Determine TimeZone from a JSON String?

问题

I'm querying a JSON API that returns something like this:

{
  "created_time": "2017-01-05T16:32:29+0100",
  "updated_time": "2017-01-11T09:38:41+0100",
  "id": "23842536731240607"
}

I need to store the times in UTC format, but in order to change the timezone, I first need to parse it as a ZonedDateTime.

To convert "+0100" to "+01:00" is easy enough. But how can I parse the (created/updated)_time into a ZonedDateTime so I can convert it to UTC?

回答1:

Well let me break down the problem statement.

First if you are querying an API then it can be assumed that they are following some standard Date-Time format (even if you are creating one). Looking over the given date it looks like they follow - ** ISO 8601 - Date and time format **

So the problem is how to parse ISO 8601 - Date and time format

What are best options available ?

Using Joda Time.

Using Date Time API Java-8

//Joda
String jtDate = "2010-01-01T12:00:00+01:00";
DateTimeFormatter yoda = ISODateTimeFormat.dateTimeNoMillis();
System.out.println(parser2.parseDateTime(jtDate));

//using Java 8 (As you specified - To convert "+0100" to "+01:00"    is easy enough.)
String strDate = "2017-01-05T16:32:29+01:00";
DateTimeFormatter timeFormatter = DateTimeFormatter.ISO_DATE_TIME;
TemporalAccessor convertMe = timeFormatter.parse(strDate);
Date date = Date.from(Instant.from(convertMe));
System.out.println(date);

Hope it helps :)

回答2:

There are some options.

First, as you say, inserting a colon in zone offset is not that difficult. After you’ve done that, getting a ZonedDateTime is straightforward:

    ZonedDateTime zdt = ZonedDateTime.parse("2017-01-11T09:38:41+01:00");
    System.out.println(zdt);

This prints:

2017-01-11T09:38:41+01:00

Alternatively, funnily, while ZonedDateTime.parse(String) needs a colon in the offset, ZoneId.of() does not, so you may split off the offset and do:

    ZoneId zi = ZoneId.of("+0100");
    LocalDateTime ldt = LocalDateTime.parse("2017-01-11T09:38:41");
    ZonedDateTime zdt = ldt.atZone(zi);

The result is the same as before.

If you prefer not to modify your string prior to parsing it, there is also:

    DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ssZ");
    ZonedDateTime zdt = ZonedDateTime.parse("2017-01-11T09:38:41+0100", dtf);

Also this gives the same result.

Edit: Note: I am using ZonedDateTime since you asked for this in your question. You may consider it more correct to use OffsetDateTime. Most of the code is practically the same. The version that splits off the offset would go like this:

    ZoneOffset zo = ZoneOffset.of("+0100");
    LocalDateTime ldt = LocalDateTime.parse("2017-01-11T09:38:41");
    OffsetDateTime odt = ldt.atOffset(zo);

To convert to UTC, as mentioned at end of Question, apply another ZoneOffset, the constant ZoneOffset.UTC.

OffsetDateTime odtUtc = odt.withOffsetSameInstant( ZoneOffset.UTC );

来源：https://stackoverflow.com/questions/41612687/determine-timezone-from-a-json-string

标签

java

json

zoneddatetime