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Hibernate 一对一连接表单向关联
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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。
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一、模型介绍
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一个人（Person）对应一个地址（Address）。
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二、实体（省略getter、setter方法）
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public class Person11tab {
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private int personid;
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private String name;
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private int age;
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private Address11tab address11tab;
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public class Address11tab {
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private int addressid;
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private String addressdetail;
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三、表模型
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mysql> desc address_11tab;
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+---------------+--------------+------+-----+---------+----------------+
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| Field | Type | Null | Key | Default | Extra |
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+---------------+--------------+------+-----+---------+----------------+
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| addressid | int(11) | NO | PRI | NULL | auto_increment |
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| addressdetail | varchar(255) | YES | | NULL | |
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+---------------+--------------+------+-----+---------+----------------+
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mysql> desc join_11tab;
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+--------------+---------+------+-----+---------+-------+
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| Field | Type | Null | Key | Default | Extra |
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+--------------+---------+------+-----+---------+-------+
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| personid | int(11) | NO | PRI | | |
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| address11tab | int(11) | YES | UNI | NULL | |
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+--------------+---------+------+-----+---------+-------+
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mysql> desc person_11tab;
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+----------+--------------+------+-----+---------+----------------+
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| Field | Type | Null | Key | Default | Extra |
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+----------+--------------+------+-----+---------+----------------+
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| personid | int(11) | NO | PRI | NULL | auto_increment |
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| name | varchar(255) | YES | | NULL | |
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| age | int(11) | YES | | NULL | |
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+----------+--------------+------+-----+---------+----------------+
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四、生成的SQL脚本
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/* Formatted on 2007/08/20 16:52 (QP5 v5.50) */
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CREATE TABLE `join_11tab` (
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`personid` int(11) NOT NULL,
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`address11tab` int(11) default NULL,
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PRIMARY KEY (`personid`),
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UNIQUE KEY `address11tab` (`address11tab`),
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KEY `FK6B44BE20C4CC3D33` (`address11tab`),
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KEY `FK6B44BE209049BB1F` (`personid`),
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CONSTRAINT `FK6B44BE209049BB1F` FOREIGN KEY (`personid`) REFERENCES `person_11tab` (`personid`),
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CONSTRAINT `FK6B44BE20C4CC3D33` FOREIGN KEY (`address11tab`) REFERENCES `address_11tab` (`addressid`)
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) ENGINE=InnoDB DEFAULT CHARSET=gbk;
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/* Formatted on 2007/08/20 16:53 (QP5 v5.50) */
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CREATE TABLE `address_11tab` (
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`addressid` int(11) NOT NULL auto_increment,
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`addressdetail` varchar(255) default NULL,
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PRIMARY KEY (`addressid`)
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) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=gbk;
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/* Formatted on 2007/08/20 16:53 (QP5 v5.50) */
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CREATE TABLE `person_11tab` (
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`personid` int(11) NOT NULL auto_increment,
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`name` varchar(255) default NULL,
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`age` int(11) default NULL,
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PRIMARY KEY (`personid`)
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) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=gbk;
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五、映射方法：在Person中添加Address属性，映射配置为：
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<!--使用join元素显式确定链接表-->
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<join table="join_11tab">
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<key column="personid"/>
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<!--映射1-1关联属性，其中unique=“true”属性确定为“1-1”-->
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<many-to-one name="address11tab" unique="true"/>
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</join>
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<hibernate-mapping>
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<class name="com.lavasoft.dx._1_1_tab.Person11tab" table="PERSON_11tab">
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<id name="personid">
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<generator class="identity"/>
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</id>
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<property name="name"/>
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<property name="age"/>
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<!--使用join元素显式确定链接表-->
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<join table="join_11tab">
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<key column="personid"/>
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<!--映射1-1关联属性，其中unique=“true”属性确定为“1-1”-->
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<many-to-one name="address11tab" unique="true"/>
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</join>
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</class>
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</hibernate-mapping>
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<hibernate-mapping>
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<class name="com.lavasoft.dx._1_1_tab.Address11tab" table="ADDRESS_11tab">
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<id name="addressid">
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<generator class="identity"/>
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</id>
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<property name="addressdetail"/>
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</class>
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</hibernate-mapping>
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六、测试方法
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public class Test_11tab {
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public static void main(String[] args){
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Person11tab p1=new Person11tab();
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p1.setAge(21);
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p1.setName("p1");
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Address11tab add1=new Address11tab();
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add1.setAddressdetail("郑州市经三路");
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p1.setAddress11tab(add1);
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Session session= HibernateUtil.getCurrentSession();
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Transaction tx=session.beginTransaction();
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session.save(add1);
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session.save(p1);
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tx.commit();
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HibernateUtil.closeSession();
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}
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}
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七、测试结果
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1) :正常保存. 推荐这么干!
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session.save(add1);
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session.save(p1);
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Hibernate: insert into ADDRESS_11tab (addressdetail) values (?)
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Hibernate: insert into PERSON_11tab (name, age) values (?, ?)
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Hibernate: insert into join_11tab (address11tab, personid) values (?, ?)
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2) :正常保存.
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session.save(p1);
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session.save(add1);
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Hibernate: insert into PERSON_11tab (name, age) values (?, ?)
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Hibernate: insert into join_11tab (address11tab, personid) values (?, ?)
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Hibernate: insert into ADDRESS_11tab (addressdetail) values (?)
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Hibernate: update join_11tab set address11tab=? where personid=?
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3) :正常保存.
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// session.save(p1);
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session.save(add1);
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Hibernate: insert into ADDRESS_11tab (addressdetail) values (?)
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4) : 发生异常,不能保存.
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session.save(p1);
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// session.save(add1);
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Hibernate: insert into PERSON_11tab (name, age) values (?, ?)
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Hibernate: insert into join_11tab (address11tab, personid) values (?, ?)
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Exception in thread "main" org.hibernate.TransientObjectException: com.lavasoft.dx._1_1_tab.Address11tab
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本文转自 leizhimin 51CTO博客，原文链接：http://blog.51cto.com/lavasoft/39312，如需转载请自行联系原作者