null) security.checkWrite(path);
1018 if (isInvalid()) {
1019 throw new IOException("Invalid file path");
1020 }
1021 return fs.createFileExclusively(path);
1022 }
1023
1024 /**
1025 * Deletes the file or directory denoted by this abstract pathname. If
1026 * this pathname denotes a directory, then the directory must be empty in
1027 * order to be deleted.
1028 *
1029 * <p> Note that the {@link java.nio.file.Files} class defines the {@link
1030 * java.nio.file.Files#delete(Path) delete} method to throw an {@link IOException}
1031 * when a file cannot be deleted. This is useful for error reporting and to
1032 * diagnose why a file cannot be deleted.
1033 *
1034 * @return <code>true</code> if and only if the file or directory is
1035 * successfully deleted; <code>false</code> otherwise
1036 *
1037 * @throws SecurityException
1038 * If a security manager exists and its {@link
1039 * java.lang.SecurityManager#checkDelete} method denies
1040 * delete access to the file
1041 */
1042 public boolean delete() {
1043 SecurityManager security = System.getSecurityManager();
1044 if (security != null) {
1045 security.checkDelete(path);
1046 }
1047 if (isInvalid()) {
1048 return false;
1049 }
1050 return fs.delete(this);
1051 }
1052
1053 /**
1054 * Requests that the file or directory denoted by this abstract
1055 * pathname be deleted when the virtual machine terminates.
1056 * Files (or directories) are deleted in the reverse order that
1057 * they are registered. Invoking this method to delete a file or
1058 * directory that is already registered for deletion has no effect.
1059 * Deletion will be attempted only for normal termination of the
1060 * virtual machine, as defined by the Java Language Specification.
1061 *
1062 * <p> Once deletion has been requested, it is not possible to cancel the
1063 * request. This method should therefore be used with care.
1064 *
1065 * <P>
1066 * Note: this method should <i>not</i> be used for file-locking, as
1067 * the resulting protocol cannot be made to work reliably. The
1068 * {@link java.nio.channels.FileLock FileLock}
1069 * facility should be used instead.
1070 *
1071 * @throws SecurityException
1072 * If a security manager exists and its {@link
1073 * java.lang.SecurityManager#checkDelete} method denies
1074 * delete access to the file
1075 *
1076 * @see #delete
1077 *
1078 * @since 1.2
1079 */
1080 public void deleteOnExit() {
1081 SecurityManager security = System.getSecurityManager();
1082 if (security != null) {
1083 security.checkDelete(path);
1084 }
1085 if (isInvalid()) {
1086 return;
1087 }
1088 DeleteOnExitHook.add(path);
1089 }
1090
1091 /**
1092 * Returns an array of strings naming the files and directories in the
1093 * directory denoted by this abstract pathname.
1094 *
1095 * <p> If this abstract pathname does not denote a directory, then this
1096 * method returns {@code null}. Otherwise an array of strings is
1097 * returned, one for each file or directory in the directory. Names
1098 * denoting the directory itself and the directory's parent directory are
1099 * not included in the result. Each string is a file name rather than a
1100 * complete path.
1101 *
1102 * <p> There is no guarantee that the name strings in the resulting array
1103 * will appear in any specific order; they are not, in particular,
1104 * guaranteed to appear in alphabetical order.
1105 *
1106 * <p> Note that the {@link java.nio.file.Files} class defines the {@link
1107 * java.nio.file.Files#newDirectoryStream(Path) newDirectoryStream} method to
1108 * open a directory and iterate over the names of the files in the directory.
1109 * This may use less resources when working with very large directories, and
1110 * may be more responsive when working with remote directories.
1111 *
1112 * @return An array of strings naming the files and directories in the
1113 * directory denoted by this abstract pathname. The array will be
1114 * empty if the directory is empty. Returns {@code null} if
1115 * this abstract pathname does not denote a directory, or if an
1116 * I/O error occurs.
1117 *
1118 * @throws SecurityException
1119 * If a security manager exists and its {@link
1120 * SecurityManager#checkRead(String)} method denies read access to
1121 * the directory
1122 */
1123 public String[] list() {
1124 SecurityManager security = System.getSecurityManager();
1125 if (security != null) {
1126 security.checkRead(path);
1127 }
1128 if (isInvalid()) {
1129 return null;
1130 }
1131 return fs.list(this);
1132 }
1133
1134 /**
1135 * Returns an array of strings naming the files and directories in the
1136 * directory denoted by this abstract pathname that satisfy the specified
1137 * filter. The behavior of this method is the same as that of the
1138 * {@link #list()} method, except that the strings in the returned array
1139 * must satisfy the filter. If the given {@code filter} is {@code null}
1140 * then all names are accepted. Otherwise, a name satisfies the filter if
1141 * and only if the value {@code true} results when the {@link
1142 * FilenameFilter#accept FilenameFilter.accept(File, String)} method
1143 * of the filter is invoked on this abstract pathname and the name of a
1144 * file or directory in the directory that it denotes.
1145 *
1146 * @param filter
1147 * A filename filter
1148 *
1149 * @return An array of strings naming the files and directories in the
1150 * directory denoted by this abstract pathname that were accepted
1151 * by the given {@code filter}. The array will be empty if the
1152 * directory is empty or if no names were accepted by the filter.
1153 * Returns {@code null} if this abstract pathname does not denote
1154 * a directory, or if an I/O error occurs.
1155 *
1156 * @throws SecurityException
1157 * If a security manager exists and its {@link
1158 * SecurityManager#checkRead(String)} method denies read access to
1159 * the directory
1160 *
1161 * @see java.nio.file.Files#newDirectoryStream(Path,String)
1162 */
1163 public String[] list(FilenameFilter filter) {
1164 String names[] = list();
1165 if ((names == null) || (filter == null)) {
1166 return names;
1167 }
1168 List<String> v = new ArrayList<>();
1169 for (int i = 0 ; i < names.length ; i++) {
1170 if (filter.accept(this, names[i])) {
1171 v.add(names[i]);
1172 }
1173 }
1174 return v.toArray(new String[v.size()]);
1175 }
1176
1177 /**
1178 * Returns an array of abstract pathnames denoting the files in the
1179 * directory denoted by this abstract pathname.
1180 *
1181 * <p> If this abstract pathname does not denote a directory, then this
1182 * method returns {@code null}. Otherwise an array of {@code File} objects
1183 * is returned, one for each file or directory in the directory. Pathnames
1184 * denoting the directory itself and the directory's parent directory are
1185 * not included in the result. Each resulting abstract pathname is
1186 * constructed from this abstract pathname using the {@link #File(File,
1187 * String) File(File, String)} constructor. Therefore if this
1188 * pathname is absolute then each resulting pathname is absolute; if this
1189 * pathname is relative then each resulting pathname will be relative to
1190 * the same directory.
1191 *
1192 * <p> There is no guarantee that the name strings in the resulting array
1193 * will appear in any specific order; they are not, in particular,
1194 * guaranteed to appear in alphabetical order.
1195 *
1196 * <p> Note that the {@link java.nio.file.Files} class defines the {@link
1197 * java.nio.file.Files#newDirectoryStream(Path) newDirectoryStream} method
1198 * to open a directory and iterate over the names of the files in the
1199 * directory. This may use less resources when working with very large
1200 * directories.
1201 *
1202 * @return An array of abstract pathnames denoting the files and
1203 * directories in the directory denoted by this abstract pathname.
1204 * The array will be empty if the directory is empty. Returns
1205 * {@code null} if this abstract pathname does not denote a
1206 * directory, or if an I/O error occurs.
1207 *
1208 * @throws SecurityException
1209 * If a security manager exists and its {@link
1210 * SecurityManager#checkRead(String)} method denies read access to
1211 * the directory
1212 *
1213 * @since 1.2
1214 */
1215 public File[] listFiles() {
1216 String[] ss = list();
1217 if (ss == null) return null;
1218 int n = ss.length;
1219 File[] fs = new File[n];
1220 for (int i = 0; i < n; i++) {
1221 fs[i] = new File(ss[i], this);
1222 }
1223 return fs;
1224 }
1225
1226 /**
1227 * Returns an array of abstract pathnames denoting the files and
1228 * directories in the directory denoted by this abstract pathname that
1229 * satisfy the specified filter. The behavior of this method is the same
1230 * as that of the {@link #listFiles()} method, except that the pathnames in
1231 * the returned array must satisfy the filter. If the given {@code filter}
1232 * is {@code null} then all pathnames are accepted. Otherwise, a pathname
1233 * satisfies the filter if and only if the value {@code true} results when
1234 * the {@link FilenameFilter#accept
1235 * FilenameFilter.accept(File, String)} method of the filter is
1236 * invoked on this abstract pathname and the name of a file or directory in
1237 * the directory that it denotes.
1238 *
1239 * @param filter
1240 * A filename filter
1241 *
1242 * @return An array of abstract pathnames denoting the files and
1243 * directories in the directory denoted by this abstract pathname.
1244 * The array will be empty if the directory is empty. Returns
1245 * {@code null} if this abstract pathname does not denote a
1246 * directory, or if an I/O error occurs.
1247 *
1248 * @throws SecurityException
1249 * If a security manager exists and its {@link
1250 * SecurityManager#checkRead(String)} method denies read access to
1251 * the directory
1252 *
1253 * @since 1.2
1254 * @see java.nio.file.Files#newDirectoryStream(Path,String)
1255 */
1256 public File[] listFiles(FilenameFilter filter) {
1257 String ss[] = list();
1258 if (ss == null) return null;
1259 ArrayList<File> files = new ArrayList<>();
1260 for (String s : ss)
1261 if ((filter == null) || filter.accept(this, s))
1262 files.add(new File(s, this));
1263 return files.toArray(new File[files.size()]);
1264 }
1265
1266 /**
1267 * Returns an array of abstract pathnames denoting the files and
1268 * directories in the directory denoted by this abstract pathname that
1269 * satisfy the specified filter. The behavior of this method is the same
1270 * as that of the {@link #listFiles()} method, except that the pathnames in
1271 * the returned array must satisfy the filter. If the given {@code filter}
1272 * is {@code null} then all pathnames are accepted. Otherwise, a pathname
1273 * satisfies the filter if and only if the value {@code true} results when
1274 * the {@link FileFilter#accept FileFilter.accept(File)} method of the
1275 * filter is invoked on the pathname.
1276 *
1277 * @param filter
1278 * A file filter
1279 *
1280 * @return An array of abstract pathnames denoting the files and
1281 * directories in the directory denoted by this abstract pathname.
1282 * The array will be empty if the directory is empty. Returns
1283 * {@code null} if this abstract pathname does not denote a
1284 * directory, or if an I/O error occurs.
1285 *
1286 * @throws SecurityException
1287 * If a security manager exists and its {@link
1288 * SecurityManager#checkRead(String)} method denies read access to
1289 * the directory
1290 *
1291 * @since 1.2
1292 * @see java.nio.file.Files#newDirectoryStream(Path,java.nio.file.DirectoryStream.Filter)
1293 */
1294 public File[] listFiles(FileFilter filter) {
1295 String ss[] = list();
1296 if (ss == null) return null;
1297 ArrayList<File> files = new ArrayList<>();
1298 for (String s : ss) {
1299 File f = new File(s, this);
1300 if ((filter == null) || filter.accept(f))
1301 files.add(f);
1302 }
1303 return files.toArray(new File[files.size()]);
1304 }
1305
1306 /**
1307 * Creates the directory named by this abstract pathname.
1308 *
1309 * @return <code>true</code> if and only if the directory was
1310 * created; <code>false</code> otherwise
1311 *
1312 * @throws SecurityException
1313 * If a security manager exists and its {@link
1314 * java.lang.SecurityManager#checkWrite(java.lang.String)}
1315 * method does not permit the named directory to be created
1316 */
1317 public boolean mkdir() {
1318 SecurityManager security = System.getSecurityManager();
1319 if (security != null) {
1320 security.checkWrite(path);
1321 }
1322 if (isInvalid()) {
1323 return false;
1324 }
1325 return fs.createDirectory(this);
1326 }
1327
1328 /**
1329 * Creates the directory named by this abstract pathname, including any
1330 * necessary but nonexistent parent directories. Note that if this
1331 * operation fails it may have succeeded in creating some of the necessary
1332 * parent directories.
1333 *
1334 * @return <code>true</code> if and only if the directory was created,
1335 * along with all necessary parent directories; <code>false</code>
1336 * otherwise
1337 *
1338 * @throws SecurityException
1339 * If a security manager exists and its {@link
1340 * java.lang.SecurityManager#checkRead(java.lang.String)}
1341 * method does not permit verification of the existence of the
1342 * named directory and all necessary parent directories; or if
1343 * the {@link
1344 * java.lang.SecurityManager#checkWrite(java.lang.String)}
1345 * method does not permit the named directory and all necessary
1346 * parent directories to be created
1347 */
1348 public boolean mkdirs() {
1349 if (exists()) {
1350 return false;
1351 }
1352 if (mkdir()) {
1353 return true;
1354 }
1355 File canonFile = null;
1356 try {
1357 canonFile = getCanonicalFile();
1358 } catch (IOException e) {
1359 return false;
1360 }
1361
1362 File parent = canonFile.getParentFile();
1363 return (parent != null && (parent.mkdirs() || parent.exists()) &&
1364 canonFile.mkdir());
1365 }
1366
1367 /**
1368 * Renames the file denoted by this abstract pathname.
1369 *
1370 * <p> Many aspects of the behavior of this method are inherently
1371 * platform-dependent: The rename operation might not be able to move a
1372 * file from one filesystem to another, it might not be atomic, and it
1373 * might not succeed if a file with the destination abstract pathname
1374 * already exists. The return value should always be checked to make sure
1375 * that the rename operation was successful.
1376 *
1377 * <p> Note that the {@link java.nio.file.Files} class defines the {@link
1378 * java.nio.file.Files#move move} method to move or rename a file in a
1379 * platform independent manner.
1380 *
1381 * @param dest The new abstract pathname for the named file
1382 *
1383 * @return <code>true</code> if and only if the renaming succeeded;
1384 * <code>false</code> otherwise
1385 *
1386 * @throws SecurityException
1387 * If a security manager exists and its {@link
1388 * java.lang.SecurityManager#checkWrite(java.lang.String)}
1389 * method denies write access to either the old or new pathnames
1390 *
1391 * @throws NullPointerException
1392 * If parameter <code>dest</code> is <code>null</code>
1393 */
1394 public boolean renameTo(File dest) {
1395 SecurityManager security = System.getSecurityManager();
1396 if (security != null) {
1397 security.checkWrite(path);
1398 security.checkWrite(dest.path);
1399 }
1400 if (dest == null) {
1401 throw new NullPointerException();
1402 }
1403 if (this.isInvalid() || dest.isInvalid()) {
1404 return false;
1405 }
1406 return fs.rename(this, dest);
1407 }
1408
1409 /**
1410 * Sets the last-modified time of the file or directory named by this
1411 * abstract pathname.
1412 *
1413 * <p> All platforms support file-modification times to the nearest second,
1414 * but some provide more precision. The argument will be truncated to fit
1415 * the supported precision. If the operation succeeds and no intervening
1416 * operations on the file take place, then the next invocation of the
1417 * {@link #lastModified} method will return the (possibly
1418 * truncated) <code>time</code> argument that was passed to this method.
1419 *
1420 * @param time The new last-modified time, measured in milliseconds since
1421 * the epoch (00:00:00 GMT, January 1, 1970)
1422 *
1423 * @return <code>true</code> if and only if the operation succeeded;
1424 * <code>false</code> otherwise
1425 *
1426 * @throws IllegalArgumentException If the argument is negative
1427 *
1428 * @throws SecurityException
1429 * If a security manager exists and its {@link
1430 * java.lang.SecurityManager#checkWrite(java.lang.String)}
1431 * method denies write access to the named file
1432 *
1433 * @since 1.2
1434 */
1435 public boolean setLastModified(long time) {
1436 if (time < 0) throw new IllegalArgumentException("Negative time");
1437 SecurityManager security = System.getSecurityManager();
1438 if (security != null) {
1439 security.checkWrite(path);
1440 }
1441 if (isInvalid()) {
1442 return false;
1443 }
1444 return fs.setLastModifiedTime(this, time);
1445 }
1446
1447 /**
1448 * Marks the file or directory named by this abstract pathname so that
1449 * only read operations are allowed. After invoking this method the file
1450 * or directory will not change until it is either deleted or marked
1451 * to allow write access. On some platforms it may be possible to start the
1452 * Java virtual machine with special privileges that allow it to modify
1453 * files that are marked read-only. Whether or not a read-only file or
1454 * directory may be deleted depends upon the underlying system.
1455 *
1456 * @return <code>true</code> if and only if the operation succeeded;
1457 * <code>false</code> otherwise
1458 *
1459 * @throws SecurityException
1460 * If a security manager exists and its {@link
1461 * java.lang.SecurityManager#checkWrite(java.lang.String)}
1462 * method denies write access to the named file
1463 *
1464 * @since 1.2
1465 */
1466 public boolean setReadOnly() {
1467 SecurityManager security = System.getSecurityManager();
1468 if (security != null) {
1469 security.checkWrite(path);
1470 }
1471 if (isInvalid()) {
1472 return false;
1473 }
1474 return fs.setReadOnly(this);
1475 }
1476
1477 /**
1478 * Sets the owner's or everybody's write permission for this abstract
1479 * pathname. On some platforms it may be possible to start the Java virtual
1480 * machine with special privileges that allow it to modify files that
1481 * disallow write operations.
1482 *
1483 * <p> The {@link java.nio.file.Files} class defines methods that operate on
1484 * file attributes including file permissions. This may be used when finer
1485 * manipulation of file permissions is required.
1486 *
1487 * @param writable
1488 * If <code>true</code>, sets the access permission to allow write
1489 * operations; if <code>false</code> to disallow write operations
1490 *
1491 * @param ownerOnly
1492 * If <code>true</code>, the write permission applies only to the
1493 * owner's write permission; otherwise, it applies to everybody. If
1494 * the underlying file system can not distinguish the owner's write
1495 * permission from that of others, then the permission will apply to
1496 * everybody, regardless of this value.
1497 *
1498 * @return <code>true</code> if and only if the operation succeeded. The
1499 * operation will fail if the user does not have permission to change
1500 * the access permissions of this abstract pathname.
1501 *
1502 * @throws SecurityException
1503 * If a security manager exists and its {@link
1504 * java.lang.SecurityManager#checkWrite(java.lang.String)}
1505 * method denies write access to the named file
1506 *
1507 * @since 1.6
1508 */
1509 public boolean setWritable(boolean writable, boolean ownerOnly) {
1510 SecurityManager security = System.getSecurityManager();
1511 if (security != null) {
1512 security.checkWrite(path);
1513 }
1514 if (isInvalid()) {
1515 return false;
1516 }
1517 return fs.setPermission(this, FileSystem.ACCESS_WRITE, writable, ownerOnly);
1518 }
1519
1520 /**
1521 * A convenience method to set the owner's write permission for this abstract
1522 * pathname. On some platforms it may be possible to start the Java virtual
1523 * machine with special privileges that allow it to modify files that
1524 * disallow write operations.
1525 *
1526 * <p> An invocation of this method of the form {@code file.setWritable(arg)}
1527 * behaves in exactly the same way as the invocation
1528 *
1529 * <pre>{@code
1530 * file.setWritable(arg, true)
1531 * }</pre>
1532 *
1533 * @param writable
1534 * If <code>true</code>, sets the access permission to allow write
1535 * operations; if <code>false</code> to disallow write operations
1536 *
1537 * @return <code>true</code> if and only if the operation succeeded. The
1538 * operation will fail if the user does not have permission to
1539 * change the access permissions of this abstract pathname.
1540 *
1541 * @throws SecurityException
1542 * If a security manager exists and its {@link
1543 * java.lang.SecurityManager#checkWrite(java.lang.String)}
1544 * method denies write access to the file
1545 *
1546 * @since 1.6
1547 */
1548 public boolean setWritable(boolean writable) {
1549 return setWritable(writable, true);
1550 }
1551
1552 /**
1553 * Sets the owner's or everybody's read permission for this abstract
1554 * pathname. On some platforms it may be possible to start the Java virtual
1555 * machine with special privileges that allow it to read files that are
1556 * marked as unreadable.
1557 *
1558 * <p> The {@link java.nio.file.Files} class defines methods that operate on
1559 * file attributes including file permissions. This may be used when finer
1560 * manipulation of file permissions is required.
1561 *
1562 * @param readable
1563 * If <code>true</code>, sets the access permission to allow read
1564 * operations; if <code>false</code> to disallow read operations
1565 *
1566 * @param ownerOnly
1567 * If <code>true</code>, the read permission applies only to the
1568 * owner's read permission; otherwise, it applies to everybody. If
1569 * the underlying file system can not distinguish the owner's read
1570 * permission from that of others, then the permission will apply to
1571 * everybody, regardless of this value.
1572 *
1573 * @return <code>true</code> if and only if the operation succeeded. The
1574 * operation will fail if the user does not have permission to
1575 * change the access permissions of this abstract pathname. If
1576 * <code>readable</code> is <code>false</code> and the underlying
1577 * file system does not implement a read permission, then the
1578 * operation will fail.
1579 *
1580 * @throws SecurityException
1581 * If a security manager exists and its {@link
1582 * java.lang.SecurityManager#checkWrite(java.lang.String)}
1583 * method denies write access to the file
1584 *
1585 * @since 1.6
1586 */
1587 public boolean setReadable(boolean readable, boolean ownerOnly) {
1588 SecurityManager security = System.getSecurityManager();
1589 if (security != null) {
1590 security.checkWrite(path);
1591 }
1592 if (isInvalid()) {
1593 return false;
1594 }
1595 return fs.setPermission(this, FileSystem.ACCESS_READ, readable, ownerOnly);
1596 }
1597
1598 /**
1599 * A convenience method to set the owner's read permission for this abstract
1600 * pathname. On some platforms it may be possible to start the Java virtual
1601 * machine with special privileges that allow it to read files that are
1602 * marked as unreadable.
1603 *
1604 * <p>An invocation of this method of the form {@code file.setReadable(arg)}
1605 * behaves in exactly the same way as the invocation
1606 *
1607 * <pre>{@code
1608 * file.setReadable(arg, true)
1609 * }</pre>
1610 *
1611 * @param readable
1612 * If <code>true</code>, sets the access permission to allow read
1613 * operations; if <code>false</code> to disallow read operations
1614 *
1615 * @return <code>true</code> if and only if the operation succeeded. The
1616 * operation will fail if the user does not have permission to
1617 * change the access permissions of this abstract pathname. If
1618 * <code>readable</code> is <code>false</code> and the underlying
1619 * file system does not implement a read permission, then the
1620 * operation will fail.
1621 *
1622 * @throws SecurityException
1623 * If a security manager exists and its {@link
1624 * java.lang.SecurityManager#checkWrite(java.lang.String)}
1625 * method denies write access to the file
1626 *
1627 * @since 1.6
1628 */
1629 public boolean setReadable(boolean readable) {
1630 return setReadable(readable, true);
1631 }
1632
1633 /**
1634 * Sets the owner's or everybody's execute permission for this abstract
1635 * pathname. On some platforms it may be possible to start the Java virtual
1636 * machine with special privileges that allow it to execute files that are
1637 * not marked executable.
1638 *
1639 * <p> The {@link java.nio.file.Files} class defines methods that operate on
1640 * file attributes including file permissions. This may be used when finer
1641 * manipulation of file permissions is required.
1642 *
1643 * @param executable
1644 * If <code>true</code>, sets the access permission to allow execute
1645 * operations; if <code>false</code> to disallow execute operations
1646 *
1647 * @param ownerOnly
1648 * If <code>true</code>, the execute permission applies only to the
1649 * owner's execute permission; otherwise, it applies to everybody.
1650 * If the underlying file system can not distinguish the owner's
1651 * execute permission from that of others, then the permission will
1652 * apply to everybody, regardless of this value.
1653 *
1654 * @return <code>true</code> if and only if the operation succeeded. The
1655 * operation will fail if the user does not have permission to
1656 * change the access permissions of this abstract pathname. If
1657 * <code>executable</code> is <code>false</code> and the underlying
1658 * file system does not implement an execute permission, then the
1659 * operation will fail.
1660 *
1661 * @throws SecurityException
1662 * If a security manager exists and its {@link
1663 * java.lang.SecurityManager#checkWrite(java.lang.String)}
1664 * method denies write access to the file
1665 *
1666 * @since 1.6
1667 */
1668 public boolean setExecutable(boolean executable, boolean ownerOnly) {
1669 SecurityManager security = System.getSecurityManager();
1670 if (security != null) {
1671 security.checkWrite(path);
1672 }
1673 if (isInvalid()) {
1674 return false;
1675 }
1676 return fs.setPermission(this, FileSystem.ACCESS_EXECUTE, executable, ownerOnly);
1677 }
1678
1679 /**
1680 * A convenience method to set the owner's execute permission for this
1681 * abstract pathname. On some platforms it may be possible to start the Java
1682 * virtual machine with special privileges that allow it to execute files
1683 * that are not marked executable.
1684 *
1685 * <p>An invocation of this method of the form {@code file.setExcutable(arg)}
1686 * behaves in exactly the same way as the invocation
1687 *
1688 * <pre>{@code
1689 * file.setExecutable(arg, true)
1690 * }</pre>
1691 *
1692 * @param executable
1693 * If <code>true</code>, sets the access permission to allow execute
1694 * operations; if <code>false</code> to disallow execute operations
1695 *
1696 * @return <code>true</code> if and only if the operation succeeded. The
1697 * operation will fail if the user does not have permission to
1698 * change the access permissions of this abstract pathname. If
1699 * <code>executable</code> is <code>false</code> and the underlying
1700 * file system does not implement an execute permission, then the
1701 * operation will fail.
1702 *
1703 * @throws SecurityException
1704 * If a security manager exists and its {@link
1705 * java.lang.SecurityManager#checkWrite(java.lang.String)}
1706 * method denies write access to the file
1707 *
1708 * @since 1.6
1709 */
1710 public boolean setExecutable(boolean executable) {
1711 return setExecutable(executable, true);
1712 }
1713
1714 /**
1715 * Tests whether the application can execute the file denoted by this
1716 * abstract pathname. On some platforms it may be possible to start the
1717 * Java virtual machine with special privileges that allow it to execute
1718 * files that are not marked executable. Consequently this method may return
1719 * {@code true} even though the file does not have execute permissions.
1720 *
1721 * @return <code>true</code> if and only if the abstract pathname exists
1722 * <em>and</em> the application is allowed to execute the file
1723 *
1724 * @throws SecurityException
1725 * If a security manager exists and its {@link
1726 * java.lang.SecurityManager#checkExec(java.lang.String)}
1727 * method denies execute access to the file
1728 *
1729 * @since 1.6
1730 */
1731 public boolean canExecute() {
1732 SecurityManager security = System.getSecurityManager();
1733 if (security != null) {
1734 security.checkExec(path);
1735 }
1736 if (isInvalid()) {
1737 return false;
1738 }
1739 return fs.checkAccess(this, FileSystem.ACCESS_EXECUTE);
1740 }
1741
1742
1743 /* -- Filesystem interface -- */
1744
1745 /**
1746 * List the available filesystem roots.
1747 *
1748 * <p> A particular Java platform may support zero or more
1749 * hierarchically-organized file systems. Each file system has a
1750 * {@code root} directory from which all other files in that file system
1751 * can be reached. Windows platforms, for example, have a root directory
1752 * for each active drive; UNIX platforms have a single root directory,
1753 * namely {@code "/"}. The set of available filesystem roots is affected
1754 * by various system-level operations such as the insertion or ejection of
1755 * removable media and the disconnecting or unmounting of physical or
1756 * virtual disk drives.
1757 *
1758 * <p> This method returns an array of {@code File} objects that denote the
1759 * root directories of the available filesystem roots. It is guaranteed
1760 * that the canonical pathname of any file physically present on the local
1761 * machine will begin with one of the roots returned by this method.
1762 *
1763 * <p> The canonical pathname of a file that resides on some other machine
1764 * and is accessed via a remote-filesystem protocol such as SMB or NFS may
1765 * or may not begin with one of the roots returned by this method. If the
1766 * pathname of a remote file is syntactically indistinguishable from the
1767 * pathname of a local file then it will begin with one of the roots
1768 * returned by this method. Thus, for example, {@code File} objects
1769 * denoting the root directories of the mapped network drives of a Windows
1770 * platform will be returned by this method, while {@code File} objects
1771 * containing UNC pathnames will not be returned by this method.
1772 *
1773 * <p> Unlike most methods in this class, this method does not throw
1774 * security exceptions. If a security manager exists and its {@link
1775 * SecurityManager#checkRead(String)} method denies read access to a
1776 * particular root directory, then that directory will not appear in the
1777 * result.
1778 *
1779 * @return An array of {@code File} objects denoting the available
1780 * filesystem roots, or {@code null} if the set of roots could not
1781 * be determined. The array will be empty if there are no
1782 * filesystem roots.
1783 *
1784 * @since 1.2
1785 * @see java.nio.file.FileStore
1786 */
1787 public static File[] listRoots() {
1788 return fs.listRoots();
1789 }
1790
1791
1792 /* -- Disk usage -- */
1793
1794 /**
1795 * Returns the size of the partition <a href="#partName">named</a> by this
1796 * abstract pathname.
1797 *
1798 * @return The size, in bytes, of the partition or {@code 0L} if this
1799 * abstract pathname does not name a partition
1800 *
1801 * @throws SecurityException
1802 * If a security manager has been installed and it denies
1803 * {@link RuntimePermission}{@code ("getFileSystemAttributes")}
1804 * or its {@link SecurityManager#checkRead(String)} method denies
1805 * read access to the file named by this abstract pathname
1806 *
1807 * @since 1.6
1808 */
1809 public long getTotalSpace() {
1810 SecurityManager sm = System.getSecurityManager();
1811 if (sm != null) {
1812 sm.checkPermission(new RuntimePermission("getFileSystemAttributes"));
1813 sm.checkRead(path);
1814 }
1815 if (isInvalid()) {
1816 return 0L;
1817 }
1818 return fs.getSpace(this, FileSystem.SPACE_TOTAL);
1819 }
1820
1821 /**
1822 * Returns the number of unallocated bytes in the partition <a
1823 * href="#partName">named</a> by this abstract path name.
1824 *
1825 * <p> The returned number of unallocated bytes is a hint, but not
1826 * a guarantee, that it is possible to use most or any of these
1827 * bytes. The number of unallocated bytes is most likely to be
1828 * accurate immediately after this call. It is likely to be made
1829 * inaccurate by any external I/O operations including those made
1830 * on the system outside of this virtual machine. This method
1831 * makes no guarantee that write operations to this file system
1832 * will succeed.
1833 *
1834 * @return The number of unallocated bytes on the partition or {@code 0L}
1835 * if the abstract pathname does not name a partition. This
1836 * value will be less than or equal to the total file system size
1837 * returned by {@link #getTotalSpace}.
1838 *
1839 * @throws SecurityException
1840 * If a security manager has been installed and it denies
1841 * {@link RuntimePermission}{@code ("getFileSystemAttributes")}
1842 * or its {@link SecurityManager#checkRead(String)} method denies
1843 * read access to the file named by this abstract pathname
1844 *
1845 * @since 1.6
1846 */
1847 public long getFreeSpace() {
1848 SecurityManager sm = System.getSecurityManager();
1849 if (sm != null) {
1850 sm.checkPermission(new RuntimePermission("getFileSystemAttributes"));
1851 sm.checkRead(path);
1852 }
1853 if (isInvalid()) {
1854 return 0L;
1855 }
1856 return fs.getSpace(this, FileSystem.SPACE_FREE);
1857 }
1858
1859 /**
1860 * Returns the number of bytes available to this virtual machine on the
1861 * partition <a href="#partName">named</a> by this abstract pathname. When
1862 * possible, this method checks for write permissions and other operating
1863 * system restrictions and will therefore usually provide a more accurate
1864 * estimate of how much new data can actually be written than {@link
1865 * #getFreeSpace}.
1866 *
1867 * <p> The returned number of available bytes is a hint, but not a
1868 * guarantee, that it is possible to use most or any of these bytes. The
1869 * number of unallocated bytes is most likely to be accurate immediately
1870 * after this call. It is likely to be made inaccurate by any external
1871 * I/O operations including those made on the system outside of this
1872 * virtual machine. This method makes no guarantee that write operations
1873 * to this file system will succeed.
1874 *
1875 * @return The number of available bytes on the partition or {@code 0L}
1876 * if the abstract pathname does not name a partition. On
1877 * systems where this information is not available, this method
1878 * will be equivalent to a call to {@link #getFreeSpace}.
1879 *
1880 * @throws SecurityException
1881 * If a security manager has been installed and it denies
1882 * {@link RuntimePermission}{@code ("getFileSystemAttributes")}
1883 * or its {@link SecurityManager#checkRead(String)} method denies
1884 * read access to the file named by this abstract pathname
1885 *
1886 * @since 1.6
1887 */
1888 public long getUsableSpace() {
1889 SecurityManager sm = System.getSecurityManager();
1890 if (sm != null) {
1891 sm.checkPermission(new RuntimePermission("getFileSystemAttributes"));
1892 sm.checkRead(path);
1893 }
1894 if (isInvalid()) {
1895 return 0L;
1896 }
1897 return fs.getSpace(this, FileSystem.SPACE_USABLE);
1898 }
1899
1900 /* -- Temporary files -- */
1901
1902 private static class TempDirectory {
1903 private TempDirectory() { }
1904
1905 // temporary directory location
1906 private static final File tmpdir = new File(
1907 GetPropertyAction.privilegedGetProperty("java.io.tmpdir"));
1908 static File location() {
1909 return tmpdir;
1910 }
1911
1912 // file name generation
1913 private static final SecureRandom random = new SecureRandom();
1914 private static int shortenSubName(int subNameLength, int excess,
1915 int nameMin) {
1916 int newLength = Math.max(nameMin, subNameLength - excess);
1917 if (newLength < subNameLength) {
1918 return newLength;
1919 }
1920 return subNameLength;
1921 }
1922 static File generateFile(String prefix, String suffix, File dir)
1923 throws IOException
1924 {
1925 long n = random.nextLong();
1926 String nus = Long.toUnsignedString(n);
1927
1928 // Use only the file name from the supplied prefix
1929 prefix = (new File(prefix)).getName();
1930
1931 int prefixLength = prefix.length();
1932 int nusLength = nus.length();
1933 int suffixLength = suffix.length();;
1934
1935 String name;
1936 int nameMax = fs.getNameMax(dir.getPath());
1937 int excess = prefixLength + nusLength + suffixLength - nameMax;
1938 if (excess <= 0) {
1939 name = prefix + nus + suffix;
1940 } else {
1941 // Name exceeds the maximum path component length: shorten it
1942
1943 // Attempt to shorten the prefix length to no less then 3
1944 prefixLength = shortenSubName(prefixLength, excess, 3);
1945 excess = prefixLength + nusLength + suffixLength - nameMax;
1946
1947 if (excess > 0) {
1948 // Attempt to shorten the suffix length to no less than
1949 // 0 or 4 depending on whether it begins with a dot ('.')
1950 suffixLength = shortenSubName(suffixLength, excess,
1951 suffix.indexOf(".") == 0 ? 4 : 0);
1952 suffixLength = shortenSubName(suffixLength, excess, 3);
1953 excess = prefixLength + nusLength + suffixLength - nameMax;
1954 }
1955
1956 if (excess > 0 && excess <= nusLength - 5) {
1957 // Attempt to shorten the random character string length
1958 // to no less than 5
1959 nusLength = shortenSubName(nusLength, excess, 5);
1960 }
1961
1962 StringBuilder sb =
1963 new StringBuilder(prefixLength + nusLength + suffixLength);
1964 sb.append(prefixLength < prefix.length() ?
1965 prefix.substring(0, prefixLength) : prefix);
1966 sb.append(nusLength < nus.length() ?
1967 nus.substring(0, nusLength) : nus);
1968 sb.append(suffixLength < suffix.length() ?
1969 suffix.substring(0, suffixLength) : suffix);
1970 name = sb.toString();
1971 }
1972
1973 // Normalize the path component
1974 name = fs.normalize(name);
1975
1976 File f = new File(dir, name);
1977 if (!name.equals(f.getName()) || f.isInvalid()) {
1978 if (System.getSecurityManager() != null)
1979 throw new IOException("Unable to create temporary file");
1980 else
1981 throw new IOException("Unable to create temporary file, "
1982 + name);
1983 }
1984 return f;
1985 }
1986 }
1987
1988 /**
1989 * <p> Creates a new empty file in the specified directory, using the
1990 * given prefix and suffix strings to generate its name. If this method
1991 * returns successfully then it is guaranteed that:
1992 *
1993 * <ol>
1994 * <li> The file denoted by the returned abstract pathname did not exist
1995 * before this method was invoked, and
1996 * <li> Neither this method nor any of its variants will return the same
1997 * abstract pathname again in the current invocation of the virtual
1998 * machine.
1999 * </ol>
2000 *
2001 * This method provides only part of a temporary-file facility. To arrange
2002 * for a file created by this method to be deleted automatically, use the
2003 * {@link #deleteOnExit} method.
2004 *
2005 * <p> The <code>prefix</code> argument must be at least three characters
2006 * long. It is recommended that the prefix be a short, meaningful string
2007 * such as <code>"hjb"</code> or <code>"mail"</code>. The
2008 * <code>suffix</code> argument may be <code>null</code>, in which case the
2009 * suffix <code>".tmp"</code> will be used.
2010 *
2011 * <p> To create the new file, the prefix and the suffix may first be
2012 * adjusted to fit the limitations of the underlying platform. If the
2013 * prefix is too long then it will be truncated, but its first three
2014 * characters will always be preserved. If the suffix is too long then it
2015 * too will be truncated, but if it begins with a period character
2016 * (<code>'.'</code>) then the period and the first three characters
2017 * following it will always be preserved. Once these adjustments have been
2018 * made the name of the new file will be generated by concatenating the
2019 * prefix, five or more internally-generated characters, and the suffix.
2020 *
2021 * <p> If the <code>directory</code> argument is <code>null</code> then the
2022 * system-dependent default temporary-file directory will be used. The
2023 * default temporary-file directory is specified by the system property
2024 * <code>java.io.tmpdir</code>. On UNIX systems the default value of this
2025 * property is typically <code>"/tmp"</code> or <code>"/var/tmp"</code>; on
2026 * Microsoft Windows systems it is typically <code>"C:\\WINNT\\TEMP"</code>. A different
2027 * value may be given to this system property when the Java virtual machine
2028 * is invoked, but programmatic changes to this property are not guaranteed
2029 * to have any effect upon the temporary directory used by this method.
2030 *
2031 * @param prefix The prefix string to be used in generating the file's
2032 * name; must be at least three characters long
2033 *
2034 * @param suffix The suffix string to be used in generating the file's
2035 * name; may be <code>null</code>, in which case the
2036 * suffix <code>".tmp"</code> will be used
2037 *
2038 * @param directory The directory in which the file is to be created, or
2039 * <code>null</code> if the default temporary-file
2040 * directory is to be used
2041 *
2042 * @return An abstract pathname denoting a newly-created empty file
2043 *
2044 * @throws IllegalArgumentException
2045 * If the <code>prefix</code> argument contains fewer than three
2046 * characters
2047 *
2048 * @throws IOException If a file could not be created
2049 *
2050 * @throws SecurityException
2051 * If a security manager exists and its {@link
2052 * java.lang.SecurityManager#checkWrite(java.lang.String)}
2053 * method does not allow a file to be created
2054 *
2055 * @since 1.2
2056 */
2057 public static File createTempFile(String prefix, String suffix,
2058 File directory)
2059 throws IOException
2060 {
2061 if (prefix.length() < 3) {
2062 throw new IllegalArgumentException("Prefix string \"" + prefix +
2063 "\" too short: length must be at least 3");
2064 }
2065 if (suffix == null)
2066 suffix = ".tmp";
2067
2068 File tmpdir = (directory != null) ? directory
2069 : TempDirectory.location();
2070 SecurityManager sm = System.getSecurityManager();
2071 File f;
2072 do {
2073 f = TempDirectory.generateFile(prefix, suffix, tmpdir);
2074
2075 if (sm != null) {
2076 try {
2077 sm.checkWrite(f.getPath());
2078 } catch (SecurityException se) {
2079 // don't reveal temporary directory location
2080 if (directory == null)
2081 throw new SecurityException("Unable to create temporary file");
2082 throw se;
2083 }
2084 }
2085 } while ((fs.getBooleanAttributes(f) & FileSystem.BA_EXISTS) != 0);
2086
2087 if (!fs.createFileExclusively(f.getPath()))
2088 throw new IOException("Unable to create temporary file");
2089
2090 return f;
2091 }
2092
2093 /**
2094 * Creates an empty file in the default temporary-file directory, using
2095 * the given prefix and suffix to generate its name. Invoking this method
2096 * is equivalent to invoking {@link #createTempFile(java.lang.String,
2097 * java.lang.String, java.io.File)
2098 * createTempFile(prefix, suffix, null)}.
2099 *
2100 * <p> The {@link
2101 * java.nio.file.Files#createTempFile(String,String,java.nio.file.attribute.FileAttribute[])
2102 * Files.createTempFile} method provides an alternative method to create an
2103 * empty file in the temporary-file directory. Files created by that method
2104 * may have more restrictive access permissions to files created by this
2105 * method and so may be more suited to security-sensitive applications.
2106 *
2107 * @param prefix The prefix string to be used in generating the file's
2108 * name; must be at least three characters long
2109 *
2110 * @param suffix The suffix string to be used in generating the file's
2111 * name; may be <code>null</code>, in which case the
2112 * suffix <code>".tmp"</code> will be used
2113 *
2114 * @return An abstract pathname denoting a newly-created empty file
2115 *
2116 * @throws IllegalArgumentException
2117 * If the <code>prefix</code> argument contains fewer than three
2118 * characters
2119 *
2120 * @throws IOException If a file could not be created
2121 *
2122 * @throws SecurityException
2123 * If a security manager exists and its {@link
2124 * java.lang.SecurityManager#checkWrite(java.lang.String)}
2125 * method does not allow a file to be created
2126 *
2127 * @since 1.2
2128 * @see java.nio.file.Files#createTempDirectory(String,FileAttribute[])
2129 */
2130 public static File createTempFile(String prefix, String suffix)
2131 throws IOException
2132 {
2133 return createTempFile(prefix, suffix, null);
2134 }
2135
2136 /* -- Basic infrastructure -- */
2137
2138 /**
2139 * Compares two abstract pathnames lexicographically. The ordering
2140 * defined by this method depends upon the underlying system. On UNIX
2141 * systems, alphabetic case is significant in comparing pathnames; on Microsoft Windows
2142 * systems it is not.
2143 *
2144 * @param pathname The abstract pathname to be compared to this abstract
2145 * pathname
2146 *
2147 * @return Zero if the argument is equal to this abstract pathname, a
2148 * value less than zero if this abstract pathname is
2149 * lexicographically less than the argument, or a value greater
2150 * than zero if this abstract pathname is lexicographically
2151 * greater than the argument
2152 *
2153 * @since 1.2
2154 */
2155 public int compareTo(File pathname) {
2156 return fs.compare(this, pathname);
2157 }
2158
2159 /**
2160 * Tests this abstract pathname for equality with the given object.
2161 * Returns <code>true</code> if and only if the argument is not
2162 * <code>null</code> and is an abstract pathname that denotes the same file
2163 * or directory as this abstract pathname. Whether or not two abstract
2164 * pathnames are equal depends upon the underlying system. On UNIX
2165 * systems, alphabetic case is significant in comparing pathnames; on Microsoft Windows
2166 * systems it is not.
2167 *
2168 * @param obj The object to be compared with this abstract pathname
2169 *
2170 * @return <code>true</code> if and only if the objects are the same;
2171 * <code>false</code> otherwise
2172 */
2173 public boolean equals(Object obj) {
2174 if ((obj != null) && (obj instanceof File)) {
2175 return compareTo((File)obj) == 0;
2176 }
2177 return false;
2178 }
2179
2180 /**
2181 * Computes a hash code for this abstract pathname. Because equality of
2182 * abstract pathnames is inherently system-dependent, so is the computation
2183 * of their hash codes. On UNIX systems, the hash code of an abstract
2184 * pathname is equal to the exclusive <em>or</em> of the hash code
2185 * of its pathname string and the decimal value
2186 * <code>1234321</code>. On Microsoft Windows systems, the hash
2187 * code is equal to the exclusive <em>or</em> of the hash code of
2188 * its pathname string converted to lower case and the decimal
2189 * value <code>1234321</code>. Locale is not taken into account on
2190 * lowercasing the pathname string.
2191 *
2192 * @return A hash code for this abstract pathname
2193 */
2194 public int hashCode() {
2195 return fs.hashCode(this);
2196 }
2197
2198 /**
2199 * Returns the pathname string of this abstract pathname. This is just the
2200 * string returned by the {@link #getPath} method.
2201 *
2202 * @return The string form of this abstract pathname
2203 */
2204 public String toString() {
2205 return getPath();
2206 }
2207
2208 /**
2209 * WriteObject is called to save this filename.
2210 * The separator character is saved also so it can be replaced
2211 * in case the path is reconstituted on a different host type.
2212 *
2213 * @serialData Default fields followed by separator character.
2214 */
2215 private synchronized void writeObject(java.io.ObjectOutputStream s)
2216 throws IOException
2217 {
2218 s.defaultWriteObject();
2219 s.writeChar(separatorChar); // Add the separator character
2220 }
2221
2222 /**
2223 * readObject is called to restore this filename.
2224 * The original separator character is read. If it is different
2225 * than the separator character on this system, then the old separator
2226 * is replaced by the local separator.
2227 */
2228 private synchronized void readObject(java.io.ObjectInputStream s)
2229 throws IOException, ClassNotFoundException
2230 {
2231 ObjectInputStream.GetField fields = s.readFields();
2232 String pathField = (String)fields.get("path", null);
2233 char sep = s.readChar(); // read the previous separator char
2234 if (sep != separatorChar)
2235 pathField = pathField.replace(sep, separatorChar);
2236 String path = fs.normalize(pathField);
2237 UNSAFE.putObject(this, PATH_OFFSET, path);
2238 UNSAFE.putIntVolatile(this, PREFIX_LENGTH_OFFSET, fs.prefixLength(path));
2239 }
2240
2241 private static final long PATH_OFFSET;
2242 private static final long PREFIX_LENGTH_OFFSET;
2243 private static final jdk.internal.misc.Unsafe UNSAFE;
2244 static {
2245 try {
2246 jdk.internal.misc.Unsafe unsafe = jdk.internal.misc.Unsafe.getUnsafe();
2247 PATH_OFFSET = unsafe.objectFieldOffset(
2248 File.class.getDeclaredField("path"));
2249 PREFIX_LENGTH_OFFSET = unsafe.objectFieldOffset(
2250 File.class.getDeclaredField("prefixLength"));
2251 UNSAFE = unsafe;
2252 } catch (ReflectiveOperationException e) {
2253 throw new Error(e);
2254 }
2255 }
2256
2257
2258 /** use serialVersionUID from JDK 1.0.2 for interoperability */
2259 private static final long serialVersionUID = 301077366599181567L;
2260
2261 // -- Integration with java.nio.file --
2262
2263 private transient volatile Path filePath;
2264
2265 /**
2266 * Returns a {@link Path java.nio.file.Path} object constructed from the
2267 * this abstract path. The resulting {@code Path} is associated with the
2268 * {@link java.nio.file.FileSystems#getDefault default-filesystem}.
2269 *
2270 * <p> The first invocation of this method works as if invoking it were
2271 * equivalent to evaluating the expression:
2272 * <blockquote><pre>
2273 * {@link java.nio.file.FileSystems#getDefault FileSystems.getDefault}().{@link
2274 * java.nio.file.FileSystem#getPath getPath}(this.{@link #getPath getPath}());
2275 * </pre></blockquote>
2276 * Subsequent invocations of this method return the same {@code Path}.
2277 *
2278 * <p> If this abstract pathname is the empty abstract pathname then this
2279 * method returns a {@code Path} that may be used to access the current
2280 * user directory.
2281 *
2282 * @return a {@code Path} constructed from this abstract path
2283 *
2284 * @throws java.nio.file.InvalidPathException
2285 * if a {@code Path} object cannot be constructed from the abstract
2286 * path (see {@link java.nio.file.FileSystem#getPath FileSystem.getPath})
2287 *
2288 * @since 1.7
2289 * @see Path#toFile
2290 */
2291 public Path toPath() {
2292 Path result = filePath;
2293 if (result == null) {
2294 synchronized (this) {
2295 result = filePath;
2296 if (result == null) {
2297 result = FileSystems.getDefault().getPath(path);
2298 filePath = result;
2299 }
2300 }
2301 }
2302 return result;
2303 }
2304 }