示例数据表：team(班级)、certificate(身份证)、student(学生)

Team.hbm.xml

<?xml version="1.0" encoding="utf-8"?>

<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<>

<hibernate-mapping>

<class name="edu.dgut.ke.model.Team" table="TEAM" lazy ="true" ><>

<id name="id" type="java.lang.String">

<column name="ID" length="32" />

<generator />

</id>

<property name="teamname" type="java.lang.String">

<column name="TEAMNAME" length="32" not-null="true" unique="true" />

</property>

<set name="students" inverse="true" cascade="all" lazy="true" > <>

<key>

<column name="TEAMID" length="32" not-null="true" />

</key>

<one-to-many />

</set>

</class>

</hibernate-mapping>

Certificate.hbm.xml

<?xml version="1.0" encoding="utf-8"?>

<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<>

<hibernate-mapping>

<class name="edu.dgut.ke.model.Certificate" table="CERTIFICATE" lazy="true" ><>

<id name="id" type="java.lang.String">

<column name="ID" length="32" />

<generator>

</generator>

</id>

<property name="describe" type="java.lang.String">

<column name="`DESCRIBE`" length="50" not-null="true" />

</property>

<one-to-one name="student"

constrained="true" ><>

</one-to-one>

</class>

</hibernate-mapping>

Student.hbm.xml

<?xml version="1.0" encoding="utf-8"?>

<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<>

<hibernate-mapping>

<class name="edu.dgut.ke.model.Student" table="STUDENT" lazy="true" >

<id name="id" type="java.lang.String">

<column name="ID" length="32" />

<generator />

</id>

<many-to-one name="certificate"

unique="true"

column="cardId"

cascade="all"

>

</many-to-one>

<many-to-one name="team">

<column name="TEAMID" length="32" not-null="true" />

</many-to-one>

<property name="studentname" type="java.lang.String">

<column name="STUDENTNAME" length="16" not-null="true" unique="true" />

</property>

</class>

</hibernate-mapping>

注意：对one-to-one 关系进行延迟加载和其他关系相比稍微有些不同。many-to-one 的延迟加载是在配置文件的class 标签

上设置 lazy="true" ，one-to-many 和 many-to-many 的延迟加载是在 set 标签中设置lazy="true"。而one-to-one 不只要在 classs

标签设置 lazy="true"，而且要在one-to-one 标签中设置constrained="true" 。

如果不设置constrained="true"，则一对一查询使用默认的预先抓取策略(fetch="join")。

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