Hibernate之对象关系映射02一对一单向主键关联

hibernate映射关系有一对一、一对多、多对一、多对多；其中每一种又分单向和双向，主键和外键。需要配置实体类、实体类的映射文件，对应为数据库表间的关系；此篇先讲非注解方式的。

一对一单向主键关联：基于主键关联的持久化类不能拥有自己的主键生成策略，它的主键由关联类负责生成。

本文实例参考自：http://lavasoft.blog.51cto.com/62575/39304

Address11pk.java

private int addressId;private String detailAddress;

Person11pk.java

private int personId;private String personName;private int age;private Address11pk address11pk;

表结构

-- 一对一单向主键关联（关联对方主键的一方）DROP TABLE IF EXISTS person_11pk;CREATE TABLE person_11pk (  person_id int(11) PRIMARY KEY,  person_name varchar(255),  age int(3)) ENGINE=InnoDB DEFAULT CHARSET=utf8;-- 一对一单向主键关联（由自己生成主键的一方）DROP TABLE IF EXISTS address_11pk;CREATE TABLE address_11pk (  address_id int(11) PRIMARY KEY auto_increment,  detail_address varchar(255)) ENGINE=InnoDB DEFAULT CHARSET=utf8;ALTER TABLE person_11pk ADD CONSTRAINT fk_11pk_personid FOREIGN KEY(person_id) REFERENCES address_11pk(address_id);-- SELECT * FROM address_11pk;-- SELECT * FROM person_11pk;

Address11pk.hbm.xml

<?xml version='1.0' encoding='utf-8'?><!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"  "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"><hibernate-mapping>  <class name="com.ack.hibernateMapping.entity.Address11pk" table="address_11pk"><id name="addressId" column="address_id"><generator class="identity"/></id><property name="detailAddress" column="detail_address"/>  </class></hibernate-mapping>

Person11pk.hbm.xml

<?xml version='1.0' encoding='utf-8'?><!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"  "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"><hibernate-mapping>  <class name="com.ack.hibernateMapping.entity.Person11pk" table="person_11pk"><id name="personId" column="person_id"><generator class="foreign">  <param name="property">address11pk</param></generator></id><property name="personName" column="person_name"/><property name="age"/><one-to-one name="address11pk" constrained="true"/>  </class></hibernate-mapping>

关键在于：在不主动生成主键的一方生成策略为foreign，one-to-one设置为constrained="true";

在hibernate.cfg.xml中加入类映射文件的引用。

Test_pa_11pk_single.java

public class Test_pa_11pk_single {public static void main(String[] args) {Person11pk p1 = new Person11pk();p1.setPersonName("陈三");Address11pk add1 = new Address11pk();add1.setDetailAddress("丽水市莲都区");p1.setAddress11pk(add1);Session session = HibernateUtil.getCurrentSession();session.beginTransaction();session.save(add1);session.save(p1);session.getTransaction().commit();}}

先save add1，再save p1，sql语句如下：

insert into address_11pk(detail_address) values(?)insert into person_11pk(person_name, age, person_id) values(?, ?, ?)

先save p1，再save add1，sql语句如下：

insert into address_11pk(detail_address) values(?)insert into person_11pk(person_name, age, person_id) values(?, ?, ?)

值save p1，sql语句如下：

insert into address_11pk(detail_address) values(?)insert into person_11pk(person_name, age, person_id) values(?, ?, ?)

只save add1，sql语句如下：

insert into address_11pk(detail_address) values(?)

对于与熔岩博客中的运行结果差别，我仔细对照过文件的配置，并且运行了两次来确认我这里录入的结果。估计可能是hibernate版本的区别。我这里用的是hibernate-search-5.5.4.Final-dist。