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Hibernate ORM 5.4.0.CR1 发布，数据持久层框架

Hibernate ORM 5.4.0 的第一个候选版本已发布。

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改进 EntityGraph

JPA 的 EntityGraph 功能定义和使用起来很麻烦。Hibernate ORM 5.4 增加了2个新功能，可帮助您更轻松地使用 EntityGraphs。请注意，所有这些改进都被视为孵化阶段。

EntityGraph 的解析功能

第一个功能是能够从 String 创建图形。例如，给定一个 Person 实体，我们可能想要确保这个 person 的 spouse 可被快速地取出：

final EntityGraph eg = org.hibernate.graph.EntityGraphs.parse( Person.class, "spouse", entityManager );      
      final Person personAndSpouse = entityManager.find( Person.class, 1,          Collections.singletonMap( "javax.persistence.fetchgraph", eg );

此解析支持 EntityGraph 创建的所有功能，包括子图和子类图。有关深入讨论和示例，请参阅文档。

EntityGraph 的操作功能

This is mainly about combining graphs. E.g.

final EntityGraph eg1 = org.hibernate.graph.EntityGraphs.parse( Person.class, "spouse", entityManager );      final EntityGraph eg2 = org.hibernate.graph.EntityGraphs.parse( Person.class, "spouse(age, dob)", entityManager );      final EntityGraph combinedGraph = org.hibernate.graph.EntityGraphs.merge( entityManager, Person.class, eg1, eg2 )      
      final Person personAndSpouse = entityManager.find( Person.class, 1,          Collections.singletonMap( "javax.persistence.fetchgraph", combinedGraph );

This is a very trivial example meant just for illustration. It can actually be much more easily defined as:

final EntityGraph combinedGraph = org.hibernate.graph.EntityGraphs.parse( Person.class, "spouse( age, dob )", entityManager );      
      final Person personAndSpouse = entityManager.find( Person.class, 1,          Collections.singletonMap( "javax.persistence.fetchgraph", combinedGraph );