1 Date Time API
因为之前的日期时间 API 存在诸多问题，Java 8通过发布新的Date-Time API (JSR 310)来进一步加强对日期与时间的处理，最常用的几个类是：
1.LocalTime:用来操作时间的，如”18:24:44.488”(18点24分44秒488毫秒)
2.LocalDate:用来操作日期的，如”2016-06-12”(2016年6月12日)
3.LocalDateTime:用来操作日期和时间的，如”2018-07-29T18:24:44.488”(2018年7月29日 18点24分44秒488毫秒)
2 案例
因为并不复杂，主要是知道怎么用即可，所以直接贴练习案例了；
主要涉及：时间、日期、时区、转换和格式化：
//main方法
public static void main(String[] args) {
//1 本地时间
localTime();
//2 本地日期
localDate();
//3 本地日期时间
localDateTime();
//4 时区日期时间
zonedDateTime();
//5 操作两个日期
period();
//6 操作两个时间
duration();
//7 Date Canlder的转换
toInstant();
//8 格式化
formatting();
}
– –1 localTime() – –
/**
* The LocalTime represents time without a date.
*/
public static void localTime() {
//An instance of current LocalTime can be created from the system clock
LocalTime localTime = LocalTime.now();
System.out.println("localTime: " + localTime);
//create a LocalTime representing 06:30 AM by parsing a string representation
LocalTime sixThirty = LocalTime.parse("06:30");
System.out.println("sixThirty: " + sixThirty);
//The Factory method “of” can be used to create a LocalTime
LocalTime sixThirty1 = LocalTime.of(6, 30);
System.out.println("sixThirty1: " + sixThirty1);
//creates a LocalTime by parsing a string and adds an hour to it by using the “plus” API
LocalTime sevenThirty = LocalTime.parse("06:30").plus(1, ChronoUnit.HOURS);
System.out.println("sevenThirty: " + sevenThirty);
//Various getter methods are available which can be used to get specific units of time like hour
int currentHour = LocalTime.parse("06:30").getHour();
System.out.println("currentHour: " + currentHour);
//check if a specific time is before or after another specific time
boolean isbefore = LocalTime.parse("06:30").isBefore(LocalTime.parse("07:30"));
System.out.println("currentHour: " + currentHour);
//The max, min and noon time of a day can be obtained by constants in LocalTime class
LocalTime maxTime = LocalTime.MAX;
System.out.println("maxTime: " + maxTime);
}localTime()执行结果：
----------------localTime()------------------
localTime: 18:49:07.315
sixThirty: 06:30
sixThirty1: 06:30
sevenThirty: 07:30
currentHour: 6
currentHour: 6
maxTime: 23:59:59.999999999
– –2 localDate() – –
/**
* The LocalDate represents a date in ISO format (yyyy-MM-dd) without time.
*/
public static void localDate() {
//LocalDate final类型 一旦赋值不可改变
LocalDate localDate = LocalDate.now();
System.out.println("localDate: " + localDate);
//进行一次重新赋值 未报错 但值也未改变
localDate.of(2008, 8, 8);
System.out.println("localDate: " + localDate);
//获取一个日期 方式一
LocalDate localDate1 = LocalDate.of(2008, 8, 8);
System.out.println("localDate1: " + localDate1);
//获取一个日期 方式二
LocalDate localDate2 = LocalDate.parse("2008-08-09");
System.out.println("localDate2: " + localDate2);
//获取明天日期
LocalDate tomorrow = LocalDate.now().plusDays(1);
System.out.println("tomorrow: " + tomorrow);
//获得当前减去一个月的日期(它接受一个枚举时间单位)
LocalDate previousMonthSameDay = LocalDate.now().minus(1, ChronoUnit.MONTHS);
System.out.println("previousMonthSameDay: " + previousMonthSameDay);
//得到一个日期并获取其是一周中的周几
DayOfWeek saturday = LocalDate.parse("2018-07-28").getDayOfWeek();
System.out.println("saturday: " + saturday);
//得到一个日期并获取其是一个月中的哪一天
int twelve = LocalDate.parse("2018-07-28").getDayOfMonth();
System.out.println("twelve: " + twelve);
//当前年份是否是闰年
boolean leapYear = LocalDate.now().isLeapYear();
System.out.println("leapYear: " + leapYear);
//两个时间的关联关系
boolean notBefore = LocalDate.parse("2016-06-12").isBefore(LocalDate.now());
System.out.println("2016-06-12 notBefore: " + notBefore);
boolean isAfter = LocalDate.parse("2016-06-12").isAfter(LocalDate.now());
System.out.println("2016-06-12 isAfter: " + isAfter);
//时间边界 获取某个日期的起始时间 如(2016-06-12 00:00:00)
LocalDateTime beginningOfDay = LocalDate.parse("2016-06-12").atStartOfDay();
System.out.println("beginningOfDay: " + beginningOfDay);
//时间边界 获取某个日期的当月的起始天 如(2016-06-12的那个月第一天是2016-06-01)
LocalDate firstDayOfMonth = LocalDate.parse("2016-06-12").with(TemporalAdjusters.firstDayOfMonth());
System.out.println("firstDayOfMonth: " + firstDayOfMonth);
}
localDate()执行结果：
----------------localDate()------------------
localDate: 2018-07-29
localDate: 2018-07-29
localDate1: 2008-08-08
localDate2: 2008-08-09
tomorrow: 2018-07-30
previousMonthSameDay: 2018-06-29
saturday: SATURDAY
twelve: 28
leapYear: false
2016-06-12 notBefore: true
2016-06-12 isAfter: false
beginningOfDay: 2016-06-12T00:00
firstDayOfMonth: 2016-06-01
– –3 localDateTime() – –
/**
* The LocalDateTime is used to represent a combination of date and time.
*/
public static void localDateTime() {
// LocalDateTime can be obtained from the system clock similar to LocalDate and LocalTime
LocalDateTime localDateTime = LocalDateTime.now();
System.out.println("localDateTime: " + localDateTime);
//create an instance using the factory “of” and “parse” methods
LocalDateTime localDateTime1 = LocalDateTime.of(2015, Month.FEBRUARY, 20, 06, 30);
System.out.println("localDateTime1: " + localDateTime1);
LocalDateTime localDateTime2 = LocalDateTime.parse("2015-02-20T06:30:00");
System.out.println("localDateTime2: " + localDateTime2);
//the usage of “plus” and “minus” methods
LocalDateTime localDateTimeplusOneDay = localDateTime.plusDays(1);
System.out.println("localDateTimeplusOneDay: " + localDateTimeplusOneDay);
LocalDateTime localDateTimeMinusTwoHours = localDateTime.minusHours(2);
System.out.println("localDateTimeMinusTwoHours: " + localDateTimeMinusTwoHours);
//LocalDateTime reset
LocalDateTime localDateTimeReset = localDateTime.withDayOfMonth(10).withYear(2012);
System.out.println("localDateTimeReset: " + localDateTimeReset);
//LocalDateTime get month,day and seconds
Month month = localDateTime.getMonth();
int day = localDateTime.getDayOfMonth();
int seconds = localDateTime.getSecond();
System.out.println("Month: [" + month + "] day: [" + day + "] seconds: [" + seconds + "]");
//get LocalDate from LocalDateTime
LocalDate toLocalDate = localDateTime.toLocalDate();
System.out.println("toLocalDate: " + toLocalDate);
//get LocalTime from LocalDateTime
LocalTime toLocalTime = localDateTime.toLocalTime();
System.out.println("toLocalTime: " + toLocalTime);
}localDateTime()执行结果：
----------------localDateTime()------------------
localDateTime: 2018-07-29T18:49:07.350
localDateTime1: 2015-02-20T06:30
localDateTime2: 2015-02-20T06:30
localDateTimeplusOneDay: 2018-07-30T18:49:07.350
localDateTimeMinusTwoHours: 2018-07-29T16:49:07.350
localDateTimeReset: 2012-07-10T18:49:07.350
Month: [JULY] day: [29] seconds: [7]
toLocalDate: 2018-07-29
toLocalTime: 18:49:07.350
– –4 zonedDateTime() – –
/**
* Java 8 provides ZonedDateTime when we need to deal with time zone specific date and time.
* The ZoneId is an identifier used to represent different zones. There are about 40 different time zones.
*/
public static void zonedDateTime() {
//Create a Zone for Tokyo
ZoneId tokyoZoneId = ZoneId.of("Asia/Tokyo");
System.out.println("tokyoZoneId: " + tokyoZoneId);
//A set of all zone ids can be obtained
Set<String> allZoneIds = ZoneId.getAvailableZoneIds();
System.out.println("allZoneIds: " + allZoneIds);
// Get the current date and time
ZonedDateTime zonedDateTime = ZonedDateTime.parse("2012-12-12T10:15:30+05:30[Asia/Tokyo]");
System.out.println("zonedDateTime: " + zonedDateTime);
//The LocalDateTime can be converted to a specific zone
LocalDateTime localDateTime = LocalDateTime.now();
ZonedDateTime tokyoZonedDateTime = ZonedDateTime.of(localDateTime, tokyoZoneId);
System.out.println("tokyoZonedDateTime: " + tokyoZonedDateTime);
//Get currentZone
ZoneId currentZone = ZoneId.systemDefault();
System.out.println("currentZone: " + currentZone);
//The ZonedDateTime provides parse method to get time zone specific date time
ZonedDateTime parseZonedDateTime = ZonedDateTime.parse("2015-05-03T10:15:30+01:00[Asia/Tokyo]");
System.out.println("parseZonedDateTime: " + parseZonedDateTime);
//获取一个固定(2小时)偏移量(相对于格林尼治时间)的时间
ZoneOffset offset = ZoneOffset.of("+02:00");
OffsetDateTime offSetByTwo = OffsetDateTime.of(localDateTime, offset);
System.out.println("localDateTime: " + localDateTime + " and offSetByTwo: " + offSetByTwo);
}zonedDateTime()执行结果：
----------------zonedDateTime()------------------
tokyoZoneId: Asia/Tokyo
allZoneIds: [Asia/Aden, America/Cuiaba, Etc/GMT+9, Etc/GMT+8, Africa/Nairobi...]
zonedDateTime: 2012-12-12T10:15:30+09:00[Asia/Tokyo]
tokyoZonedDateTime: 2018-07-29T18:49:07.370+09:00[Asia/Tokyo]
currentZone: Asia/Shanghai
parseZonedDateTime: 2015-05-03T10:15:30+09:00[Asia/Tokyo]
localDateTime: 2018-07-29T18:49:07.370 and offSetByTwo: 2018-07-29T18:49:07.370+02:00
– –5 period() – –
/**
* The Period class is widely used to modify values of given a date
* or to obtain the difference between two dates.
*/
public static void period() {
//Get a initialDate
LocalDate initialDate = LocalDate.parse("2018-05-10");
System.out.println("initialDate: " + initialDate);
//The Date can be manipulated using Period as shown in the following code snippet.
LocalDate finalDate = initialDate.plus(Period.ofDays(5));
System.out.println("finalDate: " + finalDate);
//The Period class has various getter methods such as getYears,
// getMonths and getDays to get values from a Period object
int betweenTwoDate = Period.between(finalDate, initialDate).getDays();
System.out.println("betweenTwoDate: " + betweenTwoDate);
//The Period between two dates can be obtained in a specific unit such as days or month or years,
// using ChronoUnit.between
Long intervalDays = ChronoUnit.DAYS.between(initialDate, finalDate);
Long intervalMonths = ChronoUnit.MONTHS.between(initialDate, finalDate);
System.out.println("intervalDays: " + intervalDays + ", intervalMonths: " + intervalMonths);
}period()执行结果：
----------------period()------------------
initialDate: 2018-05-10
finalDate: 2018-05-15
betweenTwoDate: -5
intervalDays: 5, intervalMonths: 0
– –6 duration() – –
/**
* the Duration class is use to deal with Time.
*/
public static void duration() {
//Get a initialTime
LocalTime initialTime = LocalTime.of(6, 30, 0);
System.out.println("initialTime: " + initialTime);
//Add a duration of 30 seconds to make a LocalTime of 06:30:30am
LocalTime finalTime = initialTime.plus(Duration.ofSeconds(30));
System.out.println("finalTime: " + finalTime);
//The Duration between two instants can be obtained either as a Duration or as a specific unit
Long intervalSeconds = Duration.between(finalTime, initialTime).getSeconds();
System.out.println("intervalSeconds: " + intervalSeconds);
//Use the between() method of the ChronoUnit class
Long intervalSeconds1 = ChronoUnit.SECONDS.between(finalTime, initialTime);
System.out.println("intervalSeconds1: " + intervalSeconds1);
}duration()执行结果：
----------------duration()------------------
initialTime: 06:30
finalTime: 06:30:30
intervalSeconds: -30
intervalSeconds1: -30
– –7 toInstant() – –
/**
* the toInstant() method which helps to convert existing Date and Calendar instance to new Date Time API
*/
public static void toInstant() {
//Date transform to LocalDateTime
LocalDateTime localDateTime = LocalDateTime.ofInstant(new Date().toInstant(), ZoneId.systemDefault());
System.out.println("localDateTime: " + localDateTime);
//Calendar transform to LocalDateTime
LocalDateTime localDateTime1 = LocalDateTime.ofInstant(Calendar.getInstance().toInstant(), ZoneId.systemDefault());
System.out.println("localDateTime1: " + localDateTime1);
//The LocalDateTime can be constructed from epoch seconds as below
//The result of the below code would be a LocalDateTime representing 2016-06-13T11:34:50
LocalDateTime localDateTime2 = LocalDateTime.ofEpochSecond(1465817690, 0, ZoneOffset.UTC);
System.out.println("localDateTime2: " + localDateTime2);
}toInstant()执行结果：
----------------toInstant()------------------
localDateTime: 2018-07-29T18:49:07.373
localDateTime1: 2018-07-29T18:49:07.377
localDateTime2: 2016-06-13T11:34:50
– –8 formatting() – –
/**
* the easy formatting of Date and Time
*/
public static void formatting() {
//Get the LocalDateTime
LocalDateTime localDateTime = LocalDateTime.of(2015, Month.JANUARY, 25, 6, 30);
//标准格式化
String localDateFormat = localDateTime.format(DateTimeFormatter.ISO_DATE);
System.out.println("localDateFormat: " + localDateFormat);
//格式化成yyyy/MM/dd
String localDateFormat1 = localDateTime.format(DateTimeFormatter.ofPattern("yyyy/MM/dd"));
System.out.println("localDateFormat1: " + localDateFormat1);
//格式化成SIMPLIFIED_CHINESE
String localDateFormat2 = localDateTime.format(DateTimeFormatter.ofLocalizedDateTime(FormatStyle.MEDIUM).withLocale(Locale.CHINA));
System.out.println("localDateFormat2: " + localDateFormat2);
}formatting()执行结果：
----------------formatting()------------------
localDateFormat: 2015-01-25
localDateFormat1: 2015/01/25
localDateFormat2: 2015-1-25 6:30:00
涉及代码：–>GitHub
参考文献：
[1] http://www.baeldung.com/java-8-date-time-intro
[2] https://www.tutorialspoint.com/java8/java8_datetime_api.htm
[3] https://docs.oracle.com/javase/7/docs/api/java/util/Date.html
[4] https://java2blog.com/java-8-tutorial/