hibernate双向一对一主键关联映射XML与注解版

╰+攻爆jí腚メ 2022-06-16 04:47 227阅读 0赞

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：

![20170505223114218][]

**(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"/>
            
            <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 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

![20170505224843405][]

idcard表

![20170505224852015][]

示例: [ http://download.csdn.net/detail/u011781521/9834854][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][http_download.csdn.net_detail_u011781521_9834858]

[20170505223114218]: /images/20220616/985c74b12a1140ab92829dbd004f35f6.png
[20170505224843405]: /images/20220616/8705afd12ce74e7984b0168469363e0c.png
[20170505224852015]: /images/20220616/71532948811b49729c77d6c6cd989169.png
[http_download.csdn.net_detail_u011781521_9834854]: http://download.csdn.net/detail/u011781521/9834854
[http_download.csdn.net_detail_u011781521_9834858]: http://download.csdn.net/detail/u011781521/9834858