1 /*
2 * Copyright (c) 1994, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
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.AccessController;
35 import java.security.SecureRandom;
36 import java.nio.file.Path;
37 import java.nio.file.FileSystems;
38 import sun.security.action.GetPropertyAction;
39
40 /**
41 * An abstract representation of file and directory pathnames.
42 *
43 * <p> User interfaces and operating systems use system-dependent <em>pathname
44 * strings</em> to name files and directories. This class presents an
45 * abstract, system-independent view of hierarchical pathnames. An
46 * <em>abstract pathname</em> has two components:
47 *
48 * <ol>
49 * <li> An optional system-dependent <em>prefix</em> string,
50 * such as a disk-drive specifier, <code>"/"</code> for the UNIX root
51 * directory, or <code>"\\\\"</code> for a Microsoft Windows UNC pathname, and
52 * <li> A sequence of zero or more string <em>names</em>.
53 * </ol>
54 *
55 * The first name in an abstract pathname may be a directory name or, in the
56 * case of Microsoft Windows UNC pathnames, a hostname. Each subsequent name
57 * in an abstract pathname denotes a directory; the last name may denote
58 * either a directory or a file. The <em>empty</em> abstract pathname has no
59 * prefix and an empty name sequence.
60 *
61 * <p> The conversion of a pathname string to or from an abstract pathname is
62 * inherently system-dependent. When an abstract pathname is converted into a
63 * pathname string, each name is separated from the next by a single copy of
64 * the default <em>separator character</em>. The default name-separator
65 * character is defined by the system property <code>file.separator</code>, and
66 * is made available in the public static fields <code>{@link
67 * #separator}</code> and <code>{@link #separatorChar}</code> of this class.
68 * When a pathname string is converted into an abstract pathname, the names
69 * within it may be separated by the default name-separator character or by any
70 * other name-separator character that is supported by the underlying system.
71 *
72 * <p> A pathname, whether abstract or in string form, may be either
73 * <em>absolute</em> or <em>relative</em>. An absolute pathname is complete in
74 * that no other information is required in order to locate the file that it
75 * denotes. A relative pathname, in contrast, must be interpreted in terms of
76 * information taken from some other pathname. By default the classes in the
77 * <code>java.io</code> package always resolve relative pathnames against the
78 * current user directory. This directory is named by the system property
79 * <code>user.dir</code>, and is typically the directory in which the Java
80 * virtual machine was invoked.
81 *
82 * <p> The <em>parent</em> of an abstract pathname may be obtained by invoking
83 * the {@link #getParent} method of this class and consists of the pathname's
84 * prefix and each name in the pathname's name sequence except for the last.
85 * Each directory's absolute pathname is an ancestor of any <tt>File</tt>
86 * object with an absolute abstract pathname which begins with the directory's
87 * absolute pathname. For example, the directory denoted by the abstract
88 * pathname <tt>"/usr"</tt> is an ancestor of the directory denoted by the
89 * pathname <tt>"/usr/local/bin"</tt>.
90 *
91 * <p> The prefix concept is used to handle root directories on UNIX platforms,
92 * and drive specifiers, root directories and UNC pathnames on Microsoft Windows platforms,
93 * as follows:
94 *
95 * <ul>
96 *
97 * <li> For UNIX platforms, the prefix of an absolute pathname is always
98 * <code>"/"</code>. Relative pathnames have no prefix. The abstract pathname
99 * denoting the root directory has the prefix <code>"/"</code> and an empty
100 * name sequence.
101 *
102 * <li> For Microsoft Windows platforms, the prefix of a pathname that contains a drive
103 * specifier consists of the drive letter followed by <code>":"</code> and
104 * possibly followed by <code>"\\"</code> if the pathname is absolute. The
105 * prefix of a UNC pathname is <code>"\\\\"</code>; the hostname and the share
106 * name are the first two names in the name sequence. A relative pathname that
107 * does not specify a drive has no prefix.
108 *
109 * </ul>
110 *
111 * <p> Instances of this class may or may not denote an actual file-system
112 * object such as a file or a directory. If it does denote such an object
113 * then that object resides in a <i>partition</i>. A partition is an
114 * operating system-specific portion of storage for a file system. A single
115 * storage device (e.g. a physical disk-drive, flash memory, CD-ROM) may
116 * contain multiple partitions. The object, if any, will reside on the
117 * partition <a name="partName">named</a> by some ancestor of the absolute
118 * form of this pathname.
119 *
120 * <p> A file system may implement restrictions to certain operations on the
121 * actual file-system object, such as reading, writing, and executing. These
122 * restrictions are collectively known as <i>access permissions</i>. The file
123 * system may have multiple sets of access permissions on a single object.
124 * For example, one set may apply to the object's <i>owner</i>, and another
125 * may apply to all other users. The access permissions on an object may
126 * cause some methods in this class to fail.
127 *
128 * <p> Instances of the <code>File</code> class are immutable; that is, once
129 * created, the abstract pathname represented by a <code>File</code> object
130 * will never change.
131 *
132 * <h3>Interoperability with {@code java.nio.file} package</h3>
133 *
134 * <p> The <a href="../../java/nio/file/package-summary.html">{@code java.nio.file}</a>
135 * package defines interfaces and classes for the Java virtual machine to access
136 * files, file attributes, and file systems. This API may be used to overcome
137 * many of the limitations of the {@code java.io.File} class.
138 * The {@link #toPath toPath} method may be used to obtain a {@link
139 * Path} that uses the abstract path represented by a {@code File} object to
140 * locate a file. The resulting {@code Path} may be used with the {@link
141 * java.nio.file.Files} class to provide more efficient and extensive access to
142 * additional file operations, file attributes, and I/O exceptions to help
143 * diagnose errors when an operation on a file fails.
144 *
145 * @author unascribed
146 * @since JDK1.0
147 */
148
149 public class File
150 implements Serializable, Comparable<File>
151 {
152
153 /**
154 * The FileSystem object representing the platform's local file system.
155 */
156 private static final FileSystem fs = DefaultFileSystem.getFileSystem();
157
158 /**
159 * This abstract pathname's normalized pathname string. A normalized
160 * pathname string uses the default name-separator character and does not
161 * contain any duplicate or redundant separators.
162 *
163 * @serial
164 */
165 private final String path;
166
167 /**
168 * Enum type that indicates the status of a file path.
169 */
170 private static enum PathStatus { INVALID, CHECKED };
171
172 /**
173 * The flag indicating whether the file path is invalid.
174 */
175 private transient PathStatus status = null;
176
177 /**
178 * Check if the file has an invalid path. Currently, the inspection of
179 * a file path is very limited, and it only covers Nul character check.
180 * Returning true means the path is definitely invalid/garbage. But
181 * returning false does not guarantee that the path is valid.
182 *
183 * @return true if the file path is invalid.
184 */
185 final boolean isInvalid() {
186 if (status == null) {
187 status = (this.path.indexOf('\u0000') < 0) ? PathStatus.CHECKED
188 : PathStatus.INVALID;
189 }
190 return status == PathStatus.INVALID;
191 }
192
193 /**
194 * The length of this abstract pathname's prefix, or zero if it has no
195 * prefix.
196 */
197 private final transient int prefixLength;
198
199 /**
200 * Returns the length of this abstract pathname's prefix.
201 * For use by FileSystem classes.
202 */
203 int getPrefixLength() {
204 return prefixLength;
205 }
206
207 /**
208 * The system-dependent default name-separator character. This field is
209 * initialized to contain the first character of the value of the system
210 * property <code>file.separator</code>. On UNIX systems the value of this
211 * field is <code>'/'</code>; on Microsoft Windows systems it is <code>'\\'</code>.
212 *
213 * @see java.lang.System#getProperty(java.lang.String)
214 */
215 public static final char separatorChar = fs.getSeparator();
216
217 /**
218 * The system-dependent default name-separator character, represented as a
219 * string for convenience. This string contains a single character, namely
220 * <code>{@link #separatorChar}</code>.
221 */
222 public static final String separator = "" + separatorChar;
223
224 /**
225 * The system-dependent path-separator character. This field is
226 * initialized to contain the first character of the value of the system
227 * property <code>path.separator</code>. This character is used to
228 * separate filenames in a sequence of files given as a <em>path list</em>.
229 * On UNIX systems, this character is <code>':'</code>; on Microsoft Windows systems it
230 * is <code>';'</code>.
231 *
232 * @see java.lang.System#getProperty(java.lang.String)
233 */
234 public static final char pathSeparatorChar = fs.getPathSeparator();
235
236 /**
237 * The system-dependent path-separator character, represented as a string
238 * for convenience. This string contains a single character, namely
239 * <code>{@link #pathSeparatorChar}</code>.
240 */
241 public static final String pathSeparator = "" + pathSeparatorChar;
242
243
244 /* -- Constructors -- */
245
246 /**
247 * Internal constructor for already-normalized pathname strings.
248 */
249 private File(String pathname, int prefixLength) {
250 this.path = pathname;
251 this.prefixLength = prefixLength;
252 }
253
254 /**
255 * Internal constructor for already-normalized pathname strings.
256 * The parameter order is used to disambiguate this method from the
257 * public(File, String) constructor.
258 */
259 private File(String child, File parent) {
260 assert parent.path != null;
261 assert (!parent.path.equals(""));
262 this.path = fs.resolve(parent.path, child);
263 this.prefixLength = parent.prefixLength;
264 }
265
266 /**
267 * Creates a new <code>File</code> instance by converting the given
268 * pathname string into an abstract pathname. If the given string is
269 * the empty string, then the result is the empty abstract pathname.
270 *
271 * @param pathname A pathname string
272 * @throws NullPointerException
273 * If the <code>pathname</code> argument is <code>null</code>
274 */
275 public File(String pathname) {
276 if (pathname == null) {
277 throw new NullPointerException();
278 }
279 this.path = fs.normalize(pathname);
280 this.prefixLength = fs.prefixLength(this.path);
281 }
282
283 /* Note: The two-argument File constructors do not interpret an empty
284 parent abstract pathname as the current user directory. An empty parent
285 instead causes the child to be resolved against the system-dependent
286 directory defined by the FileSystem.getDefaultParent method. On Unix
287 this default is "/", while on Microsoft Windows it is "\\". This is required for
288 compatibility with the original behavior of this class. */
289
290 /**
291 * Creates a new <code>File</code> instance from a parent pathname string
292 * and a child pathname string.
293 *
294 * <p> If <code>parent</code> is <code>null</code> then the new
295 * <code>File</code> instance is created as if by invoking the
296 * single-argument <code>File</code> constructor on the given
297 * <code>child</code> pathname string.
298 *
299 * <p> Otherwise the <code>parent</code> pathname string is taken to denote
300 * a directory, and the <code>child</code> pathname string is taken to
301 * denote either a directory or a file. If the <code>child</code> pathname
302 * string is absolute then it is converted into a relative pathname in a
303 * system-dependent way. If <code>parent</code> is the empty string then
304 * the new <code>File</code> instance is created by converting
305 * <code>child</code> into an abstract pathname and resolving the result
306 * against a system-dependent default directory. Otherwise each pathname
307 * string is converted into an abstract pathname and the child abstract
308 * pathname is resolved against the parent.
309 *
310 * @param parent The parent pathname string
311 * @param child The child pathname string
312 * @throws NullPointerException
313 * If <code>child</code> is <code>null</code>
314 */
315 public File(String parent, String child) {
316 if (child == null) {
317 throw new NullPointerException();
318 }
319 if (parent != null) {
320 if (parent.equals("")) {
321 this.path = fs.resolve(fs.getDefaultParent(),
322 fs.normalize(child));
323 } else {
324 this.path = fs.resolve(fs.normalize(parent),
325 fs.normalize(child));
326 }
327 } else {
328 this.path = fs.normalize(child);
329 }
330 this.prefixLength = fs.prefixLength(this.path);
331 }
332
333 /**
334 * Creates a new <code>File</code> instance from a parent abstract
335 * pathname and a child pathname string.
336 *
337 * <p> If <code>parent</code> is <code>null</code> then the new
338 * <code>File</code> instance is created as if by invoking the
339 * single-argument <code>File</code> constructor on the given
340 * <code>child</code> pathname string.
341 *
342 * <p> Otherwise the <code>parent</code> abstract pathname is taken to
343 * denote a directory, and the <code>child</code> pathname string is taken
344 * to denote either a directory or a file. If the <code>child</code>
345 * pathname string is absolute then it is converted into a relative
346 * pathname in a system-dependent way. If <code>parent</code> is the empty
347 * abstract pathname then the new <code>File</code> instance is created by
348 * converting <code>child</code> into an abstract pathname and resolving
349 * the result against a system-dependent default directory. Otherwise each
350 * pathname string is converted into an abstract pathname and the child
351 * abstract pathname is resolved against the parent.
352 *
353 * @param parent The parent abstract pathname
354 * @param child The child pathname string
355 * @throws NullPointerException
356 * If <code>child</code> is <code>null</code>
357 */
358 public File(File parent, String child) {
359 if (child == null) {
360 throw new NullPointerException();
361 }
362 if (parent != null) {
363 if (parent.path.equals("")) {
364 this.path = fs.resolve(fs.getDefaultParent(),
365 fs.normalize(child));
366 } else {
367 this.path = fs.resolve(parent.path,
368 fs.normalize(child));
369 }
370 } else {
371 this.path = fs.normalize(child);
372 }
373 this.prefixLength = fs.prefixLength(this.path);
374 }
375
376 /**
377 * Creates a new <tt>File</tt> instance by converting the given
378 * <tt>file:</tt> URI into an abstract pathname.
379 *
380 * <p> The exact form of a <tt>file:</tt> URI is system-dependent, hence
381 * the transformation performed by this constructor is also
382 * system-dependent.
383 *
384 * <p> For a given abstract pathname <i>f</i> it is guaranteed that
385 *
386 * <blockquote><tt>
387 * new File(</tt><i> f</i><tt>.{@link #toURI() toURI}()).equals(</tt><i> f</i><tt>.{@link #getAbsoluteFile() getAbsoluteFile}())
388 * </tt></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 <tt>file:</tt> 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 * <tt>"file"</tt>, a non-empty path component, and undefined
400 * authority, query, and fragment components
401 *
402 * @throws NullPointerException
403 * If <tt>uri</tt> is <tt>null</tt>
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.getAuthority() != null)
423 throw new IllegalArgumentException("URI has an authority component");
424 if (uri.getFragment() != null)
425 throw new IllegalArgumentException("URI has a fragment component");
426 if (uri.getQuery() != 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 <code>{@link #getPath}</code>
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 <tt>"."</tt> and <tt>".."</tt> 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 <code>{@link
608 * java.lang.SecurityManager#checkRead}</code> method denies
609 * read access to the file
610 *
611 * @since JDK1.1
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 <code>{@link
636 * java.lang.SecurityManager#checkRead}</code> 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 <tt>file:</tt> 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><tt>
699 * new {@link #File(java.net.URI) File}(</tt><i> f</i><tt>.toURI()).equals(</tt><i> f</i><tt>.{@link #getAbsoluteFile() getAbsoluteFile}())
700 * </tt></blockquote>
701 *
702 * so long as the original abstract pathname, the URI, and the new abstract
703 * pathname are all created in (possibly different invocations of) the same
704 * Java virtual machine. Due to the system-dependent nature of abstract
705 * pathnames, however, this relationship typically does not hold when a
706 * <tt>file:</tt> URI that is created in a virtual machine on one operating
707 * system is converted into an abstract pathname in a virtual machine on a
708 * different operating system.
709 *
710 * <p> Note that when this abstract pathname represents a UNC pathname then
711 * all components of the UNC (including the server name component) are encoded
712 * in the {@code URI} path. The authority component is undefined, meaning
713 * that it is represented as {@code null}. The {@link Path} class defines the
714 * {@link Path#toUri toUri} method to encode the server name in the authority
715 * component of the resulting {@code URI}. The {@link #toPath toPath} method
716 * may be used to obtain a {@code Path} representing this abstract pathname.
717 *
718 * @return An absolute, hierarchical URI with a scheme equal to
719 * <tt>"file"</tt>, a path representing this abstract pathname,
720 * and undefined authority, query, and fragment components
721 * @throws SecurityException If a required system property value cannot
722 * be accessed.
723 *
724 * @see #File(java.net.URI)
725 * @see java.net.URI
726 * @see java.net.URI#toURL()
727 * @since 1.4
728 */
729 public URI toURI() {
730 try {
731 File f = getAbsoluteFile();
732 String sp = slashify(f.getPath(), f.isDirectory());
733 if (sp.startsWith("//"))
734 sp = "//" + sp;
735 return new URI("file", null, sp, null);
736 } catch (URISyntaxException x) {
737 throw new Error(x); // Can't happen
738 }
739 }
740
741
742 /* -- Attribute accessors -- */
743
744 /**
745 * Tests whether the application can read the file denoted by this
746 * abstract pathname. On some platforms it may be possible to start the
747 * Java virtual machine with special privileges that allow it to read
748 * files that are marked as unreadable. Consequently this method may return
749 * {@code true} even though the file does not have read permissions.
750 *
751 * @return <code>true</code> if and only if the file specified by this
752 * abstract pathname exists <em>and</em> can be read by the
753 * application; <code>false</code> otherwise
754 *
755 * @throws SecurityException
756 * If a security manager exists and its <code>{@link
757 * java.lang.SecurityManager#checkRead(java.lang.String)}</code>
758 * method denies read access to the file
759 */
760 public boolean canRead() {
761 SecurityManager security = System.getSecurityManager();
762 if (security != null) {
763 security.checkRead(path);
764 }
765 if (isInvalid()) {
766 return false;
767 }
768 return fs.checkAccess(this, FileSystem.ACCESS_READ);
769 }
770
771 /**
772 * Tests whether the application can modify the file denoted by this
773 * abstract pathname. On some platforms it may be possible to start the
774 * Java virtual machine with special privileges that allow it to modify
775 * files that are marked read-only. Consequently this method may return
776 * {@code true} even though the file is marked read-only.
777 *
778 * @return <code>true</code> if and only if the file system actually
779 * contains a file denoted by this abstract pathname <em>and</em>
780 * the application is allowed to write to the file;
781 * <code>false</code> otherwise.
782 *
783 * @throws SecurityException
784 * If a security manager exists and its <code>{@link
785 * java.lang.SecurityManager#checkWrite(java.lang.String)}</code>
786 * method denies write access to the file
787 */
788 public boolean canWrite() {
789 SecurityManager security = System.getSecurityManager();
790 if (security != null) {
791 security.checkWrite(path);
792 }
793 if (isInvalid()) {
794 return false;
795 }
796 return fs.checkAccess(this, FileSystem.ACCESS_WRITE);
797 }
798
799 /**
800 * Tests whether the file or directory denoted by this abstract pathname
801 * exists.
802 *
803 * @return <code>true</code> if and only if the file or directory denoted
804 * by this abstract pathname exists; <code>false</code> otherwise
805 *
806 * @throws SecurityException
807 * If a security manager exists and its <code>{@link
808 * java.lang.SecurityManager#checkRead(java.lang.String)}</code>
809 * method denies read access to the file or directory
810 */
811 public boolean exists() {
812 SecurityManager security = System.getSecurityManager();
813 if (security != null) {
814 security.checkRead(path);
815 }
816 if (isInvalid()) {
817 return false;
818 }
819 return ((fs.getBooleanAttributes(this) & FileSystem.BA_EXISTS) != 0);
820 }
821
822 /**
823 * Tests whether the file denoted by this abstract pathname is a
824 * directory.
825 *
826 * <p> Where it is required to distinguish an I/O exception from the case
827 * that the file is not a directory, or where several attributes of the
828 * same file are required at the same time, then the {@link
829 * java.nio.file.Files#readAttributes(Path,Class,LinkOption[])
830 * Files.readAttributes} method may be used.
831 *
832 * @return <code>true</code> if and only if the file denoted by this
833 * abstract pathname exists <em>and</em> is a directory;
834 * <code>false</code> otherwise
835 *
836 * @throws SecurityException
837 * If a security manager exists and its <code>{@link
838 * java.lang.SecurityManager#checkRead(java.lang.String)}</code>
839 * method denies read access to the file
840 */
841 public boolean isDirectory() {
842 SecurityManager security = System.getSecurityManager();
843 if (security != null) {
844 security.checkRead(path);
845 }
846 if (isInvalid()) {
847 return false;
848 }
849 return ((fs.getBooleanAttributes(this) & FileSystem.BA_DIRECTORY)
850 != 0);
851 }
852
853 /**
854 * Tests whether the file denoted by this abstract pathname is a normal
855 * file. A file is <em>normal</em> if it is not a directory and, in
856 * addition, satisfies other system-dependent criteria. Any non-directory
857 * file created by a Java application is guaranteed to be a normal file.
858 *
859 * <p> Where it is required to distinguish an I/O exception from the case
860 * that the file is not a normal file, or where several attributes of the
861 * same file are required at the same time, then the {@link
862 * java.nio.file.Files#readAttributes(Path,Class,LinkOption[])
863 * Files.readAttributes} method may be used.
864 *
865 * @return <code>true</code> if and only if the file denoted by this
866 * abstract pathname exists <em>and</em> is a normal file;
867 * <code>false</code> otherwise
868 *
869 * @throws SecurityException
870 * If a security manager exists and its <code>{@link
871 * java.lang.SecurityManager#checkRead(java.lang.String)}</code>
872 * method denies read access to the file
873 */
874 public boolean isFile() {
875 SecurityManager security = System.getSecurityManager();
876 if (security != null) {
877 security.checkRead(path);
878 }
879 if (isInvalid()) {
880 return false;
881 }
882 return ((fs.getBooleanAttributes(this) & FileSystem.BA_REGULAR) != 0);
883 }
884
885 /**
886 * Tests whether the file named by this abstract pathname is a hidden
887 * file. The exact definition of <em>hidden</em> is system-dependent. On
888 * UNIX systems, a file is considered to be hidden if its name begins with
889 * a period character (<code>'.'</code>). On Microsoft Windows systems, a file is
890 * considered to be hidden if it has been marked as such in the filesystem.
891 *
892 * @return <code>true</code> if and only if the file denoted by this
893 * abstract pathname is hidden according to the conventions of the
894 * underlying platform
895 *
896 * @throws SecurityException
897 * If a security manager exists and its <code>{@link
898 * java.lang.SecurityManager#checkRead(java.lang.String)}</code>
899 * method denies read access to the file
900 *
901 * @since 1.2
902 */
903 public boolean isHidden() {
904 SecurityManager security = System.getSecurityManager();
905 if (security != null) {
906 security.checkRead(path);
907 }
908 if (isInvalid()) {
909 return false;
910 }
911 return ((fs.getBooleanAttributes(this) & FileSystem.BA_HIDDEN) != 0);
912 }
913
914 /**
915 * Returns the time that the file denoted by this abstract pathname was
916 * last modified.
917 *
918 * <p> Where it is required to distinguish an I/O exception from the case
919 * where {@code 0L} is returned, or where several attributes of the
920 * same file are required at the same time, or where the time of last
921 * access or the creation time are required, then the {@link
922 * java.nio.file.Files#readAttributes(Path,Class,LinkOption[])
923 * Files.readAttributes} method may be used.
924 *
925 * @return A <code>long</code> value representing the time the file was
926 * last modified, measured in milliseconds since the epoch
927 * (00:00:00 GMT, January 1, 1970), or <code>0L</code> if the
928 * file does not exist or if an I/O error occurs
929 *
930 * @throws SecurityException
931 * If a security manager exists and its <code>{@link
932 * java.lang.SecurityManager#checkRead(java.lang.String)}</code>
933 * method denies read access to the file
934 */
935 public long lastModified() {
936 SecurityManager security = System.getSecurityManager();
937 if (security != null) {
938 security.checkRead(path);
939 }
940 if (isInvalid()) {
941 return 0L;
942 }
943 return fs.getLastModifiedTime(this);
944 }
945
946 /**
947 * Returns the length of the file denoted by this abstract pathname.
948 * The return value is unspecified if this pathname denotes a directory.
949 *
950 * <p> Where it is required to distinguish an I/O exception from the case
951 * that {@code 0L} is returned, or where several attributes of the same file
952 * are required at the same time, then the {@link
953 * java.nio.file.Files#readAttributes(Path,Class,LinkOption[])
954 * Files.readAttributes} method may be used.
955 *
956 * @return The length, in bytes, of the file denoted by this abstract
957 * pathname, or <code>0L</code> if the file does not exist. Some
958 * operating systems may return <code>0L</code> for pathnames
959 * denoting system-dependent entities such as devices or pipes.
960 *
961 * @throws SecurityException
962 * If a security manager exists and its <code>{@link
963 * java.lang.SecurityManager#checkRead(java.lang.String)}</code>
964 * method denies read access to the file
965 */
966 public long length() {
967 SecurityManager security = System.getSecurityManager();
968 if (security != null) {
969 security.checkRead(path);
970 }
971 if (isInvalid()) {
972 return 0L;
973 }
974 return fs.getLength(this);
975 }
976
977
978 /* -- File operations -- */
979
980 /**
981 * Atomically creates a new, empty file named by this abstract pathname if
982 * and only if a file with this name does not yet exist. The check for the
983 * existence of the file and the creation of the file if it does not exist
984 * are a single operation that is atomic with respect to all other
985 * filesystem activities that might affect the file.
986 * <P>
987 * Note: this method should <i>not</i> be used for file-locking, as
988 * the resulting protocol cannot be made to work reliably. The
989 * {@link java.nio.channels.FileLock FileLock}
990 * facility should be used instead.
991 *
992 * @return <code>true</code> if the named file does not exist and was
993 * successfully created; <code>false</code> if the named file
994 * already exists
995 *
996 * @throws IOException
997 * If an I/O error occurred
998 *
999 * @throws SecurityException
1000 * If a security manager exists and its <code>{@link
1001 * java.lang.SecurityManager#checkWrite(java.lang.String)}</code>
1002 * method denies write access to the file
1003 *
1004 * @since 1.2
1005 */
1006 public boolean createNewFile() throws IOException {
1007 SecurityManager security = System.getSecurityManager();
1008 if (security != null) security.checkWrite(path);
1009 if (isInvalid()) {
1010 throw new IOException("Invalid file path");
1011 }
1012 return fs.createFileExclusively(path);
1013 }
1014
1015 /**
1016 * Deletes the file or directory denoted by this abstract pathname. If
1017 * this pathname denotes a directory, then the directory must be empty in
1018 * order to be deleted.
1019 *
1020 * <p> Note that the {@link java.nio.file.Files} class defines the {@link
1021 * java.nio.file.Files#delete(Path) delete} method to throw an {@link IOException}
1022 * when a file cannot be deleted. This is useful for error reporting and to
1023 * diagnose why a file cannot be deleted.
1024 *
1025 * @return <code>true</code> if and only if the file or directory is
1026 * successfully deleted; <code>false</code> otherwise
1027 *
1028 * @throws SecurityException
1029 * If a security manager exists and its <code>{@link
1030 * java.lang.SecurityManager#checkDelete}</code> method denies
1031 * delete access to the file
1032 */
1033 public boolean delete() {
1034 SecurityManager security = System.getSecurityManager();
1035 if (security != null) {
1036 security.checkDelete(path);
1037 }
1038 if (isInvalid()) {
1039 return false;
1040 }
1041 return fs.delete(this);
1042 }
1043
1044 /**
1045 * Requests that the file or directory denoted by this abstract
1046 * pathname be deleted when the virtual machine terminates.
1047 * Files (or directories) are deleted in the reverse order that
1048 * they are registered. Invoking this method to delete a file or
1049 * directory that is already registered for deletion has no effect.
1050 * Deletion will be attempted only for normal termination of the
1051 * virtual machine, as defined by the Java Language Specification.
1052 *
1053 * <p> Once deletion has been requested, it is not possible to cancel the
1054 * request. This method should therefore be used with care.
1055 *
1056 * <P>
1057 * Note: this method should <i>not</i> be used for file-locking, as
1058 * the resulting protocol cannot be made to work reliably. The
1059 * {@link java.nio.channels.FileLock FileLock}
1060 * facility should be used instead.
1061 *
1062 * @throws SecurityException
1063 * If a security manager exists and its <code>{@link
1064 * java.lang.SecurityManager#checkDelete}</code> method denies
1065 * delete access to the file
1066 *
1067 * @see #delete
1068 *
1069 * @since 1.2
1070 */
1071 public void deleteOnExit() {
1072 SecurityManager security = System.getSecurityManager();
1073 if (security != null) {
1074 security.checkDelete(path);
1075 }
1076 if (isInvalid()) {
1077 return;
1078 }
1079 DeleteOnExitHook.add(path);
1080 }
1081
1082 /**
1083 * Returns an array of strings naming the files and directories in the
1084 * directory denoted by this abstract pathname.
1085 *
1086 * <p> If this abstract pathname does not denote a directory, then this
1087 * method returns {@code null}. Otherwise an array of strings is
1088 * returned, one for each file or directory in the directory. Names
1089 * denoting the directory itself and the directory's parent directory are
1090 * not included in the result. Each string is a file name rather than a
1091 * complete path.
1092 *
1093 * <p> There is no guarantee that the name strings in the resulting array
1094 * will appear in any specific order; they are not, in particular,
1095 * guaranteed to appear in alphabetical order.
1096 *
1097 * <p> Note that the {@link java.nio.file.Files} class defines the {@link
1098 * java.nio.file.Files#newDirectoryStream(Path) newDirectoryStream} method to
1099 * open a directory and iterate over the names of the files in the directory.
1100 * This may use less resources when working with very large directories, and
1101 * may be more responsive when working with remote directories.
1102 *
1103 * @return An array of strings naming the files and directories in the
1104 * directory denoted by this abstract pathname. The array will be
1105 * empty if the directory is empty. Returns {@code null} if
1106 * this abstract pathname does not denote a directory, or if an
1107 * I/O error occurs.
1108 *
1109 * @throws SecurityException
1110 * If a security manager exists and its {@link
1111 * SecurityManager#checkRead(String)} method denies read access to
1112 * the directory
1113 */
1114 public String[] list() {
1115 SecurityManager security = System.getSecurityManager();
1116 if (security != null) {
1117 security.checkRead(path);
1118 }
1119 if (isInvalid()) {
1120 return null;
1121 }
1122 return fs.list(this);
1123 }
1124
1125 /**
1126 * Returns an array of strings naming the files and directories in the
1127 * directory denoted by this abstract pathname that satisfy the specified
1128 * filter. The behavior of this method is the same as that of the
1129 * {@link #list()} method, except that the strings in the returned array
1130 * must satisfy the filter. If the given {@code filter} is {@code null}
1131 * then all names are accepted. Otherwise, a name satisfies the filter if
1132 * and only if the value {@code true} results when the {@link
1133 * FilenameFilter#accept FilenameFilter.accept(File, String)} method
1134 * of the filter is invoked on this abstract pathname and the name of a
1135 * file or directory in the directory that it denotes.
1136 *
1137 * @param filter
1138 * A filename filter
1139 *
1140 * @return An array of strings naming the files and directories in the
1141 * directory denoted by this abstract pathname that were accepted
1142 * by the given {@code filter}. The array will be empty if the
1143 * directory is empty or if no names were accepted by the filter.
1144 * Returns {@code null} if this abstract pathname does not denote
1145 * a directory, or if an I/O error occurs.
1146 *
1147 * @throws SecurityException
1148 * If a security manager exists and its {@link
1149 * SecurityManager#checkRead(String)} method denies read access to
1150 * the directory
1151 *
1152 * @see java.nio.file.Files#newDirectoryStream(Path,String)
1153 */
1154 public String[] list(FilenameFilter filter) {
1155 String names[] = list();
1156 if ((names == null) || (filter == null)) {
1157 return names;
1158 }
1159 List<String> v = new ArrayList<>();
1160 for (int i = 0 ; i < names.length ; i++) {
1161 if (filter.accept(this, names[i])) {
1162 v.add(names[i]);
1163 }
1164 }
1165 return v.toArray(new String[v.size()]);
1166 }
1167
1168 /**
1169 * Returns an array of abstract pathnames denoting the files in the
1170 * directory denoted by this abstract pathname.
1171 *
1172 * <p> If this abstract pathname does not denote a directory, then this
1173 * method returns {@code null}. Otherwise an array of {@code File} objects
1174 * is returned, one for each file or directory in the directory. Pathnames
1175 * denoting the directory itself and the directory's parent directory are
1176 * not included in the result. Each resulting abstract pathname is
1177 * constructed from this abstract pathname using the {@link #File(File,
1178 * String) File(File, String)} constructor. Therefore if this
1179 * pathname is absolute then each resulting pathname is absolute; if this
1180 * pathname is relative then each resulting pathname will be relative to
1181 * the same directory.
1182 *
1183 * <p> There is no guarantee that the name strings in the resulting array
1184 * will appear in any specific order; they are not, in particular,
1185 * guaranteed to appear in alphabetical order.
1186 *
1187 * <p> Note that the {@link java.nio.file.Files} class defines the {@link
1188 * java.nio.file.Files#newDirectoryStream(Path) newDirectoryStream} method
1189 * to open a directory and iterate over the names of the files in the
1190 * directory. This may use less resources when working with very large
1191 * directories.
1192 *
1193 * @return An array of abstract pathnames denoting the files and
1194 * directories in the directory denoted by this abstract pathname.
1195 * The array will be empty if the directory is empty. Returns
1196 * {@code null} if this abstract pathname does not denote a
1197 * directory, or if an I/O error occurs.
1198 *
1199 * @throws SecurityException
1200 * If a security manager exists and its {@link
1201 * SecurityManager#checkRead(String)} method denies read access to
1202 * the directory
1203 *
1204 * @since 1.2
1205 */
1206 public File[] listFiles() {
1207 String[] ss = list();
1208 if (ss == null) return null;
1209 int n = ss.length;
1210 File[] fs = new File[n];
1211 for (int i = 0; i < n; i++) {
1212 fs[i] = new File(ss[i], this);
1213 }
1214 return fs;
1215 }
1216
1217 /**
1218 * Returns an array of abstract pathnames denoting the files and
1219 * directories in the directory denoted by this abstract pathname that
1220 * satisfy the specified filter. The behavior of this method is the same
1221 * as that of the {@link #listFiles()} method, except that the pathnames in
1222 * the returned array must satisfy the filter. If the given {@code filter}
1223 * is {@code null} then all pathnames are accepted. Otherwise, a pathname
1224 * satisfies the filter if and only if the value {@code true} results when
1225 * the {@link FilenameFilter#accept
1226 * FilenameFilter.accept(File, String)} method of the filter is
1227 * invoked on this abstract pathname and the name of a file or directory in
1228 * the directory that it denotes.
1229 *
1230 * @param filter
1231 * A filename filter
1232 *
1233 * @return An array of abstract pathnames denoting the files and
1234 * directories in the directory denoted by this abstract pathname.
1235 * The array will be empty if the directory is empty. Returns
1236 * {@code null} if this abstract pathname does not denote a
1237 * directory, or if an I/O error occurs.
1238 *
1239 * @throws SecurityException
1240 * If a security manager exists and its {@link
1241 * SecurityManager#checkRead(String)} method denies read access to
1242 * the directory
1243 *
1244 * @since 1.2
1245 * @see java.nio.file.Files#newDirectoryStream(Path,String)
1246 */
1247 public File[] listFiles(FilenameFilter filter) {
1248 String ss[] = list();
1249 if (ss == null) return null;
1250 ArrayList<File> files = new ArrayList<>();
1251 for (String s : ss)
1252 if ((filter == null) || filter.accept(this, s))
1253 files.add(new File(s, this));
1254 return files.toArray(new File[files.size()]);
1255 }
1256
1257 /**
1258 * Returns an array of abstract pathnames denoting the files and
1259 * directories in the directory denoted by this abstract pathname that
1260 * satisfy the specified filter. The behavior of this method is the same
1261 * as that of the {@link #listFiles()} method, except that the pathnames in
1262 * the returned array must satisfy the filter. If the given {@code filter}
1263 * is {@code null} then all pathnames are accepted. Otherwise, a pathname
1264 * satisfies the filter if and only if the value {@code true} results when
1265 * the {@link FileFilter#accept FileFilter.accept(File)} method of the
1266 * filter is invoked on the pathname.
1267 *
1268 * @param filter
1269 * A file filter
1270 *
1271 * @return An array of abstract pathnames denoting the files and
1272 * directories in the directory denoted by this abstract pathname.
1273 * The array will be empty if the directory is empty. Returns
1274 * {@code null} if this abstract pathname does not denote a
1275 * directory, or if an I/O error occurs.
1276 *
1277 * @throws SecurityException
1278 * If a security manager exists and its {@link
1279 * SecurityManager#checkRead(String)} method denies read access to
1280 * the directory
1281 *
1282 * @since 1.2
1283 * @see java.nio.file.Files#newDirectoryStream(Path,java.nio.file.DirectoryStream.Filter)
1284 */
1285 public File[] listFiles(FileFilter filter) {
1286 String ss[] = list();
1287 if (ss == null) return null;
1288 ArrayList<File> files = new ArrayList<>();
1289 for (String s : ss) {
1290 File f = new File(s, this);
1291 if ((filter == null) || filter.accept(f))
1292 files.add(f);
1293 }
1294 return files.toArray(new File[files.size()]);
1295 }
1296
1297 /**
1298 * Creates the directory named by this abstract pathname.
1299 *
1300 * @return <code>true</code> if and only if the directory was
1301 * created; <code>false</code> otherwise
1302 *
1303 * @throws SecurityException
1304 * If a security manager exists and its <code>{@link
1305 * java.lang.SecurityManager#checkWrite(java.lang.String)}</code>
1306 * method does not permit the named directory to be created
1307 */
1308 public boolean mkdir() {
1309 SecurityManager security = System.getSecurityManager();
1310 if (security != null) {
1311 security.checkWrite(path);
1312 }
1313 if (isInvalid()) {
1314 return false;
1315 }
1316 return fs.createDirectory(this);
1317 }
1318
1319 /**
1320 * Creates the directory named by this abstract pathname, including any
1321 * necessary but nonexistent parent directories. Note that if this
1322 * operation fails it may have succeeded in creating some of the necessary
1323 * parent directories.
1324 *
1325 * @return <code>true</code> if and only if the directory was created,
1326 * along with all necessary parent directories; <code>false</code>
1327 * otherwise
1328 *
1329 * @throws SecurityException
1330 * If a security manager exists and its <code>{@link
1331 * java.lang.SecurityManager#checkRead(java.lang.String)}</code>
1332 * method does not permit verification of the existence of the
1333 * named directory and all necessary parent directories; or if
1334 * the <code>{@link
1335 * java.lang.SecurityManager#checkWrite(java.lang.String)}</code>
1336 * method does not permit the named directory and all necessary
1337 * parent directories to be created
1338 */
1339 public boolean mkdirs() {
1340 if (exists()) {
1341 return false;
1342 }
1343 if (mkdir()) {
1344 return true;
1345 }
1346 File parent = getParentFile();
1347 if (parent == null) {
1348 return false;
1349 }
1350 parent.mkdirs();
1351 return mkdir();
1352 }
1353
1354 /**
1355 * Renames the file denoted by this abstract pathname.
1356 *
1357 * <p> Many aspects of the behavior of this method are inherently
1358 * platform-dependent: The rename operation might not be able to move a
1359 * file from one filesystem to another, it might not be atomic, and it
1360 * might not succeed if a file with the destination abstract pathname
1361 * already exists. The return value should always be checked to make sure
1362 * that the rename operation was successful.
1363 *
1364 * <p> Note that the {@link java.nio.file.Files} class defines the {@link
1365 * java.nio.file.Files#move move} method to move or rename a file in a
1366 * platform independent manner.
1367 *
1368 * @param dest The new abstract pathname for the named file
1369 *
1370 * @return <code>true</code> if and only if the renaming succeeded;
1371 * <code>false</code> otherwise
1372 *
1373 * @throws SecurityException
1374 * If a security manager exists and its <code>{@link
1375 * java.lang.SecurityManager#checkWrite(java.lang.String)}</code>
1376 * method denies write access to either the old or new pathnames
1377 *
1378 * @throws NullPointerException
1379 * If parameter <code>dest</code> is <code>null</code>
1380 */
1381 public boolean renameTo(File dest) {
1382 SecurityManager security = System.getSecurityManager();
1383 if (security != null) {
1384 security.checkWrite(path);
1385 security.checkWrite(dest.path);
1386 }
1387 if (dest == null) {
1388 throw new NullPointerException();
1389 }
1390 if (this.isInvalid() || dest.isInvalid()) {
1391 return false;
1392 }
1393 return fs.rename(this, dest);
1394 }
1395
1396 /**
1397 * Sets the last-modified time of the file or directory named by this
1398 * abstract pathname.
1399 *
1400 * <p> All platforms support file-modification times to the nearest second,
1401 * but some provide more precision. The argument will be truncated to fit
1402 * the supported precision. If the operation succeeds and no intervening
1403 * operations on the file take place, then the next invocation of the
1404 * <code>{@link #lastModified}</code> method will return the (possibly
1405 * truncated) <code>time</code> argument that was passed to this method.
1406 *
1407 * @param time The new last-modified time, measured in milliseconds since
1408 * the epoch (00:00:00 GMT, January 1, 1970)
1409 *
1410 * @return <code>true</code> if and only if the operation succeeded;
1411 * <code>false</code> otherwise
1412 *
1413 * @throws IllegalArgumentException If the argument is negative
1414 *
1415 * @throws SecurityException
1416 * If a security manager exists and its <code>{@link
1417 * java.lang.SecurityManager#checkWrite(java.lang.String)}</code>
1418 * method denies write access to the named file
1419 *
1420 * @since 1.2
1421 */
1422 public boolean setLastModified(long time) {
1423 if (time < 0) throw new IllegalArgumentException("Negative time");
1424 SecurityManager security = System.getSecurityManager();
1425 if (security != null) {
1426 security.checkWrite(path);
1427 }
1428 if (isInvalid()) {
1429 return false;
1430 }
1431 return fs.setLastModifiedTime(this, time);
1432 }
1433
1434 /**
1435 * Marks the file or directory named by this abstract pathname so that
1436 * only read operations are allowed. After invoking this method the file
1437 * or directory will not change until it is either deleted or marked
1438 * to allow write access. On some platforms it may be possible to start the
1439 * Java virtual machine with special privileges that allow it to modify
1440 * files that are marked read-only. Whether or not a read-only file or
1441 * directory may be deleted depends upon the underlying system.
1442 *
1443 * @return <code>true</code> if and only if the operation succeeded;
1444 * <code>false</code> otherwise
1445 *
1446 * @throws SecurityException
1447 * If a security manager exists and its <code>{@link
1448 * java.lang.SecurityManager#checkWrite(java.lang.String)}</code>
1449 * method denies write access to the named file
1450 *
1451 * @since 1.2
1452 */
1453 public boolean setReadOnly() {
1454 SecurityManager security = System.getSecurityManager();
1455 if (security != null) {
1456 security.checkWrite(path);
1457 }
1458 if (isInvalid()) {
1459 return false;
1460 }
1461 return fs.setReadOnly(this);
1462 }
1463
1464 /**
1465 * Sets the owner's or everybody's write permission for this abstract
1466 * pathname. On some platforms it may be possible to start the Java virtual
1467 * machine with special privileges that allow it to modify files that
1468 * disallow write operations.
1469 *
1470 * <p> The {@link java.nio.file.Files} class defines methods that operate on
1471 * file attributes including file permissions. This may be used when finer
1472 * manipulation of file permissions is required.
1473 *
1474 * @param writable
1475 * If <code>true</code>, sets the access permission to allow write
1476 * operations; if <code>false</code> to disallow write operations
1477 *
1478 * @param ownerOnly
1479 * If <code>true</code>, the write permission applies only to the
1480 * owner's write permission; otherwise, it applies to everybody. If
1481 * the underlying file system can not distinguish the owner's write
1482 * permission from that of others, then the permission will apply to
1483 * everybody, regardless of this value.
1484 *
1485 * @return <code>true</code> if and only if the operation succeeded. The
1486 * operation will fail if the user does not have permission to change
1487 * the access permissions of this abstract pathname.
1488 *
1489 * @throws SecurityException
1490 * If a security manager exists and its <code>{@link
1491 * java.lang.SecurityManager#checkWrite(java.lang.String)}</code>
1492 * method denies write access to the named file
1493 *
1494 * @since 1.6
1495 */
1496 public boolean setWritable(boolean writable, boolean ownerOnly) {
1497 SecurityManager security = System.getSecurityManager();
1498 if (security != null) {
1499 security.checkWrite(path);
1500 }
1501 if (isInvalid()) {
1502 return false;
1503 }
1504 return fs.setPermission(this, FileSystem.ACCESS_WRITE, writable, ownerOnly);
1505 }
1506
1507 /**
1508 * A convenience method to set the owner's write permission for this abstract
1509 * pathname. On some platforms it may be possible to start the Java virtual
1510 * machine with special privileges that allow it to modify files that
1511 * disallow write operations.
1512 *
1513 * <p> An invocation of this method of the form <tt>file.setWritable(arg)</tt>
1514 * behaves in exactly the same way as the invocation
1515 *
1516 * <pre>
1517 * file.setWritable(arg, true) </pre>
1518 *
1519 * @param writable
1520 * If <code>true</code>, sets the access permission to allow write
1521 * operations; if <code>false</code> to disallow write operations
1522 *
1523 * @return <code>true</code> if and only if the operation succeeded. The
1524 * operation will fail if the user does not have permission to
1525 * change the access permissions of this abstract pathname.
1526 *
1527 * @throws SecurityException
1528 * If a security manager exists and its <code>{@link
1529 * java.lang.SecurityManager#checkWrite(java.lang.String)}</code>
1530 * method denies write access to the file
1531 *
1532 * @since 1.6
1533 */
1534 public boolean setWritable(boolean writable) {
1535 return setWritable(writable, true);
1536 }
1537
1538 /**
1539 * Sets the owner's or everybody's read permission for this abstract
1540 * pathname. On some platforms it may be possible to start the Java virtual
1541 * machine with special privileges that allow it to read files that are
1542 * marked as unreadable.
1543 *
1544 * <p> The {@link java.nio.file.Files} class defines methods that operate on
1545 * file attributes including file permissions. This may be used when finer
1546 * manipulation of file permissions is required.
1547 *
1548 * @param readable
1549 * If <code>true</code>, sets the access permission to allow read
1550 * operations; if <code>false</code> to disallow read operations
1551 *
1552 * @param ownerOnly
1553 * If <code>true</code>, the read permission applies only to the
1554 * owner's read permission; otherwise, it applies to everybody. If
1555 * the underlying file system can not distinguish the owner's read
1556 * permission from that of others, then the permission will apply to
1557 * everybody, regardless of this value.
1558 *
1559 * @return <code>true</code> if and only if the operation succeeded. The
1560 * operation will fail if the user does not have permission to
1561 * change the access permissions of this abstract pathname. If
1562 * <code>readable</code> is <code>false</code> and the underlying
1563 * file system does not implement a read permission, then the
1564 * operation will fail.
1565 *
1566 * @throws SecurityException
1567 * If a security manager exists and its <code>{@link
1568 * java.lang.SecurityManager#checkWrite(java.lang.String)}</code>
1569 * method denies write access to the file
1570 *
1571 * @since 1.6
1572 */
1573 public boolean setReadable(boolean readable, boolean ownerOnly) {
1574 SecurityManager security = System.getSecurityManager();
1575 if (security != null) {
1576 security.checkWrite(path);
1577 }
1578 if (isInvalid()) {
1579 return false;
1580 }
1581 return fs.setPermission(this, FileSystem.ACCESS_READ, readable, ownerOnly);
1582 }
1583
1584 /**
1585 * A convenience method to set the owner's read permission for this abstract
1586 * pathname. On some platforms it may be possible to start the Java virtual
1587 * machine with special privileges that allow it to read files that that are
1588 * marked as unreadable.
1589 *
1590 * <p>An invocation of this method of the form <tt>file.setReadable(arg)</tt>
1591 * behaves in exactly the same way as the invocation
1592 *
1593 * <pre>
1594 * file.setReadable(arg, true) </pre>
1595 *
1596 * @param readable
1597 * If <code>true</code>, sets the access permission to allow read
1598 * operations; if <code>false</code> to disallow read operations
1599 *
1600 * @return <code>true</code> if and only if the operation succeeded. The
1601 * operation will fail if the user does not have permission to
1602 * change the access permissions of this abstract pathname. If
1603 * <code>readable</code> is <code>false</code> and the underlying
1604 * file system does not implement a read permission, then the
1605 * operation will fail.
1606 *
1607 * @throws SecurityException
1608 * If a security manager exists and its <code>{@link
1609 * java.lang.SecurityManager#checkWrite(java.lang.String)}</code>
1610 * method denies write access to the file
1611 *
1612 * @since 1.6
1613 */
1614 public boolean setReadable(boolean readable) {
1615 return setReadable(readable, true);
1616 }
1617
1618 /**
1619 * Sets the owner's or everybody's execute permission for this abstract
1620 * pathname. On some platforms it may be possible to start the Java virtual
1621 * machine with special privileges that allow it to execute files that are
1622 * not marked executable.
1623 *
1624 * <p> The {@link java.nio.file.Files} class defines methods that operate on
1625 * file attributes including file permissions. This may be used when finer
1626 * manipulation of file permissions is required.
1627 *
1628 * @param executable
1629 * If <code>true</code>, sets the access permission to allow execute
1630 * operations; if <code>false</code> to disallow execute operations
1631 *
1632 * @param ownerOnly
1633 * If <code>true</code>, the execute permission applies only to the
1634 * owner's execute permission; otherwise, it applies to everybody.
1635 * If the underlying file system can not distinguish the owner's
1636 * execute permission from that of others, then the permission will
1637 * apply to everybody, regardless of this value.
1638 *
1639 * @return <code>true</code> if and only if the operation succeeded. The
1640 * operation will fail if the user does not have permission to
1641 * change the access permissions of this abstract pathname. If
1642 * <code>executable</code> is <code>false</code> and the underlying
1643 * file system does not implement an execute permission, then the
1644 * operation will fail.
1645 *
1646 * @throws SecurityException
1647 * If a security manager exists and its <code>{@link
1648 * java.lang.SecurityManager#checkWrite(java.lang.String)}</code>
1649 * method denies write access to the file
1650 *
1651 * @since 1.6
1652 */
1653 public boolean setExecutable(boolean executable, boolean ownerOnly) {
1654 SecurityManager security = System.getSecurityManager();
1655 if (security != null) {
1656 security.checkWrite(path);
1657 }
1658 if (isInvalid()) {
1659 return false;
1660 }
1661 return fs.setPermission(this, FileSystem.ACCESS_EXECUTE, executable, ownerOnly);
1662 }
1663
1664 /**
1665 * A convenience method to set the owner's execute permission for this
1666 * abstract pathname. On some platforms it may be possible to start the Java
1667 * virtual machine with special privileges that allow it to execute files
1668 * that are not marked executable.
1669 *
1670 * <p>An invocation of this method of the form <tt>file.setExcutable(arg)</tt>
1671 * behaves in exactly the same way as the invocation
1672 *
1673 * <pre>
1674 * file.setExecutable(arg, true) </pre>
1675 *
1676 * @param executable
1677 * If <code>true</code>, sets the access permission to allow execute
1678 * operations; if <code>false</code> to disallow execute operations
1679 *
1680 * @return <code>true</code> if and only if the operation succeeded. The
1681 * operation will fail if the user does not have permission to
1682 * change the access permissions of this abstract pathname. If
1683 * <code>executable</code> is <code>false</code> and the underlying
1684 * file system does not implement an excute permission, then the
1685 * operation will fail.
1686 *
1687 * @throws SecurityException
1688 * If a security manager exists and its <code>{@link
1689 * java.lang.SecurityManager#checkWrite(java.lang.String)}</code>
1690 * method denies write access to the file
1691 *
1692 * @since 1.6
1693 */
1694 public boolean setExecutable(boolean executable) {
1695 return setExecutable(executable, true);
1696 }
1697
1698 /**
1699 * Tests whether the application can execute the file denoted by this
1700 * abstract pathname. On some platforms it may be possible to start the
1701 * Java virtual machine with special privileges that allow it to execute
1702 * files that are not marked executable. Consequently this method may return
1703 * {@code true} even though the file does not have execute permissions.
1704 *
1705 * @return <code>true</code> if and only if the abstract pathname exists
1706 * <em>and</em> the application is allowed to execute the file
1707 *
1708 * @throws SecurityException
1709 * If a security manager exists and its <code>{@link
1710 * java.lang.SecurityManager#checkExec(java.lang.String)}</code>
1711 * method denies execute access to the file
1712 *
1713 * @since 1.6
1714 */
1715 public boolean canExecute() {
1716 SecurityManager security = System.getSecurityManager();
1717 if (security != null) {
1718 security.checkExec(path);
1719 }
1720 if (isInvalid()) {
1721 return false;
1722 }
1723 return fs.checkAccess(this, FileSystem.ACCESS_EXECUTE);
1724 }
1725
1726
1727 /* -- Filesystem interface -- */
1728
1729 /**
1730 * List the available filesystem roots.
1731 *
1732 * <p> A particular Java platform may support zero or more
1733 * hierarchically-organized file systems. Each file system has a
1734 * {@code root} directory from which all other files in that file system
1735 * can be reached. Windows platforms, for example, have a root directory
1736 * for each active drive; UNIX platforms have a single root directory,
1737 * namely {@code "/"}. The set of available filesystem roots is affected
1738 * by various system-level operations such as the insertion or ejection of
1739 * removable media and the disconnecting or unmounting of physical or
1740 * virtual disk drives.
1741 *
1742 * <p> This method returns an array of {@code File} objects that denote the
1743 * root directories of the available filesystem roots. It is guaranteed
1744 * that the canonical pathname of any file physically present on the local
1745 * machine will begin with one of the roots returned by this method.
1746 *
1747 * <p> The canonical pathname of a file that resides on some other machine
1748 * and is accessed via a remote-filesystem protocol such as SMB or NFS may
1749 * or may not begin with one of the roots returned by this method. If the
1750 * pathname of a remote file is syntactically indistinguishable from the
1751 * pathname of a local file then it will begin with one of the roots
1752 * returned by this method. Thus, for example, {@code File} objects
1753 * denoting the root directories of the mapped network drives of a Windows
1754 * platform will be returned by this method, while {@code File} objects
1755 * containing UNC pathnames will not be returned by this method.
1756 *
1757 * <p> Unlike most methods in this class, this method does not throw
1758 * security exceptions. If a security manager exists and its {@link
1759 * SecurityManager#checkRead(String)} method denies read access to a
1760 * particular root directory, then that directory will not appear in the
1761 * result.
1762 *
1763 * @return An array of {@code File} objects denoting the available
1764 * filesystem roots, or {@code null} if the set of roots could not
1765 * be determined. The array will be empty if there are no
1766 * filesystem roots.
1767 *
1768 * @since 1.2
1769 * @see java.nio.file.FileStore
1770 */
1771 public static File[] listRoots() {
1772 return fs.listRoots();
1773 }
1774
1775
1776 /* -- Disk usage -- */
1777
1778 /**
1779 * Returns the size of the partition <a href="#partName">named</a> by this
1780 * abstract pathname.
1781 *
1782 * @return The size, in bytes, of the partition or <tt>0L</tt> if this
1783 * abstract pathname does not name a partition
1784 *
1785 * @throws SecurityException
1786 * If a security manager has been installed and it denies
1787 * {@link RuntimePermission}<tt>("getFileSystemAttributes")</tt>
1788 * or its {@link SecurityManager#checkRead(String)} method denies
1789 * read access to the file named by this abstract pathname
1790 *
1791 * @since 1.6
1792 */
1793 public long getTotalSpace() {
1794 SecurityManager sm = System.getSecurityManager();
1795 if (sm != null) {
1796 sm.checkPermission(new RuntimePermission("getFileSystemAttributes"));
1797 sm.checkRead(path);
1798 }
1799 if (isInvalid()) {
1800 return 0L;
1801 }
1802 return fs.getSpace(this, FileSystem.SPACE_TOTAL);
1803 }
1804
1805 /**
1806 * Returns the number of unallocated bytes in the partition <a
1807 * href="#partName">named</a> by this abstract path name.
1808 *
1809 * <p> The returned number of unallocated bytes is a hint, but not
1810 * a guarantee, that it is possible to use most or any of these
1811 * bytes. The number of unallocated bytes is most likely to be
1812 * accurate immediately after this call. It is likely to be made
1813 * inaccurate by any external I/O operations including those made
1814 * on the system outside of this virtual machine. This method
1815 * makes no guarantee that write operations to this file system
1816 * will succeed.
1817 *
1818 * @return The number of unallocated bytes on the partition or <tt>0L</tt>
1819 * if the abstract pathname does not name a partition. This
1820 * value will be less than or equal to the total file system size
1821 * returned by {@link #getTotalSpace}.
1822 *
1823 * @throws SecurityException
1824 * If a security manager has been installed and it denies
1825 * {@link RuntimePermission}<tt>("getFileSystemAttributes")</tt>
1826 * or its {@link SecurityManager#checkRead(String)} method denies
1827 * read access to the file named by this abstract pathname
1828 *
1829 * @since 1.6
1830 */
1831 public long getFreeSpace() {
1832 SecurityManager sm = System.getSecurityManager();
1833 if (sm != null) {
1834 sm.checkPermission(new RuntimePermission("getFileSystemAttributes"));
1835 sm.checkRead(path);
1836 }
1837 if (isInvalid()) {
1838 return 0L;
1839 }
1840 return fs.getSpace(this, FileSystem.SPACE_FREE);
1841 }
1842
1843 /**
1844 * Returns the number of bytes available to this virtual machine on the
1845 * partition <a href="#partName">named</a> by this abstract pathname. When
1846 * possible, this method checks for write permissions and other operating
1847 * system restrictions and will therefore usually provide a more accurate
1848 * estimate of how much new data can actually be written than {@link
1849 * #getFreeSpace}.
1850 *
1851 * <p> The returned number of available bytes is a hint, but not a
1852 * guarantee, that it is possible to use most or any of these bytes. The
1853 * number of unallocated bytes is most likely to be accurate immediately
1854 * after this call. It is likely to be made inaccurate by any external
1855 * I/O operations including those made on the system outside of this
1856 * virtual machine. This method makes no guarantee that write operations
1857 * to this file system will succeed.
1858 *
1859 * @return The number of available bytes on the partition or <tt>0L</tt>
1860 * if the abstract pathname does not name a partition. On
1861 * systems where this information is not available, this method
1862 * will be equivalent to a call to {@link #getFreeSpace}.
1863 *
1864 * @throws SecurityException
1865 * If a security manager has been installed and it denies
1866 * {@link RuntimePermission}<tt>("getFileSystemAttributes")</tt>
1867 * or its {@link SecurityManager#checkRead(String)} method denies
1868 * read access to the file named by this abstract pathname
1869 *
1870 * @since 1.6
1871 */
1872 public long getUsableSpace() {
1873 SecurityManager sm = System.getSecurityManager();
1874 if (sm != null) {
1875 sm.checkPermission(new RuntimePermission("getFileSystemAttributes"));
1876 sm.checkRead(path);
1877 }
1878 if (isInvalid()) {
1879 return 0L;
1880 }
1881 return fs.getSpace(this, FileSystem.SPACE_USABLE);
1882 }
1883
1884 /* -- Temporary files -- */
1885
1886 private static class TempDirectory {
1887 private TempDirectory() { }
1888
1889 // temporary directory location
1890 private static final File tmpdir = new File(AccessController
1891 .doPrivileged(new GetPropertyAction("java.io.tmpdir")));
1892 static File location() {
1893 return tmpdir;
1894 }
1895
1896 // file name generation
1897 private static final SecureRandom random = new SecureRandom();
1898 static File generateFile(String prefix, String suffix, File dir)
1899 throws IOException
1900 {
1901 long n = random.nextLong();
1902 if (n == Long.MIN_VALUE) {
1903 n = 0; // corner case
1904 } else {
1905 n = Math.abs(n);
1906 }
1907 String name = prefix + Long.toString(n) + suffix;
1908 File f = new File(dir, name);
1909 if (!name.equals(f.getName()) || f.isInvalid())
1910 throw new IOException("Unable to create temporary file");
1911 return f;
1912 }
1913 }
1914
1915 /**
1916 * <p> Creates a new empty file in the specified directory, using the
1917 * given prefix and suffix strings to generate its name. If this method
1918 * returns successfully then it is guaranteed that:
1919 *
1920 * <ol>
1921 * <li> The file denoted by the returned abstract pathname did not exist
1922 * before this method was invoked, and
1923 * <li> Neither this method nor any of its variants will return the same
1924 * abstract pathname again in the current invocation of the virtual
1925 * machine.
1926 * </ol>
1927 *
1928 * This method provides only part of a temporary-file facility. To arrange
1929 * for a file created by this method to be deleted automatically, use the
1930 * <code>{@link #deleteOnExit}</code> method.
1931 *
1932 * <p> The <code>prefix</code> argument must be at least three characters
1933 * long. It is recommended that the prefix be a short, meaningful string
1934 * such as <code>"hjb"</code> or <code>"mail"</code>. The
1935 * <code>suffix</code> argument may be <code>null</code>, in which case the
1936 * suffix <code>".tmp"</code> will be used.
1937 *
1938 * <p> To create the new file, the prefix and the suffix may first be
1939 * adjusted to fit the limitations of the underlying platform. If the
1940 * prefix is too long then it will be truncated, but its first three
1941 * characters will always be preserved. If the suffix is too long then it
1942 * too will be truncated, but if it begins with a period character
1943 * (<code>'.'</code>) then the period and the first three characters
1944 * following it will always be preserved. Once these adjustments have been
1945 * made the name of the new file will be generated by concatenating the
1946 * prefix, five or more internally-generated characters, and the suffix.
1947 *
1948 * <p> If the <code>directory</code> argument is <code>null</code> then the
1949 * system-dependent default temporary-file directory will be used. The
1950 * default temporary-file directory is specified by the system property
1951 * <code>java.io.tmpdir</code>. On UNIX systems the default value of this
1952 * property is typically <code>"/tmp"</code> or <code>"/var/tmp"</code>; on
1953 * Microsoft Windows systems it is typically <code>"C:\\WINNT\\TEMP"</code>. A different
1954 * value may be given to this system property when the Java virtual machine
1955 * is invoked, but programmatic changes to this property are not guaranteed
1956 * to have any effect upon the temporary directory used by this method.
1957 *
1958 * @param prefix The prefix string to be used in generating the file's
1959 * name; must be at least three characters long
1960 *
1961 * @param suffix The suffix string to be used in generating the file's
1962 * name; may be <code>null</code>, in which case the
1963 * suffix <code>".tmp"</code> will be used
1964 *
1965 * @param directory The directory in which the file is to be created, or
1966 * <code>null</code> if the default temporary-file
1967 * directory is to be used
1968 *
1969 * @return An abstract pathname denoting a newly-created empty file
1970 *
1971 * @throws IllegalArgumentException
1972 * If the <code>prefix</code> argument contains fewer than three
1973 * characters
1974 *
1975 * @throws IOException If a file could not be created
1976 *
1977 * @throws SecurityException
1978 * If a security manager exists and its <code>{@link
1979 * java.lang.SecurityManager#checkWrite(java.lang.String)}</code>
1980 * method does not allow a file to be created
1981 *
1982 * @since 1.2
1983 */
1984 public static File createTempFile(String prefix, String suffix,
1985 File directory)
1986 throws IOException
1987 {
1988 if (prefix.length() < 3)
1989 throw new IllegalArgumentException("Prefix string too short");
1990 if (suffix == null)
1991 suffix = ".tmp";
1992
1993 File tmpdir = (directory != null) ? directory
1994 : TempDirectory.location();
1995 SecurityManager sm = System.getSecurityManager();
1996 File f;
1997 do {
1998 f = TempDirectory.generateFile(prefix, suffix, tmpdir);
1999
2000 if (sm != null) {
2001 try {
2002 sm.checkWrite(f.getPath());
2003 } catch (SecurityException se) {
2004 // don't reveal temporary directory location
2005 if (directory == null)
2006 throw new SecurityException("Unable to create temporary file");
2007 throw se;
2008 }
2009 }
2010 } while ((fs.getBooleanAttributes(f) & FileSystem.BA_EXISTS) != 0);
2011
2012 if (!fs.createFileExclusively(f.getPath()))
2013 throw new IOException("Unable to create temporary file");
2014
2015 return f;
2016 }
2017
2018 /**
2019 * Creates an empty file in the default temporary-file directory, using
2020 * the given prefix and suffix to generate its name. Invoking this method
2021 * is equivalent to invoking <code>{@link #createTempFile(java.lang.String,
2022 * java.lang.String, java.io.File)
2023 * createTempFile(prefix, suffix, null)}</code>.
2024 *
2025 * <p> The {@link
2026 * java.nio.file.Files#createTempFile(String,String,java.nio.file.attribute.FileAttribute[])
2027 * Files.createTempFile} method provides an alternative method to create an
2028 * empty file in the temporary-file directory. Files created by that method
2029 * may have more restrictive access permissions to files created by this
2030 * method and so may be more suited to security-sensitive applications.
2031 *
2032 * @param prefix The prefix string to be used in generating the file's
2033 * name; must be at least three characters long
2034 *
2035 * @param suffix The suffix string to be used in generating the file's
2036 * name; may be <code>null</code>, in which case the
2037 * suffix <code>".tmp"</code> will be used
2038 *
2039 * @return An abstract pathname denoting a newly-created empty file
2040 *
2041 * @throws IllegalArgumentException
2042 * If the <code>prefix</code> argument contains fewer than three
2043 * characters
2044 *
2045 * @throws IOException If a file could not be created
2046 *
2047 * @throws SecurityException
2048 * If a security manager exists and its <code>{@link
2049 * java.lang.SecurityManager#checkWrite(java.lang.String)}</code>
2050 * method does not allow a file to be created
2051 *
2052 * @since 1.2
2053 * @see java.nio.file.Files#createTempDirectory(String,FileAttribute[])
2054 */
2055 public static File createTempFile(String prefix, String suffix)
2056 throws IOException
2057 {
2058 return createTempFile(prefix, suffix, null);
2059 }
2060
2061 /* -- Basic infrastructure -- */
2062
2063 /**
2064 * Compares two abstract pathnames lexicographically. The ordering
2065 * defined by this method depends upon the underlying system. On UNIX
2066 * systems, alphabetic case is significant in comparing pathnames; on Microsoft Windows
2067 * systems it is not.
2068 *
2069 * @param pathname The abstract pathname to be compared to this abstract
2070 * pathname
2071 *
2072 * @return Zero if the argument is equal to this abstract pathname, a
2073 * value less than zero if this abstract pathname is
2074 * lexicographically less than the argument, or a value greater
2075 * than zero if this abstract pathname is lexicographically
2076 * greater than the argument
2077 *
2078 * @since 1.2
2079 */
2080 public int compareTo(File pathname) {
2081 return fs.compare(this, pathname);
2082 }
2083
2084 /**
2085 * Tests this abstract pathname for equality with the given object.
2086 * Returns <code>true</code> if and only if the argument is not
2087 * <code>null</code> and is an abstract pathname that denotes the same file
2088 * or directory as this abstract pathname. Whether or not two abstract
2089 * pathnames are equal depends upon the underlying system. On UNIX
2090 * systems, alphabetic case is significant in comparing pathnames; on Microsoft Windows
2091 * systems it is not.
2092 *
2093 * @param obj The object to be compared with this abstract pathname
2094 *
2095 * @return <code>true</code> if and only if the objects are the same;
2096 * <code>false</code> otherwise
2097 */
2098 public boolean equals(Object obj) {
2099 if ((obj != null) && (obj instanceof File)) {
2100 return compareTo((File)obj) == 0;
2101 }
2102 return false;
2103 }
2104
2105 /**
2106 * Computes a hash code for this abstract pathname. Because equality of
2107 * abstract pathnames is inherently system-dependent, so is the computation
2108 * of their hash codes. On UNIX systems, the hash code of an abstract
2109 * pathname is equal to the exclusive <em>or</em> of the hash code
2110 * of its pathname string and the decimal value
2111 * <code>1234321</code>. On Microsoft Windows systems, the hash
2112 * code is equal to the exclusive <em>or</em> of the hash code of
2113 * its pathname string converted to lower case and the decimal
2114 * value <code>1234321</code>. Locale is not taken into account on
2115 * lowercasing the pathname string.
2116 *
2117 * @return A hash code for this abstract pathname
2118 */
2119 public int hashCode() {
2120 return fs.hashCode(this);
2121 }
2122
2123 /**
2124 * Returns the pathname string of this abstract pathname. This is just the
2125 * string returned by the <code>{@link #getPath}</code> method.
2126 *
2127 * @return The string form of this abstract pathname
2128 */
2129 public String toString() {
2130 return getPath();
2131 }
2132
2133 /**
2134 * WriteObject is called to save this filename.
2135 * The separator character is saved also so it can be replaced
2136 * in case the path is reconstituted on a different host type.
2137 * <p>
2138 * @serialData Default fields followed by separator character.
2139 */
2140 private synchronized void writeObject(java.io.ObjectOutputStream s)
2141 throws IOException
2142 {
2143 s.defaultWriteObject();
2144 s.writeChar(separatorChar); // Add the separator character
2145 }
2146
2147 /**
2148 * readObject is called to restore this filename.
2149 * The original separator character is read. If it is different
2150 * than the separator character on this system, then the old separator
2151 * is replaced by the local separator.
2152 */
2153 private synchronized void readObject(java.io.ObjectInputStream s)
2154 throws IOException, ClassNotFoundException
2155 {
2156 ObjectInputStream.GetField fields = s.readFields();
2157 String pathField = (String)fields.get("path", null);
2158 char sep = s.readChar(); // read the previous separator char
2159 if (sep != separatorChar)
2160 pathField = pathField.replace(sep, separatorChar);
2161 String path = fs.normalize(pathField);
2162 UNSAFE.putObject(this, PATH_OFFSET, path);
2163 UNSAFE.putIntVolatile(this, PREFIX_LENGTH_OFFSET, fs.prefixLength(path));
2164 }
2165
2166 private static final long PATH_OFFSET;
2167 private static final long PREFIX_LENGTH_OFFSET;
2168 private static final sun.misc.Unsafe UNSAFE;
2169 static {
2170 try {
2171 sun.misc.Unsafe unsafe = sun.misc.Unsafe.getUnsafe();
2172 PATH_OFFSET = unsafe.objectFieldOffset(
2173 File.class.getDeclaredField("path"));
2174 PREFIX_LENGTH_OFFSET = unsafe.objectFieldOffset(
2175 File.class.getDeclaredField("prefixLength"));
2176 UNSAFE = unsafe;
2177 } catch (ReflectiveOperationException e) {
2178 throw new Error(e);
2179 }
2180 }
2181
2182
2183 /** use serialVersionUID from JDK 1.0.2 for interoperability */
2184 private static final long serialVersionUID = 301077366599181567L;
2185
2186 // -- Integration with java.nio.file --
2187
2188 private volatile transient Path filePath;
2189
2190 /**
2191 * Returns a {@link Path java.nio.file.Path} object constructed from the
2192 * this abstract path. The resulting {@code Path} is associated with the
2193 * {@link java.nio.file.FileSystems#getDefault default-filesystem}.
2194 *
2195 * <p> The first invocation of this method works as if invoking it were
2196 * equivalent to evaluating the expression:
2197 * <blockquote><pre>
2198 * {@link java.nio.file.FileSystems#getDefault FileSystems.getDefault}().{@link
2199 * java.nio.file.FileSystem#getPath getPath}(this.{@link #getPath getPath}());
2200 * </pre></blockquote>
2201 * Subsequent invocations of this method return the same {@code Path}.
2202 *
2203 * <p> If this abstract pathname is the empty abstract pathname then this
2204 * method returns a {@code Path} that may be used to access the current
2205 * user directory.
2206 *
2207 * @return a {@code Path} constructed from this abstract path
2208 *
2209 * @throws java.nio.file.InvalidPathException
2210 * if a {@code Path} object cannot be constructed from the abstract
2211 * path (see {@link java.nio.file.FileSystem#getPath FileSystem.getPath})
2212 *
2213 * @since 1.7
2214 * @see Path#toFile
2215 */
2216 public Path toPath() {
2217 Path result = filePath;
2218 if (result == null) {
2219 synchronized (this) {
2220 result = filePath;
2221 if (result == null) {
2222 result = FileSystems.getDefault().getPath(path);
2223 filePath = result;
2224 }
2225 }
2226 }
2227 return result;
2228 }
2229 }