Hibernate一对一关联关系介绍和简单demo

开头说两句：
Hibernate一对一关系分为两种：
1.主键关联一对一映射：例如在两个表a,b中，一个字段在a表中是主键，a表中的该字段级联b表中的字段，该字段在b表中作为主键，也就是当a表中该字段修改时，b表中的字段随之改变;通过<one-to-one>元素配置，
2.唯一外键关联一对一映射：一对多关系的一种特例，主键表对应实体类的配置文件中通过one-to-one元素配置。
在这里我说一下第一种情况，第二种情况就不再说明了，好了，我们开始做demo.

demo介绍：有两个表，分别是register表和userInfo表，关系：当一个用户注册时，在register表中出现这条信息，同样会在userInfo表出现这条信息。这体现了register同userInfo表的关联

1.新建工程，工程目录如下：

2.新建Register.java和UserInfo.java两个java文件，以下依次为代码：

/*************Register.java***************/
package com.feng.dao;

public class Register {

    private String name;
    private String pwd;
    private String email;

    private UserInfo userInfo;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPwd() {
        return pwd;
    }

    public void setPwd(String pwd) {
        this.pwd = pwd;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public UserInfo getUserInfo() {
        return userInfo;
    }

    public void setUserInfo(UserInfo userInfo) {
        this.userInfo = userInfo;
    }

}

/****************UserInfo.java********************/
package com.feng.dao;

public class UserInfo {

    private String name;
    private String realName;
    private Register register;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getRealName() {
        return realName;
    }

    public void setRealName(String realName) {
        this.realName = realName;
    }

    public Register getRegister() {
        return register;
    }

    public void setRegister(Register register) {
        this.register = register;
    }

}

3.数据库分为两个表，分别为：register和userInfo


4.创建java类映射文件register.hbm.xml和userInfo.hbm.xml,以下依次为两个文件：

<?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 package="com.feng.dao">
    <class name="Register" table="register">
        <id name="name" type="java.lang.String" column="name" >
        </id>
        <property name="pwd" type="java.lang.String" column="pwd"/>
        <property name="email" column="email"></property>
        <one-to-one name="userInfo" class="UserInfo" cascade="all"/>
    </class>
</hibernate-mapping>

<?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 package="com.feng.dao">
    <class name="UserInfo" table="userinfo">
        <id name="name" type="java.lang.String" column="name" >
            <generator class="foreign"> 
                <param name="property">register</param>
            </generator>
        </id>

        <property name="realName" type="java.lang.String" column="realName"/>
        <one-to-one name="register" class="Register" constrained="true"/>
    </class>
</hibernate-mapping>

5.创建整个工程的映射文件hibernate.cfg.xml

<!-- ~ Hibernate, Relational Persistence for Idiomatic Java ~ ~ License: 
    GNU Lesser General Public License (LGPL), version 2.1 or later. ~ See the 
    lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>. -->
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql://localhost:3306/hibernatedemo</property>
        <property name="connection.username">root</property>
        <property name="connection.password"></property>
        <property name="connection.characterEncoding">utf8</property>
        <property name="connection.pool_siez">10</property>
        <property name="dialect">org.hibernate.dialect.MySQL5Dialect</property>
        <property name="show_sql">true</property>
        <property name="format_sql">true</property>
        <mapping resource="com/feng/dao/register.hbm.xml" />
        <mapping resource="com/feng/dao/userInfo.hbm.xml"/>
    </session-factory>

</hibernate-configuration>

6.编写测试类,Test.java

package com.feng.test;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.boot.MetadataSources;
import org.hibernate.boot.registry.StandardServiceRegistry;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;

import com.feng.dao.Register;
import com.feng.dao.UserInfo;

public class Test {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        // 1.进行配置文件的读取
        StandardServiceRegistryBuilder ssrb = new StandardServiceRegistryBuilder();
        StandardServiceRegistry sr = ssrb.configure().build();
        // 2.由config得到一个会话工厂//得到sessionFactory
        SessionFactory sf = new MetadataSources(sr).buildMetadata().buildSessionFactory();
        // 3.由sessionFacatory得到session
        Session session = sf.openSession();

        Transaction tran = session.beginTransaction(); 

        Register login =new Register();
        login.setEmail("132@456789.com");
        login.setName("lisi");
        login.setPwd("456");
        UserInfo ui =new UserInfo();
        ui.setRealName("hehhe");
        login.setUserInfo(ui);
        ui.setRegister(login);

        session.save(login);

        tran.commit(); // 一定要提交事务！！！！！！！
        // 4.记得关闭session
        session.close();
        sf.close();
    }
}

执行成功，结果就不展示了，就是在register表插入数据的同时，也向userInfo表插入了数据。
还是最后那句话：