hibernate一对一，一对多，多对一，多对多关系映射与级联

总结一下hibernate的多种关系映射与级联（1）one-to-many （一对多）          实体类中one方封装一个set集合（set集合装的是many对象）作为属性，并初始化。实体many方封装一个one对象。         以UserInfo---EmailInfo---LetterInfo 三张表来级联说明主控方的选择与cascade的配置         1)生成配置文件。          2)选择主控方，设置级联操作。(one-tomany,many-to-one 一般选择many一方作为主控方)              inverse = false;表示主控方,关系表的维护由主控方维护。一般在one-to-many或many-to-many中设置              cascade级联：属性值有：                    none,all,save-update,delete, lock,refresh,evict,replicate,persist, merge,delete-orphan(one-to-many)               inverse在双向关系中 inverse 只需要在一方配置即可（其中cascade级联与inverse一起使用）           3)在级联查询与删除中cascade在set标签中配置。          4)添加，修改cascade配置以主控方要影响的对象为根据配置。例如：以Letter做主控方添加email，user。  //LetterInfo.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"><!--     Mapping file autogenerated by MyEclipse Persistence Tools--><hibernate-mapping>    <class name="com.sxt.entity.LetterInfo" table="letter_info" catalog="email">        <id name="id" type="java.lang.Integer">            <column name="id" />            <generator class="native" />        </id>        <property name="title" type="java.lang.String">            <column name="title" length="30" not-null="true" />        </property>        <!-- 在要级联的地方(主控方要影响的)添加cascade不一定在set -->         <many-to-one name="email" class="com.sxt.entity.EmailInfo" cascade="all">            <column name="eid" not-null="true" />        </many-to-one>    </class></hibernate-mapping>//EmailInfo.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"><!--     Mapping file autogenerated by MyEclipse Persistence Tools--><hibernate-mapping>    <class name="com.sxt.entity.EmailInfo" table="email_info" catalog="email">        <id name="id" type="java.lang.Integer">            <column name="id" />            <generator class="native" />        </id>        <property name="address" type="java.lang.String">            <column name="address" length="20" not-null="true" />        </property>     <!-- 对于user,email为主控，要影响user  -->        <many-to-one name="user" class="com.sxt.entity.UserInfo" cascade="all">            <column name="uid" not-null="true" />        </many-to-one>       <!-- 此处指明letter为主控 -->        <set name="letters" inverse="true">            <key>                <column name="eid" not-null="true" />            </key>            <one-to-many class="com.sxt.entity.LetterInfo" />        </set>    </class></hibernate-mapping>              // UserInfo.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"><!--     Mapping file autogenerated by MyEclipse Persistence Tools--><hibernate-mapping>    <class name="com.sxt.entity.UserInfo" table="user_info" catalog="email">        <id name="id" type="java.lang.Integer">            <column name="id" />            <generator class="native" />        </id>        <property name="name" type="java.lang.String">            <column name="name" length="20" not-null="true" />        </property>        <set name="emails" inverse="true">            <key>                <column name="uid" not-null="true" />            </key>            <one-to-many class="com.sxt.entity.EmailInfo" />        </set>    </class></hibernate-mapping>//test.java/*** 以letter为主控：(many方为主控，推荐)* 在要影响的地方添加cascade*/public void testAddLetter(){Session session = HibernateSessionFactory.getSession();LetterInfo letter = new LetterInfo("华山论剑");EmailInfo email = new EmailInfo("[e-mail]");UserInfo user = new UserInfo("黄蓉");letter.setEmail(email);email.setUser(user);Transaction tx = session.beginTransaction();session.save(letter);tx.commit();HibernateSessionFactory.closeSession();}        /*** 删除用户同时删除邮箱与邮箱内的邮件* letter为主控配置inverse，cascade在set中配置（与查询一样）* */public void testDeleteUser(){Session session = HibernateSessionFactory.getSession();UserInfo user = (UserInfo) session.get(UserInfo.class,25);//EmailInfo email = (EmailInfo)session.get(EmailInfo.class,2);Transaction tx = session.beginTransaction();session.delete(user);tx.commit();HibernateSessionFactory.closeSession();} /**     * 以user为主控：(one 方为主控)     *  瞬时态数据持久化需要注意:     *   对象数据需要双向设置     *        *        */public void testAddUser(){Session session = HibernateSessionFactory.getSession();Transaction tx = session.beginTransaction();UserInfo user = new UserInfo("萨斯");EmailInfo e1 = new EmailInfo("[e-mail]");LetterInfo letter = new LetterInfo("欢迎你，萨斯");letter.setEmail(e1);e1.getLetters().add(letter);e1.setUser(user);user.getEmails().add(e1);session.save(user);tx.commit();HibernateSessionFactory.closeSession();}public void testQueryUser(){Session session = HibernateSessionFactory.getSession();UserInfo ui = (UserInfo)session.get(UserInfo.class, 1);System.out.println(ui.getName());   Set<EmailInfo>emails = ui.getEmails();   for (EmailInfo ei : emails) {System.out.println(ei.getAddress());Set<LetterInfo> letters = ei.getLetters();for (LetterInfo letter : letters) {System.out.print("\t"+letter.getTitle());}System.out.println("");}   HibernateSessionFactory.closeSession();}     public void testQueryEmail(){Session session = HibernateSessionFactory.getSession();LetterInfo letter = (LetterInfo)session.get(LetterInfo.class, 1);System.out.println("信件:"+letter.getTitle());EmailInfo email= letter.getEmail();System.out.println("\t"+email.getAddress());UserInfo user = email.getUser();System.out.println("\t\t"+user.getName());HibernateSessionFactory.closeSession();}        //one-to-one     以cardInfo-personInfo    //CardInfo.hbm.xml文件    <?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"><!--     Mapping file autogenerated by MyEclipse Persistence Tools--><hibernate-mapping>    <class name="com.sxt.entity.CardInfo" table="card_info" catalog="students">        <id name="cid" type="java.lang.Integer">            <column name="cid" />            <generator class="native" />        </id>       <one-to-one name="person"/>        <property name="code" type="java.lang.String">            <column name="code" length="20" not-null="true" />        </property>    </class></hibernate-mapping>//PersonInfo.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"><!--     Mapping file autogenerated by MyEclipse Persistence Tools--><hibernate-mapping>    <class name="com.sxt.entity.PersonInfo" table="person_info" catalog="students">        <id name="pid" type="java.lang.Integer">            <column name="pid" />            <generator class="native" />        </id>        <property name="name" type="java.lang.String">            <column name="name" length="20" not-null="true" />        </property>        <one-to-one name="card"/>    </class></hibernate-mapping>/*** one-to-one*   */public void test5(){Session session = HibernateSessionFactory.getSession();PersonInfo person = (PersonInfo)session.get(PersonInfo.class,1);   System.out.println(person.getName()+"\t"+person.getCard().getCode());   HibernateSessionFactory.closeSession();}many-to-many   以studentinfo-teacherInfo为例//TeacherInfo.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"><!--     Mapping file autogenerated by MyEclipse Persistence Tools--><hibernate-mapping>    <class name="com.sxt.entity.TeacherInfo" table="teacher_info" catalog="students">        <id name="id" type="java.lang.Integer">            <column name="id" />            <generator class="native" />        </id>        <property name="name" type="java.lang.String">            <column name="name" length="20" not-null="true" />        </property>        <set name="students">            <key column="tid"/>            <many-to-many class="com.sxt.entity.StudentInfo" column="sid"/>        </set>    </class></hibernate-mapping>//StudentInfo.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"><!--     Mapping file autogenerated by MyEclipse Persistence Tools--><hibernate-mapping>    <class name="com.sxt.entity.StudentInfo" table="student_info" catalog="students">        <id name="id" type="java.lang.Integer">            <column name="id" />            <generator class="native" />        </id>        <property name="name" type="java.lang.String">            <column name="name" length="20" not-null="true" />        </property>        <set name="teachers" inverse="false" table="student_teacher_info" cascade="all">            <key column="sid" not-null="true"/>            <many-to-many class="com.sxt.entity.TeacherInfo" column="tid"/>        </set>    </class></hibernate-mapping>//java部分/*** many-to-many:级联操作之添加数据(包括添加瞬时态与持久态)*/public void test2(){Session session = HibernateSessionFactory.getSession();//添加瞬时态数据// StudentInfo stu = new StudentInfo("郭靖");// Set<TeacherInfo> teachers = new HashSet<TeacherInfo>();// TeacherInfo t1 = new TeacherInfo("洪七公");// TeacherInfo t2 = new TeacherInfo("江南七怪");//根据持久态数据添加关系Transaction transaction = session.beginTransaction();TeacherInfo t1 = (TeacherInfo) session.get(TeacherInfo.class,1);TeacherInfo t2 = (TeacherInfo) session.get(TeacherInfo.class,2);Set<TeacherInfo> teachers = new HashSet<TeacherInfo>();teachers.add(t1);teachers.add(t2);//以学生为主控方，学生维护关系表StudentInfo stu = (StudentInfo) session.get(StudentInfo.class,1);stu.setTeachers(teachers);session.update(stu);transaction.commit();HibernateSessionFactory.closeSession();}/*** many-to-many:级联操作之更新数据(删除)*/public void test3(){Session session = HibernateSessionFactory.getSession();//TeacherInfo ti = (TeacherInfo) session.get(TeacherInfo.class,5);Transaction tx = session.beginTransaction();StudentInfo  stu = (StudentInfo)session.get(StudentInfo.class, 1);TeacherInfo  t  = (TeacherInfo)session.get(TeacherInfo.class, 2);// session.delete(stu);//删除关系与学生//仅删除关系，不删除老师stu.getTeachers().remove(t);session.update(stu);tx.commit();HibernateSessionFactory.closeSession();}/*** 测试many-to-many:级联操作之更新数据(修改);*/public void test4(){Session session = HibernateSessionFactory.getSession();StudentInfo stu = (StudentInfo)session.get(StudentInfo.class, 1);TeacherInfo t1 = (TeacherInfo)session.get(TeacherInfo.class,1);TeacherInfo t2 = (TeacherInfo)session.get(TeacherInfo.class,2);        stu.getTeachers().remove(t1);        stu.getTeachers().add(t2);Transaction tx = session.beginTransaction();session.update(stu);tx.commit();HibernateSessionFactory.closeSession();}