java - 在 Java 中计算出 Linux 纪元时间属于哪一天

Question

这个问题已经有答案了:

How can I create a Java 8 LocalDate from a long Epoch time in Milliseconds? (8 个回答)

已关闭 3 年前。

我正在尝试弄清楚如何确定给定的 Linux Epoch TS 属于哪一天。

为了帮助解释更多，我给出以下示例:

我已经使用 JODATIME 尝试过此操作，但无法获得有效的解决方案。

// some code here that I need.... <---??

// The time set here below is (Tue 2019-09-10 14:05:00 UTC)
final long timestamp = 1568124300000L


if (timestamp = xxxxx) {
    System.out.println("The day it belongs to is: " + dayEpoch);
}

理想情况下，我希望打印的输出是:

The day it belongs to is: 2019-09-10

如果您提供实现此目的的代码示例，我将不胜感激:)

Answer 1

您可以使用java.time满足您的要求:

第一个选项(首选):OffsetDateTime

final long timestamp = 1568124300000L;

// create an Instant from the timestamp
Instant instant = Instant.ofEpochMilli(timestamp);
// create a datetime object from the Instant
OffsetDateTime offsetDateTime = OffsetDateTime.ofInstant(instant, ZoneId.of("UTC"));
// print it in your desired formatting
System.out.println("The day it belongs to is: "
                    + offsetDateTime.format(DateTimeFormatter.ofPattern("yyyy-MM-dd")));

第二个选项(有效，但不太合适):ZonedDateTime

final long timestamp = 1568124300000L;

// create an Instant from the timestamp
Instant instant = Instant.ofEpochMilli(timestamp);
// create a datetime object from the Instant
ZonedDateTime zonedDateTime = ZonedDateTime.ofInstant(instant, ZoneId.of("UTC"));
// print it in your desired formatting
System.out.println("The day it belongs to is: "
                    + zonedDateTime.format(DateTimeFormatter.ofPattern("yyyy-MM-dd")));

Please note that you can have different ZoneIds. You have clearly written that it is UTC in your case, so I took that one for the example. There is ZoneId.systemDefault(); to get a local timezone, the output for that is the same (date) on my system.
For using this, you will have to be using Java 8 or the ThreeTen-Backport…