关系数据库表之间的关系:
1 正确 1
1 正确 许多
许多 正确 许多
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
@Test
public 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many
session.save(student);
session.save(certificate1);
session.save(certificate2);
session.getTransaction().commit();
} catch (Exception e) {
session.getTransaction().rollback();
e.printStackTrace();
} finally {
HibernateUtil.closeSession(session);
} } @Test
public 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);
}
} @Test
public 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:
@Test
public 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:cc
Hibernate: 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)对象被延迟载入了,many2one中，get支持延迟载入
loadTest:
@Test
public 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:
3
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=?
证书名称:cc
Hibernate: 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都被延迟载入
补充表结构及实体类源代码:
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;
}
@Override
public 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;
} }
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