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Hibernate一对多单向关系

1.   数据库schema

Teachers:

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.javaStudent.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.xmlStudent.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
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      

 

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