在Java中把时间单位转换为持续时间的实例

java.util.concurrent.TimeUnit java.util.concurrent.TimeUnit 早在以前的Java时代（1.5）就被引入，但从那时起，它已经被扩展了好几次。在这篇博文中，你将学习如何使用 ，将一个给定的java.util.concurrent.TimeUnit 时间单位转换成一个持续时间。

前提条件

你需要JDK 11+才能使用这些例子：

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问题

在Java中把给定的时间单位转换为期限

解决方法

使用java.concurrent.TimeUnit 枚举。

Java 11

• TimeUnit.convert(Duration duration):

long yearInMillis = TimeUnit.MILLISECONDS.convert(Duration.ofDays(365));
long hourInMillis = TimeUnit.MILLISECONDS.convert(Duration.ofHours(1));
long minuteInMillis = TimeUnit.MILLISECONDS.convert(Duration.ofMinutes(1));
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• TimeUnit.convert(Duration duration) 使用 。java.time.ChronoUnit

long yearInMillis = TimeUnit.MILLISECONDS.convert(Duration.of(365, TimeUnit.DAYS.toChronoUnit()));
long hourInMillis = TimeUnit.MILLISECONDS.convert(Duration.of(1, TimeUnit.HOURS.toChronoUnit()));
long minuteInMillis = TimeUnit.MILLISECONDS.convert(Duration.of(1, TimeUnit.MINUTES.toChronoUnit()));
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前Java 11

• 通用的TimeUnit.convert(long sourceDuration, TimeUnit sourceUnit)

long yearInMillis = TimeUnit.DAYS.toMillis(365);
long hourInMillis = TimeUnit.HOURS.toMillis(1);
long minuteInMillis = TimeUnit.MINUTES.toMillis(1);
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• TimeUnit.toMillis(long duration),TimeUnit.toSeconds(long duration) 等方法。

long yearInMillis = TimeUnit.MILLISECONDS.convert(365, TimeUnit.DAYS);
long hourInMillis = TimeUnit.MILLISECONDS.convert(1, TimeUnit.HOURS);
long minuteInMillis = TimeUnit.MILLISECONDS.convert(1, TimeUnit.MINUTES);
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最后的例子

class Java11TimeUnitConvertTests {

    public static final long DAYS_IN_A_YEAR = 365L;
    public static final long HOURS_IN_A_DAY = 24L;
    public static final long MINUTES_IN_AN_HOUR = 60L;
    public static final long SECONDS_IN_A_MINUTE = 60L;
    public static final long MILLISECONDS_IN_A_SECOND = 1000L;
    @Test
    void aYearInMillis() {

        // A year in milliseconds
        long yearInMillis = TimeUnit.MILLISECONDS.convert(Duration.ofDays(365)); // since Java 11

        assertThat(yearInMillis)
                .isEqualTo(DAYS_IN_A_YEAR * HOURS_IN_A_DAY * MINUTES_IN_AN_HOUR * SECONDS_IN_A_MINUTE * MILLISECONDS_IN_A_SECOND)
                .isEqualTo(TimeUnit.DAYS.toMillis(365))
                .isEqualTo(TimeUnit.MILLISECONDS.convert(365, TimeUnit.DAYS))
                .isEqualTo(TimeUnit.MILLISECONDS.convert(Duration.of(365, TimeUnit.DAYS.toChronoUnit()))); // since Java 11

    }

    @Test
    void anHourInMillis() {

        long hourInMillis = TimeUnit.MILLISECONDS.convert(Duration.ofHours(1)); // since Java 11
        
        assertThat(hourInMillis)
                .isEqualTo(MINUTES_IN_AN_HOUR * SECONDS_IN_A_MINUTE * MILLISECONDS_IN_A_SECOND)
                .isEqualTo(TimeUnit.HOURS.toMillis(1))
                .isEqualTo(TimeUnit.MILLISECONDS.convert(1, TimeUnit.HOURS))
                .isEqualTo(TimeUnit.MILLISECONDS.convert(Duration.of(1, TimeUnit.HOURS.toChronoUnit()))); // since Java 11
    }

    @Test
    void aMinuteInMillis() {
        
        long minuteInMillis = TimeUnit.MILLISECONDS.convert(Duration.ofMinutes(1)); // since Java 11
        
        assertThat(minuteInMillis)
                .isEqualTo(SECONDS_IN_A_MINUTE * MILLISECONDS_IN_A_SECOND)
                .isEqualTo(TimeUnit.MINUTES.toMillis(1))
                .isEqualTo(TimeUnit.MILLISECONDS.convert(1, TimeUnit.MINUTES))
                .isEqualTo(TimeUnit.MILLISECONDS.convert(Duration.of(1, TimeUnit.MINUTES.toChronoUnit()))); // since Java 11
    }

    @ParameterizedTest
    @MethodSource("timeUnitToDuration")
    void convertTimeUnitToDuration(TimeUnit unit, Duration duration, long expectedResult) {
        long actualResult = unit.convert(duration);

        assertThat(actualResult).isEqualTo(expectedResult);
    }

    private static Stream<Arguments> timeUnitToDuration() {
        return Stream.of(
                Arguments.of(TimeUnit.DAYS, Duration.ofHours(24), 1), // 24h = 1d
                Arguments.of(TimeUnit.DAYS, Duration.ofHours(40), 1), // 40h = 1d
                Arguments.of(TimeUnit.DAYS, Duration.ofHours(48), 2), // 48h = 2d
                Arguments.of(TimeUnit.DAYS, Duration.ofHours(50), 2),  // 50h = 2d
                Arguments.of(TimeUnit.MILLISECONDS, Duration.ofSeconds(1), 1000),  // 1s = 1000ms
                Arguments.of(TimeUnit.MILLISECONDS, Duration.ofSeconds(11), 11000),  // 1s = 11000ms
                Arguments.of(TimeUnit.SECONDS, Duration.ofHours(1), 3600),  // 1h = 3600s
                Arguments.of(TimeUnit.HOURS, Duration.ofSeconds(4_000), 1),  // 4000s = 1h
                Arguments.of(TimeUnit.HOURS, Duration.ofSeconds(1_0000), 2)  // 10000s = 2h
        );
    }
}
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源代码

本文的源代码可以在Github上找到：https://github.com/kolorobot/java9-and-beyond