Java LocalDate(), LocalDateTime(), ZonedDateTime(), Calendar() 和 Date() 教程
已发表: 2020-07-18
在 Java 上，我们曾经发布过如何将当前时间转换为纪元时间以及如何计算两个 Java 日期实例之间的差异的教程。
在本教程中，我们将介绍以下所有 Java 日期和日历 API：
本地日期（）：
LocalDate 是一个不可变的日期时间对象，它表示一个日期，通常被视为年-月-日。 也可以访问其他日期字段，例如一年中的某一天、一周中的某一天和一年中的一周。
本地日期时间（）：
LocalDateTime 是一个不可变的日期时间对象，它表示日期时间，通常被视为年-月-日-时-分-秒。
分区日期时间（）：
ZonedDateTime 是具有时区的日期时间的不可变表示。 此类存储所有日期和时间字段，精度为纳秒和时区，区域偏移用于处理不明确的本地日期时间。
日历（）：
Calendar 类是一个抽象类，它提供了在特定时刻和一组日历字段（例如 YEAR、MONTH、DAY_OF_MONTH、HOUR 等）之间进行转换以及操作日历字段（例如获取日期）的方法下周的。 时间的瞬间可以用毫秒值表示，该值是从 1970 年 1 月 1 日 00:00:00.000 GMT（格里高利）纪元的偏移量。
日期（）：
Date 类表示特定的时间瞬间，精度为毫秒。
让我们开始吧：
创建文件：CrunchifyDateTimeCalendarTutorial.java
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 |
package crunchify.com.tutorials; import java.text.ParseException; import java.text.SimpleDateFormat; import java.time.LocalDate; import java.time.LocalDateTime; import java.time.Period; import java.time.ZonedDateTime; import java.time.temporal.ChronoUnit; import java.util.Calendar; import java.util.Date; import java.util.GregorianCalendar; /** * @author Crunchify.com * version: 1.0 * Tutorial: Java LocalDate(), LocalDateTime(), ZonedDateTime(), Calendar() and Date() Tutorial */ public class CrunchifyDateTimeCalendarTutorial { public static void main(String[] args) { // ************************************************ LocalDate ********************************************** // LocalDate is an immutable date-time object that represents a date, often viewed as year-month-day. Other date fields, such as // day-of-year, day-of-week and week-of-year, can also be accessed. For example, the value "2nd October 2007" can be stored in a // LocalDate. crunchifyLog("============ LocalDate test Start ============"); LocalDate currentLocalDate = LocalDate.now(); LocalDate currentLocalNewDate = LocalDate.of(2019, 1, 11); crunchifyLog("LocalDate.now(): " + currentLocalDate); crunchifyLog("LocalDate.of(2019, 1, 11): " + currentLocalNewDate); // Period: A date-based amount of time in the ISO-8601 calendar system, such as '2 years, 3 months and 4 days'. Period period = Period.between(currentLocalDate, currentLocalNewDate); crunchifyLog("Month differences: " + period.getMonths()); if (period.getMonths() <= -3) { crunchifyLog("result: " + currentLocalNewDate + " is older than 3 months!"); } LocalDate currentLocalDateNew = LocalDate.now(); LocalDate threeMonthAgo = LocalDate.now().plusMonths(-3); crunchifyLog("LocalDate.now(): " + currentLocalDateNew); crunchifyLog("LocalDate.now().plusMonths(-3): " + threeMonthAgo); LocalDate crunchifyLocalDate = LocalDate.of(2019, 1, 11); // is this date older than 6 months? if (crunchifyLocalDate.isBefore(threeMonthAgo)) { crunchifyLog("crunchifyLocalDate.isBefore(threeMonthAgo) result: " + crunchifyLocalDate + " is older than 3 months!"); } crunchifyLog("============ LocalDate test End ============ \n"); // ************************************************ LocalDateTime ********************************************** // LocalDateTime is an immutable date-time object that represents a date-time, often viewed as year-month-day-hour-minute-second. // Other date and time fields, such as day-of-year, day-of-week and week-of-year, can also be accessed. Time is represented to // nanosecond precision. For example, the value "2nd October 2007 at 13:45.30.123456789" can be stored in a LocalDateTime. crunchifyLog("============ LocalDateTime test Start ============"); LocalDateTime currentDate2 = LocalDateTime.now(); LocalDateTime fourMonthAgo = LocalDateTime.now().plusMonths(-4); crunchifyLog("LocalDateTime.now(): " + currentLocalDate); crunchifyLog("LocalDateTime.now().plusMonths(-4): " + fourMonthAgo); LocalDateTime newDate2 = LocalDateTime.of(2019, 7, 1, 0, 0, 0); // Checks if this date-time is before the specified date-time. if (newDate2.isBefore(fourMonthAgo)) { crunchifyLog("isBefore() result: " + newDate2 + " is older than 4 months!"); } long findGap = ChronoUnit.MONTHS.between(currentDate2, newDate2); crunchifyLog(findGap); if (findGap <= -4) { crunchifyLog("findGap result: " + newDate2 + " is older than 4 months!"); } crunchifyLog("============ LocalDateTime test End ============ \n"); // ************************************************ ZonedDateTime ********************************************** // ZonedDateTime is an immutable representation of a date-time with a time-zone. This class stores all date and time fields, to a // precision of nanoseconds, and a time-zone, with a zone offset used to handle ambiguous local date-times. For example, the value // "2nd October 2007 at 13:45.30.123456789 +02:00 in the Europe/Paris time-zone" can be stored in a ZonedDateTime. crunchifyLog("============ ZonedDateTime test Start ============"); ZonedDateTime crunchifyNow = ZonedDateTime.now(); ZonedDateTime thirtyDaysAgo = crunchifyNow.plusDays(-30); crunchifyLog("ZonedDateTime.now() :" + crunchifyNow); crunchifyLog("now.plusDays(-30) :" + thirtyDaysAgo); ZonedDateTime fiftyDaysAgo = crunchifyNow.plusDays(-50); crunchifyLog("now.plusDays(-50) :" + fiftyDaysAgo); if (fiftyDaysAgo.isBefore(thirtyDaysAgo)) { crunchifyLog("fiftyDaysAgo.isBefore(thirtyDaysAgo): " + thirtyDaysAgo + " is older than 30 days!"); } // ChronoUnit: A standard set of date periods units. // This set of units provide unit-based access to manipulate a date, time or date-time. The standard set of units can be extended by // implementing TemporalUnit. long crunchifyBetween = ChronoUnit.DAYS.between(crunchifyNow, fiftyDaysAgo); crunchifyLog(crunchifyBetween); if (crunchifyBetween < -30) { crunchifyLog("crunchifyBetween < -30 result: " + thirtyDaysAgo + " is older than 30 days!"); } crunchifyLog("============ ZonedDateTime test End ============ \n"); // ************************************************ Calendar ********************************************** // The Calendar class is an abstract class that provides methods for converting between a specific instant in time and a set of // calendar fields such as YEAR, MONTH, DAY_OF_MONTH, HOUR, and so on, and for manipulating the calendar fields, such as getting the // date of the next week. An instant in time can be represented by a millisecond value that is an offset from the Epoch, January 1, // 1970 00:00:00.000 GMT (Gregorian). crunchifyLog("============ Calendar test Start ============"); SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd"); Calendar fiveMonthsAgo = Calendar.getInstance(); crunchifyLog("Calendar.getInstance(): " + sdf.format(fiveMonthsAgo.getTime())); // Adds or subtracts the specified amount of time to the given calendar field, based on the calendar's rules. fiveMonthsAgo.add(Calendar.MONTH, -5); crunchifyLog("Calendar.MONTH, -5): " + sdf.format(fiveMonthsAgo.getTime())); Calendar crunchifyCalendar = new GregorianCalendar(2019, 7, 11); if (crunchifyCalendar.before(threeMonthAgo)) { crunchifyLog("crunchifyCalendar.before(threeMonthAgo) result : " + sdf.format(crunchifyCalendar.getTime()) + " is older than 5 months"); } crunchifyLog("============ Calendar test End ============ \n"); // ************************************************ Date ********************************************** // Date: The class Date represents a specific instant in time, with millisecond precision. crunchifyLog("============ Date test Start ============"); SimpleDateFormat sdf5 = new SimpleDateFormat("yyyy-MM-dd"); Date crunchifyToday = new Date(); crunchifyLog("new Date(): " + sdf5.format(crunchifyToday)); Calendar twentyDaysAgo = Calendar.getInstance(); twentyDaysAgo.add(Calendar.DAY_OF_MONTH, -20); Date thirtyDaysAgoDate = twentyDaysAgo.getTime(); crunchifyLog("twentyDaysAgo.getTime(): " + sdf5.format(thirtyDaysAgoDate)); Date crunchifyNewDate = null; try { // Parses text from the beginning of the given string to produce a date. The method may not use the entire text of the given string. crunchifyNewDate = sdf5.parse("2019-07-11"); } catch (ParseException e) { e.printStackTrace(); } if (crunchifyNewDate.before(thirtyDaysAgoDate)) { crunchifyLog(sdf.format(crunchifyNewDate) + " is older than 30 days!"); } crunchifyLog("============ Date test End ============ \n"); } private static void crunchifyLog(Object crunchifyString) { System.out.println(crunchifyString); } } |
只需在 IntelliJ IDEA 中运行它：
控制台输出。
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 |
/ Library / Java / JavaVirtualMachines / jdk - 13.0.1.jdk / Contents / Home / bin / java - javaagent : / Applications / IntelliJ IDEA . app / Contents / lib / idea_rt . jar = 50895 : / Applications / IntelliJ IDEA . app / Contents / bin - Dfile . encoding = UTF - 8 - classpath / Users / crunchify / Documents / C / crunchify - github / CrunchifyTutorials / target / classes : / Users / crunchify / Documents / C / crunchify - github / CrunchifyTutorials / WebContent / WEB - INF / lib / zxing - 2.1.jar : / Users / crunchify / Documents / C / crunchify - github / CrunchifyTutorials / WebContent / WEB - INF / lib / commons - logging - 1.1.2.jar : / Users / crunchify / Documents / C / crunchify - github / CrunchifyTutorials / WebContent / WEB - INF / lib / commons - collections - 3.2.1.jar : / Users / crunchify / Documents / C / crunchify - github / CrunchifyTutorials / WebContent / WEB - INF / lib / javax . mail . jar : / Users / crunchify / Documents / C / crunchify - github / CrunchifyTutorials / WebContent / WEB - INF / lib / commons - io - 2.4.jar : / Users / crunchify / Documents / C / crunchify - github / CrunchifyTutorials / WebContent / WEB - INF / lib / commons - lang - 2.6.jar : / Users / crunchify / Documents / C / crunchify - github / CrunchifyTutorials / WebContent / WEB - INF / lib / commons - configuration - 1.9.jar : / Users / crunchify / Documents / C / crunchify - github / CrunchifyTutorials / WebContent / WEB - INF / lib / log4j - 1.2.17.jar : / Users / crunchify / Documents / C / crunchify - github / CrunchifyTutorials / WebContent / WEB - INF / lib / commons - beanutils - 1.8.3.jar : / Users / crunchify / . m2 / repository / org / glassfish / javax . json / 1.0.4 / javax . json - 1.0.4.jar : / Users / crunchify / . m2 / repository / com / github / wnameless / json - flattener / 0.2.2 / json - flattener - 0.2.2.jar : / Users / crunchify / . m2 / repository / com / eclipsesource / minimal - json / minimal - json / 0.9.4 / minimal - json - 0.9.4.jar : / Users / crunchify / . m2 / repository / org / apache / commons / commons - lang3 / 3.4 / commons - lang3 - 3.4.jar : / Users / crunchify / . m2 / repository / com / google / code / gson / gson / 2.8.0 / gson - 2.8.0.jar : / Users / crunchify / . m2 / repository / net / jodah / expiringmap / 0.5.7 / expiringmap - 0.5.7.jar : / Users / crunchify / . m2 / repository / org / apache / httpcomponents / httpclient / 4.3.6 / httpclient - 4.3.6.jar : / Users / crunchify / . m2 / repository / org / apache / httpcomponents / httpcore / 4.3.3 / httpcore - 4.3.3.jar : / Users / crunchify / . m2 / repository / commons - codec / commons - codec / 1.6 / commons - codec - 1.6.jar : / Users / crunchify / . m2 / repository / org / json / json / 20151123 / json - 20151123.jar : / Users / crunchify / . m2 / repository / net / spy / spymemcached / 2.12.3 / spymemcached - 2.12.3.jar : / Users / crunchify / . m2 / repository / com / whalin / Memcached - Java - Client / 3.0.2 / Memcached - Java - Client - 3.0.2.jar : / Users / crunchify / . m2 / repository / commons - pool / commons - pool / 1.5.6 / commons - pool - 1.5.6.jar : / Users / crunchify / . m2 / repository / org / slf4j / slf4j - api / 1.6.4 / slf4j - api - 1.6.4.jar : / Users / crunchify / . m2 / repository / com / googlecode / xmemcached / xmemcached / 2.4.5 / xmemcached - 2.4.5.jar : / Users / crunchify / . m2 / repository / com / paypal / sdk / rest - api - sdk / 1.14.0 / rest - api - sdk - 1.14.0.jar : / Users / crunchify / . m2 / repository / commons - dbcp / commons - dbcp / 20030825.184428 / commons - dbcp - 20030825.184428.jar : / Users / crunchify / . m2 / repository / javax / ws / rs / javax . ws . rs - api / 2.0 / javax . ws . rs - api - 2.0.jar : / Users / crunchify / . m2 / repository / org / hamcrest / hamcrest - all / 1.3 / hamcrest - all - 1.3.jar : / Users / crunchify / . m2 / repository / log4j / log4j / 1.2.17 / log4j - 1.2.17.jar : / Users / crunchify / . m2 / repository / com / google / guava / guava / 19.0 / guava - 19.0.jar : / Users / crunchify / . m2 / repository / com / googlecode / json - simple / json - simple / 1.1 / json - simple - 1.1.jar : / Users / crunchify / . m2 / repository / commons - net / commons - net / 2.0 / commons - net - 2.0.jar : / Users / crunchify / . m2 / repository / asm / asm / 3.3.1 / asm - 3.3.1.jar : / Users / crunchify / . m2 / repository / axis / axis / 1.4 / axis - 1.4.jar : / Users / crunchify / . m2 / repository / org / apache / axis / axis - jaxrpc / 1.4 / axis - jaxrpc - 1.4.jar : / Users / crunchify / . m2 / repository / axis / axis - wsdl4j / 1.5.1 / axis - wsdl4j - 1.5.1.jar : / Users / crunchify / . m2 / repository / commons - beanutils / commons - beanutils / 1.8.3 / commons - beanutils - 1.8.3.jar : / Users / crunchify / . m2 / repository / commons - collections / commons - collections / 3.2.1 / commons - collections - 3.2.1.jar : / Users / crunchify / . m2 / repository / commons - configuration / commons - configuration / 1.10 / commons - configuration - 1.10.jar : / Users / crunchify / . m2 / repository / commons - io / commons - io / 2.4 / commons - io - 2.4.jar : / Users / crunchify / . m2 / repository / commons - discovery / commons - discovery / 0.5 / commons - discovery - 0.5.jar : / Users / crunchify / . m2 / repository / commons - lang / commons - lang / 2.6 / commons - lang - 2.6.jar : / Users / crunchify / . m2 / repository / commons - logging / commons - logging / 1.1.3 / commons - logging - 1.1.3.jar : / Users / crunchify / . m2 / repository / commons - logging / commons - logging - api / 1.1 / commons - logging - api - 1.1.jar : / Users / crunchify / . m2 / repository / javax / mail / mail / 1.4.7 / mail - 1.4.7.jar : / Users / crunchify / . m2 / repository / javax / activation / activation / 1.1 / activation - 1.1.jar : / Users / crunchify / . m2 / repository / javax / xml / jaxrpc - api / 1.1 / jaxrpc - api - 1.1.jar : / Users / crunchify / . m2 / repository / javax / servlet / javax . servlet - api / 3.1.0 / javax . servlet - api - 3.1.0.jar : / Users / crunchify / . m2 / repository / org / apache / axis / axis - saaj / 1.4 / axis - saaj - 1.4.jar : / Users / crunchify / . m2 / repository / wsdl4j / wsdl4j / 1.6.3 / wsdl4j - 1.6.3.jar : / Users / crunchify / . m2 / repository / com / google / zxing / core / 3.2.1 / core - 3.2.1.jar : / Users / crunchify / . m2 / repository / org / apache / commons / commons - compress / 1.9 / commons - compress - 1.9.jar : / Users / crunchify / . m2 / repository / mysql / mysql - connector - java / 5.1.6 / mysql - connector - java - 5.1.6.jar : / Users / crunchify / . m2 / repository / junit / junit / 4.12 / junit - 4.12.jar : / Users / crunchify / . m2 / repository / org / hamcrest / hamcrest - core / 1.3 / hamcrest - core - 1.3.jar : / Users / crunchify / . m2 / repository / ch / qos / logback / logback - classic / 1.2.3 / logback - classic - 1.2.3.jar : / Users / crunchify / . m2 / repository / ch / qos / logback / logback - core / 1.2.3 / logback - core - 1.2.3.jar : / Users / crunchify / . m2 / repository / org / springframework / spring - context / 5.1.3.RELEASE / spring - context - 5.1.3.RELEASE.jar : / Users / crunchify / . m2 / repository / org / springframework / spring - aop / 5.1.3.RELEASE / spring - aop - 5.1.3.RELEASE.jar : / Users / crunchify / . m2 / repository / org / springframework / spring - beans / 5.1.3.RELEASE / spring - beans - 5.1.3.RELEASE.jar : / Users / crunchify / . m2 / repository / org / springframework / spring - core / 5.1.3.RELEASE / spring - core - 5.1.3.RELEASE.jar : / Users / crunchify / . m2 / repository / org / springframework / spring - jcl / 5.1.3.RELEASE / spring - jcl - 5.1.3.RELEASE.jar : / Users / crunchify / . m2 / repository / org / springframework / spring - expression / 5.1.3.RELEASE / spring - expression - 5.1.3.RELEASE.jar : / Users / crunchify / . m2 / repository / org / springframework / spring - context - support / 5.1.3.RELEASE / spring - context - support - 5.1.3.RELEASE.jar crunchify . com . tutorials . CrunchifyDateTimeCalendarTutorial ============ LocalDate test Start ============ LocalDate . now ( ) : 2020 - 07 - 18 LocalDate . of ( 2019 , 1 , 11 ) : 2019 - 01 - 11 Month differences : - 6 result : 2019 - 01 - 11 is older than 3 months ! LocalDate . now ( ) : 2020 - 07 - 18 LocalDate . now ( ) . plusMonths ( - 3 ) : 2020 - 04 - 18 crunchifyLocalDate . isBefore ( threeMonthAgo ) result : 2019 - 01 - 11 is older than 3 months ! ============ LocalDate test End ============ ============ LocalDateTime test Start ============ LocalDateTime . now ( ) : 2020 - 07 - 18 LocalDateTime . now ( ) . plusMonths ( - 4 ) : 2020 - 03 - 18T10 : 27 : 28.285711 isBefore ( ) result : 2019 - 07 - 01T00 : 00 is older than 4 months ! - 12 findGap result : 2019 - 07 - 01T00 : 00 is older than 4 months ! ============ LocalDateTime test End ============ ============ ZonedDateTime test Start ============ ZonedDateTime . now ( ) : 2020 - 07 - 18T10 : 27 : 28.286147 - 05 : 00 [ America / Chicago ] now . plusDays ( - 30 ) : 2020 - 06 - 18T10 : 27 : 28.286147 - 05 : 00 [ America / Chicago ] now . plusDays ( - 50 ) : 2020 - 05 - 29T10 : 27 : 28.286147 - 05 : 00 [ America / Chicago ] fiftyDaysAgo . isBefore ( thirtyDaysAgo ) : 2020 - 06 - 18T10 : 27 : 28.286147 - 05 : 00 [ America / Chicago ] is older than 30 days ! - 50 crunchifyBetween < - 30 result : 2020 - 06 - 18T10 : 27 : 28.286147 - 05 : 00 [ America / Chicago ] is older than 30 days ! ============ ZonedDateTime test End ============ ============ Calendar test Start ============ Calendar . getInstance ( ) : 2020 - 07 - 18 Calendar . MONTH , - 5 ) : 2020 - 02 - 18 ============ Calendar test End ============ ============ Date test Start ============ new Date ( ) : 2020 - 07 - 18 twentyDaysAgo . getTime ( ) : 2020 - 06 - 28 2019 - 07 - 11 is older than 30 days ! ============ Date test End ============ Process finished with exit code 0 |
我希望本教程可以帮助您利用所有这些日期和时间 API。