hi!

In case anybody is interested: Here is my take on this very common
problem of handling timestamps expressed in arbitrary timezones:

I understand that there is no easy and portable way to store timestamps
with timezone information in the database. Thus I'm using SQL type
TIMESTAMP (which has no timezone information) to store timestamp
information and normalize all timestamps in the database to UTC.

A UTC database timestamp is mapped as a Hibernate timestamp type to a
java.util.Date. A java.util.Date also has no timezone information.

However, the getter/setter for a timestamp property on the Java entity
type returns/takes a java.util.Calendar object. A java.util.Calendar
contains timezone information, thus to the client of the Java class
there can never be any doubt in which timezone a timestamp is expressed.

(I use Hibernate field access for the Hibernate mapping because of the
above.)

The setter immediately converts the Calendar timestamp to a
java.util.Date in UTC to set the entity's field. Conversely, the getter
constructs a java.util.Calendar with timezone UTC and initializes it
from the entity's field.

Thus, the information about the timezone in which the client originally
expressed a timestamp is lost, but the timezone handling is otherwise
correct.

  cheers,
  gerald