一、创建数据库表
--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>
学生类配置文件
<?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>
学生证类配置文件
<?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">
<!--
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>
<!-- 学生信息 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>
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) {
save();
find();
}
public static void save() {
Student stu1 = new Student();
stu1.setSid(20151109);
stu1.setSname("钱七");
stu1.setSex("女");
Paper paper=new Paper();
paper.setPid(9001);
paper.setPdesc("钱七的学生证");
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());
}
}
发现可以 通过学生证，找到学生
但反过来，如果通过学生，找到学生证呢，显示是不能的，因为学生类中配置文件没有实现关联
修改学生类的配置文件 property-ref="student"用来指定Paper类中的属性
<?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" 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("钱七");
stu1.setSex("女");
Paper paper=new Paper();
paper.setPid(9001);
paper.setPdesc("钱七的学生证");
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());
}
}
时间： 2024-10-06 00:10:42