How to use JPA2's @Cacheable instead of Hibernate's @Cache

Typically , I use Hibernate's @Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE) to cache an @Entity class , and it works well.

In JPA2 , there's another @Cacheable annotation that seems to be the same functionality with Hibernate's @Cache. To make my entity class independent of hibernate's package , I want to give it a try. But I cannot make it work. Each time a simple id query still hits the DB.

Can anybody tell me where goes wrong ? Thanks.

Entity class :

@Entity
//@Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE)
@Cacheable(true) 
public class User implements Serializable
{
 // properties
}

Test class :

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations={"classpath:app.xml"})
@TransactionConfiguration(transactionManager="transactionManager")
public class UserCacheTest
{
  @Inject protected UserDao userDao;

  @Transactional
  @Test
  public void testGet1()
  {
    assertNotNull(userDao.get(2L));
  }

  @Transactional
  @Test
  public void testGet2()
  {
    assertNotNull(userDao.get(2L));
  }

  @Transactional
  @Test
  public void testGet3()
  {
    assertNotNull(userDao.get(2L));
  }
}

The test result shows each "get" hits DB layer (with hibernate.show_sql=true).

Persistence.xml :

<property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/>
<property name="hibernate.show_sql" value="true"/>
<property name="hibernate.format_sql" value="true" />
<property name="hibernate.use_outer_join" value="true"/>

<property name="hibernate.cache.provider_class" value="org.hibernate.cache.SingletonEhCacheProvider"/>
<property name="hibernate.cache.use_second_level_cache" value="true"/>
<property name="hibernate.cache.use_query_cache" value="true"/>

JPA code :

@Override
public T get(Serializable id)
{
  return em.find(clazz, id);
}