hibernate进阶一对一映射

本文主要是介绍hibernate进阶一对一映射，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

1.基于外键的映射

package cn.itcast.c_one2one;// 用户
public class User {private int userId;private String userName;// 用户与身份证信息， 一对一关系private IdCard idCard;public IdCard getIdCard() {return idCard;}public void setIdCard(IdCard idCard) {this.idCard = idCard;}public int getUserId() {return userId;}public void setUserId(int userId) {this.userId = userId;}public String getUserName() {return userName;}public void setUserName(String userName) {this.userName = userName;}
}

package cn.itcast.c_one2one;// 身份证
public class IdCard {// 身份证号(主键)private String cardNum;// 对象唯一表示(Object Identified, OID)private String place; //  身份证地址// 身份证与用户，一对一的关系private User user;public String getCardNum() {return cardNum;}public void setCardNum(String cardNum) {this.cardNum = cardNum;}public String getPlace() {return place;}public void setPlace(String place) {this.place = place;}public User getUser() {return user;}public void setUser(User user) {this.user = user;}
}

User.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN""http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"><hibernate-mapping package="cn.itcast.c_one2one"><class name="User" table="t_user"><id name="userId"><generator class="native"></generator></id>	<property name="userName" length="20"></property><!-- 一对一映射： 没有外键方--><one-to-one name="idCard" class="IdCard"></one-to-one></class></hibernate-mapping>

IdCard.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN""http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"><hibernate-mapping package="cn.itcast.c_one2one"><class name="IdCard" table="t_IdCard"><id name="cardNum"><generator class="assigned"></generator></id>	<property name="place" length="20"></property><!-- 一对一映射，有外键方特殊的		多对一unique="true"   给外键字段添加唯一约束--><many-to-one name="user" unique="true" column="user_id" class="User" cascade="save-update"></many-to-one></class></hibernate-mapping>

public class App {private static SessionFactory sf;static {sf = new Configuration().configure().addClass(IdCard.class)   .addClass(User.class)   // 测试时候使用.buildSessionFactory();}@Testpublic void getSave() {Session session = sf.openSession();session.beginTransaction();// 用户User user = new User();user.setUserName("Jack");// 身份证IdCard idCard = new IdCard();idCard.setCardNum("441202XXX");idCard.setPlace("广州XXX");// 关系idCard.setUser(user);// ----保存----session.save(idCard);session.getTransaction().commit();session.close();}}

2.基于主键的映射

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN""http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"><hibernate-mapping package="cn.itcast.c_one2one2"><class name="IdCard" table="t_IdCard"><id name="user_id"><!-- id 节点指定的是主键映射, 即user_id是主键主键生成方式： foreign  即把别的表的主键作为当前表的主键；property (关键字不能修改)指定引用的对象     对象的全名 cn..User、  对象映射 cn.User.hbm.xml、   table(id)--><generator class="foreign"><param name="property">user</param></generator></id>	<property name="cardNum" length="20"></property><property name="place" length="20"></property><!-- 一对一映射，有外键方（基于主键的映射）constrained="true"  指定在主键上添加外键约束--><one-to-one name="user" class="User" constrained="true"  cascade="save-update"></one-to-one></class></hibernate-mapping>

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