一对一关联

Hibernate中的一对一关联

Hibernate提供了两种一对一映射关联关系的方式：

1）按照外键映射

2）按照主键映射

下面以员工账号表和员工档案表（员工账号和档案表之间是一对一的关系）为例，介绍这两种映射关系,并使用这两种 映射方式分别完成以下持久化操作

(1)保存员工档案的同时分配给员工一个账号

(2)加载员工档案的同时加载账号信息

一丶按照外键映射

Users1中：

package cn.xsy.entity.day_onetoone;

/**
 * Created by Administrator on 2017/12/30.
 */
public class Users1 {

    private Integer userid;

    private String username;

    private String userpass;

    private Resume1 resume1;

    public Integer getUserid() {
        return userid;
    }

    public void setUserid(Integer userid) {
        this.userid = userid;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getUserpass() {
        return userpass;
    }

    public void setUserpass(String userpass) {
        this.userpass = userpass;
    }

    public Resume1 getResume1() {
        return resume1;
    }

    public void setResume1(Resume1 resume1) {
        this.resume1 = resume1;
    }
}

Users1.hbm.xml中:

<?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">
<!--根节点-->
<!-- package:要映射的对象所在的包（可选，如果不指定，此文件下所有的类都要指定全路径）
    auto-import 默认为true，在写HQL的时候自动导入包名
            如果指定为false，在写HQL的时候必须要写上类的全名-->
<hibernate-mapping package="cn.xsy.entity.day_onetoone">
    <class name="Users1" table="USERS1">
        <id name="userid" column="USERID" >
            <generator class="native"></generator>
        </id>
        <property name="username" column="USERNAME" type="string"></property>
        <property name="userpass" column="USERPASS" type="string"></property>
        <one-to-one name="resume1" class="Resume1" property-ref="users1"></one-to-one>
    </class>
</hibernate-mapping>

Resume1中：

package cn.xsy.entity.day_onetoone;

/**
 * Created by Administrator on 2017/12/30.
 */
public class Resume1 {

    private Integer resid;

    private String resname;

    private String rescardno;

    private Users1 users1;

    public Integer getResid() {
        return resid;
    }

    public void setResid(Integer resid) {
        this.resid = resid;
    }

    public String getResname() {
        return resname;
    }

    public void setResname(String resname) {
        this.resname = resname;
    }

    public String getRescardno() {
        return rescardno;
    }

    public void setRescardno(String rescardno) {
        this.rescardno = rescardno;
    }

    public Users1 getUsers1() {
        return users1;
    }

    public void setUsers1(Users1 users1) {
        this.users1 = users1;
    }
}

Resume1.hbm.xml中：

<?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">
<!--根节点-->
<!-- package:要映射的对象所在的包（可选，如果不指定，此文件下所有的类都要指定全路径）
    auto-import 默认为true，在写HQL的时候自动导入包名
            如果指定为false，在写HQL的时候必须要写上类的全名-->
<hibernate-mapping package="cn.xsy.entity.day_onetoone">
    <class name="Resume1" table="RESUME1">
        <id name="resid" column="RESID" >
            <generator class="native"></generator>
        </id>
        <property name="resname" column="RESNAME" type="string"></property>
        <property name="rescardno" column="RESCARDNO" type="string"></property>
        <many-to-one name="users1" class="Users1" cascade="all" column="RESUSERID" unique="true"></many-to-one>
    </class>
</hibernate-mapping>

hibernate.cfgonetoone.xml中：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
   <!--创建Session的基础配置-->
    <session-factory>
        <property name="connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
        <property name="connection.url">jdbc:oracle:thin:@localhost:1521:orcl</property>
        <property name="connection.username">waxsy</property>
        <property name="connection.password">bsfm</property>

        <!-- JDBC 连接池(use the built-in) -->
   <!--     <property name="connection.pool_size">1</property>-->

        <!-- SQL dialect （方言）-->
        <property name="dialect">org.hibernate.dialect.Oracle10gDialect</property>

        <!-- Enable Hibernate's automatic session context management
          session工厂创建的session和当前线程绑定bind
         -->
        <property name="current_session_context_class">thread</property>

        <!-- Disable the second-level cache  启用/关闭二级缓存-->
       <!-- <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>-->

        <!-- Echo   all executed SQL to stdout 在控制台打印sql -->
        <property name="show_sql">true</property>
        <!--格式化SQL-->
        <property name="format_sql">true</property>
        <!-- Drop and re-create （重新创建）the database schema（架构） on startup （启动）
         是否根据hbm.xml自动建表 建表的策略 update create
         hbm配置文件》》》》》》》ddl  数据表
         create: 过程：先drop 再Create
         update:检查现有表的架构是否存在，真实开发中，在上线后，一定update
        -->
        <property name="hbm2ddl.auto">update</property>
         <!--关联小配置 -->


        <mapping resource="cn/xsy/entity/day_onetoone/Users1.hbm.xml"/>
        <mapping resource="cn/xsy/entity/day_onetoone/Resume.hbm.xml"/>
    </session-factory>

</hibernate-configuration
>

Test20171230_onetoone中：

package day01;


import cn.xsy.entity.day_manytomanydouble.Employee;
import cn.xsy.entity.day_manytomanydouble.Project;
import cn.xsy.entity.day_onetomanydouble.Dept;
import cn.xsy.entity.day_onetomanydouble.Emp;
import cn.xsy.entity.day_onetoone.Resume1;
import cn.xsy.entity.day_onetoone.Users1;
import cn.xsy.util.HibernateUtil;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.Transaction;
import org.junit.Test;

import java.util.List;
import java.util.Set;

/**
 * Created by Happy on 2017-12-24.
 */
public class Test20171230_onetoone {

    //一对一关联
   @Test
   public void onetoone(){

       Session session = HibernateUtil.getSession();
       Transaction tx=session.beginTransaction();
       //创建一个用户对象
       Users1 u1=new Users1();
       u1.setUserid(1);
       u1.setUsername("小涩瑶");
       //创建一个档案对象
       Resume1 r1=new Resume1();
       r1.setResid(1);
       r1.setResname("余浪北笙");
       u1.setResume1(r1);
       r1.setUsers1(u1);
       //保存r1自动保存u1
       session.save(r1);
       tx.commit();
       System.out.println("add ok!");

   }

    
}

二丶按照主键映射