Jackson deserialize ISO8601 formatted date-time into Java8 Instant

Question

I'm trying to deserialize an ISO8601 formatted date into Java8 java.time.Instant using Jackson. I registered JavaTimeModule with the ObjectMapper, and turned off the WRITE_DATES_AS_TIMESTAMPS setting.

However, if one tries to deserialize 2016-03-28T19:00:00.000+01:00 it will not work, because it seems that JavaTimeModule will only deserialize date-times formatted with UTC timezone offset (e.g. 2016-03-28T18:00:00.000Z). I then tried using @JsonFormat annotation like this:

@JsonFormat(shape=JsonFormat.Shape.STRING, pattern="yyyy-MM-dd'T'HH:mm:ss.SSSZ", timezone = "UTC") 

And like this:

@JsonFormat(shape=JsonFormat.Shape.STRING, pattern="yyyy-MM-dd'T'HH:mm:ss.SSSZ", timezone = JsonFormat.DEFAULT_TIMEZONE) 

However, neither of these work and I get an exception:

com.fasterxml.jackson.databind.JsonMappingException: Unsupported field: YearOfEra (through reference chain: org.example.Article["date"]) 

Which implies that timezone parameter is ignored and date time formatter doesn't know how to format an Instant without a timezone.

Is there a way to deserialize a ISO8601 string that's not in UTC time zone offset to Java 8 java.time.Instant using Jackson and JavaTimeModule without writing a custom deserializer?

Answer 1

You need to set the explicit time zone via XXX in your modell class:

@JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd'T'HH:mm:ss.SSSXXX") 

(see: https://docs.oracle.com/javase/7/docs/api/java/text/SimpleDateFormat.html)

Answer 2

If you want to serialize Date objects into ISO-8601, you don't need to specify a pattern at all - ISO-8601 is the default pattern. It is kind of mentioned in the JsonFormat Java doc:

Common uses include choosing between alternate representations -- for example, whether Date is to be serialized as number (Java timestamp) or String (such as ISO-8601 compatible time value) -- as well as configuring exact details with pattern() property.

[emphasasis mine] you should understand from the above text that specifying shape = STRING would mean an ISO-8601 format but you can choose something else using the pattern property.

In my experience, this always turns out a UTC date format (with the time zone rendered as +0000), which could be the default time zone in my VM (even though my operating system clock is not set to UTC).