Hibernate中如何处理一对多关系中的组合主键

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前段时间碰到这个问题，主要是hbm文件的的写法问题。我建了两个表，parent中的Pid与child中的Cid是一对多关系,Child中的cid与otherid只组合主键.如下

parent表

字段名       

类型

长度

Pid  (PK)

Character

10

Name

Character

10

 Child表

字段名   

类型

长度

cid       (PK)

Character

10

Otherid    (PK)

Smallint

 

Name

Character

10

hbm文件：

Parent.hbm.xml

<?xml version="1.0" encoding="GB2312"?><!DOCTYPE Hibernate-mapping PUBLIC   "-//Hibernate/Hibernate Mapping DTD 2.0//EN"     "Hibernate.sourceforge.net/Hibernate-mapping-2.0.dtd"'">http://Hibernate.sourceforge.net/Hibernate-mapping-2.0.dtd">

<Hibernate-mapping><class name="Parent" table="parent"><id            name="pid"            column="pid"            type="string"            unsaved-value="any"        >            <generator class="assigned"/>        </id><property name="name"/><set name="children" cascade="all-delete-orphan" inverse="true" lazy="true" >         <key column="CID" />        <one-to-many class="Child"/> </set></class></Hibernate-mapping>

Child.hbm.xml

<?xml version="1.0" encoding="GB2312"?><!DOCTYPE Hibernate-mapping PUBLIC   "-//Hibernate/Hibernate Mapping DTD 2.0//EN"     "Hibernate.sourceforge.net/Hibernate-mapping-2.0.dtd"'">http://Hibernate.sourceforge.net/Hibernate-mapping-2.0.dtd">

<Hibernate-mapping><class name="Child" table="child"><composite-id name="childpk" class="Childpk" unsaved-value="any"> <key-many-to-one name="parent" class="Parent" column="cid" /><key-property name="otherid" column="otherid" type="integer"/> </composite-id> <many-to-one name="parent" class="Parent" column="CID" cascade="save-update" not-null="true" update="false" insert="false" /><property name="name" column="name" type="string" /></class></Hibernate-mapping>

这两个hbm文件里面主要是：Parent中的<set name="children" cascade="all-delete-orphan" inverse="true" lazy="true" >         <key column="CID" />        <one-to-many class="Child"/> </set> 和Child中的<many-to-one name="parent" class="Parent" column="CID" cascade="save-update" not-null="true" update="false" insert="false" />

这两个构成一对多关系中组合主键的双向关联。另外在写PO类的时候要注意hashcode和equals写的正确

 

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