Hibernate关联之 多对一连接表单向关联

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

 

ManyToOneTabPerson.hbm.xml

<hibernate-mapping>     <class name="com.bean.Personn1tab" table="PERSON_1ntab">        <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>

ManyToOneTabAddress.hbm.xml

<hibernate-mapping>     <class name="com.bean.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.setName("p1");        p1.setAge(21);        p2.setName("p2");        p2.setAge(23);         Addressn1tab add=new Addressn1tab();         add.setAddressdetail("大连市");         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();     } }