Hibernate 一对一连接表单向关联

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原文地址：http://lavasoft.blog.51cto.com/62575/39312

Hibernate 一对一连接表单向关联

 

    这种情况很少见，但Hibernate同样允许采用连接表关联1-1.有连接表的1-1同样只需要将N-1的many-to-one元素增加unique="true"属性即可。

 

一、模型介绍

 

一个人（Person）对应一个地址（Address）。

 

二、实体（省略getter、setter方法）

public class Person11tab { private int personid; private String name; private int age; private Address11tab address11tab; public class Address11tab { private int addressid; private String addressdetail;

三、表模型

 

mysql> desc address_11tab;

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

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

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

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

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

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

 

mysql> desc join_11tab;

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

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

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

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

| address11tab | int(11) | YES  | UNI | NULL    |       |

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

 

mysql> desc person_11tab;

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

| 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

 

/* Formatted on 2007/08/20 16:52 (QP5 v5.50) */

CREATE TABLE `join_11tab` (

  `personid` int(11) NOT NULL,

  `address11tab` int(11) default NULL,

  PRIMARY KEY  (`personid`),

  UNIQUE KEY `address11tab` (`address11tab`),

  KEY `FK6B44BE20C4CC3D33` (`address11tab`),

  KEY `FK6B44BE209049BB1F` (`personid`),

  CONSTRAINT `FK6B44BE209049BB1F` FOREIGN KEY (`personid`) REFERENCES `person_11tab` (`personid`),

  CONSTRAINT `FK6B44BE20C4CC3D33` FOREIGN KEY (`address11tab`) REFERENCES `address_11tab` (`addressid`)

) ENGINE=InnoDB DEFAULT CHARSET=gbk;

 

/* Formatted on 2007/08/20 16:53 (QP5 v5.50) */

CREATE TABLE `address_11tab` (

  `addressid` int(11) NOT NULL auto_increment,

  `addressdetail` varchar(255) default NULL,

  PRIMARY KEY  (`addressid`)

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

 

/* Formatted on 2007/08/20 16:53 (QP5 v5.50) */

CREATE TABLE `person_11tab` (

  `personid` int(11) NOT NULL auto_increment,

  `name` varchar(255) default NULL,

  `age` int(11) default NULL,

  PRIMARY KEY  (`personid`)

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

 

 

五、映射方法：在Person中添加Address属性，映射配置为：

<!--使用join元素显式确定链接表--> <join table="join_11tab"> <key column="personid"/> <!--映射1-1关联属性，其中unique=“true”属性确定为“1-1”--> <many-to-one name="address11tab" unique="true"/> </join> <hibernate-mapping> <class name="com.lavasoft.dx._1_1_tab.Person11tab" table="PERSON_11tab"> <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_11tab"> <key column="personid"/> <!--映射1-1关联属性，其中unique=“true”属性确定为“1-1”--> <many-to-one name="address11tab" unique="true"/> </join> </class> </hibernate-mapping> <hibernate-mapping> <class name="com.lavasoft.dx._1_1_tab.Address11tab" table="ADDRESS_11tab"> <id name="addressid"> <generator class="identity"/> </id> <property name="addressdetail"/> </class> </hibernate-mapping>

 

六、测试方法

public class Test_11tab { public static void main(String[] args){ Person11tab p1=new Person11tab(); p1.setAge(21); p1.setName("p1"); Address11tab add1=new Address11tab(); add1.setAddressdetail("郑州市经三路"); p1.setAddress11tab(add1); Session session= HibernateUtil.getCurrentSession(); Transaction tx=session.beginTransaction(); session.save(add1); session.save(p1); tx.commit(); HibernateUtil.closeSession(); } }

 

七、测试结果

1) :正常保存. 推荐这么干! session.save(add1); session.save(p1); Hibernate: insert into ADDRESS_11tab (addressdetail) values (?) Hibernate: insert into PERSON_11tab (name, age) values (?, ?) Hibernate: insert into join_11tab (address11tab, personid) values (?, ?) 2) :正常保存. session.save(p1); session.save(add1); Hibernate: insert into PERSON_11tab (name, age) values (?, ?) Hibernate: insert into join_11tab (address11tab, personid) values (?, ?) Hibernate: insert into ADDRESS_11tab (addressdetail) values (?) Hibernate: update join_11tab set address11tab=? where personid=? 3) :正常保存. // session.save(p1); session.save(add1); Hibernate: insert into ADDRESS_11tab (addressdetail) values (?) 4) : 发生异常,不能保存. session.save(p1); // session.save(add1); Hibernate: insert into PERSON_11tab (name, age) values (?, ?) Hibernate: insert into join_11tab (address11tab, personid) values (?, ?) Exception in thread "main" org.hibernate.TransientObjectException: com.lavasoft.dx._1_1_tab.Address11tab

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