.Hibernate一对一映射与组件映射

1.按照外键映射（Hibernate提供了两种映射一对一关联关系的方式：按照外键映射和按照主键映射）

实现需要：

创建实体类Users1和Resume1

public class Users1 {

private Integer userid;

private String username;

private String userpass;

private Resume1 resume1;

}

***********

public class Resume1 {

private Integer resid;

private String resname;

private String rescardno;

private Users1 users1;

}

-----------------------

配置文件Users1.hbm.xml和Resume1.hbm.xml：

Users1.hbm.xml

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

<!DOCTYPE hibernate-mapping PUBLIC

"-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="cn.happy.onetoone_fk">

<class name="Users1" table="USERS1">

<id name="userid" column="USERID" >

<generator class="native"></generator>

</id>

<property name="username" column="USERNAME" type="string"></property>

<property name="userpass" column="USERPASS" type="string"></property>

<one-to-one name="resume1" class="Resume1" property-ref="users1"></one-to-one>

</class>

</hibernate-mapping>

*********************

Resume1.hbm.xml

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

<!DOCTYPE hibernate-mapping PUBLIC

"-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="cn.happy.onetoone_fk">

<class name="Resume1" table="RESUME1">

<id name="resid" column="RESID" >

<generator class="native"></generator>

</id>

<property name="resname" column="RESNAME" type="string"></property>

<property name="rescardno" column="RESCARDNO" type="string"></property>

<many-to-one name="users1" class="Users1" cascade="all" column="RESUSERID" unique="true"></many-to-one>

</class>

</hibernate-mapping>

------------------------------------

2.主键映射

实现需要：

创建实体类Users2和Resume2

public class Users2 {

private Integer userid;

private String username;

private String userpass;

private Resume2 resume2;

}

*******************：

public class Resume2 {

private Integer resid;

private String resname;

private String rescardno;

private Users2 users2;

}

----------------------------

配置文件Users1.hbm.xml和Resume1.hbm.xml

Users1.hbm.xml

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

<!DOCTYPE hibernate-mapping PUBLIC

"-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="cn.happy.onetoone_pk">

<class name="Users2" table="USERS2">

<id name="userid" column="USERID" >

<generator class="foreign">

<param name="property">resume2</param>

</generator>

</id>

<property name="username" column="USERNAME" type="string"></property>

<property name="userpass" column="USERPASS" type="string"></property>

<one-to-one name="resume2" class="Resume2" constrained="true"></one-to-one>

</class>

</hibernate-mapping>

************************

Resume2.hbm.xml

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

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

"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="cn.happy.onetoone_pk">

<class name="Resume2" table="RESUME2">

<id column="RESID" name="resid">

<generator class="native"/>

</id>

<property column="RESNAME" name="resname" type="string"/>

<property column="RESCARDNO" name="rescardno" type="string"/>

<one-to-one  name="users2" cascade="all" class="Users2"/>

</class>

</hibernate-mapping>

==========================================

一  。组件映射（建立关系数据模型的一个重要原则是在不会导致数据冗余的前提下，尽可能减少数据库表的数目及表之间的外键参照关系）

实现需求：

创建EmpHomeAddress和EmpInfo

public class EmpHomeAddress {

private String ehomestreet;

private String ehomecity;

private String ehomeprovince;

private String ehomezipcode;

private EmpInfo empinfo;

}

--------------

public class EmpInfo {

private Integer eid;

private String ename;

private EmpHomeAddress ehome;

}

*************************

创建配置文件EmpInfo.hbm.xml

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

<!DOCTYPE hibernate-mapping PUBLIC

"-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="cn.happy.component">

<class name="EmpInfo" table="EMPINFO">

<id name="eid" column="EID">

<generator class="native"></generator>

</id>

<property name="ename" column="ENAME" type="string"></property>

<component name="ehome" class="EmpHomeAddress">

<parent name="empinfo"/>

<property name="ehomestreet" column="EHOMESTREET" type="string"></property>

<property name="ehomecity" column="EHOMECITY" type="string"></property>

<property name="ehomeprovince" column="EHOMEPROVINCE" type="string"></property>

<property name="ehomezipcode" column="EHOMEZIPCODE" type="string"></property>

</component>

</class>

</hibernate-mapping>