hibernate映射简单实例

1创建数据库：

 --班级表
 create table grade
 (
        gid       number           primary key,  --班级ID
        gname     varchar2(50),                  --班级名称
        gdesc     varchar2(50)                   --班级介绍
 );
 --学生表
 create table student
 (
        sid       number           primary key,  --主键ID学生ID
        sname     varchar2(20),            --学生姓名
        sex       varchar2(20),            --学生性别
        gid       number           references grade(gid) ---外键班级ID
 );

 --学生证表
 create table paper
 (
        pid   number primary key,
        pdesc varchar2(100)  ,
        sid   number references student(sid) not null

 );

二、创建配置文件和持久化类：

学生类

package entity;

/*
 * 学生类
 */
public class Student implements java.io.Serializable {

    // Fields

    private static final long serialVersionUID = 1L;
    private int sid;
    private String sname;
    private String sex;
    //增加班级属性
    private Grade grade;
    //学生证类
    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;
    }

}

学生证类

 package entity;

 /*
  * 学生证类
  */

 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>

Student类配置文件

 <?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属性  -->
         <many-to-one name="grade" class="entity.Grade" cascade="save-update">
         <!--指定学生表中的外键  -->
         <column name="GID" />
         </many-to-one>
         <!-- 添加学生证的配置 -->
         <one-to-one name="paper" class="entity.Paper" cascade="all" lazy="false"/>
     </class>
 </hibernate-mapping>

Paper类配置文件

 <?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>

         <!-- 添加学生证的配置 -->
         <one-to-one name="paper" class="entity.Paper" cascade="all" lazy="false" property-ref="student"/>
     </class>
 </hibernate-mapping>

测试类

 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("王霸");
         stu1.setSex("女");

         Paper paper=new Paper();
         paper.setPid(9001);
         paper.setPdesc("王霸的学生证");
         paper.setStudent(stu1);

         stu1.setPaper(paper);

         // 建立session
                 Session session = new Configuration().configure().buildSessionFactory()
                         .openSession();
                 // 开始事务
                 Transaction transaction = session.beginTransaction();

                 // 保存学生证
                 session.save(stu1);
                 // 提交事务
                 transaction.commit();
                 // 关闭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());
     }

 }