英文:
how to convert String to Date and Time in Java
问题
我知道这实际上是一个初学者问题，但似乎我找不到任何解决方法。
因此，我有一个从JSON数据库网站获取的字符串：
DateTime = "\/Date(1598036400000)\/"
但问题是，如何将这个字符串转换为实际的日期时间？
英文:
I know this is really a beginner question, but it seems I can't find any good solution for this.
So I have a String that I get from a JSON database website that is:
DateTime = "\/Date(1598036400000)\/"
But the question is how do I convert this String to a real DateTime?
答案1
得分: 3
你需要执行几个步骤，因为原始表示中的值不是 long 类型，而是 "/Date(1598036400000)/"。该 String 内部的数字值表示的是时刻的纪元毫秒数，你需要移除其余的字符或子字符串。以下是一个示例...
public static void main(String[] args) {
// 获取原始 String 值，
String datetime = "/Date(1598036400000)/";
// 移除所有非数字的字符，
String millisStr = datetime.replace("/", "").replace("Date(", "").replace(")", "");
// 然后将其转换为 long 类型，
long millis = Long.valueOf(millisStr);
// 并从 long 创建一个时刻（Instant）
Instant instant = Instant.ofEpochMilli(millis);
// 最后使用该时刻在特定时区创建一个时间点 (ZonedDateTime)
ZonedDateTime zdt = ZonedDateTime.ofInstant(instant, ZoneId.of("CET"));
// 并打印其默认的 String 表示
System.out.println(zdt);
}
... 输出结果为
2020-08-21T21:00+02:00[CET]
如果你需要不同格式的 String，你可以使用 DateTimeFormatter，甚至考虑不同的语言或地区。以下是使用德语区域设置输出结果的示例：
System.out.println(zdt.format(
DateTimeFormatter.ofPattern("EEEE, dd. MMMM yyyy HH:mm:ss", Locale.GERMAN))
);
输出结果为
Freitag, 21. August 2020 21:00:00
英文:
You will have to perform several steps due to the value not being a long in its original representation "/Date(1598036400000)/". The numeric value inside that String is representing a moment in time in epoch milliseconds and you have to remove the remaining characters or substrings. Here's an example...
public static void main(String[] args) {
// take the original String value,
String datetime = "/Date(1598036400000)/";
// remove anything that isn't a digit,
String millisStr = datetime.replace("/", "").replace("Date(", "").replace(")", "");
// then convert it to a long,
long millis = Long.valueOf(millisStr);
// and create a moment in time (Instant) from the long
Instant instant = Instant.ofEpochMilli(millis);
// and finally use the moment in time to express that moment in a specific time zone
ZonedDateTime zdt = ZonedDateTime.ofInstant(instant, ZoneId.of("CET"));
// and print its default String representation
System.out.println(zdt);
}
... which outputs
2020-08-21T21:00+02:00[CET]
If you need a differently formatted String, you can use a DateTimeFormatter that even considers different locales or languages.
The output of
System.out.println(zdt.format(
DateTimeFormatter.ofPattern("EEEE, dd. MMMM yyyy HH:mm:ss", Locale.GERMAN))
);
is
Freitag, 21. August 2020 21:00:00
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