Java.time (Java 8) support in Freemarker

Question

Does anybody know of any plans to support the new java.time api in FreeMarker? Or has anybody code laying around for supporting classes like ZonedDateTime, LocalDateTime and Instant?

Its not hard to see how to implement these things myself, but it is actually a rather big task.

Answer 1

Let's assume that you want format new date/time objects

1. Create custom method:

   public static class FormatDateTimeMethodModel 
           implements TemplateMethodModelEx {
       public Object exec(List args) throws TemplateModelException {
           if (args.size() != 2) {
               throw new TemplateModelException("Wrong arguments");
           }
           TemporalAccessor time = (TemporalAccessor) ((StringModel) args.get(0)).getWrappedObject();
           DateTimeFormatter formatter = DateTimeFormatter.ofPattern(((SimpleScalar) args.get(1)).getAsString());
           return formatter.format(time);
       }
   }
   

2. Put this method into template model:

   templateModel.put("formatDateTime", new FormatDateTimeMethodModel());

3. And invoke this method inside of template:

   ${formatDateTime(MY_DATE, 'HH:mm')}

Answer 2

Nobody deals with that right now (2.3.24), though it's known to be missing. It probably won't be trivial to do properly, unless degrading Java 8 date/time types to java.util.Date-s when they are returned by TemplateDateModel is acceptable.

BTW, I have added this to http://freemarker.org/contribute.html, so that it won't be forgotten.

Answer 3

private static class CustomObjectWrapper extends DefaultObjectWrapper {
    @Override
    public TemplateModel wrap(Object obj) throws TemplateModelException {
        if (obj instanceof LocalDateTime) {
            Timestamp timestamp = Timestamp.valueOf((LocalDateTime) obj);
            return new SimpleDate(timestamp);
        }
        if (obj instanceof LocalDate) {
            Date date = Date.valueOf((LocalDate) obj);
            return new SimpleDate(date);
        }
        if (obj instanceof LocalTime) {
            Time time = Time.valueOf((LocalTime) obj);
            return new SimpleDate(time);
        }
        return super.wrap(obj);
    }
}


@Autowired
private freemarker.template.Configuration configuration;

configuration.setObjectWrapper(new CustomObjectWrapper());