Hibernate 多对多双向关联

一、模型介绍

 

多个人（Person）对应多个地址（Address）。

一个人可对应多个地址，一个地址也可以对应多个人。

 

二、实体（省略getter、setter方法）

 

public class Personnn_sx {

    private int personid;

    private String name;

    private int age;

    private Set addresses=new HashSet();

 

public class Addressnn_sx {

    private int addressid;

    private String addressdetail;

    private Set persons = new HashSet();

 

三、表模型

 

mysql> desc person_nn_sx;

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

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

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

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

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

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

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

 

mysql> desc address_nn_sx;

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

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

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

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

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

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

 

mysql> desc join_nn_sx;

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

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

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

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

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

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

 

四、生成的SQL脚本

 

/* Formatted on 2007/08/22 17:59 (QP5 v5.50) */

CREATE TABLE `address_nn_sx` (

  `addressid` int(11) NOT NULL auto_increment,

  `addressdetail` varchar(255) default NULL,

  PRIMARY KEY  (`addressid`)

) ENGINE=InnoDB DEFAULT CHARSET=gbk;

 

/* Formatted on 2007/08/22 17:59 (QP5 v5.50) */

CREATE TABLE `person_nn_sx` (

  `personid` int(11) NOT NULL auto_increment,

  `name` varchar(255) default NULL,

  `age` int(11) default NULL,

  PRIMARY KEY  (`personid`)

) ENGINE=InnoDB DEFAULT CHARSET=gbk;

 

/* Formatted on 2007/08/22 17:59 (QP5 v5.50) */

CREATE TABLE `join_nn_sx` (

  `addressid` int(11) NOT NULL,

  `personid` int(11) NOT NULL,

  PRIMARY KEY  (`personid`,`addressid`),

  KEY `FK6EBBC5EF6C600921` (`personid`),

  KEY `FK6EBBC5EF2A92FF3D` (`addressid`),

  CONSTRAINT `FK6EBBC5EF2A92FF3D` FOREIGN KEY (`addressid`) REFERENCES `address_nn_sx` (`addressid`),

  CONSTRAINT `FK6EBBC5EF6C600921` FOREIGN KEY (`personid`) REFERENCES `person_nn_sx` (`personid`)

) ENGINE=InnoDB DEFAULT CHARSET=gbk;

 

五、映射方法

 

<hibernate-mapping>

    <class name="com.lavasoft.sx._n_n.Personnn_sx" table="PERSON_nn_sx">

        <id name="personid">

            <generator class="identity"/>

        </id>

        <property name="name"/>

        <property name="age"/>

        <!--映射集合属性，关联到持久化类-->

        <!--table="join_1ntab_sx"指定了连接表的名字-->

        <set name="addresses"

             table="join_nn_sx"

             cascade="all">

            <!--column="personid"指定连接表中关联当前实体类的列名-->

            <key column="personid" not-null="true"/>

            <!--column="addressid"是连接表中关联本实体的外键-->

            <many-to-many column="addressid"

                          class="com.lavasoft.sx._n_n.Addressnn_sx"/>

        </set>

    </class>

</hibernate-mapping>

 

<hibernate-mapping>

    <class name="com.lavasoft.sx._n_n.Addressnn_sx"

           table="ADDRESS_nn_sx">

        <id name="addressid">

            <generator class="identity"/>

        </id>

        <property name="addressdetail"/>

        <!--table="join_nn_sx"是双向多对多的连接表-->

        <set name="persons"

             inverse="true"

             table="join_nn_sx">

            <!--column="addressid"是连接表中关联本实体的外键-->

            <key column="addressid"/>

            <many-to-many column="personid"

                          class="com.lavasoft.sx._n_n.Personnn_sx"/>

        </set>

    </class>

</hibernate-mapping>

 

六、测试方法

 

public class Test_nn_sx {

    public static void main(String[] args){

        Addressnn_sx add1=new Addressnn_sx();

        Addressnn_sx add2=new Addressnn_sx();

        Personnn_sx p1=new Personnn_sx();

        Personnn_sx p2=new Personnn_sx();

 

        add1.setAddressdetail("郑州市经三路");

        add2.setAddressdetail("合肥市宿州路");

        p1.setName("wang");

        p1.setAge(30);

        p2.setName("zhang");

        p2.setAge(22);

 

        p1.getAddresses().add(add1);

        p1.getAddresses().add(add2);

        p2.getAddresses().add(add2);

        add1.getPersons().add(p1);

        add2.getPersons().add(p1);

        add2.getPersons().add(p2);

 

 

        Session session= HibernateUtil.getCurrentSession();

        Transaction tx=session.beginTransaction();

        session.save(p1);

        session.save(p2);

//        session.saveOrUpdate(add1);

//        session.saveOrUpdate(add2);

        tx.commit();

        HibernateUtil.closeSession();

    }

}

 

七、测试结果

 

1) :正常保存.

        session.save(p1);

        session.save(p2);

//        session.saveOrUpdate(add1);

//        session.saveOrUpdate(add2);

 

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

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

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

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

  Hibernate: insert into join_nn_sx (personid, addressid) values (?, ?)

  Hibernate: insert into join_nn_sx (personid, addressid) values (?, ?)

  Hibernate: insert into join_nn_sx (personid, addressid) values (?, ?)