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 import sun.security.action.GetPropertyAction; 46 import sun.util.calendar.ZoneInfo; 47 import sun.util.calendar.ZoneInfoFile; 48 import sun.util.locale.provider.TimeZoneNameUtility; 49 50 /** 51 * <code>TimeZone</code> represents a time zone offset, and also figures out daylight 52 * savings. 53 * 54 * <p> 55 * Typically, you get a <code>TimeZone</code> using <code>getDefault</code> 56 * which creates a <code>TimeZone</code> based on the time zone where the program 57 * is running. For example, for a program running in Japan, <code>getDefault</code> 58 * creates a <code>TimeZone</code> object based on Japanese Standard Time. 59 * 60 * <p> 61 * You can also get a <code>TimeZone</code> using <code>getTimeZone</code> 62 * along with a time zone ID. For instance, the time zone ID for the 63 * U.S. Pacific Time zone is "America/Los_Angeles". So, you can get a 64 * U.S. Pacific Time <code>TimeZone</code> object with: 65 * <blockquote><pre> 66 * TimeZone tz = TimeZone.getTimeZone("America/Los_Angeles"); 67 * </pre></blockquote> 68 * You can use the <code>getAvailableIDs</code> method to iterate through 69 * all the supported time zone IDs. You can then choose a 70 * supported ID to get a <code>TimeZone</code>. 71 * If the time zone you want is not represented by one of the 72 * supported IDs, then a custom time zone ID can be specified to 73 * produce a TimeZone. The syntax of a custom time zone ID is: 74 * 75 * <blockquote><pre> 76 * <a name="CustomID"><i>CustomID:</i></a> 77 * <code>GMT</code> <i>Sign</i> <i>Hours</i> <code>:</code> <i>Minutes</i> 78 * <code>GMT</code> <i>Sign</i> <i>Hours</i> <i>Minutes</i> 79 * <code>GMT</code> <i>Sign</i> <i>Hours</i> 80 * <i>Sign:</i> one of 81 * <code>+ -</code> 82 * <i>Hours:</i> 83 * <i>Digit</i> 84 * <i>Digit</i> <i>Digit</i> 85 * <i>Minutes:</i> 86 * <i>Digit</i> <i>Digit</i> 87 * <i>Digit:</i> one of 88 * <code>0 1 2 3 4 5 6 7 8 9</code> 89 * </pre></blockquote> 90 * 91 * <i>Hours</i> must be between 0 to 23 and <i>Minutes</i> must be 92 * between 00 to 59. For example, "GMT+10" and "GMT+0010" mean ten 93 * hours and ten minutes ahead of GMT, respectively. 94 * <p> 95 * The format is locale independent and digits must be taken from the 96 * Basic Latin block of the Unicode standard. No daylight saving time 97 * transition schedule can be specified with a custom time zone ID. If 98 * the specified string doesn't match the syntax, <code>"GMT"</code> 99 * is used. 100 * <p> 101 * When creating a <code>TimeZone</code>, the specified custom time 102 * zone ID is normalized in the following syntax: 103 * <blockquote><pre> 104 * <a name="NormalizedCustomID"><i>NormalizedCustomID:</i></a> 105 * <code>GMT</code> <i>Sign</i> <i>TwoDigitHours</i> <code>:</code> <i>Minutes</i> 106 * <i>Sign:</i> one of 107 * <code>+ -</code> 108 * <i>TwoDigitHours:</i> 109 * <i>Digit</i> <i>Digit</i> 110 * <i>Minutes:</i> 111 * <i>Digit</i> <i>Digit</i> 112 * <i>Digit:</i> one of 113 * <code>0 1 2 3 4 5 6 7 8 9</code> 114 * </pre></blockquote> 115 * For example, TimeZone.getTimeZone("GMT-8").getID() returns "GMT-08:00". 116 * 117 * <h3>Three-letter time zone IDs</h3> 118 * 119 * For compatibility with JDK 1.1.x, some other three-letter time zone IDs 120 * (such as "PST", "CTT", "AST") are also supported. However, <strong>their 121 * use is deprecated</strong> because the same abbreviation is often used 122 * for multiple time zones (for example, "CST" could be U.S. "Central Standard 123 * Time" and "China Standard Time"), and the Java platform can then only 124 * recognize one of them. 125 * 126 * 127 * @see Calendar 128 * @see GregorianCalendar 129 * @see SimpleTimeZone 130 * @author Mark Davis, David Goldsmith, Chen-Lieh Huang, Alan Liu 131 * @since 1.1 132 */ 133 abstract public class TimeZone implements Serializable, Cloneable { 134 /** 135 * Sole constructor. (For invocation by subclass constructors, typically 136 * implicit.) 137 */ 138 public TimeZone() { 139 } 140 141 /** 142 * A style specifier for <code>getDisplayName()</code> indicating 143 * a short name, such as "PST." 144 * @see #LONG 145 * @since 1.2 146 */ 147 public static final int SHORT = 0; 148 149 /** 150 * A style specifier for <code>getDisplayName()</code> indicating 151 * a long name, such as "Pacific Standard Time." 152 * @see #SHORT 153 * @since 1.2 154 */ 155 public static final int LONG = 1; 156 157 // Constants used internally; unit is milliseconds 158 private static final int ONE_MINUTE = 60*1000; 159 private static final int ONE_HOUR = 60*ONE_MINUTE; 160 private static final int ONE_DAY = 24*ONE_HOUR; 161 162 // Proclaim serialization compatibility with JDK 1.1 163 static final long serialVersionUID = 3581463369166924961L; 164 165 /** 166 * Gets the time zone offset, for current date, modified in case of 167 * daylight savings. This is the offset to add to UTC to get local time. 168 * <p> 169 * This method returns a historically correct offset if an 170 * underlying <code>TimeZone</code> implementation subclass 171 * supports historical Daylight Saving Time schedule and GMT 172 * offset changes. 173 * 174 * @param era the era of the given date. 175 * @param year the year in the given date. 176 * @param month the month in the given date. 177 * Month is 0-based. e.g., 0 for January. 178 * @param day the day-in-month of the given date. 179 * @param dayOfWeek the day-of-week of the given date. 180 * @param milliseconds the milliseconds in day in <em>standard</em> 181 * local time. 182 * 183 * @return the offset in milliseconds to add to GMT to get local time. 184 * 185 * @see Calendar#ZONE_OFFSET 186 * @see Calendar#DST_OFFSET 187 */ 188 public abstract int getOffset(int era, int year, int month, int day, 189 int dayOfWeek, int milliseconds); 190 191 /** 192 * Returns the offset of this time zone from UTC at the specified 193 * date. If Daylight Saving Time is in effect at the specified 194 * date, the offset value is adjusted with the amount of daylight 195 * saving. 196 * <p> 197 * This method returns a historically correct offset value if an 198 * underlying TimeZone implementation subclass supports historical 199 * Daylight Saving Time schedule and GMT offset changes. 200 * 201 * @param date the date represented in milliseconds since January 1, 1970 00:00:00 GMT 202 * @return the amount of time in milliseconds to add to UTC to get local time. 203 * 204 * @see Calendar#ZONE_OFFSET 205 * @see Calendar#DST_OFFSET 206 * @since 1.4 207 */ 208 public int getOffset(long date) { 209 if (inDaylightTime(new Date(date))) { 210 return getRawOffset() + getDSTSavings(); 211 } 212 return getRawOffset(); 213 } 214 215 /** 216 * Gets the raw GMT offset and the amount of daylight saving of this 217 * time zone at the given time. 218 * @param date the milliseconds (since January 1, 1970, 219 * 00:00:00.000 GMT) at which the time zone offset and daylight 220 * saving amount are found 221 * @param offsets an array of int where the raw GMT offset 222 * (offset[0]) and daylight saving amount (offset[1]) are stored, 223 * or null if those values are not needed. The method assumes that 224 * the length of the given array is two or larger. 225 * @return the total amount of the raw GMT offset and daylight 226 * saving at the specified date. 227 * 228 * @see Calendar#ZONE_OFFSET 229 * @see Calendar#DST_OFFSET 230 */ 231 int getOffsets(long date, int[] offsets) { 232 int rawoffset = getRawOffset(); 233 int dstoffset = 0; 234 if (inDaylightTime(new Date(date))) { 235 dstoffset = getDSTSavings(); 236 } 237 if (offsets != null) { 238 offsets[0] = rawoffset; 239 offsets[1] = dstoffset; 240 } 241 return rawoffset + dstoffset; 242 } 243 244 /** 245 * Sets the base time zone offset to GMT. 246 * This is the offset to add to UTC to get local time. 247 * <p> 248 * If an underlying <code>TimeZone</code> implementation subclass 249 * supports historical GMT offset changes, the specified GMT 250 * offset is set as the latest GMT offset and the difference from 251 * the known latest GMT offset value is used to adjust all 252 * historical GMT offset values. 253 * 254 * @param offsetMillis the given base time zone offset to GMT. 255 */ 256 abstract public void setRawOffset(int offsetMillis); 257 258 /** 259 * Returns the amount of time in milliseconds to add to UTC to get 260 * standard time in this time zone. Because this value is not 261 * affected by daylight saving time, it is called <I>raw 262 * offset</I>. 263 * <p> 264 * If an underlying <code>TimeZone</code> implementation subclass 265 * supports historical GMT offset changes, the method returns the 266 * raw offset value of the current date. In Honolulu, for example, 267 * its raw offset changed from GMT-10:30 to GMT-10:00 in 1947, and 268 * this method always returns -36000000 milliseconds (i.e., -10 269 * hours). 270 * 271 * @return the amount of raw offset time in milliseconds to add to UTC. 272 * @see Calendar#ZONE_OFFSET 273 */ 274 public abstract int getRawOffset(); 275 276 /** 277 * Gets the ID of this time zone. 278 * @return the ID of this time zone. 279 */ 280 public String getID() 281 { 282 return ID; 283 } 284 285 /** 286 * Sets the time zone ID. This does not change any other data in 287 * the time zone object. 288 * @param ID the new time zone ID. 289 */ 290 public void setID(String ID) 291 { 292 if (ID == null) { 293 throw new NullPointerException(); 294 } 295 this.ID = ID; 296 this.zoneId = null; // invalidate cache 297 } 298 299 /** 300 * Returns a long standard time name of this {@code TimeZone} suitable for 301 * presentation to the user in the default locale. 302 * 303 * <p>This method is equivalent to: 304 * <blockquote><pre> 305 * getDisplayName(false, {@link #LONG}, 306 * Locale.getDefault({@link Locale.Category#DISPLAY})) 307 * </pre></blockquote> 308 * 309 * @return the human-readable name of this time zone in the default locale. 310 * @since 1.2 311 * @see #getDisplayName(boolean, int, Locale) 312 * @see Locale#getDefault(Locale.Category) 313 * @see Locale.Category 314 */ 315 public final String getDisplayName() { 316 return getDisplayName(false, LONG, 317 Locale.getDefault(Locale.Category.DISPLAY)); 318 } 319 320 /** 321 * Returns a long standard time name of this {@code TimeZone} suitable for 322 * presentation to the user in the specified {@code locale}. 323 * 324 * <p>This method is equivalent to: 325 * <blockquote><pre> 326 * getDisplayName(false, {@link #LONG}, locale) 327 * </pre></blockquote> 328 * 329 * @param locale the locale in which to supply the display name. 330 * @return the human-readable name of this time zone in the given locale. 331 * @exception NullPointerException if {@code locale} is {@code null}. 332 * @since 1.2 333 * @see #getDisplayName(boolean, int, Locale) 334 */ 335 public final String getDisplayName(Locale locale) { 336 return getDisplayName(false, LONG, locale); 337 } 338 339 /** 340 * Returns a name in the specified {@code style} of this {@code TimeZone} 341 * suitable for presentation to the user in the default locale. If the 342 * specified {@code daylight} is {@code true}, a Daylight Saving Time name 343 * is returned (even if this {@code TimeZone} doesn't observe Daylight Saving 344 * Time). Otherwise, a Standard Time name is returned. 345 * 346 * <p>This method is equivalent to: 347 * <blockquote><pre> 348 * getDisplayName(daylight, style, 349 * Locale.getDefault({@link Locale.Category#DISPLAY})) 350 * </pre></blockquote> 351 * 352 * @param daylight {@code true} specifying a Daylight Saving Time name, or 353 * {@code false} specifying a Standard Time name 354 * @param style either {@link #LONG} or {@link #SHORT} 355 * @return the human-readable name of this time zone in the default locale. 356 * @exception IllegalArgumentException if {@code style} is invalid. 357 * @since 1.2 358 * @see #getDisplayName(boolean, int, Locale) 359 * @see Locale#getDefault(Locale.Category) 360 * @see Locale.Category 361 * @see java.text.DateFormatSymbols#getZoneStrings() 362 */ 363 public final String getDisplayName(boolean daylight, int style) { 364 return getDisplayName(daylight, style, 365 Locale.getDefault(Locale.Category.DISPLAY)); 366 } 367 368 /** 369 * Returns a name in the specified {@code style} of this {@code TimeZone} 370 * suitable for presentation to the user in the specified {@code 371 * locale}. If the specified {@code daylight} is {@code true}, a Daylight 372 * Saving Time name is returned (even if this {@code TimeZone} doesn't 373 * observe Daylight Saving Time). Otherwise, a Standard Time name is 374 * returned. 375 * 376 * <p>When looking up a time zone name, the {@linkplain 377 * ResourceBundle.Control#getCandidateLocales(String,Locale) default 378 * <code>Locale</code> search path of <code>ResourceBundle</code>} derived 379 * from the specified {@code locale} is used. (No {@linkplain 380 * ResourceBundle.Control#getFallbackLocale(String,Locale) fallback 381 * <code>Locale</code>} search is performed.) If a time zone name in any 382 * {@code Locale} of the search path, including {@link Locale#ROOT}, is 383 * found, the name is returned. Otherwise, a string in the 384 * <a href="#NormalizedCustomID">normalized custom ID format</a> is returned. 385 * 386 * @param daylight {@code true} specifying a Daylight Saving Time name, or 387 * {@code false} specifying a Standard Time name 388 * @param style either {@link #LONG} or {@link #SHORT} 389 * @param locale the locale in which to supply the display name. 390 * @return the human-readable name of this time zone in the given locale. 391 * @exception IllegalArgumentException if {@code style} is invalid. 392 * @exception NullPointerException if {@code locale} is {@code null}. 393 * @since 1.2 394 * @see java.text.DateFormatSymbols#getZoneStrings() 395 */ 396 public String getDisplayName(boolean daylight, int style, Locale locale) { 397 if (style != SHORT && style != LONG) { 398 throw new IllegalArgumentException("Illegal style: " + style); 399 } 400 String id = getID(); 401 String name = TimeZoneNameUtility.retrieveDisplayName(id, daylight, style, locale); 402 if (name != null) { 403 return name; 404 } 405 406 if (id.startsWith("GMT") && id.length() > 3) { 407 char sign = id.charAt(3); 408 if (sign == '+' || sign == '-') { 409 return id; 410 } 411 } 412 int offset = getRawOffset(); 413 if (daylight) { 414 offset += getDSTSavings(); 415 } 416 return ZoneInfoFile.toCustomID(offset); 417 } 418 419 private static String[] getDisplayNames(String id, Locale locale) { 420 return TimeZoneNameUtility.retrieveDisplayNames(id, locale); 421 } 422 423 /** 424 * Returns the amount of time to be added to local standard time 425 * to get local wall clock time. 426 * 427 * <p>The default implementation returns 3600000 milliseconds 428 * (i.e., one hour) if a call to {@link #useDaylightTime()} 429 * returns {@code true}. Otherwise, 0 (zero) is returned. 430 * 431 * <p>If an underlying {@code TimeZone} implementation subclass 432 * supports historical and future Daylight Saving Time schedule 433 * changes, this method returns the amount of saving time of the 434 * last known Daylight Saving Time rule that can be a future 435 * prediction. 436 * 437 * <p>If the amount of saving time at any given time stamp is 438 * required, construct a {@link Calendar} with this {@code 439 * TimeZone} and the time stamp, and call {@link Calendar#get(int) 440 * Calendar.get}{@code (}{@link Calendar#DST_OFFSET}{@code )}. 441 * 442 * @return the amount of saving time in milliseconds 443 * @since 1.4 444 * @see #inDaylightTime(Date) 445 * @see #getOffset(long) 446 * @see #getOffset(int,int,int,int,int,int) 447 * @see Calendar#ZONE_OFFSET 448 */ 449 public int getDSTSavings() { 450 if (useDaylightTime()) { 451 return 3600000; 452 } 453 return 0; 454 } 455 456 /** 457 * Queries if this {@code TimeZone} uses Daylight Saving Time. 458 * 459 * <p>If an underlying {@code TimeZone} implementation subclass 460 * supports historical and future Daylight Saving Time schedule 461 * changes, this method refers to the last known Daylight Saving Time 462 * rule that can be a future prediction and may not be the same as 463 * the current rule. Consider calling {@link #observesDaylightTime()} 464 * if the current rule should also be taken into account. 465 * 466 * @return {@code true} if this {@code TimeZone} uses Daylight Saving Time, 467 * {@code false}, otherwise. 468 * @see #inDaylightTime(Date) 469 * @see Calendar#DST_OFFSET 470 */ 471 public abstract boolean useDaylightTime(); 472 473 /** 474 * Returns {@code true} if this {@code TimeZone} is currently in 475 * Daylight Saving Time, or if a transition from Standard Time to 476 * Daylight Saving Time occurs at any future time. 477 * 478 * <p>The default implementation returns {@code true} if 479 * {@code useDaylightTime()} or {@code inDaylightTime(new Date())} 480 * returns {@code true}. 481 * 482 * @return {@code true} if this {@code TimeZone} is currently in 483 * Daylight Saving Time, or if a transition from Standard Time to 484 * Daylight Saving Time occurs at any future time; {@code false} 485 * otherwise. 486 * @since 1.7 487 * @see #useDaylightTime() 488 * @see #inDaylightTime(Date) 489 * @see Calendar#DST_OFFSET 490 */ 491 public boolean observesDaylightTime() { 492 return useDaylightTime() || inDaylightTime(new Date()); 493 } 494 495 /** 496 * Queries if the given {@code date} is in Daylight Saving Time in 497 * this time zone. 498 * 499 * @param date the given Date. 500 * @return {@code true} if the given date is in Daylight Saving Time, 501 * {@code false}, otherwise. 502 */ 503 abstract public boolean inDaylightTime(Date date); 504 505 /** 506 * Gets the <code>TimeZone</code> for the given ID. 507 * 508 * @param ID the ID for a <code>TimeZone</code>, either an abbreviation 509 * such as "PST", a full name such as "America/Los_Angeles", or a custom 510 * ID such as "GMT-8:00". Note that the support of abbreviations is 511 * for JDK 1.1.x compatibility only and full names should be used. 512 * 513 * @return the specified <code>TimeZone</code>, or the GMT zone if the given ID 514 * cannot be understood. 515 */ 516 public static synchronized TimeZone getTimeZone(String ID) { 517 return getTimeZone(ID, true); 518 } 519 520 /** 521 * Gets the {@code TimeZone} for the given {@code zoneId}. 522 * 523 * @param zoneId a {@link ZoneId} from which the time zone ID is obtained 524 * @return the specified {@code TimeZone}, or the GMT zone if the given ID 525 * cannot be understood. 526 * @throws NullPointerException if {@code zoneId} is {@code null} 527 * @since 1.8 528 */ 529 public static TimeZone getTimeZone(ZoneId zoneId) { 530 String tzid = zoneId.getId(); // throws an NPE if null 531 char c = tzid.charAt(0); 532 if (c == '+' || c == '-') { 533 tzid = "GMT" + tzid; 534 } else if (c == 'Z' && tzid.length() == 1) { 535 tzid = "UTC"; 536 } 537 return getTimeZone(tzid, true); 538 } 539 540 /** 541 * Converts this {@code TimeZone} object to a {@code ZoneId}. 542 * 543 * @return a {@code ZoneId} representing the same time zone as this 544 * {@code TimeZone} 545 * @since 1.8 546 */ 547 public ZoneId toZoneId() { 548 ZoneId zId = zoneId; 549 if (zId == null) { 550 zoneId = zId = toZoneId0(); 551 } 552 return zId; 553 } 554 555 private ZoneId toZoneId0() { 556 String id = getID(); 557 TimeZone defaultZone = defaultTimeZone; 558 // are we not defaultTimeZone but our id is equal to default's? 559 if (defaultZone != this && 560 defaultZone != null && id.equals(defaultZone.getID())) { 561 // delegate to default TZ 562 return defaultZone.toZoneId(); 563 } 564 // derive it ourselves 565 if (ZoneInfoFile.useOldMapping() && id.length() == 3) { 566 if ("EST".equals(id)) 567 return ZoneId.of("America/New_York"); 568 if ("MST".equals(id)) 569 return ZoneId.of("America/Denver"); 570 if ("HST".equals(id)) 571 return ZoneId.of("America/Honolulu"); 572 } 573 return ZoneId.of(id, ZoneId.SHORT_IDS); 574 } 575 576 private static TimeZone getTimeZone(String ID, boolean fallback) { 577 TimeZone tz = ZoneInfo.getTimeZone(ID); 578 if (tz == null) { 579 tz = parseCustomTimeZone(ID); 580 if (tz == null && fallback) { 581 tz = new ZoneInfo(GMT_ID, 0); 582 } 583 } 584 return tz; 585 } 586 587 /** 588 * Gets the available IDs according to the given time zone offset in milliseconds. 589 * 590 * @param rawOffset the given time zone GMT offset in milliseconds. 591 * @return an array of IDs, where the time zone for that ID has 592 * the specified GMT offset. For example, "America/Phoenix" and "America/Denver" 593 * both have GMT-07:00, but differ in daylight saving behavior. 594 * @see #getRawOffset() 595 */ 596 public static synchronized String[] getAvailableIDs(int rawOffset) { 597 return ZoneInfo.getAvailableIDs(rawOffset); 598 } 599 600 /** 601 * Gets all the available IDs supported. 602 * @return an array of IDs. 603 */ 604 public static synchronized String[] getAvailableIDs() { 605 return ZoneInfo.getAvailableIDs(); 606 } 607 608 /** 609 * Gets the platform defined TimeZone ID. 610 **/ 611 private static native String getSystemTimeZoneID(String javaHome); 612 613 /** 614 * Gets the custom time zone ID based on the GMT offset of the 615 * platform. (e.g., "GMT+08:00") 616 */ 617 private static native String getSystemGMTOffsetID(); 618 619 /** 620 * Gets the default {@code TimeZone} of the Java virtual machine. If the 621 * cached default {@code TimeZone} is available, its clone is returned. 622 * Otherwise, the method takes the following steps to determine the default 623 * time zone. 624 * 625 * <ul> 626 * <li>Use the {@code user.timezone} property value as the default 627 * time zone ID if it's available.</li> 628 * <li>Detect the platform time zone ID. The source of the 629 * platform time zone and ID mapping may vary with implementation.</li> 630 * <li>Use {@code GMT} as the last resort if the given or detected 631 * time zone ID is unknown.</li> 632 * </ul> 633 * 634 * <p>The default {@code TimeZone} created from the ID is cached, 635 * and its clone is returned. The {@code user.timezone} property 636 * value is set to the ID upon return. 637 * 638 * @return the default {@code TimeZone} 639 * @see #setDefault(TimeZone) 640 */ 641 public static TimeZone getDefault() { 642 return (TimeZone) getDefaultRef().clone(); 643 } 644 645 /** 646 * Returns the reference to the default TimeZone object. This 647 * method doesn't create a clone. 648 */ 649 static TimeZone getDefaultRef() { 650 TimeZone defaultZone = defaultTimeZone; 651 if (defaultZone == null) { 652 // Need to initialize the default time zone. 653 defaultZone = setDefaultZone(); 654 assert defaultZone != null; 655 } 656 // Don't clone here. 657 return defaultZone; 658 } 659 660 private static synchronized TimeZone setDefaultZone() { 661 TimeZone tz; 662 // get the time zone ID from the system properties 663 String zoneID = AccessController.doPrivileged( 664 new GetPropertyAction("user.timezone")); 665 666 // if the time zone ID is not set (yet), perform the 667 // platform to Java time zone ID mapping. 668 if (zoneID == null || zoneID.isEmpty()) { 669 String javaHome = AccessController.doPrivileged( 670 new GetPropertyAction("java.home")); 671 try { 672 zoneID = getSystemTimeZoneID(javaHome); 673 if (zoneID == null) { 674 zoneID = GMT_ID; 675 } 676 } catch (NullPointerException e) { 677 zoneID = GMT_ID; 678 } 679 } 680 681 // Get the time zone for zoneID. But not fall back to 682 // "GMT" here. 683 tz = getTimeZone(zoneID, false); 684 685 if (tz == null) { 686 // If the given zone ID is unknown in Java, try to 687 // get the GMT-offset-based time zone ID, 688 // a.k.a. custom time zone ID (e.g., "GMT-08:00"). 689 String gmtOffsetID = getSystemGMTOffsetID(); 690 if (gmtOffsetID != null) { 691 zoneID = gmtOffsetID; 692 } 693 tz = getTimeZone(zoneID, true); 694 } 695 assert tz != null; 696 697 final String id = zoneID; 698 AccessController.doPrivileged(new PrivilegedAction<Void>() { 699 @Override 700 public Void run() { 701 System.setProperty("user.timezone", id); 702 return null; 703 } 704 }); 705 706 defaultTimeZone = tz; 707 return tz; 708 } 709 710 /** 711 * Sets the {@code TimeZone} that is returned by the {@code getDefault} 712 * method. {@code zone} is cached. If {@code zone} is null, the cached 713 * default {@code TimeZone} is cleared. This method doesn't change the value 714 * of the {@code user.timezone} property. 715 * 716 * @param zone the new default {@code TimeZone}, or null 717 * @throws SecurityException if the security manager's {@code checkPermission} 718 * denies {@code PropertyPermission("user.timezone", 719 * "write")} 720 * @see #getDefault 721 * @see PropertyPermission 722 */ 723 public static void setDefault(TimeZone zone) 724 { 725 SecurityManager sm = System.getSecurityManager(); 726 if (sm != null) { 727 sm.checkPermission(new PropertyPermission 728 ("user.timezone", "write")); 729 } 730 // defensive clone 731 defaultTimeZone = (zone == null) ? null : (TimeZone) zone.clone(); 732 } 733 734 /** 735 * Returns true if this zone has the same rule and offset as another zone. 736 * That is, if this zone differs only in ID, if at all. Returns false 737 * if the other zone is null. 738 * @param other the <code>TimeZone</code> object to be compared with 739 * @return true if the other zone is not null and is the same as this one, 740 * with the possible exception of the ID 741 * @since 1.2 742 */ 743 public boolean hasSameRules(TimeZone other) { 744 return other != null && getRawOffset() == other.getRawOffset() && 745 useDaylightTime() == other.useDaylightTime(); 746 } 747 748 /** 749 * Creates a copy of this <code>TimeZone</code>. 750 * 751 * @return a clone of this <code>TimeZone</code> 752 */ 753 public Object clone() 754 { 755 try { 756 return super.clone(); 757 } catch (CloneNotSupportedException e) { 758 throw new InternalError(e); 759 } 760 } 761 762 /** 763 * The null constant as a TimeZone. 764 */ 765 static final TimeZone NO_TIMEZONE = null; 766 767 // =======================privates=============================== 768 769 /** 770 * The string identifier of this <code>TimeZone</code>. This is a 771 * programmatic identifier used internally to look up <code>TimeZone</code> 772 * objects from the system table and also to map them to their localized 773 * display names. <code>ID</code> values are unique in the system 774 * table but may not be for dynamically created zones. 775 * @serial 776 */ 777 private String ID; 778 779 /** 780 * Cached {@link ZoneId} for this TimeZone 781 */ 782 private transient ZoneId zoneId; 783 784 private static volatile TimeZone defaultTimeZone; 785 786 static final String GMT_ID = "GMT"; 787 private static final int GMT_ID_LENGTH = 3; 788 789 // a static TimeZone we can reference if no AppContext is in place 790 private static volatile TimeZone mainAppContextDefault; 791 792 /** 793 * Parses a custom time zone identifier and returns a corresponding zone. 794 * This method doesn't support the RFC 822 time zone format. (e.g., +hhmm) 795 * 796 * @param id a string of the <a href="#CustomID">custom ID form</a>. 797 * @return a newly created TimeZone with the given offset and 798 * no daylight saving time, or null if the id cannot be parsed. 799 */ 800 private static final TimeZone parseCustomTimeZone(String id) { 801 int length; 802 803 // Error if the length of id isn't long enough or id doesn't 804 // start with "GMT". 805 if ((length = id.length()) < (GMT_ID_LENGTH + 2) || 806 id.indexOf(GMT_ID) != 0) { 807 return null; 808 } 809 810 ZoneInfo zi; 811 812 // First, we try to find it in the cache with the given 813 // id. Even the id is not normalized, the returned ZoneInfo 814 // should have its normalized id. 815 zi = ZoneInfoFile.getZoneInfo(id); 816 if (zi != null) { 817 return zi; 818 } 819 820 int index = GMT_ID_LENGTH; 821 boolean negative = false; 822 char c = id.charAt(index++); 823 if (c == '-') { 824 negative = true; 825 } else if (c != '+') { 826 return null; 827 } 828 829 int hours = 0; 830 int num = 0; 831 int countDelim = 0; 832 int len = 0; 833 while (index < length) { 834 c = id.charAt(index++); 835 if (c == ':') { 836 if (countDelim > 0) { 837 return null; 838 } 839 if (len > 2) { 840 return null; 841 } 842 hours = num; 843 countDelim++; 844 num = 0; 845 len = 0; 846 continue; 847 } 848 if (c < '0' || c > '9') { 849 return null; 850 } 851 num = num * 10 + (c - '0'); 852 len++; 853 } 854 if (index != length) { 855 return null; 856 } 857 if (countDelim == 0) { 858 if (len <= 2) { 859 hours = num; 860 num = 0; 861 } else { 862 hours = num / 100; 863 num %= 100; 864 } 865 } else { 866 if (len != 2) { 867 return null; 868 } 869 } 870 if (hours > 23 || num > 59) { 871 return null; 872 } 873 int gmtOffset = (hours * 60 + num) * 60 * 1000; 874 875 if (gmtOffset == 0) { 876 zi = ZoneInfoFile.getZoneInfo(GMT_ID); 877 if (negative) { 878 zi.setID("GMT-00:00"); 879 } else { 880 zi.setID("GMT+00:00"); 881 } 882 } else { 883 zi = ZoneInfoFile.getCustomTimeZone(id, negative ? -gmtOffset : gmtOffset); 884 } 885 return zi; 886 } 887 }