hibernate之5.many2one单向

关系数据库表间关系:

1 对 1 

1 对 多

多 对 多

表间关系设计

基于主键关联

基于外键关联

基于中间表

1 对 1关系实现:

基于主键关联

基于外键关联

基于中间表

 

1 对 多关系实现:

基于外键关联

基于中间表

多 对 多关系实现:

基于中间表

面向对象实体关系

1 对 1 

1 对 多

多 对 多

方向 :

单向、双向

CRUD:

many2one配置:

<?xml version="1.0"?><!DOCTYPE hibernate-mapping PUBLIC        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"        "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"><hibernate-mapping package="com.demo.model">    <class name="Certificate" table="t_certificate">        <id name="certificateId" column="certificate_id">            <generator class="sequence"><param name="sequence">SEQ_T_CERTIFICATE</param></generator>        </id>        <property name="certificateName" column="certificate_name"/>        <property name="certificateNo" column="certificate_no"/>        <many-to-one name="student" column="student_id"></many-to-one>    </class></hibernate-mapping>

<many-to-one name="student" column="student_id"></many-to-one>

增、删、改

@Testpublic void addTest() {Student student = new Student();student.setStudentName("王五");student.setAge(35);Certificate certificate1 = new Certificate();certificate1.setCertificateName("aa");certificate1.setCertificateNo("3a10001");certificate1.setStudent(student);Certificate certificate2 = new Certificate();certificate2.setCertificateName("bb");certificate2.setCertificateNo("3a10002");certificate2.setStudent(student);Session session = null;try {session = HibernateUtil.openSession();session.beginTransaction();// 先保存one,再保存manysession.save(student);session.save(certificate1);session.save(certificate2);session.getTransaction().commit();} catch (Exception e) {session.getTransaction().rollback();e.printStackTrace();} finally {HibernateUtil.closeSession(session);}}@Testpublic void deleteTest() {Student student = new Student();student.setStudentId(1);Certificate certificate1 = new Certificate();certificate1.setCertificateId(1);Certificate certificate2 = new Certificate();certificate2.setCertificateId(2);Session session = null;try {session = HibernateUtil.openSession();session.beginTransaction();session.delete(certificate1);session.delete(certificate2);session.delete(student);session.getTransaction().commit();} catch (Exception e) {session.getTransaction().rollback();e.printStackTrace();} finally {HibernateUtil.closeSession(session);}}@Testpublic void updateTest() {Student student = new Student();student.setStudentId(2);student.setStudentName("赵四");Certificate certificate1 = new Certificate();certificate1.setCertificateId(3);certificate1.setCertificateName("cc");certificate1.setCertificateNo("s0001");certificate1.setStudent(student);Certificate certificate2 = new Certificate();certificate2.setCertificateId(4);certificate2.setCertificateName("dd");certificate2.setCertificateNo("s0002");certificate2.setStudent(student);Session session = null;try {session = HibernateUtil.openSession();session.beginTransaction();session.update(certificate1);session.update(certificate2);session.update(student);session.getTransaction().commit();} catch (Exception e) {session.getTransaction().rollback();e.printStackTrace();} finally {HibernateUtil.closeSession(session);}}

getTest:

@Testpublic void updateTest() {Student student = new Student();student.setStudentId(2);student.setStudentName("赵四");Certificate certificate1 = new Certificate();certificate1.setCertificateId(3);certificate1.setCertificateName("cc");certificate1.setCertificateNo("s0001");certificate1.setStudent(student);Certificate certificate2 = new Certificate();certificate2.setCertificateId(4);certificate2.setCertificateName("dd");certificate2.setCertificateNo("s0002");certificate2.setStudent(student);Session session = null;try {session = HibernateUtil.openSession();session.beginTransaction();session.update(certificate1);session.update(certificate2);session.update(student);session.getTransaction().commit();} catch (Exception e) {session.getTransaction().rollback();e.printStackTrace();} finally {HibernateUtil.closeSession(session);}}

结果:

Hibernate: select certificat0_.certificate_id as certific1_1_0_, certificat0_.certificate_name as certific2_1_0_, certificat0_.certificate_no as certific3_1_0_, certificat0_.student_id as student4_1_0_ from t_certificate certificat0_ where certificat0_.certificate_id=?3证书名称:ccHibernate: select student0_.student_id as student1_0_0_, student0_.student_name as student2_0_0_, student0_.age as age0_0_ from t_student student0_ where student0_.student_id=?学员名称:赵四

Student(one)对象被延迟加载了,many2one中，get支持延迟加载

loadTest:

@Testpublic void loadTest() {Session session = null;try {session = HibernateUtil.openSession();session.beginTransaction();Certificate certificate = (Certificate) session.load(Certificate.class, 3);System.out.println(certificate.getCertificateId());System.out.println("证书名称:"+certificate.getCertificateName());System.out.println("学员名称:"+certificate.getStudent().getStudentName());session.getTransaction().commit();} catch (Exception e) {session.getTransaction().rollback();e.printStackTrace();} finally {HibernateUtil.closeSession(session);}}

结果:

3Hibernate: select certificat0_.certificate_id as certific1_1_0_, certificat0_.certificate_name as certific2_1_0_, certificat0_.certificate_no as certific3_1_0_, certificat0_.student_id as student4_1_0_ from t_certificate certificat0_ where certificat0_.certificate_id=?证书名称:ccHibernate: select student0_.student_id as student1_0_0_, student0_.student_name as student2_0_0_, student0_.age as age0_0_ from t_student student0_ where student0_.student_id=?学员名称:赵四

many与one都被延迟加载

补充表结构及实体类源码:

t_student

t_certificate:

Student:

package com.demo.model;import java.io.UnsupportedEncodingException;/**学生信息双向 * @author wobendiankun *2014-10-19 下午08:54:29 */public class Student {private int studentId ;private String studentName ;private int age;public int getStudentId() {return studentId;}public void setStudentId(int studentId) {this.studentId = studentId;}public String getStudentName() {return studentName;}public void setStudentName(String studentName) {this.studentName = studentName;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}@Overridepublic String toString() {String str="";if(studentName!=null){try {str=new String(studentName.getBytes("UTF-8"));} catch (UnsupportedEncodingException e) {e.printStackTrace();}}return "Student [studentId=" + studentId + ", studentName="+ str + ", age=" + age + "]";}}

Certificate

package com.demo.model;/**从业资格证书 * @author wobendiankun *2014-10-25 上午11:43:21 */public class Certificate {/** * 证书id */private int certificateId ;/** * 证书名称 */private String certificateName;/** *证书编号 */private String certificateNo ;private Student student ;public int getCertificateId() {return certificateId;}public void setCertificateId(int certificateId) {this.certificateId = certificateId;}public String getCertificateName() {return certificateName;}public void setCertificateName(String certificateName) {this.certificateName = certificateName;}public String getCertificateNo() {return certificateNo;}public void setCertificateNo(String certificateNo) {this.certificateNo = certificateNo;}public Student getStudent() {return student;}public void setStudent(Student student) {this.student = student;}}