java - 不可变对象(immutable对象)和更新

Question

如果我使用一个名为 Name 的不可变类来存储人们的姓名，并且有人想要更改他们的姓名，那么他们的姓名不应该被更新(本质上是删除旧条目并插入新条目) )？这似乎与不可变的定义(通过注释)相矛盾，因为更新实体将被忽略。如果数据库中存储的不可变类需要更新怎么办？即使它是一个不可变类，也不应该将其映射为@Immutable 吗？

Answer 1

引用文献说:

When an entity is read-only:

• Hibernate does not dirty-check the entity's simple properties or single-ended associations;
• Hibernate will not update simple properties or updatable single-ended associations;
• Hibernate will not update the version of the read-only entity if only simple properties or single-ended updatable associations are changed;

它还说:

In some ways, Hibernate treats read-only entities the same as entities that are not read-only:

• Hibernate cascades operations to associations as defined in the entity mapping.
• Hibernate updates the version if the entity has a collection with changes that dirties the entity;
• A read-only entity can be deleted.

因此，我认为您必须删除()实例，然后使用新名称再次保存()它，因为脏检查不会发生在只读实体上。

引用:Read-only entities