什么是休眠中的分离，持久和瞬态对象？ [英] What are detached, persistent and transient objects in hibernate?

问题描述

什么是hibernate中的分离，持久和瞬态对象？请解释一个例子。

解决方案

一个持久性 new 没有与 Session 关联的类在数据库中没有表示，并且没有将标识符值视为 transient Hibernate：

  Person person = new Person（）; 
 person.setName（Foobar）; 
 //人处于过渡状态
  

A 持久 实例在数据库中具有一个表示形式，一个标识符值并与 Session 关联。您可以通过将 persistent 与 Session 关联：

  Long id =（Long）session.save（person）; 
 //人现在处于持久状态
  

现在，如果我们 close Hibernate Session ，持久化实例将成为 detached 实例：它不再附加到 Session 中（但是仍然可以修改并在稍后重新附加到新的 Session 中） 。

所有这些在整个第10章。处理Hibernate文档中的对象，我只是在上面进行了解释。当然，必须阅读。

What are detached, persistent and transient objects in hibernate? Please explain with an example.

解决方案

A new instance of a persistent class which is not associated with a Session, has no representation in the database and no identifier value is considered transient by Hibernate:

Person person = new Person();
person.setName("Foobar");
// person is in a transient state

A persistent instance has a representation in the database, an identifier value and is associated with a Session. You can make a transient instance persistent by associating it with a Session:

Long id = (Long) session.save(person);
// person is now in a persistent state

Now, if we close the Hibernate Session, the persistent instance will become a detached instance: it isn't attached to a Session anymore (but can still be modified and reattached to a new Session later though).

All this is clearly explained in the whole Chapter 10. Working with objects of the Hibernate documentation that I'm only paraphrasing above. Definitely, a must-read.

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