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

http://www.timeofdate.com/city/United%20Kingdom/London/timezone/change

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)