hibernate双向一对一主键关联映射XML与注解版

栏目: Hibernate · 发布时间: 6年前

内容简介：hibernate双向一对一主键关联映射XML与注解版

双向一对一关联映射原理: 

双向的主键关联其实是单向一对一主键关联的一种特殊情况，只不过要在关联对象的两端的映射文件中都要进行<one-to-one>的配置，另外还要在主映射的主键一端采用foreign外键关联属性。

这里同样使用Person和IdCard来讨论，一个人对应着一个唯一的身份证，而且一个身份证也唯一映射着一个人，所以这就产生了双向的关联关系，Person的主键同样也是IdCard的主键，分别是主键的同时也是外键，这种关联关系成为双向一对一映射，表现到关系模型中可如下图：

hibernate双向一对一主键关联映射XML与注解版

(1)XML版

SQL文件:

CREATE TABLE `person` (
  `id` varchar(255) NOT NULL,
  `pname` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE TABLE `idcard` (
  `id` varchar(255) NOT NULL,
  `cardnum` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

Person类:

package Hibernate_demo1.Demo11.Entity;

public class Person {
	private String id;
	private String pname;
	private IdCard idcards;
	public String getId() {
		return id;
	}
	public void setId(String id) {
		this.id = id;
	}
	public String getPname() {
		return pname;
	}
	public void setPname(String pname) {
		this.pname = pname;
	}
	public IdCard getIdcards() {
		return idcards;
	}
	public void setIdcards(IdCard idcards) {
		this.idcards = idcards;
	}
	
}

IdCard类:

package Hibernate_demo1.Demo11.Entity;

public class IdCard {
	
	private String id;
	private String cardNum;
	private Person persons;
	
	
	
	public Person getPersons() {
		return persons;
	}
	public void setPersons(Person persons) {
		this.persons = persons;
	}
	public String getId() {
		return id;
	}
	public void setId(String id) {
		this.id = id;
	}
	public String getCardNum() {
		return cardNum;
	}
	public void setCardNum(String cardNum) {
		this.cardNum = cardNum;
	}
}

IdCard.hbm.xml映射文件

<?xml version="1.0"?>  
<!DOCTYPE hibernate-mapping PUBLIC   
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"  
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">  
<hibernate-mapping>  
    <class name="Hibernate_demo1.Demo11.Entity.IdCard" table="IdCard">  
        <id name="id" type="java.lang.String"> 
            <column name="id"/>
            <generator class="uuid">  
            </generator>  
        </id>  
        <property name="cardNum" column="cardNum"/>
        <!-- 
                        在映射文件中添加外键属性persons，并添加对应的<one-to-one>标签
                        目的是强制约束person类来实现一对一的映射关系，最后在映射中将constrained属性设为true
                        保证强制约束关系。
         -->
        <one-to-one name="persons" constrained="true"></one-to-one>
    </class>  
</hibernate-mapping>

双向一对一唯一外键映射关键映射代码——在IdCard端新加入如下标签映射： 

<one-to-one name="person"property-ref="idCard"/>

注意：一对一唯一外键关联双向采用<one-to-one>标签映射，必须指定<one-to-one>标签中的property-ref属性为关系字段的名称。

Person.hbm.xml映射文件

<?xml version="1.0"?>  
<!DOCTYPE hibernate-mapping PUBLIC   
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"  
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">  
<hibernate-mapping>  
    <class name="Hibernate_demo1.Demo11.Entity.Person" table="person">  
        <id name="id">  
            <generator class="uuid">  
            </generator>  
        </id>  
        
        <property name="pname" column="pname"/>  
        
        <!--  
            one-to-one标签指示Hibernate如何加载其关联对象，默认根据主键加载，也就是拿到关系字段值，根据对端的主键来加载关联对象 
         --> 
        <one-to-one name="idcards"></one-to-one> 
    </class>  
</hibernate-mapping>

测试类: 

package Hibernate_demo1.Demo11;

import org.hibernate.Session;

import Hibernate_demo1.Demo11.Entity.IdCard;
import Hibernate_demo1.Demo11.Entity.Person;
import Hibernate_demo1.Demo11.Util.HibernateUtils;

public class App 
{
    public static void main( String[] args )
    {
    	Session session = null;
    	try{  
    		  
    	    session = HibernateUtils.getSession();
    	    session.beginTransaction();  
    	      
    	    //创建person对象，并保存  
            Person person=new Person();  
            person.setPname("fendo");  
            session.save(person);  
              
            //创建idCard对象，并保存  
            IdCard idcard=new IdCard();  
            idcard.setCardNum("123456789");  
            idcard.setPersons(person);
            session.save(idcard);  
    	      
    	    session.getTransaction().commit();  
    	}catch(Exception e){  
    	    e.printStackTrace();  
    	    session.getTransaction().rollback();  
    	}finally{  
    	    HibernateUtils.closeSession(session);  
    	}
    }
}

执行结果如下: 

Hibernate: 
    insert 
    into
        person
        (pname, id) 
    values
        (?, ?)
Hibernate: 
    insert 
    into
        IdCard
        (cardNum, id) 
    values
        (?, ?)

运行结果如下:

Person表

hibernate双向一对一主键关联映射XML与注解版

idcard表

hibernate双向一对一主键关联映射XML与注解版

示例: http://download.csdn.net/detail/u011781521/9834854

(2)注解版

Person类:

package Hibernate_demo1.Demo12.Entity;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToOne;
import javax.persistence.PrimaryKeyJoinColumn;
import javax.persistence.Table;

import org.hibernate.annotations.GenericGenerator;

@Entity
@Table(name="person")
public class Person {
	
	@Id
        @GenericGenerator(name="uuidGenerator", strategy="uuid")
        @GeneratedValue(generator="uuidGenerator")
	private String id;
	
	@Column(name="pname")
	private String pname;
	
        @OneToOne(cascade=CascadeType.ALL)
        @PrimaryKeyJoinColumn
	private IdCard idcards;
	
	public String getId() {
		return id;
	}
	public void setId(String id) {
		this.id = id;
	}
	public String getPname() {
		return pname;
	}
	public void setPname(String pname) {
		this.pname = pname;
	}
	public IdCard getIdcards() {
		return idcards;
	}
	public void setIdcards(IdCard idcards) {
		this.idcards = idcards;
	}
	
}

IdCard类: 

package Hibernate_demo1.Demo12.Entity;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToOne;
import javax.persistence.PrimaryKeyJoinColumn;
import javax.persistence.Table;

import org.hibernate.annotations.GenericGenerator;

@Entity
@Table(name="idcard")
public class IdCard {
	
	@Id
        @GenericGenerator(name="uuidGenerator", strategy="uuid")
        @GeneratedValue(generator="uuidGenerator")
	private String id;
	
	@Column(name="cardNum")
	private String cardNum;
	
	@OneToOne
        @PrimaryKeyJoinColumn
	private Person persons;
	
	
	
	public Person getPersons() {
		return persons;
	}
	public void setPersons(Person persons) {
		this.persons = persons;
	}
	public String getId() {
		return id;
	}
	public void setId(String id) {
		this.id = id;
	}
	public String getCardNum() {
		return cardNum;
	}
	public void setCardNum(String cardNum) {
		this.cardNum = cardNum;
	}
}

测试类:

package Hibernate_demo1.Demo12;

import java.util.HashSet;
import java.util.Set;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;

import Hibernate_demo1.Demo12.Entity.IdCard;
import Hibernate_demo1.Demo12.Entity.Person;



public class App 
{
    public static void main( String[] args )
    {
    	SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();  
    	Session session = sessionFactory.getCurrentSession();  
    	Transaction tx = session.beginTransaction();  
        
    	//创建person对象，并保存  
        Person person=new Person();  
        person.setPname("fendo");  
        session.save(person);  
          
        //创建idCard对象，并保存  
        IdCard idcard=new IdCard();  
        idcard.setCardNum("123456789");  
        idcard.setPersons(person);
        session.save(idcard);  
    	
        tx.commit();
        session.close();
    }
}

执行结果如下:

Hibernate: 
    insert 
    into
        person
        (pname, id) 
    values
        (?, ?)
Hibernate: 
    insert 
    into
        idcard
        (cardNum, id) 
    values
        (?, ?)

示例:  http://download.csdn.net/detail/u011781521/9834858


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