Sunday, December 21, 2014

The Value of Annotation @Temporal for Date Related Columns

The annotation @Temporal in official javadoc is described like below:
This annotation must be specified for persistent fields or properties of type java.util.Date and java.util.Calendar.

So when the field variable is a java.util.Date or java.util.Calendar, it MUST be annotated by @Temporal.

There are 3 values for @Temporal

  • TemporalType.DATE
  • TemporalType.TIME
  • TemporalType.TIMESTAMP

Here is a demo to show the usage of there 3 values. The Entity 'MyEntity' has a field called 'lastUpdateTime' which is a defined as a java.util.Date variable. let's update it in java like this:

  import java.util.Date;
//...
// MyEntity is the JPA entity, em is EntityManager context
MyEntity e = em.find(MyEntity.class, 1L); //get the row with id=1
e.setLastUpdateTime(new Date());

TemporalType.DATE


If the column annotated with @Temporal(TemporalType.DATE) like this:

  @Temporal(TemporalType.DATE)
@Column(name="LAST_UPDATE_TIME")
private Date lastUpdateTime;

The record in database after update will look like:Snap_2014.12.22 12.49.51_001


TemporalType.TIME


If the column annotatedwith @Temporal(TemporalType.TIME) like this:

  @Temporal(TemporalType.TIME)
@Column(name="LAST_UPDATE_TIME")
private Date lastUpdateTime;

The record in database after update will look like:Snap_2014.12.22 13.06.58_002


TemporalType.TIMESTAMP


If the column annotated with @Temporal(TemporalType.TIMESTAMP) like this:

  @Temporal(TemporalType.TIMESTAMP)
@Column(name="LAST_UPDATE_TIME")
private Date lastUpdateTime;

The record in database after update will look like:Snap_2014.12.22 13.10.14_003

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Has been a senior software developer, project manager for 10+ years. Dedicate himself to Alcatel-Lucent and China Telecom for delivering software solutions.

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