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Java新特性-日期

Ewall_熊猫 2022-05-24 阅读 67
Java 8java日期时间格式化时间Java编程语言

概述


  • Java 8 在​​Java.time​​ 包下提供了很多新的 API。
  • Local(本地) 简化了日期时间的处理，没有时区的问题。
  • Zoned(时区) 通过制定的时区处理日期时间。


LocalDate


  • LocalDate 只会获取​​年​​​​月​​​​日​​。


创建 LocalDate

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        LocalDate localDateOne = LocalDate.now();
        LocalDate localDateTwo = LocalDate.of(2020, 11, 28);
    }
}

获取当前年月日

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        LocalDate localDate = LocalDate.now();
        System.out.println(localDate);
    }
}

构造指定的年月日

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        LocalDate localDate = LocalDate.of(2020, 11, 28);
        System.out.println(localDate);
    }
}

获取年

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        LocalDate localDate = LocalDate.of(2021, 2, 20);

        int yearOne = localDate.getYear();
        int yearTwo = localDate.get(ChronoField.YEAR);

        System.out.println(yearOne);
        System.out.println(yearTwo);
    }
}

获取月

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        LocalDate localDate = LocalDate.of(2021, 2, 20);

        Month monthOne = localDate.getMonth();
        int monthTwo = localDate.get(ChronoField.MONTH_OF_YEAR);

        System.out.println(monthOne);
        System.out.println(monthTwo);
    }
}

获取日

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        LocalDate localDate = LocalDate.of(2021, 2, 20);

        int dayOne = localDate.getDayOfMonth();
        int dayTwo = localDate.get(ChronoField.DAY_OF_MONTH);

        System.out.println(dayOne);
        System.out.println(dayTwo);
    }
}

获取星期几

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        LocalDate localDate = LocalDate.of(2021, 2, 20);

        DayOfWeek dayOfWeekOne = localDate.getDayOfWeek();
        int dayOfWeekTwo = localDate.get(ChronoField.DAY_OF_WEEK);

        System.out.println(dayOfWeekOne);
        System.out.println(dayOfWeekTwo);
    }
}

LocalTime


  • LocalTime 只会获取​​时​​​​分​​​​秒​​。


创建 LocalTime

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        LocalTime localTimeOne = LocalTime.of(14, 14, 14);
        LocalTime localTimeTwo = LocalTime.now();
    }
}

获取小时

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        LocalTime localTime = LocalTime.now();

        int hourOne = localTime.getHour();
        int hourTwo = localTime.get(ChronoField.HOUR_OF_DAY);

        System.out.println(hourOne);
        System.out.println(hourTwo);
    }
}

获取分

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        LocalTime localTime = LocalTime.now();

        int minuteOne = localTime.getMinute();
        int minuteTwo = localTime.get(ChronoField.MINUTE_OF_HOUR);

        System.out.println(minuteOne);
        System.out.println(minuteTwo);
    }
}

获取秒

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        LocalTime localTime = LocalTime.now();
        
        int secondOne = localTime.getMinute();
        int secondTwo = localTime.get(ChronoField.SECOND_OF_MINUTE);

        System.out.println(secondOne);
        System.out.println(secondTwo);
    }
}

LocalDateTime


  • 获取年月日时分秒，相当于​​LocalDate​​​ +​​LocalTime​​。


创建 LocalDateTime

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        LocalDateTime localDateTimeOne = LocalDateTime.now();
        LocalDateTime localDateTimeTwo = LocalDateTime.of(2019,
                Month.SEPTEMBER, 10, 14, 46, 56);

        LocalDate localDate = LocalDate.now();
        LocalTime localTime = LocalTime.now();
        LocalDateTime localDateTimeThree = LocalDateTime.of(localDate, localTime);

        LocalDateTime localDateTimeFour = localDate.atTime(localTime);
        LocalDateTime localDateTimeFive = localTime.atDate(localDate);
    }
}

获取 LocalDate

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        LocalDateTime localDateTimeOne = LocalDateTime.now();

        LocalDate localDate = localDateTimeOne.toLocalDate();
        System.out.println(localDate);
    }
}

获取 LocalTime

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        LocalDateTime localDateTimeOne = LocalDateTime.now();

        LocalTime localTime = localDateTimeOne.toLocalTime();
        System.out.println(localTime);
    }
}

Instant 获取秒数

创建 Instant 对象

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        Instant instant = Instant.now();
    }
}

获取秒数

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        Instant instant = Instant.now();
        
        long currentSecond = instant.getEpochSecond();
        System.out.println(currentSecond);
    }
}

获取毫秒数

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        Instant instant = Instant.now();

        long currentMilli = instant.toEpochMilli();
        System.out.println(currentMilli);
    }
}

如果只是为了获取秒数或者毫秒数，可以使用如下的方式进行获取。

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        long l = System.currentTimeMillis();
        System.out.println(l);
    }
}

Duration


  • Duration：表示一个时间段。


创建 Duration 对象

通过 ​​Duration.between()​​​ 方法进行创建, 接收两个参数一个 ​​from​​​, 一个 ​​to​​, 表示从 from 到 to 这段时间。

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        LocalDateTime from = LocalDateTime.of(2017, Month.JANUARY, 1, 00, 0, 0);
        LocalDateTime to = LocalDateTime.of(2020, Month.SEPTEMBER, 12, 14, 28, 0);
        Duration duration = Duration.between(from, to);
    }
}

获取这段时间的总天数

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        LocalDateTime from = LocalDateTime.of(2017, Month.JANUARY, 1, 00, 0, 0);
        LocalDateTime to = LocalDateTime.of(2020, Month.SEPTEMBER, 12, 14, 28, 0);
        Duration duration = Duration.between(from, to);
        
        long days = duration.toDays();
        System.out.println(days);
    }
}

获取这段时间的小时数

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        LocalDateTime from = LocalDateTime.of(2017, Month.JANUARY, 1, 00, 0, 0);
        LocalDateTime to = LocalDateTime.of(2020, Month.SEPTEMBER, 12, 14, 28, 0);
        Duration duration = Duration.between(from, to);
        
        long hours = duration.toHours();
        System.out.println(hours);
    }
}

获取这段时间的分钟数

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        LocalDateTime from = LocalDateTime.of(2017, Month.JANUARY, 1, 00, 0, 0);
        LocalDateTime to = LocalDateTime.of(2020, Month.SEPTEMBER, 12, 14, 28, 0);
        Duration duration = Duration.between(from, to);
        
        long minutes = duration.toMinutes();
        System.out.println(minutes);
    }
}

获取这段时间的秒数

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        LocalDateTime from = LocalDateTime.of(2017, Month.JANUARY, 1, 00, 0, 0);
        LocalDateTime to = LocalDateTime.of(2020, Month.SEPTEMBER, 12, 14, 28, 0);
        Duration duration = Duration.between(from, to);
        
        long seconds = duration.getSeconds();
        System.out.println(seconds);
    }
}

获取这段时间的毫秒数

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        LocalDateTime from = LocalDateTime.of(2017, Month.JANUARY, 1, 00, 0, 0);
        LocalDateTime to = LocalDateTime.of(2020, Month.SEPTEMBER, 12, 14, 28, 0);
        Duration duration = Duration.between(from, to);
        
        long milliSeconds = duration.toMillis();
        System.out.println(milliSeconds);
    }
}

获取这段时间的纳秒数

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        LocalDateTime from = LocalDateTime.of(2017, Month.JANUARY, 1, 00, 0, 0);
        LocalDateTime to = LocalDateTime.of(2020, Month.SEPTEMBER, 12, 14, 28, 0);
        Duration duration = Duration.between(from, to);
        
        long nanoSeconds = duration.toNanos();
        System.out.println(nanoSeconds);
    }
}

日期操作

增加一年

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        LocalDateTime localDateTime = LocalDateTime.now();
        
        localDateTime = localDateTime.plusYears(1);
        localDateTime = localDateTime.plus(1, ChronoUnit.YEARS);

        System.out.println(localDateTime.toLocalDate());
        System.out.println(localDateTime.toLocalTime());
    }
}

减少一个月

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        LocalDateTime localDateTime = LocalDateTime.now();

        localDateTime = localDateTime.minusMonths(1);
        localDateTime = localDateTime.minus(1, ChronoUnit.MONTHS);

        System.out.println(localDateTime.toLocalDate());
        System.out.println(localDateTime.toLocalTime());
    }
}

通过 with 修改某些值

修改年

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        LocalDateTime localDateTime = LocalDateTime.now();

        localDateTime = localDateTime.withYear(2021);
        localDateTime = localDateTime.with(ChronoField.YEAR, 2020);

        System.out.println(localDateTime.toLocalDate());
        System.out.println(localDateTime.toLocalTime());
    }
}

时间计算

获取该年的第一天

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        LocalDateTime localDateTime = LocalDateTime.now();

        LocalDate localDate = localDateTime.toLocalDate();
        LocalDate oneDay = localDate.with(TemporalAdjusters.firstDayOfYear());

        System.out.println(oneDay);
    }
}

TemporalAdjusters 类

Java新特性-日期_Java 8

格式化时间

/**
 * @author BNTang
 */
public class Main {
    public static void main(String[] args) {
        LocalDate localDate = LocalDate.now();

        String strOne = localDate.format(DateTimeFormatter.BASIC_ISO_DATE);
        String strTwo = localDate.format(DateTimeFormatter.ISO_LOCAL_DATE);

        System.out.println("s1：" + strOne);
        System.out.println("s2：" + strTwo);

        LocalDateTime localDateTime = LocalDateTime.now();

        System.out.println("获取当前时间：" + localDateTime);

        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");

        String s = localDateTime.format(formatter);

        System.out.println("格式化当前时间：" + s);
    }
}




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