java.time

Question

我想将时间戳（纪元时间）转换为人类可读的字符串。

为此我使用calendar.setTimeInMillis(timeSinceEpoch)函数创建日历对象并以人类可读的格式获取日期时间字符串。

我很困惑，我怎么能发现时间戳（纪元时间）是今天或昨天，还是在系统当前日期和时间的同一周？

在android中是否有任何API可以实现这一点？

感谢。

Answer 1

您可以使用方法：

public static long diff(long time, int field) {
  long fieldTime = getFieldInMillis(field);
  Calendar cal = Calendar.getInstance();
  long now = cal.getTimeInMillis();
  return (time/fieldTime - now / fieldTime);
}

private static final long getFieldInMillis(int field) {
  // TODO cache values
  final Calendar cal = Calendar.getInstance();
  long now = cal.getTimeInMillis();
  cal.add(field, 1);
  long after = cal.getTimeInMillis();
  return after - now;
}

并以这种方式使用它们：

diff(time, Calendar.DAY_OF_YEAR); // 0 - today, 1 - tomorrow, -1 - yesterday
diff(time, Calendar.WEEK_OF_YEAR); // 0 - this week, -1 - last week etc.

Answer 2

非常简单：

Calendar c=Calendar.getInstance();
c.getTimeInMillis();
String cur_day=String.format("%te %B %tY",c,c,c); // This will give date like 22 February 2012

c.setTimeInMillis(time);//set your saved timestamp
String that_day=String.format("%te %B %tY",c,c,c); //this will convert timestamp into format like 22 February 2012

//you can compare days,months,year,hours,minutes,seconds and milliseconds using above method.you can find various formats in below link

有关更多格式，请参阅http://download.oracle.com/javase/1.5.0/docs/api/java/util/Formatter.html

Answer 3

您可以尝试使用它来检测今天的日期：

public static boolean isDateToday(long milliSeconds) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTimeInMillis(milliSeconds);

        Date getDate = calendar.getTime();

        calendar.setTimeInMillis(System.currentTimeMillis());
        calendar.set(Calendar.HOUR_OF_DAY, 0);
        calendar.set(Calendar.MINUTE, 0);
        calendar.set(Calendar.SECOND, 0);

        Date startDate = calendar.getTime();

        return getDate.compareTo(startDate) > 0;

    }

Answer 4

我认为这是确定两个时间戳是否在同一天的最有效方式。加上它与语言无关：

int secondsInADay   = 60*60*24;
int daysSinceEpoch1 = timestamp1/secondsInADay;
int daysSinceEpoch2 = timestamp2/secondsInADay;

if( daysSinceEpoch1 == daysSinceEpoch2 )
    ;//sameday

else if( daysSinceEpoch1 - daysSinceEpoch2 == 1 )
    ;//timestamp2 is a day before timetamp1

else if( ......

如果要与今天进行比较，请将timestamp1设置为当前时间

Answer 5

java.time

旧的日期时间 API（java.util 日期时间类型及其格式类型，SimpleDateFormat 等）已经过时且容易出错。建议完全停止使用，改用java.time，modern date-time API^*。

使用现代 API java.time 的解决方案：

现代日期时间 API 具有丰富的直观概念，例如它为我们提供了 Instant 类，它代表时间线上的一个瞬时点。有一个名为 ZonedDateTime 的类，它表示 ISO-8601 日历系统中带有时区的日期时间。为了切换到不同的时间单位（例如天、小时、分钟、周、月等），API 提供了名为介词和其他英语口语结构的方法。从 Trail: Date Time 了解有关现代日期时间 API 的更多信息。

今天、昨天、同一周等概念都受时区限制，例如今天在伦敦的某个时刻可能是明天在新加坡的某个时刻。此外，start of the week 对 Locale 敏感，例如对于 Locale.France，它从星期一开始，而对于 Locale.US，它从星期日开始。

演示：

import java.time.DayOfWeek;
import java.time.Instant;
import java.time.LocalDate;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.temporal.TemporalAdjusters;
import java.util.stream.Stream;

public class Main {
    public static void main(String[] args) {
        // Test
        Stream.of(
                    1621533017083L,
                    1621446617083L,
                    1621619417083L,
                    1621189684296L,
                    1621209600000L,
                    1621814400000L
        ).forEach(millis -> {
            System.out.println(millis);
            System.out.println(Instant.ofEpochMilli(millis));
            System.out.println("Today: " + isToday(millis, "Europe/London"));
            System.out.println("Yesterday: " + isYesterday(millis, "Europe/London"));
            System.out.println("In the current week: " + isInTheSameWeek(millis, "Europe/London"));
            System.out.println();
        });
    }

    static boolean isToday(long epochMillis, String timezone) {
        ZoneId zoneId = ZoneId.of(timezone);

        // The start of the day today at this timezone
        ZonedDateTime zdtStartOfDayToday = LocalDate.now().atStartOfDay(zoneId);
        long millisStartOfDayToday = zdtStartOfDayToday.toInstant().toEpochMilli();

        // The start of the next day at this timezone
        ZonedDateTime zdtStartOfDayNextDay = LocalDate.now().plusDays(1).atStartOfDay(zoneId);
        long millisStartOfDayNextDay = zdtStartOfDayNextDay.toInstant().toEpochMilli();

        return (epochMillis >= millisStartOfDayToday && epochMillis < millisStartOfDayNextDay);
    }

    static boolean isYesterday(long epochMillis, String timezone) {
        ZoneId zoneId = ZoneId.of(timezone);

        // The start of the day today at this timezone
        ZonedDateTime zdtStartOfDayToday = LocalDate.now().atStartOfDay(zoneId);
        long millisStartOfDayToday = zdtStartOfDayToday.toInstant().toEpochMilli();

        // The start of the day yesterday at this timezone
        ZonedDateTime zdtStartOfDayYesterday = LocalDate.now().minusDays(1).atStartOfDay(zoneId);
        long millisStartOfDayYesterday = zdtStartOfDayYesterday.toInstant().toEpochMilli();

        return (epochMillis >= millisStartOfDayYesterday && epochMillis < millisStartOfDayToday);
    }

    static boolean isInTheSameWeek(long epochMillis, String timezone) {
        ZoneId zoneId = ZoneId.of(timezone);

        // The start of the day today at this timezone
        ZonedDateTime zdtStartOfDayToday = LocalDate.now().atStartOfDay(zoneId);

        // The start of the week at this timezone
        ZonedDateTime zdtStartOfTheWeek = zdtStartOfDayToday.with(TemporalAdjusters.previousOrSame(DayOfWeek.MONDAY));
        long millisStartOfTheWeek = zdtStartOfTheWeek.toInstant().toEpochMilli();

        // The start of the next week at this timezone
        ZonedDateTime zdtStartOfTheNextWeek = zdtStartOfDayToday.with(TemporalAdjusters.next(DayOfWeek.MONDAY));
        long millisStartOfTheNextWeek = zdtStartOfTheNextWeek.toInstant().toEpochMilli();

        return (epochMillis >= millisStartOfTheWeek && epochMillis < millisStartOfTheNextWeek);
    }
}

输出：

1621533017083
2021-05-20T17:50:17.083Z
Today: true
Yesterday: false
In the current week: true

1621446617083
2021-05-19T17:50:17.083Z
Today: false
Yesterday: true
In the current week: true

1621619417083
2021-05-21T17:50:17.083Z
Today: false
Yesterday: false
In the current week: true

1621189684296
2021-05-16T18:28:04.296Z
Today: false
Yesterday: false
In the current week: false

1621209600000
2021-05-17T00:00:00Z
Today: false
Yesterday: false
In the current week: true

1621814400000
2021-05-24T00:00:00Z
Today: false
Yesterday: false
In the current week: false

ONLINE DEMO

^{* 出于任何原因，如果您必须坚持使用 Java 6 或 Java 7，您可以使用 ThreeTen-Backport，它将大部分 java.time 功能向后移植到 Java 6 & 7. 如果您正在为 Android 项目工作并且您的 Android API 级别仍然不符合 Java-8，请检查 Java 8+ APIs available through desugaring 和 How to use ThreeTenABP in Android Project。}

如何检查时间戳（纪元时间）是今天还是昨天[android]

5 个答案:

java.time