在Hibernate中映射多级继承 [英] Mapping multi-Level inheritance in Hibernate

问题描述

目前我有这样的结构：

  A 
 | 
 +  -  B 
 | 
 +  -  C 
  

它使用连接表映射到每个子类的一个表。由于历史原因，我也使用鉴别器，所以目前情况如 Hibernate手册第9.1.3节。

问题：扩展这样一个结构的映射：

  A 
 | 
 +  -  B 
 | | 
 | D 
 | 
 +  -  C 
  

我可以< subclass> a < subclass> 在hibernate映射中？

未经测试 ，但根据您发布的链接，如果您使用的是hibernate3

 <休眠映射> 
< class name =Atable =A> 
< id name =idtype =longcolumn =a_id> 
< generator class =native/> 
< / id> 
< discriminator column =discriminator_coltype =string/> 
< property name =type =/> 
<！ -  ...  - > 
< / class> 
< subclass name =Bextends =Adiscriminator-value =B> 
<！ -  ...  - > 
< / subclass> 
< subclass name =Dextends =Bdiscriminator-value =D> 
<！ -  ...  - > 
< / subclass> 
< subclass name =Cextends =Adiscriminator-value =C> 
<！ -  ...  - > 
< / subclass> 
< / hibernate-mapping> 
  

Currently I have a structure like this:

A
|
+--B
|
+--C

It's mapped with one table per subclass using joined tables. For historic reasons I also use a discriminator, so the current situation is as described in Section 9.1.3 of the Hibernate manual.

Question: How do I extend the mapping for a structure like this:

A
|
+--B
|  |
|  D
|
+--C

Can I <subclass> a <subclass> in the hibernate mapping? What <key>s do I need?

解决方案

not tested but, according to the link you posted if you are using hibernate3

<hibernate-mapping>
  <class name="A" table="A">
    <id name="id" type="long" column="a_id">
      <generator class="native"/>
    </id>
    <discriminator column="discriminator_col" type="string"/>
    <property name="" type=""/>
    <!-- ... -->
  </class>
  <subclass name="B" extends="A" discriminator-value="B">
    <!-- ... -->
  </subclass>
  <subclass name="D" extends="B" discriminator-value="D">
    <!-- ... -->
  </subclass>
  <subclass name="C" extends="A" discriminator-value="C">
    <!-- ... -->
  </subclass>
</hibernate-mapping>

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