.Hibernate一对一映射与组件映射

Posted 2020-08-06 零星一点

 

 

       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>