14-hibernate实战 一对一对象关系模型映射(公民和身份证)

Person.java

package cn.itcast.hibernate.domain;public class Person {private int id;private String name;private IdCard idCard;public int getId() {return id;}public void setId(int id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public IdCard getIdCard() {return idCard;}public void setIdCard(IdCard idCard) {this.idCard = idCard;}}

Person.hbm.xml

<?xml version="1.0"?><!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN""http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"><hibernate-mapping package="cn.itcast.hibernate.domain"><class name="Person"><id name="id"><generator class="native" /></id><property name="name" /><one-to-one name="idCard"></one-to-one></class></hibernate-mapping>

IdCard.java

package cn.itcast.hibernate.domain;import java.util.Date;public class IdCard {private int id;private Date usefulLife;private Person person;public int getId() {return id;}public void setId(int id) {this.id = id;}public Date getUsefulLife() {return usefulLife;}public void setUsefulLife(Date usefulLife) {this.usefulLife = usefulLife;}public Person getPerson() {return person;}public void setPerson(Person person) {this.person = person;}}

IdCard.hbm.xml

<?xml version="1.0"?><!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN""http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"><hibernate-mapping package="cn.itcast.hibernate.domain"><class name="IdCard" table="id_card" ><id name="id"><generator class="foreign"><param name="property">person</param></generator></id><property name="usefulLife"  column="useful_life"/><one-to-one name="person"  constrained="true"/></class></hibernate-mapping>

One2One.java

package cn.itcast.hibernate;import java.util.Date;import org.hibernate.Session;import org.hibernate.Transaction;import cn.itcast.hibernate.domain.IdCard;import cn.itcast.hibernate.domain.Person;public class One2One {public static void main(String[] args) {add();query(1);}// 查询static void query(int personId) {Session session = null;Transaction transaction = null;try {session = HibernateUtil.getSession();transaction = session.beginTransaction();//查询主对象时候执行一次SQL语句/*Person person=(Person) session.get(Person.class, personId);System.out.println(person.getIdCard().getUsefulLife());*/System.out.println("****************************************************************");//查询从对象的时候执行的2次SQL语句IdCard idCard=(IdCard) session.get(IdCard.class, personId);System.out.println(idCard.getPerson().getName());transaction.commit();} finally {if (session != null)session.close();}}// 添加static Person add() {Session session = null;Transaction transaction = null;try {session = HibernateUtil.getSession();transaction = session.beginTransaction();IdCard idCard = new IdCard();idCard.setUsefulLife(new Date());// 在这里，person是主对象，IdCard是从对象// IdCard的主键既是主键，也是外键Person person = new Person();person.setName("p1");person.setIdCard(idCard);idCard.setPerson(person);session.save(person);session.save(idCard);transaction.commit();return person;} finally {if (session != null)session.close();}}}

sql

Hibernate:     insert     into        Person        (name)     values        (?)Hibernate:     insert     into        id_card        (useful_life, id)     values        (?, ?)****************************************************************Hibernate:     select        idcard0_.id as id3_0_,        idcard0_.useful_life as useful2_3_0_     from        id_card idcard0_     where        idcard0_.id=?Hibernate:     select        person0_.id as id4_1_,        person0_.name as name4_1_,        idcard1_.id as id3_0_,        idcard1_.useful_life as useful2_3_0_     from        Person person0_     left outer join        id_card idcard1_             on person0_.id=idcard1_.id     where        person0_.id=?p1