Hibernate：是否可以手动将对象添加到二级缓存？

Question

In my project I want to cache few objects but not whole table. So my problem is, is there a API that i could use to manually add objects to hibernate second level cache ? ( Or is there a way to specify table data region for second level cache ? )

Answer 1

You can annotate with @Cacheable(true) the entities you want to cache

@Cacheable(true)
@Entity
public class Person { ... }

and then in your persistence.xml configuration file, you need to set the shared-cache-mode element to use ENABLE_SELECTIVE :

<shared-cache-mode>ENABLE_SELECTIVE</shared-cache-mode>

so now:

Caching is enabled for all entities for Cacheable(true) is specified. All other entities are not cached.

To specify regions, you can use the Hibernate specific @Cache annotation:

@Cacheable(true)
@Cache(usage=CacheConcurrencyStrategy.READ_WRITE, region="your-entity-region")
@Entity
public class Person { ... }

Now, you have to enable the 2nd-level cache:

<prop key="hibernate.cache.use_second_level_cache">true</prop>
<property name="hibernate.cache.region.factory_class">ehcache</property>

To add entities to the 2nd level cache, you just need to just load the entity (and it will be cached automatically):

Person person = entityManager.find(Person.class, 1L);