『提问』联合主键（compsite-id）所引起的问题

A表中first、second 作为主键同时也是B表的联合主键。原有系统还在使用，不能做修改。所以新建ID列的方法在此不能用。请问如何编写hbm文件
3x
A表 B表
first --------------------------------> first
second----------------------------->second
name item
配置文件：
A.hbm.xml


<?xml version="1.0"?> 
<!DOCTYPE hibernate-mapping PUBLIC 
"-//Hibernate/Hibernate Mapping DTD//EN" 
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd" > 

<hibernate-mapping package="com.travelsky.poc"> 
<class name="A" table="A"> 
<composite-id > 
<key-property column="FIRST" name="First" type="integer" /> 
<key-property column="SECOND" name="Second" 
type="integer" /> 
</composite-id > 

<property column="NAME" name="Name" type="string" /> 

</class> 
</hibernate-mapping>

B.hbm.xml


<?xml version="1.0"?> 
<!DOCTYPE hibernate-mapping PUBLIC 
"-//Hibernate/Hibernate Mapping DTD//EN" 
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd" > 

<hibernate-mapping package="com.travelsky.poc"> 
<class name="B" table="B"> 
<composite-id > 
[b]此处改如何填写 [/b]
</composite-id > 

<property column="NAME" name="Name" type="string" /> 
</class> 
</hibernate-mapping>