android - ormlite是否支持继承？

Question

ormlite 是否支持这三种继承策略？

• 每个类层次结构的表
• 每个子类的表
• 每个具体类的表

我找到了 this discussion on the ORMLite user group ，但我不确定它是否回答了我的问题。

特别是我想使用“每个类层次结构的表”。如果 ormlite 框架不支持它们，我将制作一个类并忘记继承，但我更愿意使用继承。

Answer 1

ORMLite不自动支持这些，不。我不确定您是否真的阅读了链接到的线程，因为它非常具体:

What I need is: If I have class A as a superclass, and I have direct subclasses B and C, and I run a query for all records/objects of class A, I do want to have all objects of class A, B and C returned.

是的，ORMLite 不这样做，目前我没有计划支持它。除非我对如何实现这一点有误，否则它的复杂性超出了我所说的“精简版”。 Hibernate 支持此类结构的方式是使用外键、多个表和魔术连接。

这个问题给出了一些关于如何使用 ORMLite 实现继承的想法:

1) You could have class A and an associated table -- so it can't be abstract. Then you could have have B and C which subclass A and have all of As fields each in a separate table. You could then create a special DAO for A which would also query for B and C and add them into your results for A.

2) Another way to do it is you could make classes B and C not be subclasses but instead have a foreign object to A. You can then query all of the As and some of them would be B's A part and some C's A part and some just A. You then could also query Bs and Cs and use the A DAO to refresh and get the A's fields you would not be able to cast. A could also have some sort of enum which said whether it was a A, B, or C. You could also do some magic where you could say getSubClassObject(), if would look at the enum and query the B or C dao for the associated object with the right foreign key for the A object.