Java 8 | 时间操作示例

今天全是代码，不多说了。摘抄自 Github

public class Java8DateTimeExamples {

    // This class shows the usage of the Java 8 date/time API
    // For more information have a look at this blog post:
    // http://www.mscharhag.com/2014/02/java-8-datetime-api.html

    private static void dateTimes() {
        // dates, e.g. 2014-02-18

        // the current date
        LocalDate currentDate = LocalDate.now();

        // 2014-02-10
        LocalDate tenthFeb2014 = LocalDate.of(2014, Month.FEBRUARY, 10);

        // months values start at 1 (2014-08-01)
        LocalDate firstAug2014 = LocalDate.of(2014, 8, 1);

        // the 65th day of 2010 (2010-03-06)
        LocalDate sixtyFifthDayOf2010 = LocalDate.ofYearDay(2010, 65);


        // times, e.g. 19:12:30.733

        LocalTime currentTime = LocalTime.now(); // current time
        LocalTime midday = LocalTime.of(12, 0); // 12:00
        LocalTime afterMidday = LocalTime.of(13, 30, 15); // 13:30:15

        // 12345th second of day (03:25:45)
        LocalTime fromSecondsOfDay = LocalTime.ofSecondOfDay(12345);

        // dates with times, e.g. 2014-02-18T19:08:37.950
        LocalDateTime currentDateTime = LocalDateTime.now();

        // 2014-10-02 12:30
        LocalDateTime secondAug2014 = LocalDateTime.of(2014, 10, 2, 12, 30);

        // 2014-12-24 12:00
        LocalDateTime christmas2014 = LocalDateTime.of(2014, Month.DECEMBER, 24, 12, 0);


        // By default LocalDate and LocalTime will use the system clock in the default time zone
        // We can change this by providing a timezone or an alternative clock implementation

        // current (local) time in Los Angeles
        LocalTime currentTimeInLosAngeles = LocalTime.now(ZoneId.of("America/Los_Angeles"));

        // current time in UTC time zone
        LocalTime nowInUtc = LocalTime.now(Clock.systemUTC());


        System.out.println("date/time creation: currentDate: " + currentDate);
        System.out.println("date/time creation: tenthFeb2014: " + tenthFeb2014);
        System.out.println("date/time creation: firstAug2014: " + firstAug2014);
        System.out.println("date/time creation: sixtyFifthDayOf2010: " + sixtyFifthDayOf2010);
        System.out.println("date/time creation: currentTime: " + currentTime);
        System.out.println("date/time creation: midday: " + midday);
        System.out.println("date/time creation: afterMidday: " + afterMidday);
        System.out.println("date/time creation: fromSecondsOfDay: " + fromSecondsOfDay);
        System.out.println("date/time creation: currentTimeInLosAngeles: " + currentTimeInLosAngeles);
        System.out.println("date/time creation: currentDateTime: " + currentDateTime);
        System.out.println("date/time creation: secondAug2014: " + secondAug2014);
        System.out.println("date/time creation: christmas2014: " + christmas2014);
    }



    private static void dateTimeInformation() {
        LocalDate date = LocalDate.of(2014, 2, 15); // 2014-06-15

        boolean isBefore = LocalDate.now().isBefore(date); // false

        // information about the month
        Month february = date.getMonth(); // FEBRUARY
        int februaryIntValue = february.getValue(); // 2
        int minLength = february.minLength(); // 28
        int maxLength = february.maxLength(); // 29
        Month firstMonthOfQuarter = february.firstMonthOfQuarter(); // JANUARY

        // information about the year
        int year = date.getYear(); // 2014
        int dayOfYear = date.getDayOfYear(); // 46
        int lengthOfYear = date.lengthOfYear(); // 365
        boolean isLeapYear = date.isLeapYear(); // false

        DayOfWeek dayOfWeek = date.getDayOfWeek();
        int dayOfWeekIntValue = dayOfWeek.getValue(); // 6
        String dayOfWeekName = dayOfWeek.name(); // SATURDAY

        int dayOfMonth = date.getDayOfMonth(); // 15
        LocalDateTime startOfDay = date.atStartOfDay(); // 2014-02-15T00:00

        // time information
        LocalTime time = LocalTime.of(15, 30); // 15:30:00
        int hour = time.getHour(); // 15
        int second = time.getSecond(); // 0
        int minute = time.getMinute(); // 30
        int secondOfDay = time.toSecondOfDay(); // 55800

        System.out.println("dateTimeInformation: february: " + february);
        System.out.println("dateTimeInformation: februaryIntValue: " + februaryIntValue);
        System.out.println("dateTimeInformation: firstMonthOfQuarter: " + firstMonthOfQuarter);
        System.out.println("dateTimeInformation: minLength: " + minLength);
        System.out.println("dateTimeInformation: maxLength: " + maxLength);
        System.out.println("dateTimeInformation: year: " + year);
        System.out.println("dateTimeInformation: dayOfYear: " + dayOfYear);
        System.out.println("dateTimeInformation: lengthOfYear: " + lengthOfYear);
        System.out.println("dateTimeInformation: isLeapYear: " + isLeapYear);
        System.out.println("dateTimeInformation: dayOfWeekName: " + dayOfWeekName);
        System.out.println("dateTimeInformation: dayOfWeekIntValue: " + dayOfWeekIntValue);
        System.out.println("dateTimeInformation: dayOfMonth: " + dayOfMonth);
        System.out.println("dateTimeInformation: startOfDay: " + startOfDay);
        System.out.println("dateTimeInformation: hour: " + hour);
        System.out.println("dateTimeInformation: second: " + second);
        System.out.println("dateTimeInformation: minute: " + minute);
        System.out.println("dateTimeInformation: secondOfDay: " + secondOfDay);
        System.out.println("dateTimeInformation: isBefore: " + isBefore);
    }


    private static void year() {
        Year currentYear = Year.now();
        Year twoThousand = Year.of(2000);
        boolean isLeap = currentYear.isLeap(); // false
        int length = currentYear.length(); // 365

        // sixtyFourth day of 2014 (2014-03-05)
        LocalDate date = Year.of(2014).atDay(64);

        System.out.println("year: currentYear: " + currentYear);
        System.out.println("year: twoThousand: " + twoThousand);
        System.out.println("year: isLeap: " + isLeap);
        System.out.println("year: length: " + length);
        System.out.println("year: date: " + date);
    }


    private static void periodsAndDurations() {

        // periods

        LocalDate firstDate = LocalDate.of(2010, 5, 17); // 2010-05-17
        LocalDate secondDate = LocalDate.of(2015, 3, 7); // 2015-03-07
        Period period = Period.between(firstDate, secondDate);

        int days = period.getDays(); // 18
        int months = period.getMonths(); // 9
        int years = period.getYears(); // 4
        boolean isNegative = period.isNegative(); // false

        Period twoMonthsAndFiveDays = Period.ofMonths(2).plusDays(5);
        LocalDate sixthOfJanuary = LocalDate.of(2014, 1, 6);

        // add two months and five days to 2014-01-06, result is 2014-03-11
        LocalDate eleventhOfMarch = sixthOfJanuary.plus(twoMonthsAndFiveDays);


        // durations

        Instant firstInstant= Instant.ofEpochSecond( 1294881180 ); // 2011-01-13 01:13
        Instant secondInstant = Instant.ofEpochSecond(1294708260); // 2011-01-11 01:11

        Duration between = Duration.between(firstInstant, secondInstant);

        // negative because firstInstant is after secondInstant (-172920)
        long seconds = between.getSeconds();

        // get absolute result in minutes (2882)
        long absoluteResult = between.abs().toMinutes();

        // two hours in seconds (7200)
        long twoHoursInSeconds = Duration.ofHours(2).getSeconds();

        System.out.println("periodsAndDurations: days: " + days);
        System.out.println("periodsAndDurations: months: " + months);
        System.out.println("periodsAndDurations: years: " + years);
        System.out.println("periodsAndDurations: isNegative: " + isNegative);
        System.out.println("periodsAndDurations: eleventhOfMarch: " + eleventhOfMarch);
        System.out.println("periodsAndDurations: seconds: " + seconds);
        System.out.println("periodsAndDurations: absoluteResult: " + absoluteResult);
        System.out.println("periodsAndDurations: twoHoursInSeconds: " + twoHoursInSeconds);
    }


    private static void additionSubtraction() {
        LocalDate tomorrow = LocalDate.now().plusDays(1);

        // before 5 houres and 30 minutes
        LocalDateTime dateTime = LocalDateTime.now().minusHours(5).minusMinutes(30);

        System.out.println("additionSubtraction: tomorrow: " + tomorrow);
        System.out.println("additionSubtraction: dateTime: " + dateTime);
    }


    private static void parsingFormatting() {
        // 2014-04-01 10:45
        LocalDateTime dateTime = LocalDateTime.of(2014, Month.APRIL, 1, 10, 45);

        // format as basic ISO date format (20140220)
        String asBasicIsoDate = dateTime.format(DateTimeFormatter.BASIC_ISO_DATE);

        // format as ISO week date (2014-W08-4)
        String asIsoWeekDate = dateTime.format(DateTimeFormatter.ISO_WEEK_DATE);

        // format ISO date time (2014-02-20T20:04:05.867)
        String asIsoDateTime = dateTime.format(DateTimeFormatter.ISO_DATE_TIME);

        // using a custom pattern (01/04/2014)
        String asCustomPattern = dateTime.format(DateTimeFormatter.ofPattern("dd/MM/yyyy"));

        // french date formatting (1. avril 2014)
        String frenchDate = dateTime.format(DateTimeFormatter.ofPattern("d. MMMM yyyy", new Locale("fr")));

        // using short german date/time formatting (01.04.14 10:45)
        DateTimeFormatter formatter = DateTimeFormatter.ofLocalizedDateTime(FormatStyle.SHORT).withLocale(new Locale("de"));
        String germanDateTime = dateTime.format(formatter);

        // parsing date strings
        LocalDate fromIsoDate = LocalDate.parse("2014-01-20");
        LocalDate fromIsoWeekDate = LocalDate.parse("2014-W14-2", DateTimeFormatter.ISO_WEEK_DATE);
        LocalDate fromCustomPattern = LocalDate.parse("20.01.2014", DateTimeFormatter.ofPattern("dd.MM.yyyy"));

        System.out.println("parsingFormatting: asBasicIsoDate: " + asBasicIsoDate);
        System.out.println("parsingFormatting: asIsoWeekDate: " + asIsoWeekDate);
        System.out.println("parsingFormatting: asIsoDateTime: " + asIsoDateTime);
        System.out.println("parsingFormatting: asCustomPattern: " + asCustomPattern);
        System.out.println("parsingFormatting: fromIsoDate: " + fromIsoDate);
        System.out.println("parsingFormatting: fromIsoWeekDate: " + fromIsoWeekDate);
        System.out.println("parsingFormatting: fromCustomPattern: " + fromCustomPattern);
        System.out.println("parsingFormatting: frenchDate: " + frenchDate);
        System.out.println("parsingFormatting: germanDateTime: " + germanDateTime);
    }


    private static void temporalAdjuster() {
        LocalDate date = LocalDate.of(2014, Month.FEBRUARY, 25); // 2014-02-25

        // first day of february 2014 (2014-02-01)
        LocalDate firstDayOfMonth = date.with(TemporalAdjusters.firstDayOfMonth());

        // last day of february 2014 (2014-02-28)
        LocalDate lastDayOfMonth = date.with(TemporalAdjusters.lastDayOfMonth());

        // more fluent using static imports

        // last day of 2014 (2014-12-31)
        LocalDate lastDayOfYear = date.with(lastDayOfYear());

        // first day of next month (2014-03-01)
        LocalDate firstDayOfNextMonth = date.with(firstDayOfNextMonth());

        // next sunday (2014-03-02)
        LocalDate nextSunday = date.with(next(DayOfWeek.SUNDAY));

        System.out.println("temporalAdjuster: firstDayOfMonth: " + firstDayOfMonth);
        System.out.println("temporalAdjuster: lastDayOfMonth: " + lastDayOfMonth);
        System.out.println("temporalAdjuster: lastDayOfYear: " + lastDayOfYear);
        System.out.println("temporalAdjuster: firstDayOfNextMonth: " + firstDayOfNextMonth);
        System.out.println("temporalAdjuster: nextSunday: " + nextSunday);
    }


    private static void timezones() {
        ZoneId losAngeles = ZoneId.of("America/Los_Angeles");
        ZoneId berlin = ZoneId.of("Europe/Berlin");

        // 2014-02-20 12:00
        LocalDateTime dateTime = LocalDateTime.of(2014, 02, 20, 12, 0);

        // 2014-02-20 12:00, Europe/Berlin (+01:00)
        ZonedDateTime berlinDateTime = ZonedDateTime.of(dateTime, berlin);

        // 2014-02-20 03:00, America/Los_Angeles (-08:00)
        ZonedDateTime losAngelesDateTime = berlinDateTime.withZoneSameInstant(losAngeles);

        int offsetInSeconds = losAngelesDateTime.getOffset().getTotalSeconds(); // -28800

        // a collection of all available zones
        Set<String> allZoneIds = ZoneId.getAvailableZoneIds();

        // using offsets
        LocalDateTime date = LocalDateTime.of(2013, Month.JULY, 20, 3, 30);
        ZoneOffset offset = ZoneOffset.of("+05:00");

        // 2013-07-20 22:30 +05:00
        OffsetDateTime plusFive = OffsetDateTime.of(date, offset);

        // 2013-07-19 20:30 -02:00
        OffsetDateTime minusTwo = plusFive.withOffsetSameInstant(ZoneOffset.ofHours(-2));

        System.out.println("timezones: berlinDateTime: " + berlinDateTime);
        System.out.println("timezones: losAngelesDateTime: " + losAngelesDateTime);
        System.out.println("timezones: offsetInSeconds: " + offsetInSeconds);
        System.out.println("timezones: allZoneIds: " + allZoneIds);
        System.out.println("timezones: offset: " + offset);
        System.out.println("timezones: plusFive: " + plusFive);
        System.out.println("timezones: minusTwo: " + minusTwo);
    }


    private static void conversion() {

        // LocalDate/LocalTime <-> LocalDateTime
        LocalDate date = LocalDate.now();
        LocalTime time = LocalTime.now();
        LocalDateTime dateTimeFromDateAndTime = LocalDateTime.of(date, time);
        LocalDate dateFromDateTime = LocalDateTime.now().toLocalDate();
        LocalTime timeFromDateTime = LocalDateTime.now().toLocalTime();

        // Instant <-> LocalDateTime
        Instant instant = Instant.now();
        LocalDateTime dateTimeFromInstant = LocalDateTime.ofInstant(instant, ZoneId.of("America/Los_Angeles"));
        Instant instantFromDateTime = LocalDateTime.now().toInstant(ZoneOffset.ofHours(-2));

        // convert from/to old date/calendar/timezone classes
        Instant instantFromDate = new Date().toInstant();
        Instant instantFromCalendar = Calendar.getInstance().toInstant();
        ZoneId zoneId = TimeZone.getDefault().toZoneId();
        ZonedDateTime zonedDateTimeFromGregorianCalendar = new GregorianCalendar().toZonedDateTime();
        Date dateFromInstant = Date.from(Instant.now());
        TimeZone timeZone = TimeZone.getTimeZone(ZoneId.of("America/Los_Angeles"));
        GregorianCalendar gregorianCalendar = GregorianCalendar.from(ZonedDateTime.now());
    }


    private static void timestamps() {
        // current time
        Instant now = Instant.now();

        // from unix timestamp, 2010-01-01 12:00:00
        Instant fromUnixTimestamp = Instant.ofEpochSecond(1262347200);

        // same time in millis
        Instant fromEpochMilli = Instant.ofEpochMilli(1262347200000l);

        // parsing from ISO 8601
        Instant fromIso8601 = Instant.parse("2010-01-01T12:00:00Z");

        // toString() returns ISO 8601 format
        String toIso8601 = now.toString();

        // as unix timestamp
        long toUnixTimestamp = now.getEpochSecond();

        // in millis
        long toEpochMillis = now.toEpochMilli();

        // native plusSeconds() method to add 10 seconds
        Instant nowPlusTenSeconds = now.plusSeconds(10);

        // no native support for units like days.
        Instant nowPlusTwoDays = now.plus(2, ChronoUnit.DAYS);
        Instant nowMinusTwoDays = now.minus(Duration.ofDays(2));

        System.out.println("timestamps now: " + now);
        System.out.println("timestamps fromUnixTimestamp: " + fromUnixTimestamp);
        System.out.println("timestamps fromEpochMilli: " + fromEpochMilli);
        System.out.println("timestamps fromIso8601: " + fromIso8601);
        System.out.println("timestamps toIso8601: " + toIso8601);
        System.out.println("timestamps toUnixTimestamp: " + toUnixTimestamp);
        System.out.println("timestamps toEpochMillis: " + toEpochMillis);
        System.out.println("timestamps nowPlusTenSeconds: " + nowPlusTenSeconds);
        System.out.println("timestamps nowPlusTwoDays: " + nowPlusTwoDays);
        System.out.println("timestamps nowMinusTwoDays: " + nowMinusTwoDays);
    }



    public static void main(String[] args) {
        dateTimes();
        dateTimeInformation();
        year();
        temporalAdjuster();
        additionSubtraction();
        timezones();
        timestamps();
        periodsAndDurations();
        parsingFormatting();
        conversion();
    }
}