java中如何处理夏令时?
在国际化的项目中，处理时间时经常会遇到夏令时(BST,British Summer Time)问题，发明夏令时（以及冬令时）主要是为了省电。
冷知识：中国历史上也曾经采用过(1986-1991)夏令时，后来因为各种原因，最终取消了这一制度（参见：https://baijiahao.baidu.com/s?id=1700703328355099602&wfr=spider&for=pc）
但欧美国家仍在广泛使用，以2022年为例：根据网上找到的资料
伦敦 在2022-03-27 ~ 2002-10-30 为夏令时期间。
java中如何知道某个地区，在某个时间点是否处于夏令时呢？
/**
* 夏令时测试(by菩提树下的杨过)
*/
@Test
public void testTimeZone() {
LocalTime time = LocalTime.of(10, 20);
ZoneId zoneId = ZoneId.of("Europe/London");
// A summer date-time
ZonedDateTime zdtSummer = ZonedDateTime.of(LocalDate.of(2022, 10, 15), time, zoneId);
System.out.println(zdtSummer);
// A winter date-time
ZonedDateTime zdtWinter = ZonedDateTime.of(LocalDate.of(2022, 11, 15), time, zoneId);
System.out.println(zdtWinter);
}
输出:
2022-10-15T10:20+01:00[Europe/London] 2022-11-15T10:20Z [Europe/London]
即：2022-10-15 10:20:00 这个时间，对于London来说，时区的offset为+1，即向前拨快了1小时（夏令时)
而2022-11-15 10:20:00 这个时间，London的时区offset为Z(即Zero 零)，即没有向前调整（不是夏令时)
通过这个测试，可以看到JDK里已经自带了夏令时的判断。
那么问题来了，ZoneId在构建时，要传入“Europe/London”这样的地区标识，JDK里支持多少种这类地区标识呢？
/**
* 输出全球所有时区（by菩提树下的杨过)
*/
@Test
public void getAvailableZoneIds() {
Calendar c = Calendar.getInstance();
System.out.println("year:" + c.get(Calendar.YEAR) + ",month:" + (c.get(Calendar.MONTH) + 1) + ",day:" + c.get(Calendar.DAY_OF_MONTH) + "\n");
TreeMap<String, String> result = new TreeMap<>();
//遍历所有ZoneId，并以今天9点时刻做为依赖，打印出每个ZoneId对应的时区
for (String strZoneId : ZoneId.getAvailableZoneIds()) {
LocalTime time = LocalTime.of(9, 0);
ZoneId zoneId = ZoneId.of(strZoneId);
ZonedDateTime zonedDateTime = ZonedDateTime.of(LocalDate.of(c.get(Calendar.YEAR), c.get(Calendar.MONTH) + 1, c.get(Calendar.DAY_OF_MONTH)), time, zoneId);
String offset = zonedDateTime.getOffset().toString();
if ("Z".equalsIgnoreCase(offset)) {
offset = "+00:00";
} else if (!offset.contains(":")) {
offset = offset + ":00";
}
result.put(strZoneId, "GMT" + offset);
}
for (Map.Entry<String, String> entry : result.entrySet()) {
System.out.println(entry.getValue() + "\t" + entry.getKey());
}
}
输出：
year:2024,month:5,day:17 GMT+00:00 Africa/Abidjan GMT+00:00 Africa/Accra GMT+03:00 Africa/Addis_Ababa GMT+01:00 Africa/Algiers GMT+03:00 Africa/Asmara GMT+03:00 Africa/Asmera GMT+00:00 Africa/Bamako GMT+01:00 Africa/Bangui GMT+00:00 Africa/Banjul GMT+00:00 Africa/Bissau GMT+02:00 Africa/Blantyre GMT+01:00 Africa/Brazzaville GMT+02:00 Africa/Bujumbura GMT+02:00 Africa/Cairo GMT+01:00 Africa/Casablanca GMT+02:00 Africa/Ceuta GMT+00:00 Africa/Conakry GMT+00:00 Africa/Dakar GMT+03:00 Africa/Dar_es_Salaam GMT+03:00 Africa/Djibouti GMT+01:00 Africa/Douala GMT+01:00 Africa/El_Aaiun GMT+00:00 Africa/Freetown GMT+02:00 Africa/Gaborone GMT+02:00 Africa/Harare GMT+02:00 Africa/Johannesburg GMT+03:00 Africa/Juba GMT+03:00 Africa/Kampala GMT+02:00 Africa/Khartoum GMT+02:00 Africa/Kigali GMT+01:00 Africa/Kinshasa GMT+01:00 Africa/Lagos GMT+01:00 Africa/Libreville GMT+00:00 Africa/Lome GMT+01:00 Africa/Luanda GMT+02:00 Africa/Lubumbashi GMT+02:00 Africa/Lusaka GMT+01:00 Africa/Malabo GMT+02:00 Africa/Maputo GMT+02:00 Africa/Maseru GMT+02:00 Africa/Mbabane GMT+03:00 Africa/Mogadishu GMT+00:00 Africa/Monrovia GMT+03:00 Africa/Nairobi GMT+01:00 Africa/Ndjamena GMT+01:00 Africa/Niamey GMT+00:00 Africa/Nouakchott GMT+00:00 Africa/Ouagadougou GMT+01:00 Africa/Porto-Novo GMT+01:00 Africa/Sao_Tome GMT+00:00 Africa/Timbuktu GMT+02:00 Africa/Tripoli GMT+01:00 Africa/Tunis GMT+02:00 Africa/Windhoek GMT-09:00 America/Adak GMT-08:00 America/Anchorage GMT-04:00 America/Anguilla GMT-04:00 America/Antigua GMT-03:00 America/Araguaina GMT-03:00 America/Argentina/Buenos_Aires GMT-03:00 America/Argentina/Catamarca GMT-03:00 America/Argentina/ComodRivadavia GMT-03:00 America/Argentina/Cordoba GMT-03:00 America/Argentina/Jujuy GMT-03:00 America/Argentina/La_Rioja GMT-03:00 America/Argentina/Mendoza GMT-03:00 America/Argentina/Rio_Gallegos GMT-03:00 America/Argentina/Salta GMT-03:00 America/Argentina/San_Juan GMT-03:00 America/Argentina/San_Luis GMT-03:00 America/Argentina/Tucuman GMT-03:00 America/Argentina/Ushuaia GMT-04:00 America/Aruba GMT-04:00 America/Asuncion GMT-05:00 America/Atikokan GMT-09:00 America/Atka GMT-03:00 America/Bahia GMT-05:00 America/Bahia_Banderas GMT-04:00 America/Barbados GMT-03:00 America/Belem GMT-06:00 America/Belize GMT-04:00 America/Blanc-Sablon GMT-04:00 America/Boa_Vista GMT-05:00 America/Bogota GMT-06:00 America/Boise GMT-03:00 America/Buenos_Aires GMT-06:00 America/Cambridge_Bay GMT-04:00 America/Campo_Grande GMT-05:00 America/Cancun GMT-04:00 America/Caracas GMT-03:00 America/Catamarca GMT-03:00 America/Cayenne GMT-05:00 America/Cayman GMT-05:00 America/Chicago GMT-06:00 America/Chihuahua GMT-05:00 America/Coral_Harbour GMT-03:00 America/Cordoba GMT-06:00 America/Costa_Rica GMT-07:00 America/Creston GMT-04:00 America/Cuiaba GMT-04:00 America/Curacao GMT+00:00 America/Danmarkshavn GMT-07:00 America/Dawson GMT-07:00 America/Dawson_Creek GMT-06:00 America/Denver GMT-04:00 America/Detroit GMT-04:00 America/Dominica GMT-06:00 America/Edmonton GMT-05:00 America/Eirunepe GMT-06:00 America/El_Salvador GMT-07:00 America/Ensenada GMT-07:00 America/Fort_Nelson GMT-04:00 America/Fort_Wayne GMT-03:00 America/Fortaleza GMT-03:00 America/Glace_Bay GMT-02:00 America/Godthab GMT-03:00 America/Goose_Bay GMT-04:00 America/Grand_Turk GMT-04:00 America/Grenada GMT-04:00 America/Guadeloupe GMT-06:00 America/Guatemala GMT-05:00 America/Guayaquil GMT-04:00 America/Guyana GMT-03:00 America/Halifax GMT-04:00 America/Havana GMT-07:00 America/Hermosillo GMT-04:00 America/Indiana/Indianapolis GMT-05:00 America/Indiana/Knox GMT-04:00 America/Indiana/Marengo GMT-04:00 America/Indiana/Petersburg GMT-05:00 America/Indiana/Tell_City GMT-04:00 America/Indiana/Vevay GMT-04:00 America/Indiana/Vincennes GMT-04:00 America/Indiana/Winamac GMT-04:00 America/Indianapolis GMT-06:00 America/Inuvik GMT-04:00 America/Iqaluit GMT-05:00 America/Jamaica GMT-03:00 America/Jujuy GMT-08:00 America/Juneau GMT-04:00 America/Kentucky/Louisville GMT-04:00 America/Kentucky/Monticello GMT-05:00 America/Knox_IN GMT-04:00 America/Kralendijk GMT-04:00 America/La_Paz GMT-05:00 America/Lima GMT-07:00 America/Los_Angeles GMT-04:00 America/Louisville GMT-04:00 America/Lower_Princes GMT-03:00 America/Maceio GMT-06:00 America/Managua GMT-04:00 America/Manaus GMT-04:00 America/Marigot GMT-04:00 America/Martinique GMT-05:00 America/Matamoros GMT-06:00 America/Mazatlan GMT-03:00 America/Mendoza GMT-05:00 America/Menominee GMT-05:00 America/Merida GMT-08:00 America/Metlakatla GMT-05:00 America/Mexico_City GMT-02:00 America/Miquelon GMT-03:00 America/Moncton GMT-05:00 America/Monterrey GMT-03:00 America/Montevideo GMT-04:00 America/Montreal GMT-04:00 America/Montserrat GMT-04:00 America/Nassau GMT-04:00 America/New_York GMT-04:00 America/Nipigon GMT-08:00 America/Nome GMT-02:00 America/Noronha GMT-05:00 America/North_Dakota/Beulah GMT-05:00 America/North_Dakota/Center GMT-05:00 America/North_Dakota/New_Salem GMT-06:00 America/Ojinaga GMT-05:00 America/Panama GMT-04:00 America/Pangnirtung GMT-03:00 America/Paramaribo GMT-07:00 America/Phoenix GMT-04:00 America/Port-au-Prince GMT-04:00 America/Port_of_Spain GMT-05:00 America/Porto_Acre GMT-04:00 America/Porto_Velho GMT-04:00 America/Puerto_Rico GMT-03:00 America/Punta_Arenas GMT-05:00 America/Rainy_River GMT-05:00 America/Rankin_Inlet GMT-03:00 America/Recife GMT-06:00 America/Regina GMT-05:00 America/Resolute GMT-05:00 America/Rio_Branco GMT-03:00 America/Rosario GMT-07:00 America/Santa_Isabel GMT-03:00 America/Santarem GMT-04:00 America/Santiago GMT-04:00 America/Santo_Domingo GMT-03:00 America/Sao_Paulo GMT+00:00 America/Scoresbysund GMT-06:00 America/Shiprock GMT-08:00 America/Sitka GMT-04:00 America/St_Barthelemy GMT-02:30 America/St_Johns GMT-04:00 America/St_Kitts GMT-04:00 America/St_Lucia GMT-04:00 America/St_Thomas GMT-04:00 America/St_Vincent GMT-06:00 America/Swift_Current GMT-06:00 America/Tegucigalpa GMT-03:00 America/Thule GMT-04:00 America/Thunder_Bay GMT-07:00 America/Tijuana GMT-04:00 America/Toronto GMT-04:00 America/Tortola GMT-07:00 America/Vancouver GMT-04:00 America/Virgin GMT-07:00 America/Whitehorse GMT-05:00 America/Winnipeg GMT-08:00 America/Yakutat GMT-06:00 America/Yellowknife GMT+08:00 Antarctica/Casey GMT+07:00 Antarctica/Davis GMT+10:00 Antarctica/DumontDUrville GMT+11:00 Antarctica/Macquarie GMT+05:00 Antarctica/Mawson GMT+12:00 Antarctica/McMurdo GMT-03:00 Antarctica/Palmer GMT-03:00 Antarctica/Rothera GMT+12:00 Antarctica/South_Pole GMT+03:00 Antarctica/Syowa GMT+02:00 Antarctica/Troll GMT+06:00 Antarctica/Vostok GMT+02:00 Arctic/Longyearbyen GMT+03:00 Asia/Aden GMT+06:00 Asia/Almaty GMT+03:00 Asia/Amman GMT+12:00 Asia/Anadyr GMT+05:00 Asia/Aqtau GMT+05:00 Asia/Aqtobe GMT+05:00 Asia/Ashgabat GMT+05:00 Asia/Ashkhabad GMT+05:00 Asia/Atyrau GMT+03:00 Asia/Baghdad GMT+03:00 Asia/Bahrain GMT+04:00 Asia/Baku GMT+07:00 Asia/Bangkok GMT+07:00 Asia/Barnaul GMT+03:00 Asia/Beirut GMT+06:00 Asia/Bishkek GMT+08:00 Asia/Brunei GMT+05:30 Asia/Calcutta GMT+09:00 Asia/Chita GMT+08:00 Asia/Choibalsan GMT+08:00 Asia/Chongqing GMT+08:00 Asia/Chungking GMT+05:30 Asia/Colombo GMT+06:00 Asia/Dacca GMT+03:00 Asia/Damascus GMT+06:00 Asia/Dhaka GMT+09:00 Asia/Dili GMT+04:00 Asia/Dubai GMT+05:00 Asia/Dushanbe GMT+03:00 Asia/Famagusta GMT+03:00 Asia/Gaza GMT+08:00 Asia/Harbin GMT+03:00 Asia/Hebron GMT+07:00 Asia/Ho_Chi_Minh GMT+08:00 Asia/Hong_Kong GMT+07:00 Asia/Hovd GMT+08:00 Asia/Irkutsk GMT+03:00 Asia/Istanbul GMT+07:00 Asia/Jakarta GMT+09:00 Asia/Jayapura GMT+03:00 Asia/Jerusalem GMT+04:30 Asia/Kabul GMT+12:00 Asia/Kamchatka GMT+05:00 Asia/Karachi GMT+06:00 Asia/Kashgar GMT+05:45 Asia/Kathmandu GMT+05:45 Asia/Katmandu GMT+09:00 Asia/Khandyga GMT+05:30 Asia/Kolkata GMT+07:00 Asia/Krasnoyarsk GMT+08:00 Asia/Kuala_Lumpur GMT+08:00 Asia/Kuching GMT+03:00 Asia/Kuwait GMT+08:00 Asia/Macao GMT+08:00 Asia/Macau GMT+11:00 Asia/Magadan GMT+08:00 Asia/Makassar GMT+08:00 Asia/Manila GMT+04:00 Asia/Muscat GMT+03:00 Asia/Nicosia GMT+07:00 Asia/Novokuznetsk GMT+07:00 Asia/Novosibirsk GMT+06:00 Asia/Omsk GMT+05:00 Asia/Oral GMT+07:00 Asia/Phnom_Penh GMT+07:00 Asia/Pontianak GMT+09:00 Asia/Pyongyang GMT+03:00 Asia/Qatar GMT+06:00 Asia/Qyzylorda GMT+06:30 Asia/Rangoon GMT+03:00 Asia/Riyadh GMT+07:00 Asia/Saigon GMT+11:00 Asia/Sakhalin GMT+05:00 Asia/Samarkand GMT+09:00 Asia/Seoul GMT+08:00 Asia/Shanghai GMT+08:00 Asia/Singapore GMT+11:00 Asia/Srednekolymsk GMT+08:00 Asia/Taipei GMT+05:00 Asia/Tashkent GMT+04:00 Asia/Tbilisi GMT+04:30 Asia/Tehran GMT+03:00 Asia/Tel_Aviv GMT+06:00 Asia/Thimbu GMT+06:00 Asia/Thimphu GMT+09:00 Asia/Tokyo GMT+07:00 Asia/Tomsk GMT+08:00 Asia/Ujung_Pandang GMT+08:00 Asia/Ulaanbaatar GMT+08:00 Asia/Ulan_Bator GMT+06:00 Asia/Urumqi GMT+10:00 Asia/Ust-Nera GMT+07:00 Asia/Vientiane GMT+10:00 Asia/Vladivostok GMT+09:00 Asia/Yakutsk GMT+06:30 Asia/Yangon GMT+05:00 Asia/Yekaterinburg GMT+04:00 Asia/Yerevan GMT+00:00 Atlantic/Azores GMT-03:00 Atlantic/Bermuda GMT+01:00 Atlantic/Canary GMT-01:00 Atlantic/Cape_Verde GMT+01:00 Atlantic/Faeroe GMT+01:00 Atlantic/Faroe GMT+02:00 Atlantic/Jan_Mayen GMT+01:00 Atlantic/Madeira GMT+00:00 Atlantic/Reykjavik GMT-02:00 Atlantic/South_Georgia GMT+00:00 Atlantic/St_Helena GMT-03:00 Atlantic/Stanley GMT+10:00 Australia/ACT GMT+09:30 Australia/Adelaide GMT+10:00 Australia/Brisbane GMT+09:30 Australia/Broken_Hill GMT+10:00 Australia/Canberra GMT+10:00 Australia/Currie GMT+09:30 Australia/Darwin GMT+08:45 Australia/Eucla GMT+10:00 Australia/Hobart GMT+10:30 Australia/LHI GMT+10:00 Australia/Lindeman GMT+10:30 Australia/Lord_Howe GMT+10:00 Australia/Melbourne GMT+10:00 Australia/NSW GMT+09:30 Australia/North GMT+08:00 Australia/Perth GMT+10:00 Australia/Queensland GMT+09:30 Australia/South GMT+10:00 Australia/Sydney GMT+10:00 Australia/Tasmania GMT+10:00 Australia/Victoria GMT+08:00 Australia/West GMT+09:30 Australia/Yancowinna GMT-05:00 Brazil/Acre GMT-02:00 Brazil/DeNoronha GMT-03:00 Brazil/East GMT-04:00 Brazil/West GMT+02:00 CET GMT-05:00 CST6CDT GMT-03:00 Canada/Atlantic GMT-05:00 Canada/Central GMT-04:00 Canada/Eastern GMT-06:00 Canada/Mountain GMT-02:30 Canada/Newfoundland GMT-07:00 Canada/Pacific GMT-06:00 Canada/Saskatchewan GMT-07:00 Canada/Yukon GMT-04:00 Chile/Continental GMT-06:00 Chile/EasterIsland GMT-04:00 Cuba GMT+03:00 EET GMT-04:00 EST5EDT GMT+02:00 Egypt GMT+01:00 Eire GMT+00:00 Etc/GMT GMT+00:00 Etc/GMT+0 GMT-01:00 Etc/GMT+1 GMT-10:00 Etc/GMT+10 GMT-11:00 Etc/GMT+11 GMT-12:00 Etc/GMT+12 GMT-02:00 Etc/GMT+2 GMT-03:00 Etc/GMT+3 GMT-04:00 Etc/GMT+4 GMT-05:00 Etc/GMT+5 GMT-06:00 Etc/GMT+6 GMT-07:00 Etc/GMT+7 GMT-08:00 Etc/GMT+8 GMT-09:00 Etc/GMT+9 GMT+00:00 Etc/GMT-0 GMT+01:00 Etc/GMT-1 GMT+10:00 Etc/GMT-10 GMT+11:00 Etc/GMT-11 GMT+12:00 Etc/GMT-12 GMT+13:00 Etc/GMT-13 GMT+14:00 Etc/GMT-14 GMT+02:00 Etc/GMT-2 GMT+03:00 Etc/GMT-3 GMT+04:00 Etc/GMT-4 GMT+05:00 Etc/GMT-5 GMT+06:00 Etc/GMT-6 GMT+07:00 Etc/GMT-7 GMT+08:00 Etc/GMT-8 GMT+09:00 Etc/GMT-9 GMT+00:00 Etc/GMT0 GMT+00:00 Etc/Greenwich GMT+00:00 Etc/UCT GMT+00:00 Etc/UTC GMT+00:00 Etc/Universal GMT+00:00 Etc/Zulu GMT+02:00 Europe/Amsterdam GMT+02:00 Europe/Andorra GMT+04:00 Europe/Astrakhan GMT+03:00 Europe/Athens GMT+01:00 Europe/Belfast GMT+02:00 Europe/Belgrade GMT+02:00 Europe/Berlin GMT+02:00 Europe/Bratislava GMT+02:00 Europe/Brussels GMT+03:00 Europe/Bucharest GMT+02:00 Europe/Budapest GMT+02:00 Europe/Busingen GMT+03:00 Europe/Chisinau GMT+02:00 Europe/Copenhagen GMT+01:00 Europe/Dublin GMT+02:00 Europe/Gibraltar GMT+01:00 Europe/Guernsey GMT+03:00 Europe/Helsinki GMT+01:00 Europe/Isle_of_Man GMT+03:00 Europe/Istanbul GMT+01:00 Europe/Jersey GMT+02:00 Europe/Kaliningrad GMT+03:00 Europe/Kiev GMT+03:00 Europe/Kirov GMT+01:00 Europe/Lisbon GMT+02:00 Europe/Ljubljana GMT+01:00 Europe/London GMT+02:00 Europe/Luxembourg GMT+02:00 Europe/Madrid GMT+02:00 Europe/Malta GMT+03:00 Europe/Mariehamn GMT+03:00 Europe/Minsk GMT+02:00 Europe/Monaco GMT+03:00 Europe/Moscow GMT+03:00 Europe/Nicosia GMT+02:00 Europe/Oslo GMT+02:00 Europe/Paris GMT+02:00 Europe/Podgorica GMT+02:00 Europe/Prague GMT+03:00 Europe/Riga GMT+02:00 Europe/Rome GMT+04:00 Europe/Samara GMT+02:00 Europe/San_Marino GMT+02:00 Europe/Sarajevo GMT+04:00 Europe/Saratov GMT+03:00 Europe/Simferopol GMT+02:00 Europe/Skopje GMT+03:00 Europe/Sofia GMT+02:00 Europe/Stockholm GMT+03:00 Europe/Tallinn GMT+02:00 Europe/Tirane GMT+03:00 Europe/Tiraspol GMT+04:00 Europe/Ulyanovsk GMT+03:00 Europe/Uzhgorod GMT+02:00 Europe/Vaduz GMT+02:00 Europe/Vatican GMT+02:00 Europe/Vienna GMT+03:00 Europe/Vilnius GMT+04:00 Europe/Volgograd GMT+02:00 Europe/Warsaw GMT+02:00 Europe/Zagreb GMT+03:00 Europe/Zaporozhye GMT+02:00 Europe/Zurich GMT+01:00 GB GMT+01:00 GB-Eire GMT+00:00 GMT GMT+00:00 GMT0 GMT+00:00 Greenwich GMT+08:00 Hongkong GMT+00:00 Iceland GMT+03:00 Indian/Antananarivo GMT+06:00 Indian/Chagos GMT+07:00 Indian/Christmas GMT+06:30 Indian/Cocos GMT+03:00 Indian/Comoro GMT+05:00 Indian/Kerguelen GMT+04:00 Indian/Mahe GMT+05:00 Indian/Maldives GMT+04:00 Indian/Mauritius GMT+03:00 Indian/Mayotte GMT+04:00 Indian/Reunion GMT+04:30 Iran GMT+03:00 Israel GMT-05:00 Jamaica GMT+09:00 Japan GMT+12:00 Kwajalein GMT+02:00 Libya GMT+02:00 MET GMT-06:00 MST7MDT GMT-07:00 Mexico/BajaNorte GMT-06:00 Mexico/BajaSur GMT-05:00 Mexico/General GMT+12:00 NZ GMT+12:45 NZ-CHAT GMT-06:00 Navajo GMT+08:00 PRC GMT-07:00 PST8PDT GMT+13:00 Pacific/Apia GMT+12:00 Pacific/Auckland GMT+11:00 Pacific/Bougainville GMT+12:45 Pacific/Chatham GMT+10:00 Pacific/Chuuk GMT-06:00 Pacific/Easter GMT+11:00 Pacific/Efate GMT+13:00 Pacific/Enderbury GMT+13:00 Pacific/Fakaofo GMT+12:00 Pacific/Fiji GMT+12:00 Pacific/Funafuti GMT-06:00 Pacific/Galapagos GMT-09:00 Pacific/Gambier GMT+11:00 Pacific/Guadalcanal GMT+10:00 Pacific/Guam GMT-10:00 Pacific/Honolulu GMT-10:00 Pacific/Johnston GMT+14:00 Pacific/Kiritimati GMT+11:00 Pacific/Kosrae GMT+12:00 Pacific/Kwajalein GMT+12:00 Pacific/Majuro GMT-09:30 Pacific/Marquesas GMT-11:00 Pacific/Midway GMT+12:00 Pacific/Nauru GMT-11:00 Pacific/Niue GMT+11:00 Pacific/Norfolk GMT+11:00 Pacific/Noumea GMT-11:00 Pacific/Pago_Pago GMT+09:00 Pacific/Palau GMT-08:00 Pacific/Pitcairn GMT+11:00 Pacific/Pohnpei GMT+11:00 Pacific/Ponape GMT+10:00 Pacific/Port_Moresby GMT-10:00 Pacific/Rarotonga GMT+10:00 Pacific/Saipan GMT-11:00 Pacific/Samoa GMT-10:00 Pacific/Tahiti GMT+12:00 Pacific/Tarawa GMT+13:00 Pacific/Tongatapu GMT+10:00 Pacific/Truk GMT+12:00 Pacific/Wake GMT+12:00 Pacific/Wallis GMT+10:00 Pacific/Yap GMT+02:00 Poland GMT+01:00 Portugal GMT+09:00 ROK GMT+08:00 Singapore GMT-04:00 SystemV/AST4 GMT-03:00 SystemV/AST4ADT GMT-06:00 SystemV/CST6 GMT-05:00 SystemV/CST6CDT GMT-05:00 SystemV/EST5 GMT-04:00 SystemV/EST5EDT GMT-10:00 SystemV/HST10 GMT-07:00 SystemV/MST7 GMT-06:00 SystemV/MST7MDT GMT-08:00 SystemV/PST8 GMT-07:00 SystemV/PST8PDT GMT-09:00 SystemV/YST9 GMT-08:00 SystemV/YST9YDT GMT+03:00 Turkey GMT+00:00 UCT GMT-08:00 US/Alaska GMT-09:00 US/Aleutian GMT-07:00 US/Arizona GMT-05:00 US/Central GMT-04:00 US/East-Indiana GMT-04:00 US/Eastern GMT-10:00 US/Hawaii GMT-05:00 US/Indiana-Starke GMT-04:00 US/Michigan GMT-06:00 US/Mountain GMT-07:00 US/Pacific GMT-07:00 US/Pacific-New GMT-11:00 US/Samoa GMT+00:00 UTC GMT+00:00 Universal GMT+03:00 W-SU GMT+01:00 WET GMT+00:00 Zulu
从上面的输出可以看出，要表示中国北京时区对应的ZoneId，ZoneId并不是Asia/Beijing，而是Asia/Shanghai，另外也并非所有时区都是整点的偏移量，有些是半小时，甚至45分钟的，比如：
GMT+09:30 Australia/Darwin GMT+05:45 Asia/Kathmandu
另外有一个特殊地区：埃及开罗，2024年才开始实施夏令时，jdk 8版本并不能正确识别
仍然输出的是：
GMT+02:00 Africa/Cairo
有用到这个地区的朋友，需要升级JDK（JDK 21 验证是正确的)
作者：菩提树下的杨过
出处：http://yjmyzz.cnblogs.com
本文版权归作者和博客园共有，欢迎转载，但未经作者同意必须保留此段声明，且在文章页面明显位置给出原文连接，否则保留追究法律责任的权利。
出处：http://yjmyzz.cnblogs.com
本文版权归作者和博客园共有，欢迎转载，但未经作者同意必须保留此段声明，且在文章页面明显位置给出原文连接，否则保留追究法律责任的权利。
