hibernate 一对一、多对一 双向关联的问题——只能在多的一方添加、修改数据，不能在多的一方修改添加

本文章可能存在问题，可以参看王勇老师的视频

问题说明：一对一，多对一双向，只能在多的那方添加、修改对象；不能在一得一方添加、修改对象，结果可能是不生成update语句，添加数据，在多的方对应的表中外键为null。

以学生老师表为例：只能通过学生类添加对象、修改自己的教师。不能通过老师添加一个学生，修改自己带的学生（带哪几个，不带哪几个学生）。

下面是源码和测试文件：

可以参考：http://yangfei520.blog.51cto.com/1041581/274605

 

 

 

<?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 package="com.gem.hibernate.pojo.pko2o"><class name="Student2" ><id name="id"><generator class="identity" /></id><property name="name" not-null="true" length="25" /><many-to-one name="teacher2" class="Teacher2" column="t_id"unique="true" ></many-to-one></class> <?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 package="com.gem.hibernate.pojo.pko2o"><class name="Teacher2"><id name="t_id"><generator class="identity" /></id><property name="name" not-null="true" length="15" /><one-to-one name="student2" class="Student2" ></one-to-one></class></hibernate-mapping>public class Teacher2 {private int t_id; private String name; private Student2 student2;。。。。。。。。。。。public class Student2 {private int id; private String name; private Teacher2 teacher2;。。。。。。。。。。。。 //testpackage com.gem.hibernate.test;import org.hibernate.HibernateException;import org.hibernate.Session;import com.gem.hbn.util.hbnUtil;import com.gem.hibernate.pojo.pko2o.Student2;import com.gem.hibernate.pojo.pko2o.Teacher2;import junit.framework.TestCase;public class fko2oTest extends TestCase {Session session = null;Teacher2 tea2 = null;Student2 stu2 = null;public void testAdd() {try {session = hbnUtil.getSession();session.beginTransaction();Teacher2 t2_1 = new Teacher2();t2_1.setName("Alen");session.save(t2_1);Teacher2 t2_2 = new Teacher2();t2_2.setName("Bush");session.save(t2_2);Teacher2 t2_3 = new Teacher2();t2_3.setName("Call");session.save(t2_3);Teacher2 t2_4 = new Teacher2();t2_4.setName("David");session.save(t2_4);Student2 s2_1 = new Student2();s2_1.setName("aa");s2_1.setTeacher2(t2_1);session.save(s2_1);Student2 s2_2 = new Student2();s2_2.setName("bb");s2_2.setTeacher2(t2_2);session.save(s2_2);Student2 s2_3 = new Student2();s2_3.setName("cc");session.save(s2_3);Student2 s2_4 = new Student2();s2_4.setName("aa");session.save(s2_4);tea2 = new Teacher2();tea2.setName("lee");session.save(tea2);stu2 = new Student2();stu2.setName("Jor");stu2.setTeacher2(tea2);session.save(stu2);session.getTransaction().commit();} catch (HibernateException e) {e.printStackTrace();session.getTransaction().rollback();} finally {hbnUtil.closeSession(session);}}public void testUpdate1() {try {session = hbnUtil.getSession();session.beginTransaction();tea2 = (Teacher2) session.get(Teacher2.class, 4);stu2 = (Student2) session.get(Student2.class, 1);stu2.setName("John");stu2.setTeacher2(tea2);session.saveOrUpdate(stu2);session.getTransaction().commit();} catch (HibernateException e) {e.printStackTrace();session.getTransaction().rollback();} finally {hbnUtil.closeSession(session);}}public void testUpdate2() {try {session = hbnUtil.getSession();session.beginTransaction();stu2 = (Student2) session.get(Student2.class, 3);tea2 = (Teacher2)session.get(Teacher2.class,1);tea2.setName("2");tea2.setStudent2(stu2);session.update(tea2);session.getTransaction().commit();} catch (HibernateException e) {e.printStackTrace();session.getTransaction().rollback();} finally {hbnUtil.closeSession(session);}}public void testDel(){try {session = hbnUtil.getSession();session.beginTransaction();stu2 = (Student2) session.get(Student2.class, 3);tea2 = (Teacher2)session.get(Teacher2.class,1);tea2.setName("2");tea2.setStudent2(stu2);session.delete(tea2);session.getTransaction().commit();} catch (HibernateException e) {e.printStackTrace();session.getTransaction().rollback();} finally {hbnUtil.closeSession(session);}}}