What time zone does Hibernate use when it reads and writes a Java Calendar object to an SQL TIMESTAMP?

Question

When Hibernate writes a Java Calendar object to an SQL TIMESTAMP column, to which time zone does it adjust the date, that of the computer or that specified in the c

Answer 1

I just spent 6 hours on a similar issue and thought I would document it here. Hibernate indeed does use the JVM timezone but it can be changed by extending the CalendarType like this:

public class UTCCalendarType extends CalendarType {

    private static final TimeZone UTC = TimeZone.getTimeZone("UTC");

    /**
     * This is the original code from the class, with two changes. First we pull
     * it out of the result set with an example Calendar. Second, we set the new
     * calendar up in UTC.
     */
    @Override
    public Object get(ResultSet rs, String name) throws SQLException {
        Timestamp ts = rs.getTimestamp(name, new GregorianCalendar(UTC));
        if (ts != null) {
            Calendar cal = new GregorianCalendar(UTC);
            cal.setTime(ts);
            return cal;
        } else {
            return null;
        }
    }

    @Override
    public void set(PreparedStatement st, Object value, int index) throws SQLException {
        final Calendar cal = (Calendar) value;
        cal.setTimeZone(UTC);
        st.setTimestamp(index, new Timestamp(cal.getTime().getTime()), cal);
    }
}

the secret sauce here is :

  rs.getTimestamp(name, new GregorianCalendar(UTC));

This converts the timezone from the result set to whatever timezone you want. So what I did was use this type with any UTC calendars and the standard Hibernate type for the local time. Works slick as a whistle...