在不同的时区获取相同的日期

Question

我有一个 epochmilli 秒的时间。从这个纪元时间创建一个日期对象。

Date date = new Date(epochMilli);

假设日期是 "23 Nov 2019 00:00:00"

现在，我只想在不同的时区获得相同的日期，例如：]

日本时间：2019年11月23日00:00:00

美国时间：2019 年 11 月 23 日 00:00:00

我目前正在使用LocalDateTime或ZonedDateTime。

但是当我转换到不同的区域时，时间也会改变。但我不想这一次改变。

提前致谢。

Answer 1

不幸的是，您没有向我们展示您是如何使用 的ZonedDateTime，因此下面的示例可能会通过展示如何解析毫秒、将生成的日期时间从一个区域转换为其他区域以及如何使用不同区域解析日期时间来涵盖更多内容：

public static void main(String[] args) {
    long epochMillis = 1574208000000L;
    
    // define a formatter to be used
    DateTimeFormatter dtf = DateTimeFormatter.ofPattern("dd MMM yyyy HH:mm:ss");

    /*
     * Part 1: Getting the date time converted to different time zones
     */
    
    // parse the millis once using a specific time zone, here: UTC
    ZonedDateTime utcFromMillis = ZonedDateTime.ofInstant(Instant.ofEpochMilli(epochMillis), 
                                                            ZoneId.of("UTC"));

    // then take the UTC-ZonedDateTime as base for conversion to other time zones 
    ZonedDateTime asiaTokyoConvertedfromUtc = utcFromMillis.toInstant()
            .atZone(ZoneId.of("Asia/Tokyo"));
    ZonedDateTime americaLosAngelesConvertedfromUtc = utcFromMillis.toInstant()
            .atZone(ZoneId.of("America/Los_Angeles"));
    ZonedDateTime americaChicagoConvertedfromUtc = utcFromMillis.toInstant()
            .atZone(ZoneId.of("America/Chicago"));

    // print the results
    System.out.println("#### 1574208000000L at UTC, converted to other zones ####");
    System.out.println("UTC time zone:\t\t\t\t" + utcFromMillis.format(dtf));
    System.out.println("JST (Japan/Tokyo) time zone:\t\t"
            + asiaTokyoConvertedfromUtc.format(dtf));
    System.out.println("PST (USA/Los Angeles) time zone:\t"
            + americaLosAngelesConvertedfromUtc.format(dtf));
    System.out.println("CST (USA/Chicago) time zone:\t\t"
            + americaChicagoConvertedfromUtc.format(dtf));
    
    System.out.println();

    /*
     * Part 2: Getting the date time in different time zones
     */
    
    // parse the millis using time zone Asia/Tokyo
    ZonedDateTime asiaTokyoFromMillis = ZonedDateTime.ofInstant(
            Instant.ofEpochMilli(epochMillis), 
            ZoneId.of("Asia/Tokyo"));

    // parse the millis using time zone America/Los Angeles
    ZonedDateTime americaLosAngelesFromMillis = ZonedDateTime.ofInstant(
            Instant.ofEpochMilli(epochMillis), 
            ZoneId.of("America/Los_Angeles"));

    // parse the millis using time zone America/Chicago
    ZonedDateTime americaChicagoFromMillis = ZonedDateTime.ofInstant(
            Instant.ofEpochMilli(epochMillis), 
            ZoneId.of("America/Chicago"));

    // print the (expected) results, same as converted date times...
    System.out.println("#### 1574208000000L at different zones ####");
    System.out.println("UTC time zone:\t\t\t\t" + utcFromMillis.format(dtf));
    System.out.println("JST (Asia/Tokyo) time zone:\t\t"
            + asiaTokyoFromMillis.format(dtf));
    System.out.println("PST (USA/Los Angeles) time zone:\t"
            + americaLosAngelesFromMillis.format(dtf));
    System.out.println("CST (USA/Chicago) time zone:\t\t"
            + americaChicagoFromMillis.format(dtf));
    
    System.out.println();
    
    /*
     * Part 3: How to parse the date time instead of millis
     */
    
    // provide a parseable date time String
    String dateTime = "23 Nov 2019 00:00:00";
    
    // parse it in each desired time zone
    ZonedDateTime utc23Nov2019 = LocalDateTime.parse(dateTime, dtf)
            .atZone(ZoneId.of("UTC"));
    ZonedDateTime asiaTokyo23Nov2019 = LocalDateTime.parse(dateTime, dtf)
            .atZone(ZoneId.of("Asia/Tokyo"));
    ZonedDateTime americaChicago23Nov2019 = LocalDateTime.parse(dateTime, dtf)
            .atZone(ZoneId.of("America/Los_Angeles"));
    ZonedDateTime americaLosAngeles23Nov2019 = LocalDateTime.parse(dateTime, dtf)
            .atZone(ZoneId.of("America/Chicago"));

    // print the results, now you have the 23. Nov 2019 at 00:00:00 in each time zone
    System.out.println("#### \"23 Nov 2019 00:00:00\" at different zones ####");
    System.out.println("UTC time zone:\t\t\t\t" + utc23Nov2019.format(dtf));
    System.out.println("JST (Asia/Tokyo) time zone:\t\t"
            + asiaTokyo23Nov2019.format(dtf));
    System.out.println("PST (USA/Los Angeles) time zone:\t"
            + americaChicago23Nov2019.format(dtf));
    System.out.println("CST (USA/Chicago) time zone:\t\t"
            + americaLosAngeles23Nov2019.format(dtf));
}

这个的输出是

#### 1574208000000L at UTC, converted to other zones ####
UTC time zone:                      20 Nov 2019 00:00:00
JST (Japan/Tokyo) time zone:        20 Nov 2019 09:00:00
PST (USA/Los Angeles) time zone:    19 Nov 2019 16:00:00
CST (USA/Chicago) time zone:        19 Nov 2019 18:00:00

#### 1574208000000L at different zones ####
UTC time zone:                      20 Nov 2019 00:00:00
JST (Asia/Tokyo) time zone:         20 Nov 2019 09:00:00
PST (USA/Los Angeles) time zone:    19 Nov 2019 16:00:00
CST (USA/Chicago) time zone:        19 Nov 2019 18:00:00

#### "23 Nov 2019 00:00:00" at different zones ####
UTC time zone:                      23 Nov 2019 00:00:00
JST (Asia/Tokyo) time zone:         23 Nov 2019 00:00:00
PST (USA/Los Angeles) time zone:    23 Nov 2019 00:00:00
CST (USA/Chicago) time zone:        23 Nov 2019 00:00:00