将 Instant 格式化为字符串 [英] Format Instant to String
问题描述
我正在尝试使用新的 java 8 time-api 和模式将 Instant 格式化为字符串:
I'm trying to format an Instant to a String using the new java 8 time-api and a pattern:
Instant instant = ...;
String out = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss").format(instant);
使用上面的代码我得到一个异常,它抱怨一个不受支持的字段:
Using the code above I get an Exception which complains an unsupported field:
java.time.temporal.UnsupportedTemporalTypeException: Unsupported field: YearOfEra
at java.time.Instant.getLong(Instant.java:608)
at java.time.format.DateTimePrintContext.getValue(DateTimePrintContext.java:298)
...
推荐答案
时区
格式化Instant
需要 时区.如果没有时区,格式化程序不知道如何将即时字段转换为人工日期时间字段,因此会引发异常.
Time Zone
To format an Instant
a time-zone is required. Without a time-zone, the formatter does not know how to convert the instant to human date-time fields, and therefore throws an exception.
可以使用 withZone()
.
DateTimeFormatter formatter =
DateTimeFormatter.ofLocalizedDateTime( FormatStyle.SHORT )
.withLocale( Locale.UK )
.withZone( ZoneId.systemDefault() );
如果您特别想要一个没有明确时区的 ISO-8601 格式(正如 OP 所要求的),时区隐式为 UTC,您需要
If you specifically want an ISO-8601 format with no explicit time-zone (as the OP asked), with the time-zone implicitly UTC, you need
DateTimeFormatter.ISO_LOCAL_DATE_TIME.withZone(ZoneId.from(ZoneOffset.UTC))
生成字符串
现在使用该格式化程序生成 Instant 的字符串表示.
Generating String
Now use that formatter to generate the String representation of your Instant.
Instant instant = Instant.now();
String output = formatter.format( instant );
转储到控制台.
System.out.println("formatter: " + formatter + " with zone: " + formatter.getZone() + " and Locale: " + formatter.getLocale() );
System.out.println("instant: " + instant );
System.out.println("output: " + output );
运行时.
formatter: Localized(SHORT,SHORT) with zone: US/Pacific and Locale: en_GB
instant: 2015-06-02T21:34:33.616Z
output: 02/06/15 14:34
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