[英]Java8 parse date or date time format for a given string
I have a file that can have a date modified value with the format of a date or date time. 我有一个文件可以具有日期修改值,具有日期或日期时间的格式。 I used to parse the value as:
我曾经将值解析为:
String t = "2012-01-05T21:21:52.834Z";
logger.info(ZonedDateTime.parse(t).toEpochSecond() * 1000);
Now, the string could also be 现在,字符串也可以
t = "2012-01-05";
which threw an error 哪个引起了错误
Exception in thread "main" java.time.format.DateTimeParseException: Text '2012-01-05' could not be parsed at index 10 at java.time.format.DateTimeFormatter.parseResolved0(Unknown Source)
线程“main”中的异常java.time.format.DateTimeParseException:无法在java.time.format.DateTimeFormatter.parseResolved0(未知来源)的索引10处解析文本“2012-01-05”
If I do this string with ( Reference ) 如果我用这个字符串( 参考 )
LocalDate date = LocalDate.parse(t, DateTimeFormatter.ISO_DATE);
logger.info(date.atStartOfDay(ZoneId.of("UTC")).toEpochSecond() * 1000);
This would work. 这会奏效。 However, as I have mentioned that string could be either of these types, how can I identify the format and then get the millis accordingly?
但是,正如我已经提到的那样,字符串可以是这些类型中的任何一种,我如何识别格式然后相应地得到毫秒?
A possible solution is to use optional pattern with default values. 可能的解决方案是使用具有默认值的可选模式。 Using a
DateTimeFormatterBuilder
, you can append the wanted pattern with the time part in an optional section, ie surrounded by [...]
. 使用
DateTimeFormatterBuilder
,您可以将所需模式与时间部分附加在可选部分中,即由[...]
包围。 In the case where the fields are absent, we provide default values by setting them to 0. The OFFSET_SECONDS
field to 0 represents no offset from UTC. 在没有字段的情况下,我们通过将它们设置为0来提供默认值
OFFSET_SECONDS
字段为0表示没有与UTC的偏移。
public static void main(String[] args) {
String[] dates = { "2012-01-05T21:21:52.834Z", "2012-01-05" };
DateTimeFormatter formatter =
new DateTimeFormatterBuilder().appendPattern("yyyy-MM-dd['T'HH:mm:ss.SSSz]")
.parseDefaulting(ChronoField.HOUR_OF_DAY, 0)
.parseDefaulting(ChronoField.MINUTE_OF_HOUR, 0)
.parseDefaulting(ChronoField.SECOND_OF_MINUTE, 0)
.parseDefaulting(ChronoField.NANO_OF_SECOND, 0)
.parseDefaulting(ChronoField.OFFSET_SECONDS, 0)
.toFormatter();
for (String date : dates) {
ZonedDateTime zonedDateTime = ZonedDateTime.parse(date, formatter);
System.out.println(zonedDateTime.toEpochSecond() * 1000);
}
}
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