Question

我们什么时候需要从持久化上下文中分离实体？

Answer 1

实体的分离意味着，hibernate不再具有对实体的访问权限。让我们看看使用下面的例子。

//Thid is where the entity is in transient State (Ther data is not saved, but initialized)
User user = new user
user.setName("User1");
Configuration configuration = new Configuration().configure();
    StandardServiceRegistryBuilder builder = (StandardServiceRegistryBuilder) new StandardServiceRegistryBuilder()
            .applySettings(configuration.getProperties());
    ServiceRegistry serviceRegistry = builder.build();
    SessionFactory factory = configuration.buildSessionFactory(serviceRegistry);

    Session session = factory.openSession();
    Transaction tx = session.beginTransaction();
    user.setUserName("Hello There");//Here the data is in persistent state
    session.save(user);
    user.setUserName("Hello There Again");//Here also the data is in persistent state
            user.setUserName("Hello There Again for second time");//Here also the data is in persistent state, but the hibernate will take the last update, if you see the query in log/console, you will find only one update query.
    tx.commit();
    session.close();
    user.setUserName("Hello Again Final");//Since the session is closed, the data is not persisted, Here the entity is detached
    factory.close();
    StandardServiceRegistryBuilder.destroy(serviceRegistry);

关闭数据库后会发生实体的分离，通常在执行session.close（）后发生。

有关工作流程的更多信息，请访问https://javabrains.io/courses/hibernate_run/lessons/Understanding-State-Changes

从持久化上下文中分离实体的用例？

1 个答案: