An EntityManager instance is associated with a persistence context. A persistence context is a set of entity instances in which for any persistent entity identity there is a unique entity instance. Within the persistence context, the entity instances and their lifecycle are managed. The EntityManager ...
void lock(Object entity, LockModeType lockMode, Map<String,Object> properties) Lock an entity instance that is contained in the persistence context with the specified lock mode type and with specified properties. T merge(T entity) Merge the state of the given entity into the current persistence...
Entities are managed by the entity manager, which is represented byjavax.persistence.EntityManagerinstances. EachEntityManagerinstance is associated with a persistence context: a set of managed entity instances that exist in a particular data store. A persistence context defines the scope under which par...
Specifies whether a transaction-scoped or extended persistence context is to be used inPersistenceContext. PessimisticLockScope Defines the values of thejavax.persistence.lock.scopeproperty for pessimistic locking. SharedCacheMode Specifies how the provider must use a second-level cache for the persistence...
Persistence Context Duration: 1h 45m Persistence Context and Flushing Basics Action Queue The AUTO FlushModeType Dirty Checking Mechanism Bytecode Enhancement Dirty Checking Fetching Duration: 1h 45m Direct and Natural id fetching DTO projections vs Entity queries LAZY vs. EAGER Query-time fetching ...
Persistence, in the context of JPA, is about storing data between application sessions. When an object’s state is stored in a database, it’s said to be ‘persistent’. Book book = new Book(); book.setTitle("JPA Guide"); em.persist(book); ...
context.unitName() : null; if (StringUtils.isEmpty(persistenceUnitName)) persistenceUnitName = null; return persistenceUnitName; } 代码示例来源:origin: org.apache.tapestry/tapestry-jpa public static EntityManager getEntityManager(EntityManagerManager entityManagerManager, PersistenceContext annotation) { Strin...
持久化上下文(Persist Context)就是一个受管的Entity实例的集合。 每一个持久化上下文都关联一个持久化单元,持久化上下文不可能脱离持久化单元独立存在。 持久化上下文是一个动态概念。 尽管持久化上下文非常重要,但是开发者不直接与之打交道,持久化上下文在程序中是透明的,我们通过EntityManager间接管理它。
persistence-context-ref is included in ejb-jar_3_0.xsd by reference. It's actually defined within the javaee_5.xsd. In Java EE, the programming model for the component environment is essentially the same across the different component types (EJB, web tier, Application Client), so the ...
第一需要用 org.pringframework.stereotype.Repository 来 annotate 这个 DAO,然后在 XML 中使用 context:component-scan 对这个 package 扫描,并增加一个 bean,来自org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor 类,通过 AOP 就能解决这个问题了。如此一来我们甚至不需要前面的 template ...