--班級表create table grade(       gid       number           PRimary key,  --班級ID       gname     varchar2(50),                  --班級名稱       gdesc     varchar2(50)                   --班級介紹);--學生表create table student(       sid       number           primary key,  --主鍵ID學生ID       sname     varchar2(20),            --學生姓名       sex       varchar2(20),            --學生性別       gid       number           references grade(gid) ---外鍵班級ID);--學生證表create table paper(       pid   number primary key,       pdesc varchar2(100)  ,       sid   number references student(sid) not null       );

學生類

package entity;/* * 學生類 */public class Student implements java.io.Serializable {    // Fields    private static final long serialVersionUID = 1L;    private int sid;    private String sname;    private String sex;    //增加班級屬性    private Grade grade;    //學生證類    private Paper paper;    // Constructors    /** default constructor */    public Student() {    }    /** minimal constructor */    public Student(int sid) {        this.sid = sid;    }    /** full constructor */    public Student(int sid, String sname, String sex ) {            this.sid = sid;        this.sname = sname;        this.sex = sex;    }    // Property accessors    public int getSid() {        return this.sid;    }    public void setSid(int sid) {        this.sid = sid;    }        public String getSname() {        return this.sname;    }    public void setSname(String sname) {        this.sname = sname;    }    public String getSex() {        return this.sex;    }    public void setSex(String sex) {        this.sex = sex;    }    public Grade getGrade() {        return grade;    }    public void setGrade(Grade grade) {        this.grade = grade;    }    public Paper getPaper() {        return paper;    }    public void setPaper(Paper paper) {        this.paper = paper;    }    }

學生證類

package entity;/* * 學生證類 */public class Paper implements java.io.Serializable {    // Fields    private static final long serialVersionUID = 1L;    private int pid;    private Student student;    private String pdesc;    // Constructors    /** default constructor */    public Paper() {    }    /** minimal constructor */    public Paper(int pid) {        this.pid = pid;    }    /** full constructor */    public Paper(int pid, Student student, String pdesc) {        this.pid = pid;        this.student = student;        this.pdesc = pdesc;    }    // Property accessors    public int getPid() {        return this.pid;    }    public void setPid(int pid) {        this.pid = pid;    }    public Student getStudent() {        return this.student;    }    public void setStudent(Student student) {        this.student = student;    }    public String getPdesc() {        return this.pdesc;    }    public void setPdesc(String pdesc) {        this.pdesc = pdesc;    }}

hibernate.cfg.xml配置文件

<?xml version='1.0' encoding='UTF-8'?><!DOCTYPE hibernate-configuration PUBLIC          "-//Hibernate/Hibernate Configuration DTD 3.0//EN"          "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"><hibernate-configuration>    <session-factory>        <property name="dialect">            org.hibernate.dialect.Oracle9Dialect        </property>        <property name="connection.url">            jdbc:oracle:thin:@localhost:1521:orcl        </property>        <property name="connection.username">root</property>        <property name="connection.passWord">root</property>        <property name="connection.driver_class">            oracle.jdbc.OracleDriver        </property>        <property name="show_sql">true</property>        <property name="format_sql">true</property>        <mapping resource="entity/Grade.hbm.xml" />        <mapping resource="entity/Student.hbm.xml" />        <mapping resource="entity/Paper.hbm.xml" />    </session-factory></hibernate-configuration>

學生類配置文件

<?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"><hibernate-mapping>    <class name="entity.Student" table="STUDENT" schema="ROOT">        <id name="sid" type="java.lang.Integer">            <column name="SID" precision="22" scale="0" />            <generator class="assigned" />        </id>        <property name="sname" type="java.lang.String">            <column name="SNAME" length="20" />        </property>        <property name="sex" type="java.lang.String">            <column name="SEX" length="20" />        </property>        <!--配置grade屬性  -->        <many-to-one name="grade" class="entity.Grade" cascade="save-update">        <!--指定學生表中的外鍵  -->        <column name="GID" />        </many-to-one>        <!-- 添加學生證的配置 -->        <one-to-one name="paper" class="entity.Paper" cascade="all" lazy="false"/>    </class></hibernate-mapping>

學生證類配置文件

<?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="entity.Paper" table="PAPER" schema="ROOT">        <id name="pid" type="java.lang.Integer">            <column name="PID" precision="22" scale="0" />            <generator class="assigned" />        </id>                <property name="pdesc" type="java.lang.String">            <column name="PDESC" length="100" />        </property>        <!-- 學生信息 unique唯一的-->        <many-to-one name="student" class="entity.Student" unique="true" lazy="false">            <column name="SID" precision="22" scale="0" />        </many-to-one>    </class></hibernate-mapping>

測試類

package Test;import org.hibernate.Session;import org.hibernate.Transaction;import org.hibernate.cfg.Configuration;import entity.Paper;import entity.Student;public class Demo6 {    public static void main(String[] args) {        save();        find();    }    public static void save() {                Student stu1 = new Student();        stu1.setSid(20151109);        stu1.setSname("錢七");        stu1.setSex("女");            Paper paper=new Paper();        paper.setPid(9001);        paper.setPdesc("錢七的學生證");        paper.setStudent(stu1);                        stu1.setPaper(paper);                // 建立session                Session session = new Configuration().configure().buildSessionFactory()                        .openSession();                // 開始事務                Transaction transaction = session.beginTransaction();                                        // 保存學生證                session.save(stu1);                // 提交事務                transaction.commit();                // 關閉session                session.close();    }    public static void find() {        // 建立session        Session session = new Configuration().configure().buildSessionFactory()                .openSession();        Paper paper=(Paper) session.get(Paper.class, 9001);        System.out.println(paper.getPid()+paper.getPdesc());        Student stu1=paper.getStudent();        System.out.println(stu1.getSid()+"/t"+stu1.getSname());    }}

發現可以 通過學生證，找到學生

但反過來，如果通過學生，找到學生證呢，顯示是不能的，因為學生類中配置文件沒有實現關聯

修改學生類的配置文件property-ref="student"用來指定Paper類中的屬性

<?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>    <class name="entity.Student" table="STUDENT" schema="ROOT">        <id name="sid" type="java.lang.Integer">            <column name="SID" precision="22" scale="0" />            <generator class="assigned" />        </id>        <property name="sname" type="java.lang.String">            <column name="SNAME" length="20" />        </property>        <property name="sex" type="java.lang.String">            <column name="SEX" length="20" />        </property>        <!--配置grade屬性  -->        <many-to-one name="grade" class="entity.Grade" cascade="save-update">        <!--指定學生表中的外鍵  -->        <column name="GID" />        </many-to-one>        <!-- 添加學生證的配置 -->        <one-to-one name="paper" class="entity.Paper" cascade="all" lazy="false" property-ref="student"/>    </class></hibernate-mapping>

測試類

package Test;import org.hibernate.Session;import org.hibernate.Transaction;import org.hibernate.cfg.Configuration;import entity.Paper;import entity.Student;public class Demo6 {    public static void main(String[] args) {        findByStu();    }    public static void save() {                Student stu1 = new Student();        stu1.setSid(20151109);        stu1.setSname("錢七");        stu1.setSex("女");            Paper paper=new Paper();        paper.setPid(9001);        paper.setPdesc("錢七的學生證");        paper.setStudent(stu1);                        stu1.setPaper(paper);                // 建立session                Session session = new Configuration().configure().buildSessionFactory()                        .openSession();                // 開始事務                Transaction transaction = session.beginTransaction();                                        // 保存學生證                session.save(stu1);                // 提交事務                transaction.commit();                // 關閉session                session.close();    }    public static void find() {        // 建立session        Session session = new Configuration().configure().buildSessionFactory()                .openSession();        Paper paper=(Paper) session.get(Paper.class, 9001);        System.out.println(paper.getPid()+paper.getPdesc());        Student stu1=paper.getStudent();        System.out.println(stu1.getSid()+"/t"+stu1.getSname());    }    public static void findByStu() {        // 建立session        Session session = new Configuration().configure().buildSessionFactory()                .openSession();        Student stu=(Student) session.get(Student.class, 20151109);        System.out.println(stu.getSname());        Paper paper=stu.getPaper();        System.out.println(paper.getPid()+"/t"+paper.getPdesc());    }}