Hibernate 多对一连接表单向关联

一、模型介绍

 

多个人（Person）对应一个地址（Address）。

 

二、实体（省略getter、setter方法）

 

public class Personn1tab {

    private int personid;

    private String name;

    private int age;

    private Addressn1tab addressn1tab;

 

public class Addressn1tab {

    private int addressid;

    private String addressdetail;

 

三、表模型

 

mysql> desc address_n1tab;

+---------------+--------------+------+-----+---------+----------------+

| Field         | Type         | Null | Key | Default | Extra          |

+---------------+--------------+------+-----+---------+----------------+

| addressid     | int(11)      | NO   | PRI | NULL    | auto_increment |

| addressdetail | varchar(255) | YES  |     | NULL    |                |

+---------------+--------------+------+-----+---------+----------------+

 

mysql> desc join_n1tab;

+------------+---------+------+-----+---------+-------+

| Field      | Type    | Null | Key | Default | Extra |

+------------+---------+------+-----+---------+-------+

| personid   | int(11) | NO   | PRI |         |       |

| addressn1tab | int(11) | YES  | MUL | NULL    |       |

+------------+---------+------+-----+---------+-------+

 

mysql> desc person_n1tab;

+----------+--------------+------+-----+---------+----------------+

| Field    | Type         | Null | Key | Default | Extra          |

+----------+--------------+------+-----+---------+----------------+

| personid | int(11)      | NO   | PRI | NULL    | auto_increment |

| name     | varchar(255) | YES  |     | NULL    |                |

| age      | int(11)      | YES  |     | NULL    |                |

+----------+--------------+------+-----+---------+----------------+

 

四、生成的SQL脚本

 

CREATE TABLE `address_n1tab` (

  `addressid` int(11) NOT NULL auto_increment,

  `addressdetail` varchar(255) default NULL,

  PRIMARY KEY  (`addressid`)

) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=gbk;

 

CREATE TABLE `join_n1tab` (

  `personid` int(11) NOT NULL,

  `address11fk` int(11) default NULL,

  PRIMARY KEY  (`personid`),

  KEY `FKAC780AAADAE3A82C` (`personid`),

  KEY `FKAC780AAAC6242A64` (`address11fk`),

  CONSTRAINT `FKAC780AAAC6242A64` FOREIGN KEY (`address11fk`) REFERENCES `address_n1tab` (`addressid`),

  CONSTRAINT `FKAC780AAADAE3A82C` FOREIGN KEY (`personid`) REFERENCES `person_n1tab` (`personid`)

) ENGINE=InnoDB DEFAULT CHARSET=gbk;

 

CREATE TABLE `person_n1tab` (

  `personid` int(11) NOT NULL auto_increment,

  `name` varchar(255) default NULL,

  `age` int(11) default NULL,

  PRIMARY KEY  (`personid`)

) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=gbk;

 

 

五、映射方法

 

<hibernate-mapping>

    <class name="com.lavasoft.dx._n_1_tab.Personn1tab" table="PERSON_n1tab">

        <id name="personid">

            <generator class="identity"/>

        </id>

        <property name="name"/>

        <property name="age"/>

        <!--使用join元素显式确定链接表-->

        <join table="join_n1tab">

            <!--映射关联所用的外键-->

            <key column="personid"/>

            <many-to-one name="addressn1tab"/>

        </join>

    </class>

</hibernate-mapping>

 

<hibernate-mapping>

    <class name="com.lavasoft.dx._n_1_tab.Addressn1tab" table="ADDRESS_n1tab">

        <id name="addressid">

            <generator class="identity"/>

        </id>

        <property name="addressdetail"/>

    </class>

</hibernate-mapping>

 

 

六、测试方法

 

public class Test_n1tab {

    public static void main(String[] args){

        Personn1tab p1=new Personn1tab();

        Personn1tab p2=new Personn1tab();

 

        p1.setAge(21);

        p1.setName("p1");

 

        p2.setAge(23);

        p2.setName("p2");

 

        Addressn1tab add=new Addressn1tab();

        add.setAddressdetail("郑州市经三路");

 

        p1.setAddressn1tab(add);

        p2.setAddressn1tab(add);

 

        Session session=HibernateUtil.getCurrentSession();

        Transaction tx=session.beginTransaction();

        session.save(add);

        session.save(p1);

        session.save(p2);

        tx.commit();

        HibernateUtil.closeSession();

    }

}

 

七、测试结果

 

1) :正常保存. 推荐这么干!

 

        session.save(p1);

        session.save(p2);

 

Hibernate: insert into ADDRESS_n1tab (addressdetail) values (?)

Hibernate: insert into PERSON_n1tab (name, age) values (?, ?)

Hibernate: insert into join_n1tab (address11fk, personid) values (?, ?)

Hibernate: insert into PERSON_n1tab (name, age) values (?, ?)

Hibernate: insert into join_n1tab (address11fk, personid) values (?, ?)

 

2) :正常保存.

        session.save(p1);

        session.save(p2);

        session.save(add);

 

 Hibernate: insert into PERSON_n1tab (name, age) values (?, ?)

 Hibernate: insert into join_n1tab (address11fk, personid) values (?, ?)

 Hibernate: insert into PERSON_n1tab (name, age) values (?, ?)

 Hibernate: insert into join_n1tab (address11fk, personid) values (?, ?)