Java新特性-日期

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

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);
    }
}

posted @ 2021-02-20 08:50 BNTang 阅读(118) 评论(0) 编辑收藏举报

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BNTang

Java新特性-日期

概述

LocalDate

创建 LocalDate

获取当前年月日

构造指定的年月日

获取年

获取月

获取日

获取星期几

LocalTime

创建 LocalTime

获取小时

获取分

获取秒

LocalDateTime

创建 LocalDateTime

获取 LocalDate

获取 LocalTime

Instant 获取秒数

创建 Instant 对象

获取秒数

获取毫秒数

Duration

创建 Duration 对象

获取这段时间的总天数

获取这段时间的小时数

获取这段时间的分钟数

获取这段时间的秒数

获取这段时间的毫秒数

获取这段时间的纳秒数

日期操作

增加一年

减少一个月

通过 with 修改某些值

修改年

时间计算

获取该年的第一天

TemporalAdjusters 类

格式化时间

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