Hibernate_映射_关联关系_一对一映射2_基于外键的方式

单向关联:单向一对多单向多对一单向多对多单向一对一(只能做从有外键方到无外键方的单向关联)

<?xml version="1.0"?><!DOCTYPE hibernate-mapping PUBLIC        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"        "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"><!-- 导入包 --><hibernate-mapping package="cn.itcast.i_hbm_oneToOne"><!-- 类名 --><class name="Person" table="t_person"><id name="id" type="integer" column="id"><generator class="native" /></id><property name="name" type="string" column="name" /><!-- idCard属性,IdCard类型 表达的是本类与IdCard的一对一。 采用外键一对一映射方式,本方无外键方 property-ref属性:写的是对方映射中外键列对应的属性名--><one-to-one name="idCard" class="IdCard" property-ref="person" /></class></hibernate-mapping>

<?xml version="1.0"?><!DOCTYPE hibernate-mapping PUBLIC        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"        "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"><!-- 导入包 --><hibernate-mapping package="cn.itcast.i_hbm_oneToOne"><!-- 类名 --><class name="IdCard" table="t_idcard"><id name="id" type="integer" column="id"><generator class="native" /></id><property name="number" type="string" column="number" /><!-- person属性,Person类型 表达的是本类与Person的一对一。采用外键一对一映射方式,本方有外键方--><many-to-one name="person" class="Person" column="personId" unique="true" ></many-to-one></class></hibernate-mapping>

package cn.itcast.i_hbm_oneToOne;/** * 公民实体类 *  * @author 风清杨 * @version V1.0 */public class Person {private Integer id;// 主键idprivate String name;// 姓名private IdCard idCard;// 关联的身份证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 IdCard getIdCard() {return idCard;}public void setIdCard(IdCard idCard) {this.idCard = idCard;}@Overridepublic String toString() {return "IdCard [id=" + id + ", name=" + name + "]";}}

package cn.itcast.i_hbm_oneToOne;/** * 身份证 实体类 *  * @author 风清杨 * @version V1.0 */public class IdCard {private Integer id;// 主键private String number;// 身份证编号private Person person;// 关联的公民对象public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getNumber() {return number;}public void setNumber(String number) {this.number = number;}public Person getPerson() {return person;}public void setPerson(Person person) {this.person = person;}@Overridepublic String toString() {return "IdCard [id=" + id + ", number=" + number + "]";}}

package cn.itcast.i_hbm_oneToOne;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.Transaction;import org.hibernate.cfg.Configuration;import org.junit.Test;/** * 应用程序操作类 *  * @author 风清杨 * @version V1.0 *  */public class App {private static SessionFactory sessionFactory = new Configuration()//.configure()//.addClass(Person.class)//.addClass(IdCard.class)//.buildSessionFactory();// 保存,有关联关系@Testpublic void testSave() throws Exception {Session session = sessionFactory.openSession();Transaction tx = null;try {tx = session.beginTransaction();// ------------------------------------// 新建对象Person person = new Person();person.setName("张三");IdCard idCard = new IdCard();idCard.setNumber("10000001X");// 关联起来person.setIdCard(idCard);idCard.setPerson(person);// 保存session.save(person);session.save(idCard);// ------------------------------------tx.commit();} catch (RuntimeException e) {tx.rollback();throw e;} finally {session.close();}}// 获取,可以获取到关联的对方@Testpublic void testGet() throws Exception {Session session = sessionFactory.openSession();Transaction tx = null;try {tx = session.beginTransaction();// ------------------------------------// 获取一方数据,并显示另一方信息// Person person = (Person) session.get(Person.class, 1);// System.out.println(person);// System.out.println(person.getIdCard());IdCard idCard = (IdCard) session.get(IdCard.class, 1);System.out.println(idCard);System.out.println(idCard.getPerson());// ------------------------------------tx.commit();} catch (RuntimeException e) {tx.rollback();throw e;} finally {session.close();}}// 解除关联关系：一对一中,只能有外键可以维护关联关系@Testpublic void testRemoveRelation() throws Exception {Session session = sessionFactory.openSession();Transaction tx = null;try {tx = session.beginTransaction();// ------------------------------------// 从有外键方解除关系,可以。// IdCard idCard = (IdCard) session.get(IdCard.class, 1);// idCard.setPerson(null);// 从无外键方解除关系,不可以。Person person = (Person) session.get(Person.class, 1);person.setIdCard(null);// ------------------------------------tx.commit();} catch (RuntimeException e) {tx.rollback();throw e;} finally {session.close();}}// 删除对象,对关联对象的影响@Testpublic void testDelete() throws Exception {Session session = sessionFactory.openSession();Transaction tx = null;try {tx = session.beginTransaction();// ------------------------------------// a,如果没有关联的对方：// b,如果有关联的对方且可以维护关联关系(有外键方),它就会先删除关联关系,再删除自已。// c,如果有关联的对方且不能维护关联关系(无外键方),所以会直接执行删除自已,就会有异常。IdCard idCard = (IdCard) session.get(IdCard.class, 1);session.delete(idCard);// Person person = (Person) session.get(Person.class,1);// session.delete(person);// ------------------------------------tx.commit();} catch (RuntimeException e) {tx.rollback();throw e;} finally {session.close();}}}