Hibernate Date Format Driver Can Calculate

As a rule of thumb, its much easier if all datetime values are stored in the UTC format, and, if necessary, dealing with time zone conversions in the UI only.

By default, the TimestampType Hibernate class is going to set the PreparedStatement timestamp bind variable like this.

Hibernate Date Format Driver Can Calculate

With a Calendar object, the driver can calculate the timestamp taking into account a custom timezone.

If no Calendar object is specified, the driver uses the default timezone, which is that of the virtual machine running the application.

This method uses the given calendar to construct an appropriate millisecond value for the timestamp if the underlying database does not store timezone information.

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Luckily, the hibernate.jdbc.timezone Hibernate configuration property is a great addition.

One is marked with CreationTimestamp annotation the other is not.

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The field modifyDate however, does not have a specified Type.

The primary difference between Date and Timestamp in SQL is that Timestamp holds the date and time while the Date only holds the date.

At first glance this doesnt appear to be a big deal.

But why are they not equal.

I found a helpful answer to this question in Effective Java (2nd Edition) page 41.

There are some classes in the Java platform libraries that do extend an instantiable class and add a value component.

The equals implementation for Timestamp does violate symmetry and can cause erratic behavior if.

Timestamp and Date objects are used in the same collection or are otherwise intermixed.

The Timestamp class has a disclaimer cautioning programmers against mixing dates and timestamps.

While you wont get into trouble as long as you keep them separate, theres nothing to prevent you from mixing them, and the.

This behavior of the Timestamp class was a mistake and should not be emulated.

Bloch, Effective Java, 2nd Ed.).

Apart from a hack there are two primary ways to solve this issue.

The first way involves typing createDate and modifyDate to Timestamp.

Here is a custom UserType that converts Timestamp to Date and vise versa.

If this is not acceptable then the previous solution should be used.

This issue is not a Hibernate issue it is truly a Java issue as is stated in Effective Java (2nd Edition).

Hibernate can be challenging enough without these subtle issues that are easy to miss until a bug is reported.