一对一映射

<hibernate-mapping package="com.longtop.entity">
    <class name="TbDossier" table="TB_DOSSIER">
        <id name="sn" type="java.lang.Long" column="SN">

             //foreign方式生成同一个主键(foreign在那边就在哪边进行保存,另一方也就自动保存了....)
            <generator class="foreign">
                  <param name="property">tbStudent</param>
            </generator>
        </id>
        <property name="highSchool" type="java.lang.String">
            <column name="HIGH_SCHOOL" length="30" not-null="true" />
        </property>
 
        <property name="seniorSchool" type="java.lang.String">
            <column name="SENIOR_SCHOOL" length="20" />
        </property>
        <property name="university" type="java.lang.String">
            <column name="UNIVERSITY" length="20" />
        </property>

     //重要
        <one-to-one name="tbStudent" class="TbStudent"
           cascade="all">
        </one-to-one> 

    
    </class>
</hibernate-mapping>

 

 

tb_dossier的主键sn和对应的tb_student的主键sn是相同值，主要通过foreign的方式生成的，其中如果删除了可以级联操作cascade，即删除了tb_dossier，就会自动删除tb_student。

public class OneToOne {
   
         public static void main(String[] args) throws HibernateException {
              SessionFactory sessions =   new Configuration().configure().buildSessionFactory();
              Session session = sessions.openSession();
              Transaction tx = session.beginTransaction();
              Long start = new Date().getTime();
              System.out.println("starttime:"+start);
             
              //添加、修改、删除方法
              OneToOne.createStudent(session,
                OneToOne.newStudent(session, "leochou", "26"),
                "1中",
                "1中",
                "厦门大学");
             
              OneToOne.updateDossier(session, new Long("11"));
            // OneToOne.updateStudent(session, new Long("31"));
            //
            // OneToOne.deleteDossier(session, new Long("6"));
             
            // session.save(OneToOne.createStudent(session, "lucy", "20"));
              tx.commit();
              session.close();
             
              Long end = new Date().getTime();  
              System.out.println("endtime:"+end);
              System.out.println("总共用了"+(end-start)+"的时间");
       
         }
         private static TbStudent newStudent(Session session,String name,String age) throws HibernateException {
              TbStudent student = new TbStudent();
              student.setName(name);
              student.setAge(age);
              return student;
         }
       
         private static void createStudent(Session session,
                   TbStudent student,
                   String highSchool,
                   String seniorSchool,
                   String university) throws HibernateException {
              TbDossier dossier = new TbDossier();
              dossier.setHighSchool(highSchool);
              dossier.setSeniorSchool(seniorSchool);
              dossier.setUniversity(university);
              dossier.setTbStudent(student);
              session.save(dossier);
         }
        
         private static void updateDossier(Session session,Long sn) throws HibernateException {
              TbDossier dossier = (TbDossier) session.load(TbDossier.class, sn);
              dossier.setSeniorSchool("八中");
              dossier.getTbStudent().setName("change dossier");
              session.update(dossier);
         }
        
         private static void updateStudent(Session session,Long sn) throws HibernateException {
              TbStudent student = (TbStudent) session.load(TbStudent.class, sn);
              student.setName("change student");
              session.update(student);
         }
        
         private static void deleteDossier(Session session,Long sn) throws HibernateException {
              TbDossier dossier = (TbDossier) session.load(TbDossier.class, sn);
              session.delete(dossier);
         }
    }

注意：

       为了保证每个同学都有一个档案，所以创建学生的时候，必须session.save(tbDossier)。这样才能tb_student与tb_dossier同时创建。

（二）tb_dossier通过student_sn外键关联tb_student(这个就是多对一了..,在dossier表中多建立一个字段叫student_sn)。

              两种实现方式的最大不同在于：1、tb_dossier必须新增一个字段student_sn存放对应的tb_student的sn，2、配置文件的不同，tb_dossier主键的生成不再以来tb_student的主键，独立生成。两个的关系用<many to one>表示，注意 unique="true"必须设为true。

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping package="com.longtop.entity">
    <class name="TbDossier" table="TB_DOSSIER">
        <id name="sn" type="java.lang.Long" column="SN">
        <generator class="sequence">
        <param name="sequence">seq_tb_dossier_sn</param>
        </generator>
        </id>
        <property name="highSchool" type="java.lang.String">
            <column name="HIGH_SCHOOL" length="30" not-null="true" />
        </property>
 
        <property name="seniorSchool" type="java.lang.String">
            <column name="SENIOR_SCHOOL" length="20" />
        </property>
        <property name="university" type="java.lang.String">
            <column name="UNIVERSITY" length="20" />
        </property>
        <many-to-one name="tbStudent"
        class="com.longtop.entity.TbStudent"
        column="STUDENT_SN"
        unique="true" cascade="all">
        </many-to-one>      
    </class>
</hibernate-mapping>