java - ISO8601 with milliseconds in json using Jackson

Question

import com.fasterxml.jackson.databind.util.ISO8601DateFormat;

objectMapper.setDateFormat(new ISO8601DateFormat());

Nice but this ignores milliseconds, how can I get them in the dates without using the non-thread-safe SimpleDateFormatter?

https://github.com/FasterXML/jackson-databind/blob/master/src/main/java/com/fasterxml/jackson/databind/util/ISO8601DateFormat.java

Answer 1

ISO8601DateFormat.format calls ISO8601Utils.format(date), which in turn calls format(date, false, TIMEZONE_Z) - the false parameter tells jackson to don't include the milliseconds.

There seems to be no way to configure this class nor set any parameter, but fortunately it can be extended:

public class ISO8601WithMillisFormat extends ISO8601DateFormat {
    @Override
    public StringBuffer format(Date date, StringBuffer toAppendTo, FieldPosition fieldPosition) {
        String value = ISO8601Utils.format(date, true); // "true" to include milliseconds
        toAppendTo.append(value);
        return toAppendTo;
    }
}

Then we can use this new class in the object mapper:

ObjectMapper objectMapper = new ObjectMapper();
ISO8601DateFormat dateFormat = new ISO8601WithMillisFormat();
objectMapper.setDateFormat(dateFormat);

I've made a test with new Date() and the result was 2017-07-24T12:14:26.817Z (with the milliseconds).