Hibernate一对多单向关系

业务逻辑：

Teacher类和Student类，假定为一对多的关系，即一个教师有多个学生。

正在装载数据……

 

1.   数据库schema

Teachers表:

create table TEACHERS

(

  ID          NUMBER(10) not null,

  TEACHERNAME VARCHAR2(15)

)

alter table TEACHERS

  add constraint DERE primary key (ID)

 

Students表：

create table STUDENTS

(

  ID          NUMBER(10) not null,

  STUDENTNAME VARCHAR2(15),

  TEACHER_ID  NUMBER(10)

)

alter table STUDENTS

  add constraint RERE primary key (ID)

alter table STUDENTS

  add constraint FFF foreign key (TEACHER_ID)

  references TEACHERS (ID);

 

2.   Teacher.java和Student.java

Teacher.java

package mypack;

 

public class Teacher {

  //教师id

  private Long id;

 

  //教师名称

  private String teacherName;

 

  /**

   * 缺省构造函数

   */

  public Teacher() {

  }

 

  /**

   * 得到教师id

   * @return Long    教师id

   */

  public Long getId() {

    return id;

  }

 

  /**

   * 设置教师id

   * @param id Long    教师id

   */

  public void setId(Long id) {

    this.id = id;

  }

 

  /**

   * 得到教师名称

   * @return String    教师名称

   */

  public String getTeacherName() {

    return teacherName;

  }

  

  /**

   * 设置教师名称

   * @param teacherName String    教师名称

   */

  public void setTeacherName(String teacherName) {

    this.teacherName = teacherName;

  }

 

  /**

   * 构造函数

   * @param teacherName String

   */

  public Teacher(String teacherName) {

    this.teacherName = teacherName;

  }

}

 

Student.java

package mypack;

 

public class Student {

  //学生id

  private Long id;

 

  //学生名称

  private String studentName;

 

  //教师类

  private Teacher teacher;

 

  /**

   * 缺省构造函数

   */

  public Student() {

  }

 

  /**

   * 得到学生id

   * @return Long    学生id

   */

  public Long getId() {

    return id;

  }

 

  /**

   * 设置学生id

   * @param id Long    学生id

   */

  public void setId(Long id) {

    this.id = id;

  }

 

  /**

   * 得到学生名称

   * @return String    学生名称

   */

  public String getStudentName() {

    return studentName;

  }

 

  /**

   * 设置学生名称

   * @param studentName String    学生名称

   */

  public void setStudentName(String studentName) {

    this.studentName = studentName;

  }

 

  /**

   * 得到教师对象

   * @return Teacher    教师对象

   */

  public Teacher getTeacher() {

    return teacher;

  }

 

  /**

   * 设置教师对象

   * @param teacher Teacher    教师对象

   */

  public void setTeacher(Teacher teacher) {

    this.teacher = teacher;

  }

 

  /**

   * 构造函数

   * @param string String

   * @param teacher Teacher

   */

  public Student(String studentName, Teacher teacher) {

    this.studentName = studentName;

    this.teacher = teacher;

  }

}

 

3.   hibernate.properties

## Oracle

 

hibernate.dialect net.sf.hibernate.dialect.Oracle9Dialect

hibernate.dialect net.sf.hibernate.dialect.OracleDialect

hibernate.connection.driver_class oracle.jdbc.driver.OracleDriver

hibernate.connection.username jbcm

hibernate.connection.password jbcm

hibernate.connection.url jdbc:oracle:thin:@localhost:1521:wsy

 

4.   Teacher.hbm.xml和Student.hbm.xml

Teacher.hbm.xml

<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping

PUBLIC "-//Hibernate/Hibernate Mapping DTD 2.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping >

 

  <class name="mypack.Teacher" table="teachers" >

    <id name="id" type="long" column="ID">

      <generator class="increment"/>

    </id>

 

    <property name="teacherName" type="string" >

        <column name="teacherName" length="15" />

    </property>

 

  </class>

 

</hibernate-mapping>

 

Student.hbm.xml

<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping

PUBLIC "-//Hibernate/Hibernate Mapping DTD 2.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping >

 

  <class name="mypack.Student" table="students" >

    <id name="id" type="long" column="ID">

      <generator class="increment"/>

    </id>

 

    <property name="studentName" type="string" >

        <column name="studentName" length="15" />

    </property>

 

   <many-to-one

        name="teacher"

        column="teacher_id"

        class="mypack.Teacher"

        cascade="save-update"

       />

 

  </class>

 

</hibernate-mapping>

 

5.   数据库操作类

BusinessService.java

package mypack;

 

import net.sf.hibernate.*;

import net.sf.hibernate.cfg.Configuration;

import java.util.*;

 

public class BusinessService{

  //session工厂类

  public static SessionFactory sessionFactory;

 

  //实始化session工厂

  static{

     try{

       //建立配置类，添加Student类和Teacher类

       Configuration config = new Configuration();

       config.addClass(Student.class)

             .addClass(Teacher.class);

      //得到sessionFactory对象

      sessionFactory = config.buildSessionFactory();

    }catch(Exception e){e.printStackTrace();}

  }

 

  /**

   * 通过学生类，查找教师类

   * @param student Student

   * @throws Exception

   * @return List

   */

  public List findTeacherByStudent(Student student) throws Exception{

    Session session = sessionFactory.openSession();

    Transaction tx = null;

    try {

      tx = session.beginTransaction();

 

      List orders=(List)session.find("from Student as o where o.teacher.id="+student.getId());

      tx.commit();

      return orders;

    }catch (Exception e) {

      if (tx != null) {

        tx.rollback();

      }

      throw e;

    } finally {

      session.close();

    }

  }

 

  /**

   * 查找指定id的学生类

   * @param student_id long

   * @throws Exception

   * @return Student

   */

  public Student findStudent(long student_id) throws Exception{

    Session session = sessionFactory.openSession();

    Transaction tx = null;

    try {

      tx = session.beginTransaction();

      Student student=(Student)session.load(Student.class,new Long(student_id));

      tx.commit();

      return student;

    }catch (Exception e) {

      if (tx != null) {

        //发生错误，回滚

        tx.rollback();

      }

      throw e;

    } finally {

      //没有错误，关闭session

      session.close();

    }

  }

 

  /**

   * 级连保存Teacher对象和Student对象

   * @throws Exception

   */

  public void saveTeacherAndStudentWithCascade() throws Exception{

    Session session = sessionFactory.openSession();

    Transaction tx = null;

    try {

      tx = session.beginTransaction();

 

      Teacher teacher=new Teacher("myTeacher");

      Student student1=new Student("student1",teacher);

      Student student2=new Student("student2",teacher);

 

      session.save(student1);

      session.save(student2);

 

      tx.commit();

 

    }catch (Exception e) {

      if (tx != null) {

        //发生错误，回滚

        tx.rollback();

      }

      e.printStackTrace();

    } finally {

      // 没有错误，关闭session

      session.close();

    }

  }

 

  /**

   * 保存教师和学生对象

   * @throws Exception

   */

  public void saveTeacherAndStudent() throws Exception{

    Session session = sessionFactory.openSession();

    Transaction tx = null;

    try {

      tx = session.beginTransaction();

 

      Teacher teacher=new Teacher("teacher1");

      session.save(teacher);

 

      Student student1=new Student("student001",teacher);

      Student student2=new Student("student002",teacher);

      session.save(student1);

      session.save(student2);

      //提交事务

      tx.commit();

 

    }catch (Exception e) {

      if (tx != null) {

        //发生错误，回滚

        tx.rollback();

      }

      throw e;

    } finally {

      // 没有错误，关闭session

      session.close();

    }

  }

 

  /**

   * 输出学生对象集合

   * @param students List

   */

  public void printStudents(List students){

      for (Iterator it = students.iterator(); it.hasNext();) {

         Student student=(Student)it.next();

         System.out.println("OrderNumber of "+student.getTeacher().getTeacherName()+ " :"+student.getStudentName());

      }

  }

 

  /**

   * 测试方法

   * @throws Exception

   */

  public void test() throws Exception{

      saveTeacherAndStudent();

//      saveTeacherAndStudentWithCascade();

//      Student student=findStudent(1);

//      List students=findTeacherByStudent(student);

//      printStudents(students);

  }

 

  public static void main(String args[]) throws Exception {

    new BusinessService().test();

    sessionFactory.close();

  }

}

 

 

目录结构示意：

Classes

                  Hibernate.property

       /mypack

                  Teacher.java

                              Student.java

                  BusinessService.java

                  Teacher.hbm.xml

                              Student.hbm.xml      

 

 

参考资料：精通Hibernate:Java对象持久化技术详解  孙卫琴