映射一对一

Address  外键

package cn.itcast.one2onefk;public class Address {private Integer id;private String city;private String country;private Company company;public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getCity() {return city;}public void setCity(String city) {this.city = city;}public String getCountry() {return country;}public void setCountry(String country) {this.country = country;}public Company getCompany() {return company;}public void setCompany(Company company) {this.company = company;}}

Company

package cn.itcast.one2onefk;public class Company {private Integer id;private String name;private Address address;public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public Address getAddress() {return address;}public void setAddress(Address address) {this.address = address;}}

Address.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="cn.itcast.one2onefk.Address" table="address">      <id name="id" type="integer">         <column name="id"></column>         <generator class="increment"/>      </id>      <property name="city" type="string">        <column name="city"></column>      </property>      <property name="country" type="string">      <column name="country"></column>      </property>      <!--       one-to-one:用于映射一对一       该元素使用 property-ref（可以不加）属性指定使用被关联实体主键       以外的字段作为关联字段       如何获取company属性的值 通过address表的主键（company表的外键）获取       -->      <one-to-one name="company" property-ref="address"></one-to-one></class></hibernate-mapping>

Company.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="cn.itcast.one2onefk.Company" table="company">      <id name="id" type="integer">         <column name="id"></column>         <generator class="increment"/>      </id>      <property name="name" type="string">        <column name="name"></column>      </property>      <!--         正常是 多个公司对应一个地址        在需要存放外键的一段 增加 many-to-one           many-to-one:映射多对一关联              * address:带映射的持久化类的属性              * column:对应的表的字段,address属性的值通过company表的外键到address表中查的              * unique="true":唯一的,company表的外键列的值是唯一的,把多对一改为一对一         -->      <many-to-one name="address" column="addressId" unique="true" not-null="true"></many-to-one></class></hibernate-mapping>

App

package cn.itcast.one2onefk;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.Transaction;import org.hibernate.cfg.Configuration;import org.junit.Test;public class App {static SessionFactory sf = null;static {Configuration config = new Configuration();config.configure("cn/itcast/one2onefk/hibernate.cfg.xml");    config.addClass(Company.class);    config.addClass(Address.class);sf = config.buildSessionFactory();}@Testpublic void insert(){Session s=sf.openSession();Transaction t=s.beginTransaction();Company c=new Company();c.setName("传智博客");Address address=new Address();address.setCity("北京");address.setCountry("中国");c.setAddress(address);address.setCompany(c);//先保存地址 在保存公司 s.save(address);s.save(c);t.commit();s.close();}} 

主键

Address。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="cn.itcast.one2onepk.Address" table="address">      <id name="id" type="integer">         <column name="id"></column>         <!-- class：表示该表主键的值是参照其他表的主键         <param name="property">company</param>         表示 property表示该值参照其他的属性值          company：参照company表的主键         -->         <generator class="foreign">         <param name="property">company</param>         </generator>      </id>      <property name="city" type="string">        <column name="city"></column>      </property>      <property name="country" type="string">      <column name="country"></column>      </property>      <!-- constrained：true给表的主键增加外键约束 -->      <one-to-one name="company" constrained="true"></one-to-one></class></hibernate-mapping>

Company.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="cn.itcast.one2onepk.Company" table="company">      <id name="id" type="integer">         <column name="id"></column>         <generator class="identity"/>      </id>      <property name="name" type="string">        <column name="name"></column>      </property>      <!-- 映射1对1 -->      <one-to-one name="address"></one-to-one></class></hibernate-mapping>