Hibernate一对一外键双向关联(xml配置篇)

Hibernate一对一外键双向关联(xml配置篇)

Husband.java

package  com.one2one.bean;


public   class  Husband {
    
     private   int  id;
     private  String name;
     private  Wife wife;
     public   int  getId() {
         return  id;
    }
     public   void  setId( int  id) {
         this .id  =  id;
    }
     public  String getName() {
         return  name;
    }
     public   void  setName(String name) {
         this .name  =  name;
    }
     public  Wife getWife() {
         return  wife;
    }
     public   void  setWife(Wife wife) {
         this .wife  =  wife;
    }
    
}

Wife.java

package  com.one2one.bean;

public   class  Wife {
    
     private   int  id;
     private  String name;
     private  Husband husband;
     public   int  getId() {
         return  id;
    }
     public   void  setId( int  id) {
         this .id  =  id;
    }
     public  String getName() {
         return  name;
    }
     public   void  setName(String name) {
         this .name  =  name;
    }
     public  Husband getHusband() {
         return  husband;
    }
     public   void  setHusband(Husband husband) {
         this .husband  =  husband;
    }
    
}

映射文件
Husband.hbm.xml

<? 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.one2one.bean" >
         < class  name ="Husband"  table ="husband"  catalog ="Hibernate_One2One_fk" >
             < id  name ="id"  column ="id" >
                 < generator  class ="native" />
             </ id >
             < property  name ="name"  column ="name" />
             < one-to-one  name ="wife"  class ="Wife"  property-ref ="husband" />
         </ class >
     </ hibernate-mapping >

<one-to-one name="wife" class="Wife" property-ref="husband"/> property-ref后的husband为Wife中定义的husband属性
Wife.hbm.xml

<? 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.one2one.bean" >
         < class  name ="Wife"  table ="wife"  catalog ="Hibernate_One2One_fk" >
             < id  name ="id"  column ="id" >
                 < generator  class ="native" />
             </ id >
             < property  name ="name"  column ="name" />
             < many-to-one  name ="husband"  column ="husband_id"  unique ="true"   />
         </ class >
     </ hibernate-mapping >

<many-to-one name="husband" column="husband_id" unique="true" />
many-to-one的作用是在wife表中生成一个外键husband_id,且唯一,并参照husband表中的主键
用hibernate的hbm2ddl导出的sql

create   table  Hibernate_One2One_fk.husband (
        id  integer   not   null  auto_increment,
        name  varchar ( 255 ),
         primary   key  (id)
    )

     create   table  Hibernate_One2One_fk.wife (
        id  integer   not   null  auto_increment,
        name  varchar ( 255 ),
        husband_id  integer   unique ,
         primary   key  (id)
    )

     alter   table  Hibernate_One2One_fk.wife 
         add   index  FK37AF119039AEDD (husband_id), 
         add   constraint  FK37AF119039AEDD 
         foreign   key  (husband_id) 
         references  Hibernate_One2One_fk.husband (id)

测试示例

@Test
     public   void  save(){
        Session session = HibernateSessionFactory.getSession();
        Transaction transaction = session.beginTransaction();
         try  {
            transaction.begin();
            Husband husband = new  Husband();
            husband.setName( " 张三 " );
            session.save(husband);
            Wife wife = new  Wife();
            wife.setName( " 如花 " );
            wife.setHusband(husband);
            session.save(wife);
            transaction.commit();
        }  catch  (HibernateException e) {
            e.printStackTrace();
        }
    }
    
    @Test
     public   void  select(){
        Session session = HibernateSessionFactory.getSession();
        Husband husband = (Husband) session.get(Husband. class ,  1 );
        System.out.println(husband.getName());
        System.out.println(husband.getWife().getName());
    }