HIbernate符合Java习惯的关系数据库持久化之实例状态

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本文详细解释了对象在三种不同持久化状态中的含义：瞬态、持久化和脱管。这些状态与Hibernate会话（即持久化上下文）密切相关，并探讨了每种状态下实例的特点及其与数据库的关系。

An instance of a persistent class can be in one of three different states. These states are defined in relation to a persistence context . The Hibernate Session object is the persistence context. The three different states are as follows:

瞬态（transient）

The instance is not associated with any persistence context. It has no persistent identity or primary key value.

持久化(persistent)

The instance is currently associated with a persistence context. It has a persistent identity (primary key value) and can have a corresponding row in the database. For a particular persistence context, Hibernate guarantees that persistent identity is equivalent to Java identity in relation to the in-memory location of the object.

脱管(detached)

The instance was once associated with a persistence context, but that context was closed, or the instance was serialized to another process. It has a persistent identity and can have a corresponding row in the database. For detached instances, Hibernate does not guarantee the relationship between persistent identity and Java identity.