hibernate之一对一

1.一对一：one-to-one

（1）思路：首先Tiny就给大家带来一个一对一的案例，人与身份证的案例。 一人对应一张身份证，一张身份证对应一个人，假如人的身份证掉了，可以再补办一张，如果人不在了，那身份证就没了。所以执行删除操作时，删除卡。人还在，删除人，卡就会没有了。

（2）代码演示：

<1>hibernate的特点：表和实体类相连接，映射关系联系在一起：

A:人的实体类：

package com.zking.entity;public class User {private int uid;private String uname;private Card card;public Card getCard() {return card;}public void setCard(Card card) {this.card = card;}public User() {super();// TODO Auto-generated constructor stub}public User(String uname) {super();this.uname = uname;}public int getUid() {return uid;}public void setUid(int uid) {this.uid = uid;}public String getUname() {return uname;}public void setUname(String uname) {this.uname = uname;}}

人的映射：user.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"><!-- Generated 2017-8-22 14:32:20 by Hibernate Tools 3.5.0.Final --><hibernate-mapping>    <class name="com.zking.entity.User" table="USER">        <id name="uid" type="int">            <column name="UID" />            <generator class="native" />        </id>        <property name="uname" type="java.lang.String">            <column name="UNAME" />        </property>        <one-to-one name="card" class="com.zking.entity.Card" cascade="all-delete-orphan"></one-to-one>    </class></hibernate-mapping>

B:卡的实体类

package com.zking.entity;public class Card {private int uid;private String cnum;private User user;public User getUser() {return user;}public void setUser(User user) {this.user = user;}public Card() {super();}public Card(String cnum) {super();this.cnum = cnum;}public int getUid() {return uid;}public void setUid(int uid) {this.uid = uid;}public String getCnum() {return cnum;}public void setCnum(String cnum) {this.cnum = cnum;}}

卡的映射：

<?xml version="1.0"?><!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN""http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"><!-- Generated 2017-8-22 14:32:20 by Hibernate Tools 3.5.0.Final --><hibernate-mapping>    <class name="com.zking.entity.Card" table="CARD">        <id name="uid" type="int">            <column name="UID" />            <generator class="foreign">            <param name="property">user</param>            </generator>        </id>        <property name="cnum" type="java.lang.String">            <column name="CNUM" />        </property>        <one-to-one name="user" class="com.zking.entity.User"></one-to-one>    </class></hibernate-mapping>

<2>pom.xml的配置：添加依赖

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">  <modelVersion>4.0.0</modelVersion>  <groupId>G160628_hibernate02</groupId>  <artifactId>G160628_hibernate02</artifactId>  <packaging>war</packaging>  <version>0.0.1-SNAPSHOT</version>  <name>G160628_hibernate02 Maven Webapp</name>  <url>http://maven.apache.org</url>  <properties>        <argLine>-Dfile.encoding=UTF-8</argLine>  </properties>    <dependencies>    <dependency>      <groupId>junit</groupId>      <artifactId>junit</artifactId>      <version>4.12</version>      <scope>test</scope>    </dependency>        <dependency>    <groupId>javax.servlet</groupId>    <artifactId>javax.servlet-api</artifactId>    <version>4.0.0-b07</version>    <scope>provided</scope></dependency>            <!-- 加入hibernate依赖 -->    <dependency>   <groupId>org.hibernate</groupId>   <artifactId>hibernate-core</artifactId>   <version>5.2.10.Final</version></dependency>        <!-- Mysql依赖 -->    <dependency>    <groupId>mysql</groupId>    <artifactId>mysql-connector-java</artifactId>    <version>5.1.43</version>    </dependency>      </dependencies>  <build>    <finalName>G160628_hibernate02</finalName>  </build></project>

test:测试：

package com.zking.test;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.Transaction;import org.hibernate.cfg.Configuration;import org.junit.After;import org.junit.Before;import org.junit.Test;import com.zking.entity.Card;import com.zking.entity.User;public class TestOneToOne {private SessionFactory sessionFactory;private Session session;private Transaction transaction;//在方法执行之前执行@Beforepublic void before(){//设置配置文件Configuration configuration=new Configuration().configure();//获取sessionFactorysessionFactory = configuration.buildSessionFactory();//获取session session = sessionFactory.openSession();//开始事务transaction = session.beginTransaction();}//在方法执行之后调用@Afterpublic void after(){//提交事务transaction.commit();session.close();sessionFactory.close();}public void testAdd(){//增加User user=new User("张三");Card card=new Card("43110731");//互设user.setCard(card);card.setUser(user);session.save(user);session.save(card);}public void testGet(){//查询User user=session.get(User.class, 1);System.out.println(user.getCard().getCnum());}public void testDelete(){//删除主表//User user=session.get(User.class, 2);//session.delete(user);//删除从表Card card=session.get(Card.class, 3);card.getUser().setCard(null);session.delete(card);}}

好了，到此就一对一的案例就到此结束了，有疑惑的孩纸可以进行交流