1 /*
2 * Copyright (c) 1996, 2014, 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 /*
27 * (C) Copyright Taligent, Inc. 1996 - All Rights Reserved
28 * (C) Copyright IBM Corp. 1996 - All Rights Reserved
29 *
30 * The original version of this source code and documentation is copyrighted
31 * and owned by Taligent, Inc., a wholly-owned subsidiary of IBM. These
32 * materials are provided under terms of a License Agreement between Taligent
33 * and Sun. This technology is protected by multiple US and International
34 * patents. This notice and attribution to Taligent may not be removed.
35 * Taligent is a registered trademark of Taligent, Inc.
36 *
37 */
38
39 package java.util;
40
41 import java.io.Serializable;
42 import java.security.AccessController;
43 import java.security.PrivilegedAction;
44 import java.time.ZoneId;
45
46 import sun.misc.JavaUtilTimeZoneAccess;
47 import sun.misc.SharedSecrets;
48 import sun.security.action.GetPropertyAction;
49 import sun.util.calendar.ZoneInfo;
50 import sun.util.calendar.ZoneInfoFile;
51 import sun.util.locale.provider.TimeZoneNameUtility;
52
53 /**
54 * <code>TimeZone</code> represents a time zone offset, and also figures out daylight
55 * savings.
56 *
57 * <p>
58 * Typically, you get a <code>TimeZone</code> using <code>getDefault</code>
59 * which creates a <code>TimeZone</code> based on the time zone where the program
60 * is running. For example, for a program running in Japan, <code>getDefault</code>
61 * creates a <code>TimeZone</code> object based on Japanese Standard Time.
62 *
63 * <p>
64 * You can also get a <code>TimeZone</code> using <code>getTimeZone</code>
65 * along with a time zone ID. For instance, the time zone ID for the
66 * U.S. Pacific Time zone is "America/Los_Angeles". So, you can get a
67 * U.S. Pacific Time <code>TimeZone</code> object with:
68 * <blockquote><pre>
69 * TimeZone tz = TimeZone.getTimeZone("America/Los_Angeles");
70 * </pre></blockquote>
71 * You can use the <code>getAvailableIDs</code> method to iterate through
72 * all the supported time zone IDs. You can then choose a
73 * supported ID to get a <code>TimeZone</code>.
74 * If the time zone you want is not represented by one of the
75 * supported IDs, then a custom time zone ID can be specified to
76 * produce a TimeZone. The syntax of a custom time zone ID is:
77 *
78 * <blockquote><pre>
79 * <a name="CustomID"><i>CustomID:</i></a>
80 * <code>GMT</code> <i>Sign</i> <i>Hours</i> <code>:</code> <i>Minutes</i>
81 * <code>GMT</code> <i>Sign</i> <i>Hours</i> <i>Minutes</i>
82 * <code>GMT</code> <i>Sign</i> <i>Hours</i>
83 * <i>Sign:</i> one of
84 * <code>+ -</code>
85 * <i>Hours:</i>
86 * <i>Digit</i>
87 * <i>Digit</i> <i>Digit</i>
88 * <i>Minutes:</i>
89 * <i>Digit</i> <i>Digit</i>
90 * <i>Digit:</i> one of
91 * <code>0 1 2 3 4 5 6 7 8 9</code>
92 * </pre></blockquote>
93 *
94 * <i>Hours</i> must be between 0 to 23 and <i>Minutes</i> must be
95 * between 00 to 59. For example, "GMT+10" and "GMT+0010" mean ten
96 * hours and ten minutes ahead of GMT, respectively.
97 * <p>
98 * The format is locale independent and digits must be taken from the
99 * Basic Latin block of the Unicode standard. No daylight saving time
100 * transition schedule can be specified with a custom time zone ID. If
101 * the specified string doesn't match the syntax, <code>"GMT"</code>
102 * is used.
103 * <p>
104 * When creating a <code>TimeZone</code>, the specified custom time
105 * zone ID is normalized in the following syntax:
106 * <blockquote><pre>
107 * <a name="NormalizedCustomID"><i>NormalizedCustomID:</i></a>
108 * <code>GMT</code> <i>Sign</i> <i>TwoDigitHours</i> <code>:</code> <i>Minutes</i>
109 * <i>Sign:</i> one of
110 * <code>+ -</code>
111 * <i>TwoDigitHours:</i>
112 * <i>Digit</i> <i>Digit</i>
113 * <i>Minutes:</i>
114 * <i>Digit</i> <i>Digit</i>
115 * <i>Digit:</i> one of
116 * <code>0 1 2 3 4 5 6 7 8 9</code>
117 * </pre></blockquote>
118 * For example, TimeZone.getTimeZone("GMT-8").getID() returns "GMT-08:00".
119 *
120 * <h3>Three-letter time zone IDs</h3>
121 *
122 * For compatibility with JDK 1.1.x, some other three-letter time zone IDs
123 * (such as "PST", "CTT", "AST") are also supported. However, <strong>their
124 * use is deprecated</strong> because the same abbreviation is often used
125 * for multiple time zones (for example, "CST" could be U.S. "Central Standard
126 * Time" and "China Standard Time"), and the Java platform can then only
127 * recognize one of them.
128 *
129 *
130 * @see Calendar
131 * @see GregorianCalendar
132 * @see SimpleTimeZone
133 * @author Mark Davis, David Goldsmith, Chen-Lieh Huang, Alan Liu
134 * @since 1.1
135 */
136 abstract public class TimeZone implements Serializable, Cloneable {
137
138 static {
139 SharedSecrets.setJavaUtilTimeZoneAccess(new JavaUtilTimeZoneAccess() {
140 @Override
141 public TimeZone getDefaultRef() {
142 return TimeZone.getDefaultRef();
143 }
144 });
145 }
146
147 /**
148 * Sole constructor. (For invocation by subclass constructors, typically
149 * implicit.)
150 */
151 public TimeZone() {
152 }
153
154 /**
155 * A style specifier for <code>getDisplayName()</code> indicating
156 * a short name, such as "PST."
157 * @see #LONG
158 * @since 1.2
159 */
160 public static final int SHORT = 0;
161
162 /**
163 * A style specifier for <code>getDisplayName()</code> indicating
164 * a long name, such as "Pacific Standard Time."
165 * @see #SHORT
166 * @since 1.2
167 */
168 public static final int LONG = 1;
169
170 // Constants used internally; unit is milliseconds
171 private static final int ONE_MINUTE = 60*1000;
172 private static final int ONE_HOUR = 60*ONE_MINUTE;
173 private static final int ONE_DAY = 24*ONE_HOUR;
174
175 // Proclaim serialization compatibility with JDK 1.1
176 static final long serialVersionUID = 3581463369166924961L;
177
178 /**
179 * Gets the time zone offset, for current date, modified in case of
180 * daylight savings. This is the offset to add to UTC to get local time.
181 * <p>
182 * This method returns a historically correct offset if an
183 * underlying <code>TimeZone</code> implementation subclass
184 * supports historical Daylight Saving Time schedule and GMT
185 * offset changes.
186 *
187 * @param era the era of the given date.
188 * @param year the year in the given date.
189 * @param month the month in the given date.
190 * Month is 0-based. e.g., 0 for January.
191 * @param day the day-in-month of the given date.
192 * @param dayOfWeek the day-of-week of the given date.
193 * @param milliseconds the milliseconds in day in <em>standard</em>
194 * local time.
195 *
196 * @return the offset in milliseconds to add to GMT to get local time.
197 *
198 * @see Calendar#ZONE_OFFSET
199 * @see Calendar#DST_OFFSET
200 */
201 public abstract int getOffset(int era, int year, int month, int day,
202 int dayOfWeek, int milliseconds);
203
204 /**
205 * Returns the offset of this time zone from UTC at the specified
206 * date. If Daylight Saving Time is in effect at the specified
207 * date, the offset value is adjusted with the amount of daylight
208 * saving.
209 * <p>
210 * This method returns a historically correct offset value if an
211 * underlying TimeZone implementation subclass supports historical
212 * Daylight Saving Time schedule and GMT offset changes.
213 *
214 * @param date the date represented in milliseconds since January 1, 1970 00:00:00 GMT
215 * @return the amount of time in milliseconds to add to UTC to get local time.
216 *
217 * @see Calendar#ZONE_OFFSET
218 * @see Calendar#DST_OFFSET
219 * @since 1.4
220 */
221 public int getOffset(long date) {
222 if (inDaylightTime(new Date(date))) {
223 return getRawOffset() + getDSTSavings();
224 }
225 return getRawOffset();
226 }
227
228 /**
229 * Gets the raw GMT offset and the amount of daylight saving of this
230 * time zone at the given time.
231 * @param date the milliseconds (since January 1, 1970,
232 * 00:00:00.000 GMT) at which the time zone offset and daylight
233 * saving amount are found
234 * @param offsets an array of int where the raw GMT offset
235 * (offset[0]) and daylight saving amount (offset[1]) are stored,
236 * or null if those values are not needed. The method assumes that
237 * the length of the given array is two or larger.
238 * @return the total amount of the raw GMT offset and daylight
239 * saving at the specified date.
240 *
241 * @see Calendar#ZONE_OFFSET
242 * @see Calendar#DST_OFFSET
243 */
244 int getOffsets(long date, int[] offsets) {
245 int rawoffset = getRawOffset();
246 int dstoffset = 0;
247 if (inDaylightTime(new Date(date))) {
248 dstoffset = getDSTSavings();
249 }
250 if (offsets != null) {
251 offsets[0] = rawoffset;
252 offsets[1] = dstoffset;
253 }
254 return rawoffset + dstoffset;
255 }
256
257 /**
258 * Sets the base time zone offset to GMT.
259 * This is the offset to add to UTC to get local time.
260 * <p>
261 * If an underlying <code>TimeZone</code> implementation subclass
262 * supports historical GMT offset changes, the specified GMT
263 * offset is set as the latest GMT offset and the difference from
264 * the known latest GMT offset value is used to adjust all
265 * historical GMT offset values.
266 *
267 * @param offsetMillis the given base time zone offset to GMT.
268 */
269 abstract public void setRawOffset(int offsetMillis);
270
271 /**
272 * Returns the amount of time in milliseconds to add to UTC to get
273 * standard time in this time zone. Because this value is not
274 * affected by daylight saving time, it is called <I>raw
275 * offset</I>.
276 * <p>
277 * If an underlying <code>TimeZone</code> implementation subclass
278 * supports historical GMT offset changes, the method returns the
279 * raw offset value of the current date. In Honolulu, for example,
280 * its raw offset changed from GMT-10:30 to GMT-10:00 in 1947, and
281 * this method always returns -36000000 milliseconds (i.e., -10
282 * hours).
283 *
284 * @return the amount of raw offset time in milliseconds to add to UTC.
285 * @see Calendar#ZONE_OFFSET
286 */
287 public abstract int getRawOffset();
288
289 /**
290 * Gets the ID of this time zone.
291 * @return the ID of this time zone.
292 */
293 public String getID()
294 {
295 return ID;
296 }
297
298 /**
299 * Sets the time zone ID. This does not change any other data in
300 * the time zone object.
301 * @param ID the new time zone ID.
302 */
303 public void setID(String ID)
304 {
305 if (ID == null) {
306 throw new NullPointerException();
307 }
308 this.ID = ID;
309 this.zoneId = null; // invalidate cache
310 }
311
312 /**
313 * Returns a long standard time name of this {@code TimeZone} suitable for
314 * presentation to the user in the default locale.
315 *
316 * <p>This method is equivalent to:
317 * <blockquote><pre>
318 * getDisplayName(false, {@link #LONG},
319 * Locale.getDefault({@link Locale.Category#DISPLAY}))
320 * </pre></blockquote>
321 *
322 * @return the human-readable name of this time zone in the default locale.
323 * @since 1.2
324 * @see #getDisplayName(boolean, int, Locale)
325 * @see Locale#getDefault(Locale.Category)
326 * @see Locale.Category
327 */
328 public final String getDisplayName() {
329 return getDisplayName(false, LONG,
330 Locale.getDefault(Locale.Category.DISPLAY));
331 }
332
333 /**
334 * Returns a long standard time name of this {@code TimeZone} suitable for
335 * presentation to the user in the specified {@code locale}.
336 *
337 * <p>This method is equivalent to:
338 * <blockquote><pre>
339 * getDisplayName(false, {@link #LONG}, locale)
340 * </pre></blockquote>
341 *
342 * @param locale the locale in which to supply the display name.
343 * @return the human-readable name of this time zone in the given locale.
344 * @exception NullPointerException if {@code locale} is {@code null}.
345 * @since 1.2
346 * @see #getDisplayName(boolean, int, Locale)
347 */
348 public final String getDisplayName(Locale locale) {
349 return getDisplayName(false, LONG, locale);
350 }
351
352 /**
353 * Returns a name in the specified {@code style} of this {@code TimeZone}
354 * suitable for presentation to the user in the default locale. If the
355 * specified {@code daylight} is {@code true}, a Daylight Saving Time name
356 * is returned (even if this {@code TimeZone} doesn't observe Daylight Saving
357 * Time). Otherwise, a Standard Time name is returned.
358 *
359 * <p>This method is equivalent to:
360 * <blockquote><pre>
361 * getDisplayName(daylight, style,
362 * Locale.getDefault({@link Locale.Category#DISPLAY}))
363 * </pre></blockquote>
364 *
365 * @param daylight {@code true} specifying a Daylight Saving Time name, or
366 * {@code false} specifying a Standard Time name
367 * @param style either {@link #LONG} or {@link #SHORT}
368 * @return the human-readable name of this time zone in the default locale.
369 * @exception IllegalArgumentException if {@code style} is invalid.
370 * @since 1.2
371 * @see #getDisplayName(boolean, int, Locale)
372 * @see Locale#getDefault(Locale.Category)
373 * @see Locale.Category
374 * @see java.text.DateFormatSymbols#getZoneStrings()
375 */
376 public final String getDisplayName(boolean daylight, int style) {
377 return getDisplayName(daylight, style,
378 Locale.getDefault(Locale.Category.DISPLAY));
379 }
380
381 /**
382 * Returns a name in the specified {@code style} of this {@code TimeZone}
383 * suitable for presentation to the user in the specified {@code
384 * locale}. If the specified {@code daylight} is {@code true}, a Daylight
385 * Saving Time name is returned (even if this {@code TimeZone} doesn't
386 * observe Daylight Saving Time). Otherwise, a Standard Time name is
387 * returned.
388 *
389 * <p>When looking up a time zone name, the {@linkplain
390 * ResourceBundle.Control#getCandidateLocales(String,Locale) default
391 * <code>Locale</code> search path of <code>ResourceBundle</code>} derived
392 * from the specified {@code locale} is used. (No {@linkplain
393 * ResourceBundle.Control#getFallbackLocale(String,Locale) fallback
394 * <code>Locale</code>} search is performed.) If a time zone name in any
395 * {@code Locale} of the search path, including {@link Locale#ROOT}, is
396 * found, the name is returned. Otherwise, a string in the
397 * <a href="#NormalizedCustomID">normalized custom ID format</a> is returned.
398 *
399 * @param daylight {@code true} specifying a Daylight Saving Time name, or
400 * {@code false} specifying a Standard Time name
401 * @param style either {@link #LONG} or {@link #SHORT}
402 * @param locale the locale in which to supply the display name.
403 * @return the human-readable name of this time zone in the given locale.
404 * @exception IllegalArgumentException if {@code style} is invalid.
405 * @exception NullPointerException if {@code locale} is {@code null}.
406 * @since 1.2
407 * @see java.text.DateFormatSymbols#getZoneStrings()
408 */
409 public String getDisplayName(boolean daylight, int style, Locale locale) {
410 if (style != SHORT && style != LONG) {
411 throw new IllegalArgumentException("Illegal style: " + style);
412 }
413 String id = getID();
414 String name = TimeZoneNameUtility.retrieveDisplayName(id, daylight, style, locale);
415 if (name != null) {
416 return name;
417 }
418
419 if (id.startsWith("GMT") && id.length() > 3) {
420 char sign = id.charAt(3);
421 if (sign == '+' || sign == '-') {
422 return id;
423 }
424 }
425 int offset = getRawOffset();
426 if (daylight) {
427 offset += getDSTSavings();
428 }
429 return ZoneInfoFile.toCustomID(offset);
430 }
431
432 private static String[] getDisplayNames(String id, Locale locale) {
433 return TimeZoneNameUtility.retrieveDisplayNames(id, locale);
434 }
435
436 /**
437 * Returns the amount of time to be added to local standard time
438 * to get local wall clock time.
439 *
440 * <p>The default implementation returns 3600000 milliseconds
441 * (i.e., one hour) if a call to {@link #useDaylightTime()}
442 * returns {@code true}. Otherwise, 0 (zero) is returned.
443 *
444 * <p>If an underlying {@code TimeZone} implementation subclass
445 * supports historical and future Daylight Saving Time schedule
446 * changes, this method returns the amount of saving time of the
447 * last known Daylight Saving Time rule that can be a future
448 * prediction.
449 *
450 * <p>If the amount of saving time at any given time stamp is
451 * required, construct a {@link Calendar} with this {@code
452 * TimeZone} and the time stamp, and call {@link Calendar#get(int)
453 * Calendar.get}{@code (}{@link Calendar#DST_OFFSET}{@code )}.
454 *
455 * @return the amount of saving time in milliseconds
456 * @since 1.4
457 * @see #inDaylightTime(Date)
458 * @see #getOffset(long)
459 * @see #getOffset(int,int,int,int,int,int)
460 * @see Calendar#ZONE_OFFSET
461 */
462 public int getDSTSavings() {
463 if (useDaylightTime()) {
464 return 3600000;
465 }
466 return 0;
467 }
468
469 /**
470 * Queries if this {@code TimeZone} uses Daylight Saving Time.
471 *
472 * <p>If an underlying {@code TimeZone} implementation subclass
473 * supports historical and future Daylight Saving Time schedule
474 * changes, this method refers to the last known Daylight Saving Time
475 * rule that can be a future prediction and may not be the same as
476 * the current rule. Consider calling {@link #observesDaylightTime()}
477 * if the current rule should also be taken into account.
478 *
479 * @return {@code true} if this {@code TimeZone} uses Daylight Saving Time,
480 * {@code false}, otherwise.
481 * @see #inDaylightTime(Date)
482 * @see Calendar#DST_OFFSET
483 */
484 public abstract boolean useDaylightTime();
485
486 /**
487 * Returns {@code true} if this {@code TimeZone} is currently in
488 * Daylight Saving Time, or if a transition from Standard Time to
489 * Daylight Saving Time occurs at any future time.
490 *
491 * <p>The default implementation returns {@code true} if
492 * {@code useDaylightTime()} or {@code inDaylightTime(new Date())}
493 * returns {@code true}.
494 *
495 * @return {@code true} if this {@code TimeZone} is currently in
496 * Daylight Saving Time, or if a transition from Standard Time to
497 * Daylight Saving Time occurs at any future time; {@code false}
498 * otherwise.
499 * @since 1.7
500 * @see #useDaylightTime()
501 * @see #inDaylightTime(Date)
502 * @see Calendar#DST_OFFSET
503 */
504 public boolean observesDaylightTime() {
505 return useDaylightTime() || inDaylightTime(new Date());
506 }
507
508 /**
509 * Queries if the given {@code date} is in Daylight Saving Time in
510 * this time zone.
511 *
512 * @param date the given Date.
513 * @return {@code true} if the given date is in Daylight Saving Time,
514 * {@code false}, otherwise.
515 */
516 abstract public boolean inDaylightTime(Date date);
517
518 /**
519 * Gets the <code>TimeZone</code> for the given ID.
520 *
521 * @param ID the ID for a <code>TimeZone</code>, either an abbreviation
522 * such as "PST", a full name such as "America/Los_Angeles", or a custom
523 * ID such as "GMT-8:00". Note that the support of abbreviations is
524 * for JDK 1.1.x compatibility only and full names should be used.
525 *
526 * @return the specified <code>TimeZone</code>, or the GMT zone if the given ID
527 * cannot be understood.
528 */
529 public static synchronized TimeZone getTimeZone(String ID) {
530 return getTimeZone(ID, true);
531 }
532
533 /**
534 * Gets the {@code TimeZone} for the given {@code zoneId}.
535 *
536 * @param zoneId a {@link ZoneId} from which the time zone ID is obtained
537 * @return the specified {@code TimeZone}, or the GMT zone if the given ID
538 * cannot be understood.
539 * @throws NullPointerException if {@code zoneId} is {@code null}
540 * @since 1.8
541 */
542 public static TimeZone getTimeZone(ZoneId zoneId) {
543 String tzid = zoneId.getId(); // throws an NPE if null
544 char c = tzid.charAt(0);
545 if (c == '+' || c == '-') {
546 tzid = "GMT" + tzid;
547 } else if (c == 'Z' && tzid.length() == 1) {
548 tzid = "UTC";
549 }
550 return getTimeZone(tzid, true);
551 }
552
553 /**
554 * Converts this {@code TimeZone} object to a {@code ZoneId}.
555 *
556 * @return a {@code ZoneId} representing the same time zone as this
557 * {@code TimeZone}
558 * @since 1.8
559 */
560 public ZoneId toZoneId() {
561 ZoneId zId = zoneId;
562 if (zId == null) {
563 String id = getID();
564 if (ZoneInfoFile.useOldMapping() && id.length() == 3) {
565 if ("EST".equals(id))
566 zId = ZoneId.of("America/New_York");
567 else if ("MST".equals(id))
568 zId = ZoneId.of("America/Denver");
569 else if ("HST".equals(id))
570 zId = ZoneId.of("America/Honolulu");
571 } else {
572 zId = ZoneId.of(id, ZoneId.SHORT_IDS);
573 }
574 zoneId = zId;
575 }
576 return zId;
577 }
578
579 private static TimeZone getTimeZone(String ID, boolean fallback) {
580 TimeZone tz = ZoneInfo.getTimeZone(ID);
581 if (tz == null) {
582 tz = parseCustomTimeZone(ID);
583 if (tz == null && fallback) {
584 tz = new ZoneInfo(GMT_ID, 0);
585 }
586 }
587 return tz;
588 }
589
590 /**
591 * Gets the available IDs according to the given time zone offset in milliseconds.
592 *
593 * @param rawOffset the given time zone GMT offset in milliseconds.
594 * @return an array of IDs, where the time zone for that ID has
595 * the specified GMT offset. For example, "America/Phoenix" and "America/Denver"
596 * both have GMT-07:00, but differ in daylight saving behavior.
597 * @see #getRawOffset()
598 */
599 public static synchronized String[] getAvailableIDs(int rawOffset) {
600 return ZoneInfo.getAvailableIDs(rawOffset);
601 }
602
603 /**
604 * Gets all the available IDs supported.
605 * @return an array of IDs.
606 */
607 public static synchronized String[] getAvailableIDs() {
608 return ZoneInfo.getAvailableIDs();
609 }
610
611 /**
612 * Gets the platform defined TimeZone ID.
613 **/
614 private static native String getSystemTimeZoneID(String javaHome);
615
616 /**
617 * Gets the custom time zone ID based on the GMT offset of the
618 * platform. (e.g., "GMT+08:00")
619 */
620 private static native String getSystemGMTOffsetID();
621
622 /**
623 * Gets the default {@code TimeZone} of the Java virtual machine. If the
624 * cached default {@code TimeZone} is available, its clone is returned.
625 * Otherwise, the method takes the following steps to determine the default
626 * time zone.
627 *
628 * <ul>
629 * <li>Use the {@code user.timezone} property value as the default
630 * time zone ID if it's available.</li>
631 * <li>Detect the platform time zone ID. The source of the
632 * platform time zone and ID mapping may vary with implementation.</li>
633 * <li>Use {@code GMT} as the last resort if the given or detected
634 * time zone ID is unknown.</li>
635 * </ul>
636 *
637 * <p>The default {@code TimeZone} created from the ID is cached,
638 * and its clone is returned. The {@code user.timezone} property
639 * value is set to the ID upon return.
640 *
641 * @return the default {@code TimeZone}
642 * @see #setDefault(TimeZone)
643 */
644 public static TimeZone getDefault() {
645 return (TimeZone) getDefaultRef().clone();
646 }
647
648 /**
649 * Returns the reference to the default TimeZone object. This
650 * method doesn't create a clone.
651 */
652 static TimeZone getDefaultRef() {
653 TimeZone defaultZone = defaultTimeZone;
654 if (defaultZone == null) {
655 // Need to initialize the default time zone.
656 defaultZone = setDefaultZone();
657 assert defaultZone != null;
658 }
659 // Don't clone here.
660 return defaultZone;
661 }
662
663 private static synchronized TimeZone setDefaultZone() {
664 TimeZone tz;
665 // get the time zone ID from the system properties
666 String zoneID = AccessController.doPrivileged(
667 new GetPropertyAction("user.timezone"));
668
669 // if the time zone ID is not set (yet), perform the
670 // platform to Java time zone ID mapping.
671 if (zoneID == null || zoneID.isEmpty()) {
672 String javaHome = AccessController.doPrivileged(
673 new GetPropertyAction("java.home"));
674 try {
675 zoneID = getSystemTimeZoneID(javaHome);
676 if (zoneID == null) {
677 zoneID = GMT_ID;
678 }
679 } catch (NullPointerException e) {
680 zoneID = GMT_ID;
681 }
682 }
683
684 // Get the time zone for zoneID. But not fall back to
685 // "GMT" here.
686 tz = getTimeZone(zoneID, false);
687
688 if (tz == null) {
689 // If the given zone ID is unknown in Java, try to
690 // get the GMT-offset-based time zone ID,
691 // a.k.a. custom time zone ID (e.g., "GMT-08:00").
692 String gmtOffsetID = getSystemGMTOffsetID();
693 if (gmtOffsetID != null) {
694 zoneID = gmtOffsetID;
695 }
696 tz = getTimeZone(zoneID, true);
697 }
698 assert tz != null;
699
700 final String id = zoneID;
701 AccessController.doPrivileged(new PrivilegedAction<Void>() {
702 @Override
703 public Void run() {
704 System.setProperty("user.timezone", id);
705 return null;
706 }
707 });
708
709 defaultTimeZone = tz;
710 return tz;
711 }
712
713 /**
714 * Sets the {@code TimeZone} that is returned by the {@code getDefault}
715 * method. {@code zone} is cached. If {@code zone} is null, the cached
716 * default {@code TimeZone} is cleared. This method doesn't change the value
717 * of the {@code user.timezone} property.
718 *
719 * @param zone the new default {@code TimeZone}, or null
720 * @throws SecurityException if the security manager's {@code checkPermission}
721 * denies {@code PropertyPermission("user.timezone",
722 * "write")}
723 * @see #getDefault
724 * @see PropertyPermission
725 */
726 public static void setDefault(TimeZone zone)
727 {
728 SecurityManager sm = System.getSecurityManager();
729 if (sm != null) {
730 sm.checkPermission(new PropertyPermission
731 ("user.timezone", "write"));
732 }
733 defaultTimeZone = (TimeZone) zone.clone();
734 }
735
736 /**
737 * Returns true if this zone has the same rule and offset as another zone.
738 * That is, if this zone differs only in ID, if at all. Returns false
739 * if the other zone is null.
740 * @param other the <code>TimeZone</code> object to be compared with
741 * @return true if the other zone is not null and is the same as this one,
742 * with the possible exception of the ID
743 * @since 1.2
744 */
745 public boolean hasSameRules(TimeZone other) {
746 return other != null && getRawOffset() == other.getRawOffset() &&
747 useDaylightTime() == other.useDaylightTime();
748 }
749
750 /**
751 * Creates a copy of this <code>TimeZone</code>.
752 *
753 * @return a clone of this <code>TimeZone</code>
754 */
755 public Object clone()
756 {
757 try {
758 return super.clone();
759 } catch (CloneNotSupportedException e) {
760 throw new InternalError(e);
761 }
762 }
763
764 /**
765 * The null constant as a TimeZone.
766 */
767 static final TimeZone NO_TIMEZONE = null;
768
769 // =======================privates===============================
770
771 /**
772 * The string identifier of this <code>TimeZone</code>. This is a
773 * programmatic identifier used internally to look up <code>TimeZone</code>
774 * objects from the system table and also to map them to their localized
775 * display names. <code>ID</code> values are unique in the system
776 * table but may not be for dynamically created zones.
777 * @serial
778 */
779 private String ID;
780
781 /**
782 * Cached {@link ZoneId} for this TimeZone
783 */
784 private transient ZoneId zoneId;
785
786 private static volatile TimeZone defaultTimeZone;
787
788 static final String GMT_ID = "GMT";
789 private static final int GMT_ID_LENGTH = 3;
790
791 // a static TimeZone we can reference if no AppContext is in place
792 private static volatile TimeZone mainAppContextDefault;
793
794 /**
795 * Parses a custom time zone identifier and returns a corresponding zone.
796 * This method doesn't support the RFC 822 time zone format. (e.g., +hhmm)
797 *
798 * @param id a string of the <a href="#CustomID">custom ID form</a>.
799 * @return a newly created TimeZone with the given offset and
800 * no daylight saving time, or null if the id cannot be parsed.
801 */
802 private static final TimeZone parseCustomTimeZone(String id) {
803 int length;
804
805 // Error if the length of id isn't long enough or id doesn't
806 // start with "GMT".
807 if ((length = id.length()) < (GMT_ID_LENGTH + 2) ||
808 id.indexOf(GMT_ID) != 0) {
809 return null;
810 }
811
812 ZoneInfo zi;
813
814 // First, we try to find it in the cache with the given
815 // id. Even the id is not normalized, the returned ZoneInfo
816 // should have its normalized id.
817 zi = ZoneInfoFile.getZoneInfo(id);
818 if (zi != null) {
819 return zi;
820 }
821
822 int index = GMT_ID_LENGTH;
823 boolean negative = false;
824 char c = id.charAt(index++);
825 if (c == '-') {
826 negative = true;
827 } else if (c != '+') {
828 return null;
829 }
830
831 int hours = 0;
832 int num = 0;
833 int countDelim = 0;
834 int len = 0;
835 while (index < length) {
836 c = id.charAt(index++);
837 if (c == ':') {
838 if (countDelim > 0) {
839 return null;
840 }
841 if (len > 2) {
842 return null;
843 }
844 hours = num;
845 countDelim++;
846 num = 0;
847 len = 0;
848 continue;
849 }
850 if (c < '0' || c > '9') {
851 return null;
852 }
853 num = num * 10 + (c - '0');
854 len++;
855 }
856 if (index != length) {
857 return null;
858 }
859 if (countDelim == 0) {
860 if (len <= 2) {
861 hours = num;
862 num = 0;
863 } else {
864 hours = num / 100;
865 num %= 100;
866 }
867 } else {
868 if (len != 2) {
869 return null;
870 }
871 }
872 if (hours > 23 || num > 59) {
873 return null;
874 }
875 int gmtOffset = (hours * 60 + num) * 60 * 1000;
876
877 if (gmtOffset == 0) {
878 zi = ZoneInfoFile.getZoneInfo(GMT_ID);
879 if (negative) {
880 zi.setID("GMT-00:00");
881 } else {
882 zi.setID("GMT+00:00");
883 }
884 } else {
885 zi = ZoneInfoFile.getCustomTimeZone(id, negative ? -gmtOffset : gmtOffset);
886 }
887 return zi;
888 }
889 }