在企业实际开发中java代码中对日期的处理是非常常见，在学习java中日期的使用的时候，分为jdk8以前的传统日期处理类Date和jdk8以后的日期处理类，而jdk8之前的传统时间处理类因为存在线程安全问题等使用比较少，今天我们来一起讨论下jdk8以后的时间日期类。 jdk8之前没有支持纳秒级别的，那么在jdk8的时候也支持了纳秒级别的，这对很多对时间准确性要求很高的公司是个福音。
jdk8以后的时间类主要是三个LocalDate,LocalTime和LocalDateTime.三个类获取对象的方法都是有两种 第一是通过LocalDate.now（）方法获取对象，第二种方式是LocalDate.of()方法获取对象。三个类的主要区别是LocalDate中包含年月日星期的处理，LocalTime中包含的是对时分秒纳秒的处理，LocalDateTime则是包含其他两个类中的全部处理，其次，LocalDateTime可以实现对LocalDate和LocalTime的转换。
LocalDateTime localDateTime = LocalDateTime.now();
LocalDate localDate3 = localDateTime.toLocalDate();
LocalTime localTime = localDateTime.toLocalTime();
System.out.println(localDateTime);//2025-12-27T08:44:29.678
System.out.println(localDate3);//2025-12-27
System.out.println(localTime);//08:44:29.678
三个类中有众多的api，下面我就以LocalDate类的api举例来帮大家理解这三个日期类的使用，看下面代码。
LocalDate now = LocalDate.now();
int year = now.getYear();
//由于now是不可变对象，在下面调用增加年份方法的时候返回的是一个新的对象
LocalDate localDate = now.plusYears(1);
//plus开头的方法是在当前时间年份增加多少年，下面的with方法是修改年份到多少，同样也会返回一个新的对象，这是区别于jdk8之前的时间的原因
LocalDate localDate1 = now.withYear(2099);
System.out.println(year);
System.out.println(now);
System.out.println(localDate);
System.out.println(localDate1);
LocalDate localDate2 = now.minusYears(1);
System.out.println(localDate2);
//比较时间前后的方法 返回是布尔值
LocalDate of = LocalDate.of(2020, 5, 30);
LocalDate of1 = LocalDate.of(2025, 12, 01);
System.out.println(of.equals(of1));//返回false
System.out.println(of.isAfter(of1));//返回false
System.out.println(of.isBefore(of1));//返回true
LocalTime方法和LocalDateTime类似，获取对象可以通过调用now方法，增加日期方法是plusXXX()方法，修改某个时间的方法是withXXX()方法，减少时间的方法是minusXXX()方法。比较日期则是可以通过equal，isAfter和isBefore方法。
那么问题来了，世界上有很多的时区的 ， 如果我想获取比如美国现在的时间， 那么java中又是怎么处理的呢？ 对于这种的java中有ZoneId的概念，可以通过这个类获取当前系统默认的时区，以及比如美国的某个城市的时区。 然后将ZoneId传到ZoneDateTime方法中获取改市区的时间，话不多说，上代码演示；
Set<String> availableZoneIds = ZoneId.getAvailableZoneIds();
System.out.println(availableZoneIds);//[Asia/Aden, America/Cuiaba, Etc/GMT+9, Etc/GMT+8, Africa/Nairobi, America/Marigot, Asia/Aqtau, Pacific/Kwajalein, America/El_Salvador, Asia/Pontianak, Africa/Cairo, Pacific/Pago_Pago, Africa/Mbabane, Asia/Kuching, Pacific/Honolulu, Pacific/Rarotonga, America/Guatemala, Australia/Hobart, Europe/London, America/Belize, America/Panama, Asia/Chungking, America/Managua, America/Indiana/Petersburg, Asia/Yerevan, Europe/Brussels, GMT, Europe/Warsaw, America/Chicago, Asia/Kashgar, Chile/Continental, Pacific/Yap, CET, Etc/GMT-1, Etc/GMT-0, Europe/Jersey, America/Tegucigalpa, Etc/GMT-5, Europe/Istanbul, America/Eirunepe, Etc/GMT-4, America/Miquelon, Etc/GMT-3, Europe/Luxembourg, Etc/GMT-2, Etc/GMT-9, America/Argentina/Catamarca, Etc/GMT-8, Etc/GMT-7, Etc/GMT-6, Europe/Zaporozhye, Canada/Yukon, Canada/Atlantic, Atlantic/St_Helena, Australia/Tasmania, Libya, Europe/Guernsey, America/Grand_Turk, Asia/Samarkand, America/Argentina/Cordoba, Asia/Phnom_Penh, Africa/Kigali, Asia/Almaty, US/Alaska, Asia/Dubai, Europe/Isle_of_Man, America/Araguaina, Cuba, Asia/Novosibirsk, America/Argentina/Salta, Etc/GMT+3, Africa/Tunis, Etc/GMT+2, Etc/GMT+1, Pacific/Fakaofo, Africa/Tripoli, Etc/GMT+0, Israel, Africa/Banjul, Etc/GMT+7, Indian/Comoro, Etc/GMT+6, Etc/GMT+5, Etc/GMT+4, Pacific/Port_Moresby, US/Arizona, Antarctica/Syowa, Indian/Reunion, Pacific/Palau, Europe/Kaliningrad, America/Montevideo, Africa/Windhoek, Asia/Karachi, Africa/Mogadishu, Australia/Perth, Brazil/East, Etc/GMT, Asia/Chita, Pacific/Easter, Antarctica/Davis, Antarctica/McMurdo, Asia/Macao, America/Manaus, Africa/Freetown, Europe/Bucharest, Asia/Tomsk, America/Argentina/Mendoza, Asia/Macau, Europe/Malta, Mexico/BajaSur, Pacific/Tahiti, Africa/Asmera, Europe/Busingen, America/Argentina/Rio_Gallegos, Africa/Malabo, Europe/Skopje, America/Catamarca, America/Godthab, Europe/Sarajevo, Australia/ACT, GB-Eire, Africa/Lagos, America/Cordoba, Europe/Rome, Asia/Dacca, Indian/Mauritius, Pacific/Samoa, America/Regina, America/Fort_Wayne, America/Dawson_Creek, Africa/Algiers, Europe/Mariehamn, America/St_Johns, America/St_Thomas, Europe/Zurich, America/Anguilla, Asia/Dili, America/Denver, Africa/Bamako, Europe/Saratov, GB, Mexico/General, Pacific/Wallis, Europe/Gibraltar, Africa/Conakry, Africa/Lubumbashi, Asia/Istanbul, America/Havana, NZ-CHAT, Asia/Choibalsan, America/Porto_Acre, Asia/Omsk, Europe/Vaduz, US/Michigan, Asia/Dhaka, America/Barbados, Europe/Tiraspol, Atlantic/Cape_Verde, Asia/Yekaterinburg, America/Louisville, Pacific/Johnston, Pacific/Chatham, Europe/Ljubljana, America/Sao_Paulo, Asia/Jayapura, America/Curacao, Asia/Dushanbe, America/Guyana, America/Guayaquil, America/Martinique, Portugal, Europe/Berlin, Europe/Moscow, Europe/Chisinau, America/Puerto_Rico, America/Rankin_Inlet, Pacific/Ponape, Europe/Stockholm, Europe/Budapest, America/Argentina/Jujuy, Australia/Eucla, Asia/Shanghai, Universal, Europe/Zagreb, America/Port_of_Spain, Europe/Helsinki, Asia/Beirut, Asia/Tel_Aviv, Pacific/Bougainville, US/Central, Africa/Sao_Tome, Indian/Chagos, America/Cayenne, Asia/Yakutsk, Pacific/Galapagos, Australia/North, Europe/Paris, Africa/Ndjamena, Pacific/Fiji, America/Rainy_River, Indian/Maldives, Australia/Yancowinna, SystemV/AST4, Asia/Oral, America/Yellowknife, Pacific/Enderbury, America/Juneau, Australia/Victoria, America/Indiana/Vevay, Asia/Tashkent, Asia/Jakarta, Africa/Ceuta, Asia/Barnaul, America/Recife, America/Buenos_Aires, America/Noronha, America/Swift_Current, Australia/Adelaide, America/Metlakatla, Africa/Djibouti, America/Paramaribo, Asia/Qostanay, Europe/Simferopol, Europe/Sofia, Africa/Nouakchott, Europe/Prague, America/Indiana/Vincennes, Antarctica/Mawson, America/Kralendijk, Antarctica/Troll, Europe/Samara, Indian/Christmas, America/Antigua, Pacific/Gambier, America/Indianapolis, America/Inuvik, America/Iqaluit, Pacific/Funafuti, UTC, Antarctica/Macquarie, Canada/Pacific, America/Moncton, Africa/Gaborone, Pacific/Chuuk, Asia/Pyongyang, America/St_Vincent, Asia/Gaza, Etc/Universal, PST8PDT, Atlantic/Faeroe, Asia/Qyzylorda, Canada/Newfoundland, America/Kentucky/Louisville, America/Yakutat, America/Ciudad_Juarez, Asia/Ho_Chi_Minh, Antarctica/Casey, Europe/Copenhagen, Africa/Asmara, Atlantic/Azores, Europe/Vienna, ROK, Pacific/Pitcairn, America/Mazatlan, Australia/Queensland, Pacific/Nauru, Europe/Tirane, Asia/Kolkata, SystemV/MST7, Australia/Canberra, MET, Australia/Broken_Hill, Europe/Riga, America/Dominica, Africa/Abidjan, America/Mendoza, America/Santarem, Kwajalein, America/Asuncion, Asia/Ulan_Bator, NZ, America/Boise, Australia/Currie, EST5EDT, Pacific/Guam, Pacific/Wake, Atlantic/Bermuda, America/Costa_Rica, America/Dawson, Asia/Chongqing, Eire, Europe/Amsterdam, America/Indiana/Knox, America/North_Dakota/Beulah, Africa/Accra, Atlantic/Faroe, Mexico/BajaNorte, America/Maceio, Etc/UCT, Pacific/Apia, GMT0, America/Atka, Pacific/Niue, Australia/Lord_Howe, Europe/Dublin, Pacific/Truk, MST7MDT, America/Monterrey, America/Nassau, America/Jamaica, Asia/Bishkek, America/Atikokan, Atlantic/Stanley, Australia/NSW, US/Hawaii, SystemV/CST6, Indian/Mahe, Asia/Aqtobe, America/Sitka, Asia/Vladivostok, Africa/Libreville, Africa/Maputo, Zulu, America/Kentucky/Monticello, Africa/El_Aaiun, Africa/Ouagadougou, America/Coral_Harbour, Pacific/Marquesas, Brazil/West, America/Aruba, America/North_Dakota/Center, America/Cayman, Asia/Ulaanbaatar, Asia/Baghdad, Europe/San_Marino, America/Indiana/Tell_City, America/Tijuana, Pacific/Saipan, SystemV/YST9, Africa/Douala, America/Chihuahua, America/Ojinaga, Asia/Hovd, America/Anchorage, Chile/EasterIsland, America/Halifax, Antarctica/Rothera, America/Indiana/Indianapolis, US/Mountain, Asia/Damascus, America/Argentina/San_Luis, America/Santiago, Asia/Baku, America/Argentina/Ushuaia, Atlantic/Reykjavik, Africa/Brazzaville, Africa/Porto-Novo, America/La_Paz, Antarctica/DumontDUrville, Asia/Taipei, Antarctica/South_Pole, Asia/Manila, Asia/Bangkok, Africa/Dar_es_Salaam, Poland, Atlantic/Madeira, Antarctica/Palmer, America/Thunder_Bay, Africa/Addis_Ababa, Asia/Yangon, Europe/Uzhgorod, Brazil/DeNoronha, Asia/Ashkhabad, Etc/Zulu, America/Indiana/Marengo, America/Creston, America/Punta_Arenas, America/Mexico_City, Antarctica/Vostok, Asia/Jerusalem, Europe/Andorra, US/Samoa, PRC, Asia/Vientiane, Pacific/Kiritimati, America/Matamoros, America/Blanc-Sablon, Asia/Riyadh, Iceland, Pacific/Pohnpei, Asia/Ujung_Pandang, Atlantic/South_Georgia, Europe/Lisbon, Asia/Harbin, Europe/Oslo, Asia/Novokuznetsk, CST6CDT, Atlantic/Canary, America/Knox_IN, Asia/Kuwait, SystemV/HST10, Pacific/Efate, Africa/Lome, America/Bogota, America/Menominee, America/Adak, Pacific/Norfolk, Europe/Kirov, America/Resolute, Pacific/Kanton, Pacific/Tarawa, Africa/Kampala, Asia/Krasnoyarsk, Greenwich, SystemV/EST5, America/Edmonton, Europe/Podgorica, Australia/South, Canada/Central, Africa/Bujumbura, America/Santo_Domingo, US/Eastern, Europe/Minsk, Pacific/Auckland, Africa/Casablanca, America/Glace_Bay, Canada/Eastern, Asia/Qatar, Europe/Kiev, Singapore, Asia/Magadan, SystemV/PST8, America/Port-au-Prince, Europe/Belfast, America/St_Barthelemy, Asia/Ashgabat, Africa/Luanda, America/Nipigon, Atlantic/Jan_Mayen, Brazil/Acre, Asia/Muscat, Asia/Bahrain, Europe/Vilnius, America/Fortaleza, Etc/GMT0, US/East-Indiana, America/Hermosillo, America/Cancun, Africa/Maseru, Pacific/Kosrae, Africa/Kinshasa, Asia/Kathmandu, Asia/Seoul, Australia/Sydney, America/Lima, Australia/LHI, America/St_Lucia, Europe/Madrid, America/Bahia_Banderas, America/Montserrat, Asia/Brunei, America/Santa_Isabel, Canada/Mountain, America/Cambridge_Bay, Asia/Colombo, Australia/West, Indian/Antananarivo, Australia/Brisbane, Indian/Mayotte, US/Indiana-Starke, Asia/Urumqi, US/Aleutian, Europe/Volgograd, America/Lower_Princes, America/Vancouver, Africa/Blantyre, America/Rio_Branco, America/Danmarkshavn, America/Detroit, America/Thule, Africa/Lusaka, Asia/Hong_Kong, Iran, America/Argentina/La_Rioja, Africa/Dakar, SystemV/CST6CDT, America/Tortola, America/Porto_Velho, Asia/Sakhalin, Etc/GMT+10, America/Scoresbysund, Asia/Kamchatka, Asia/Thimbu, Africa/Harare, Etc/GMT+12, Etc/GMT+11, Navajo, America/Nome, Europe/Tallinn, Turkey, Africa/Khartoum, Africa/Johannesburg, Africa/Bangui, Europe/Belgrade, Jamaica, Africa/Bissau, Asia/Tehran, WET, Europe/Astrakhan, Africa/Juba, America/Campo_Grande, America/Belem, Etc/Greenwich, Asia/Saigon, America/Ensenada, Pacific/Midway, America/Jujuy, Africa/Timbuktu, America/Bahia, America/Goose_Bay, America/Virgin, America/Pangnirtung, Asia/Katmandu, America/Phoenix, Africa/Niamey, America/Whitehorse, Pacific/Noumea, Asia/Tbilisi, Europe/Kyiv, America/Montreal, Asia/Makassar, America/Argentina/San_Juan, Hongkong, UCT, Asia/Nicosia, America/Indiana/Winamac, SystemV/MST7MDT, America/Argentina/ComodRivadavia, America/Boa_Vista, America/Grenada, Asia/Atyrau, Australia/Darwin, Asia/Khandyga, Asia/Kuala_Lumpur, Asia/Famagusta, Asia/Thimphu, Asia/Rangoon, Europe/Bratislava, Asia/Calcutta, America/Argentina/Tucuman, Asia/Kabul, Indian/Cocos, Japan, Pacific/Tongatapu, America/New_York, Etc/GMT-12, Etc/GMT-11, America/Nuuk, Etc/GMT-10, SystemV/YST9YDT, Europe/Ulyanovsk, Etc/GMT-14, Etc/GMT-13, W-SU, America/Merida, EET, America/Rosario, Canada/Saskatchewan, America/St_Kitts, Arctic/Longyearbyen, America/Fort_Nelson, America/Caracas, America/Guadeloupe, Asia/Hebron, Indian/Kerguelen, SystemV/PST8PDT, Africa/Monrovia, Asia/Ust-Nera, Egypt, Asia/Srednekolymsk, America/North_Dakota/New_Salem, Asia/Anadyr, Australia/Melbourne, Asia/Irkutsk, America/Shiprock, America/Winnipeg, Europe/Vatican, Asia/Amman, Etc/UTC, SystemV/AST4ADT, Asia/Tokyo, America/Toronto, Asia/Singapore, Australia/Lindeman, America/Los_Angeles, SystemV/EST5EDT, Pacific/Majuro, America/Argentina/Buenos_Aires, Europe/Nicosia, Pacific/Guadalcanal, Europe/Athens, US/Pacific, Europe/Monaco]
ZoneId zoneId = ZoneId.systemDefault();//Asia/Shanghai
System.out.println(zoneId);
ZoneId marigot = ZoneId.of("America/Marigot");
System.out.println(marigot);//America/Marigot
ZonedDateTime now = ZonedDateTime.now();
ZonedDateTime now1 = ZonedDateTime.now(marigot);
System.out.println(now);//2025-12-27T09:06:55.452+08:00[Asia/Shanghai]
System.out.println(now1);//2025-12-26T21:06:55.452-04:00[America/Marigot]
int year = now.getYear();
ZonedDateTime zonedDateTime = now.plusDays(1);
ZonedDateTime zonedDateTime1 = now.minusDays(1);
DayOfWeek dayOfWeek = now.getDayOfWeek();
System.out.println(year);//2025
System.out.println(zonedDateTime);//2025-12-28T09:06:55.452+08:00[Asia/Shanghai]
System.out.println(zonedDateTime1);//2025-12-26T09:06:55.452+08:00[Asia/Shanghai]
System.out.println(dayOfWeek);//SATURDAY
jdk8中提供的时间类还是很多的，下面将的是Instant类 它是用于替换传统日期类Date的，他获取的是1970年到现在的总秒数以及不足一秒的时候他的纳秒值，
Instant now = Instant.now();
System.out.println(now);
long epochSecond = now.getEpochSecond();
int nano = now.getNano();
System.out.println(epochSecond);
System.out.println(nano);
Instant now1 = Instant.now();
int nano1 = now1.getNano();
//这中间可以做性能分析
System.out.println(nano1-nano);
那么在jdk8中优化的对时间格式化的操作是什么样的呢，有没有更加的方便呢？ jdk8中提供了DateTimeFormatt格式化，一般解析字符串成日期一般都是通过LocalDateTime.parse方法
DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH：mm：ss");
LocalDateTime now = LocalDateTime.now();
String format = dateTimeFormatter.format(now);
System.out.println(format);//2025-12-27
String str = "2099-12-27 12：12：12";
LocalDateTime parse = LocalDateTime.parse(str,dateTimeFormatter);
System.out.println(parse);
在企业的实际开发中经常还会碰到两个日期之间的间隔的计算等，这个时候jdk8有提供相应的类来处理吗？ 答案是有的， 只有你想不到 ， 没有做不到 jdk8中提供了Period类和Duration类，这两个类一般Duration类用的更多因为他可以精确到时间，并且可以实现对LocalTime和LocalDate类型的支持，Period类只支持LocalDate类型的数据类型比较
LocalDate of = LocalDate.of(2025, 12, 8);
LocalDate of1 = LocalDate.of(2026, 8, 7);
Period between = Period.between(of, of1);
System.out.println(between.getYears());//0
System.out.println(between.getMonths());//7
System.out.println(between.getDays());//30
LocalDateTime of2 = LocalDateTime.of(2024, 12, 11, 12, 12);
LocalDateTime of3 = LocalDateTime.of(2025, 12, 11, 11, 11);
Duration between1 = Duration.between(of2, of3);
System.out.println(between1.toDays());//364
