Hibernate基础知识
本文主要包括以下内容
- 对象的状态
- 一对多的单向关联
- 一对多的双向关联
- 多对多关联
- 一对一关联
对象状态的变化
对象的状态
临时状态
new持久化状态
get,save,update脱管状态
clear close evict
一对多单向操作，以班级表与学生表为例
Classes.java
package cn.itcast.hiberate.sh.domain;
import java.io.Serializable;
import java.util.Set;
public class Classes implements Serializable{
private Long cid;
private String cname;
private String description;
public Long getCid() {
return cid;
}
public void setCid(Long cid) {
this.cid = cid;
}
public String getCname() {
return cname;
}
public void setCname(String cname) {
this.cname = cname;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public Set<Student> getStudents() {
return students;
}
public void setStudents(Set<Student> students) {
this.students = students;
}
private Set students;
}
Student.java
package cn.itcast.hiberate.sh.domain;
import java.io.Serializable;
public class Student implements Serializable{
private Long sid;
private String sname;
public Long getSid() {
return sid;
}
public void setSid(Long sid) {
this.sid = sid;
}
public String getSname() {
return sname;
}
public void setSname(String sname) {
this.sname = sname;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
private String description;
}class.hbm.xml
<?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="cn.itcast.hiberate.sh.domain.Classes">
<id name="cid" length="5" type="java.lang.Long">
<generator class="increment"></generator>
</id>
<property name="cname" length="20" type="java.lang.String"></property>
<property name="description" length="100" type="java.lang.String"></property>
<!--
set元素对应类中的set集合
通过set元素使classes表与student表建立关联
key是通过外键的形式让两张表建立关联
one-to-many是通过类的形式让两个类建立关联
cascade 级联
save-update
1、当 保存班级的时候，对学生进行怎么样的操作
如果学生对象在数据库中没有对应的值，这个时候会执行save操作
如果学生对象在数据库中有对应的值，这个时候会执行update操作
delete 删除班级时同时删除学生
all save-update与delete都用
inverse 维护关系
true 不维护关系
false 维护关系
default false
-->
<set name="students" cascade="all" inverse="false">
<!--
key是用来描述外键
-->
<key>
<column name="cid"></column>
</key>
<one-to-many class="cn.itcast.hiberate.sh.domain.Student"/>
</set>
</class>
</hibernate-mapping>Student.hbm.xml
<?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="cn.itcast.hiberate.sh.domain.Student">
<id name="sid" length="5">
<generator class="increment"></generator>
</id>
<property name="sname" length="20"></property>
<property name="description" length="100"></property>
</class>
</hibernate-mapping>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>
<!--
一个session-factory只能连接一个数据库
-->
<session-factory>
<!--
数据库的用户名
-->
<property name="connection.username">root</property>
<!--
密码
-->
<property name="connection.password">root</property>
<!--
url
-->
<property name="connection.url">
jdbc:mysql://localhost:3306/hibernate
</property>
<!--
作用：根据持久化类和映射文件生成表
validate
create-drop
create
update
-->
<property name="hbm2ddl.auto">update</property>
<!--
显示hibernate内部生成的sql语句
-->
<property name="show_sql">true</property>
<mapping resource="cn/itcast/hiberate/sh/domain/Classes.hbm.xml" />
<mapping resource="cn/itcast/hiberate/sh/domain/Student.hbm.xml" />
</session-factory>
</hibernate-configuration>级联的概念与操作
cascade 级联
save-update
1、当 保存班级的时候，对学生进行怎么样的操作
如果学生对象在数据库中没有对应的值，这个时候会执行save操作
如果学生对象在数据库中有对应的值，这个时候会执行update操作
delete 删除班级时同时删除学生
all save-update与delete都用
inverse 维护关系
true 不维护关系
false 维护关系
default false一对多增删改查实例
package cn.itcast.hibernate.sh.test;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import org.hibernate.Session;
import org.hibernate.Transaction;
import org.hibernate.annotations.Type;
import org.junit.Test;
import cn.itcast.hiberate.sh.domain.Classes;
import cn.itcast.hiberate.sh.domain.Student;
import cn.itcast.hibernate.sh.utils.HiberanteUtils;
/**
* 1、新建一个班级
* 2、新建一个学生
* 3、新建一个班级的时候同时新建一个学生
* 4、已经存在一个班级，新建一个学生，建立学生与班级之间的关系
* 5、已经存在一个学生，新建一个班级，把学生加入到该班级
* 6、把一个学生从一个班级转移到另一个班级
* 7、解析一个班级和一个学生之间的关系
* 8、解除一个班级和一些学生之间的关系
* 9、解除该班级和所有的学生之间的关系
* 10、已经存在一个班级，已经存在一个学生，建立该班级与该学生之间的关系
* 11、已经存在一个班级，已经存在多个学生，建立多个学生与班级之间的关系
* 12、删除学生
* 13、删除班级
* 删除班级的时候同时删除学生
* 在删除班级之前，解除班级和学生之间的关系
* @author Think
*
*/
public class OneToManySingleTest extends HiberanteUtils{
@Test
public void testSaveClasses(){
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Classes classes = new Classes();
classes.setCname("空间信息与数字技术");
classes.setDescription("pretty good");
session.save(classes);
transaction.commit();
session.close();
}
@Test
public void testSaveStudent(){
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Student student = new Student();
student.setSname("班长");
student.setDescription("老牛：很牛");
session.save(student);
transaction.commit();
session.close();
}
@Test
public void testSaveClasses_Student(){
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Classes classes = new Classes();
classes.setCname("空间信息与数字技术2:");
classes.setDescription("很牛X");
Student student = new Student();
student.setSname("班长");
student.setDescription("老牛：很牛X");
session.save(student);
session.save(classes);
transaction.commit();
session.close();
}
/**
* 在保存班级的时候，级联保存学生
*/
@Test
public void testSaveClasses_Cascade_Student_Save(){
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Classes classes = new Classes();
classes.setCname("空间信息与数字技术3:");
classes.setDescription("很牛XX");
Student student = new Student();
student.setSname("班长");
student.setDescription("老牛：很牛XX");
Set<Student> students = new HashSet<Student>();
students.add(student);
//建立classes与student之间的关联
classes.setStudents(students);
session.save(classes);
transaction.commit();
session.close();
}
@Test
public void testSaveClasses_Cascade_Student_Update(){
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Classes classes = new Classes();
classes.setCname("空间信息与数字技术4:");
classes.setDescription("niubility");
Student student = (Student)session.get(Student.class, 2L);
student.setSname("secentary");
student.setDescription("it is pretty beautiful");
Set<Student> students = new HashSet<Student>();
students.add(student);
classes.setStudents(students);
session.save(classes);
transaction.commit();
session.close();
}
@Test
public void testUpdateClasses_Cascade_Student_Save(){
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Classes classes = (Classes)session.get(Classes.class, 5L);
Student student = new Student();
student.setSname("class flower");
student.setDescription("she is pretty girl");
classes.getStudents().add(student);
transaction.commit();
session.close();
}
@Test
public void testUpdateClasses_Cascade_Student_Update(){
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Classes classes = (Classes)session.get(Classes.class, 5L);
Set<Student> students = classes.getStudents();//为cid为5的班级的所有的学生
for(Student student:students){
student.setDescription("under pressure");
}
transaction.commit();
session.close();
}
/**
* 一个错误的演示
*/
@Test
public void testSaveClasses_Cascade_Student_Save_Error(){
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Classes classes = new Classes();
classes.setCname("空间信息与数字技术5:");
classes.setDescription("很牛XXXXXX");
Student student = new Student();
student.setSname("班长XXXXXX");
student.setDescription("老牛：很牛XXXXXX");
Set<Student> students = new HashSet<Student>();
students.add(student);
//建立classes与student之间的关联
classes.setStudents(students);
session.save(classes);
transaction.commit();
session.close();
}
/**
* 已经存在一个班级，新建一个学生，建立学生与班级之间的关系
* 通过更新班级级联保存学生 cascade
* 建立班级和学生之间的关系 inverse
*/
@Test
public void testSaveStudent_R_1(){
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Student student = new Student();
student.setSname("technical");
student.setDescription("good at thechnical");
Classes classes = (Classes)session.get(Classes.class, 1L);
classes.getStudents().add(student);
transaction.commit();
session.close();
}
/**
* Hibernate: select classes0_.cid as cid0_0_, classes0_.cname as cname0_0_, classes0_.description as descript3_0_0_ from Classes classes0_ where classes0_.cid=?
Hibernate: select max(sid) from Student
Hibernate: select students0_.cid as cid0_1_, students0_.sid as sid1_, students0_.sid as sid1_0_, students0_.sname as sname1_0_, students0_.description as descript3_1_0_ from Student students0_ where students0_.cid=?
Hibernate: insert into Student (sname, description, sid) values (?, ?, ?)
更新关系的操作
Hibernate: update Student set cid=? where sid=?
*/
@Test
public void testSaveStudent_R_2(){
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Student student = new Student();
student.setSname("技术班长");
student.setDescription("大神");
Classes classes = (Classes)session.get(Classes.class, 1L);
session.save(student);
classes.getStudents().add(student);
transaction.commit();
session.close();
}
/**
* 已经存在一个学生，新建一个班级，把学生加入到该班级
*/
@Test
public void testSaveClasses_R(){
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Classes classes = new Classes();
classes.setCname("空间信息与数字技术6");
classes.setDescription("必看，杀手锏");
Student student = (Student)session.get(Student.class, 2L);
Set<Student> students = new HashSet<Student>();
students.add(student);
classes.setStudents(students);
session.save(classes);
transaction.commit();
session.close();
}
/**
* 把一个学生从一个班级转移到另一个班级
* Hibernate: select classes0_.cid as cid0_0_, classes0_.cname as cname0_0_, classes0_.description as descript3_0_0_ from Classes classes0_ where classes0_.cid=?
Hibernate: select classes0_.cid as cid0_0_, classes0_.cname as cname0_0_, classes0_.description as descript3_0_0_ from Classes classes0_ where classes0_.cid=?
Hibernate: select student0_.sid as sid1_0_, student0_.sname as sname1_0_, student0_.description as descript3_1_0_ from Student student0_ where student0_.sid=?
Hibernate: select students0_.cid as cid0_1_, students0_.sid as sid1_, students0_.sid as sid1_0_, students0_.sname as sname1_0_, students0_.description as descript3_1_0_ from Student students0_ where students0_.cid=?
Hibernate: select students0_.cid as cid0_1_, students0_.sid as sid1_, students0_.sid as sid1_0_, students0_.sname as sname1_0_, students0_.description as descript3_1_0_ from Student students0_ where students0_.cid=?
Hibernate: update Student set cid=null where cid=? and sid=?
Hibernate: update Student set cid=? where sid=?
*/
@Test
public void testTransformClass(){
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
//Classes classes5 = (Classes)session.get(Classes.class, 5L);
Classes classes6 = (Classes)session.get(Classes.class, 6L);
Student student = (Student)session.get(Student.class, 1L);
//classes5.getStudents().remove(student);
classes6.getStudents().add(student);
transaction.commit();
session.close();
}
/**
* 解除一个班级和一些学生之间的关系
*/
@Test
public void testR_Some(){
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Classes classes = (Classes)session.get(Classes.class, 1L);
Set<Student> students = classes.getStudents();
// for(Student student:students){
// if(student.getSid().longValue()==6||student.getSid().longValue()==7){
// students.remove(student);
// }
// }
//set-->list(set转化成list)
List<Student> sList = new ArrayList<Student>(students);
for(int i=0;i<sList.size();i++){
if(sList.get(i).getSid().longValue()==6||sList.get(i).getSid().longValue()==7){
sList.remove(sList.get(i));
i--;
}
}
//list转化成set
students = new HashSet<Student>(sList);
classes.setStudents(students);
/**
* 增强for循环只能修改一次
* 1、用普通的for循环
* 2、新建一个set集合，把原来的set集合要保留的数据存放到新的set集合中
*/
transaction.commit();
session.close();
}
/*
* 解除班级与所有学生
* classes.setStudents(null);直接把班级针对student的集合设置为null
*/
@Test
public void testRealseAll(){
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Classes classes = (Classes)session.get(Classes.class, 1L);
// Set<Student> students = classes.getStudents();
// students.clear();
classes.setStudents(null);
transaction.commit();
session.close();
}
/**
* 已经存在一个班级，已经存在一个学生，建立该班级与该学生之间的关系
* 11、已经存在一个班级，已经存在多个学生，建立多个学生与班级之间的关系
*/
//删除一个学生
@Test
public void testDeleteStudent(){
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Student student = (Student)session.get(Student.class, 8L);
session.delete(student);
transaction.commit();
session.close();
}
//删除班级
@Test
public void testDeleteClasses(){
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Classes classes = (Classes)session.get(Classes.class, 5L);
//classes.setStudents(null);
session.delete(classes);
transaction.commit();
session.close();
}
@Test
public void testDeleteClasses_Cascade(){
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Classes classes = (Classes)session.get(Classes.class, 5L);
session.delete(classes);
transaction.commit();
session.close();
}
}一对多的双向关联
双向关联时Student.java和Student.hbm.xml文件都需要修改
package cn.itcast.hiberate.sh.domain;
import java.io.Serializable;
public class Student implements Serializable{
private Long sid;
private String sname;
private Classes classes;
public Classes getClasses() {
return classes;
}
public void setClasses(Classes classes) {
this.classes = classes;
}
public Long getSid() {
return sid;
}
public void setSid(Long sid) {
this.sid = sid;
}
public String getSname() {
return sname;
}
public void setSname(String sname) {
this.sname = sname;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
private String description;
}Student.hbm.xml
<?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="cn.itcast.hiberate.sh.domain.Student">
<id name="sid" length="5">
<generator class="increment"></generator>
</id>
<property name="sname" length="20"></property>
<property name="description" length="100"></property>
<!--
多对一
column 外键
-->
<many-to-one name="classes" class="cn.itcast.hiberate.sh.domain.Classes" column="cid" cascade="save-update"
unique="true"></many-to-one>
</class>
</hibernate-mapping>一对多双向操作的实例
package cn.itcast.hibernate.sh.test;
import java.util.HashSet;
import java.util.Set;
import org.hibernate.Session;
import org.hibernate.Transaction;
import org.junit.Test;
import cn.itcast.hiberate.sh.domain.Classes;
import cn.itcast.hiberate.sh.domain.Student;
import cn.itcast.hibernate.sh.utils.HiberanteUtils;
/**
* 3、新建一个班级的时候同时新建一个学生
* 4、已经存在一个班级，新建一个学生，建立学生与班级之间的关系
* 5、已经存在一个学生，新建一个班级，把学生加入到该班级
* 6、把一个学生从一个班级转移到另一个班级
* 7、解析一个班级和一个学生之间的关系
* 8、解除一个班级和一些学生之间的关系
* 9、解除该班级和所有的学生之间的关系
* 10、已经存在一个班级，已经存在一个学生，建立该班级与该学生之间的关系
* 11、已经存在一个班级，已经存在多个学生，建立多个学生与班级之间的关系
* 12、删除学生
* 13、删除班级
* 删除班级的时候同时删除学生
* 在删除班级之前，解除班级和学生之间的关系
* @author Think
*
*/
public class OneToManyTest extends HiberanteUtils{
static{
//url = "hibernate.cfg.xml";
}
@Test
public void testSaveStudent_Cascade_Classes_Save(){
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Student student = new Student();
student.setSname("class scentary");
student.setDescription("a mysterous job");
Classes classes = new Classes();
classes.setCname("class1");
classes.setDescription("interesting");
student.setClasses(classes);
// Set<Student> students = new HashSet<Student>();
// students.add(student);
//
// classes.setStudents(students);
session.save(student);
transaction.commit();
session.close();
}
/**
* 一对多，从多的一端维护关系效率比较高
*/
@Test
public void testSaveStudent_R(){
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Student student = new Student();
student.setSname("zj");
student.setDescription("pretty good");
Classes classes = (Classes)session.get(Classes.class, 2L);
student.setClasses(classes);
/*Set<Student> students = new HashSet<Student>();
students.add(student);
classes.getStudents().add(student);//在hibernate内部查看的是classes.hbm.xml*/
session.save(student);//在hibernate内部查看的是Student.hbm.xml
transaction.commit();
session.close();
}
@Test
public void testRelese_R(){
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Classes classes = (Classes)session.get(Classes.class, 2L);
Student student7 = (Student)session.get(Student.class, 7L);
Student student8 = (Student)session.get(Student.class, 8L);
student7.setClasses(null);
student8.setClasses(null);
transaction.commit();
session.close();
}
//在删除前必须解除关系，从classes得到，必须从classes删除，或者将cascade="all"
@Test
public void testDeleteS(){
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Classes classes = (Classes)session.get(Classes.class, 1L);
Set<Student> students = classes.getStudents();
//classes.setStudents(null);//解除关系
for(Student student:students){
session.delete(student);
}
transaction.commit();
session.close();
}
}注意
在删除时要注意解除关系
1、根据映射文件可以得出classes与student有关联
2、在客户端，students是由classes产生的，代表了关联关系
3、所以在删除student的时候，必须通过classes解除关系
4、解除关系以后才能进行删除
一对多的总结
1、如果让一的一方维护关系，取决于的因素有
1、在一的一方的映射文件中，set元素的inverse属性为default/false
2、在客户端的代码中，通过一的一方建立关系
3、session.save/update方法是用来操作表的，和操作关系没有关系
2、怎么样采用级联的方法通过保存一个对象从而保存关联对象
1、如果session.save操作的对象是A，这个时候应该看A.hbm.xml,看set元素中cascade是否设置有级联保存
2、在客户端通过A建立关联
3、在客户端执行session.save(A)
3、一对多的情况，多的一方维护关系效率比较高
1、在多的一方many-to-one中没有inverse属性
2、在客户端通过多的一方建立关联
多对多关联
由于配置文件位置可能改变，HiberanteUtils文件修改如下
package cn.itcast.hibernate.sh.utils;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.junit.Before;
public class HiberanteUtils {
public static SessionFactory sessionFactory;
public static String url;
//子类与父类同时有static,先执行父类的static语句块，所以这种方法不行
// static{
// /**
// * 创建configuration对象
// */
// Configuration configuration = new Configuration();
// configuration.configure(url);
// /**
// * 加载hibernate的配置文件
// */
// //configuration.configure("");
// sessionFactory = configuration.buildSessionFactory();
// }
//注意：在test方法执行之前执行before,JUnit的特性方法
@Before
public void init(){
Configuration configuration = new Configuration();
configuration.configure(url);
/**
* 加载hibernate的配置文件
*/
//configuration.configure("");
sessionFactory = configuration.buildSessionFactory();
}
}多对多用一个Course类和Student类做示例
Student.java
package cn.itcast.hiberate.sh.domain.manytomany;
import java.io.Serializable;
import java.util.Set;
public class Student implements Serializable{
private Long sid;
private String sname;
private String description;
public Long getSid() {
return sid;
}
public void setSid(Long sid) {
this.sid = sid;
}
public String getSname() {
return sname;
}
public void setSname(String sname) {
this.sname = sname;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public Set<Course> getCourses() {
return courses;
}
public void setCourses(Set<Course> courses) {
this.courses = courses;
}
private Set<Course> courses;
}Student.hbm.xml
<?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="cn.itcast.hiberate.sh.domain.manytomany.Student">
<id name="sid" type="java.lang.Long" length="5">
<generator class="increment"></generator>
</id>
<property name="sname" type="java.lang.String" length="20"></property>
<property name="description" length="100"></property>
<!--
table就是用来描述第三张表,多对多时才会出现这个属性
-->
<set name="courses" table="student_course" cascade="all">
<key>
<column name="sid"></column>
</key>
<many-to-many class="cn.itcast.hiberate.sh.domain.manytomany.Course" column="cid"></many-to-many>
</set>
</class>
</hibernate-mapping>Course.java
package cn.itcast.hiberate.sh.domain.manytomany;
import java.io.Serializable;
import java.util.Set;
public class Course implements Serializable{
private Long cid;
private String cname;
public Long getCid() {
return cid;
}
public void setCid(Long cid) {
this.cid = cid;
}
public String getCname() {
return cname;
}
public void setCname(String cname) {
this.cname = cname;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public Set<Student> getStudents() {
return students;
}
public void setStudents(Set<Student> students) {
this.students = students;
}
private String description;
private Set<Student> students;
}Course.hbm.xml
<?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="cn.itcast.hiberate.sh.domain.manytomany.Course">
<id name="cid" length="5">
<generator class="increment"></generator>
</id>
<property name="cname" length="20"></property>
<property name="description" length="100"></property>
<set name="students" table="student_course" cascade="all">
<key>
<column name="cid"></column>
</key>
<many-to-many class="cn.itcast.hiberate.sh.domain.manytomany.Student" column="sid"></many-to-many>
</set>
</class>
</hibernate-mapping>第三张表的名字是student_course，两个映射文件中定义时必须一致
多对多实例操作
package cn.itcast.hibernate.sh.test;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import org.hibernate.Session;
import org.hibernate.Transaction;
import org.junit.Test;
import cn.itcast.hiberate.sh.domain.manytomany.Course;
import cn.itcast.hiberate.sh.domain.manytomany.Student;
import cn.itcast.hibernate.sh.utils.HiberanteUtils;
/**
* 1、新建一个课程
* 2、新建一个学生
* 3、新建课程的同时新建学生 级联
* 4、已经存在一个课程，新建一个学生，建立课程和学生之间的关系
* 5、已经存在一个学生，新建一个课程，建立课程和学生之间的关系
* 6、已经存在一个课程，已经存在一个学生，建立关联
* 7、把已经存在的一些学生加入到已经存在的一个课程中
* 8、把一个学生加入到一些课程中
* 9、把多个学生加入到多个课程中
* 10、把一个已经存在的学生从一个已经的课程中移除
* 11、把一些学生从一个已经存在的课程中移除
* 12、把一个学生从一个课程转向到另外一个课程
* 13、删除课程
* 14、删除学生
* @author Think
*
*/
public class ManyToManyTest extends HiberanteUtils{
static{
url = "cn/itcast/hiberate/sh/domain/manytomany/hibernate.cfg.xml";
}
@Test
public void testCreateTable(){
}
@Test
public void testSaveStudent_Cascade_Course_Save(){
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Student student = new Student();
student.setSname("monitor3");
student.setDescription("nubility");
Course course = new Course();
course.setCname("science");
course.setDescription("pretty good");
Set<Course> courses = new HashSet<Course>();
courses.add(course);
student.setCourses(courses);
session.save(student);
transaction.commit();
session.close();
}
/**
* 已经存在一个课程，新建一个学生，建立课程和学生之间的关系
* 从课程角度出发
*/
@Test
public void testUpdateCourse_Cascade_Student_Save_R(){
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Course course = (Course)session.get(Course.class, 1L);
Student student = new Student();
student.setSname("class fans");
student.setDescription("fansof student");
course.getStudents().add(student);
//session.save(student);
transaction.commit();
session.close();
}
/**
* 已经存在一个课程，新建一个学生，建立课程和学生之间的关系
* 从学生角度出发
*/
@Test
public void testSaveStudent_R(){
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Course course = (Course)session.get(Course.class, 1L);
Student student = new Student();
student.setSname("zj");
student.setDescription("never");
Set<Course> courses = new HashSet<Course>();
courses.add(course);
student.setCourses(courses);
session.save(student);
transaction.commit();
session.close();
}
/**
* 已经存在一个课程，已经存在一个学生，建立关联
*/
@Test
public void testR(){
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Course course = (Course)session.get(Course.class, 1L);
Student student = (Student)session.get(Student.class, 2L);
student.getCourses().add(course);
transaction.commit();
session.close();
}
/**
* 把学生3,4加入到课程1中
*/
@Test
public void testR_Some(){
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Course course = (Course)session.get(Course.class, 1L);
Student student = (Student)session.get(Student.class, 3L);
Student student2 = (Student)session.get(Student.class, 4L);
// student.getCourses().add(course);
// student2.getCourses().add(course);
course.getStudents().add(student2);
course.getStudents().add(student);
transaction.commit();
session.close();
}
/**
* 把一个学生加入到一些课程中
*/
@Test
public void testR_Some_2(){
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Student student = (Student)session.get(Student.class, 3L);
List<Course> courseList = session.createQuery("from Course where cid in(1,2,3)").list();
student.getCourses().addAll(courseList);
transaction.commit();
session.close();
}
/**
* 把学生从一个课程转移到另外一个课程
*/
@Test
public void testTransform(){
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Student student = (Student) session.get(Student.class, 3L);
Course course1 = (Course)session.get(Course.class, 1L);
Course course3 = (Course)session.get(Course.class, 3L);
student.getCourses().remove(course1);
student.getCourses().add(course3);
transaction.commit();
session.close();
}
}一对一关联,以person表与adress表为例
person.java
package cn.itcast.hiberate.sh.domain.onetoone;
import java.io.Serializable;
import java.util.Set;
public class Person implements Serializable{
private Long cid;
private String cname;
private String description;
public Long getCid() {
return cid;
}
public void setCid(Long cid) {
this.cid = cid;
}
public String getCname() {
return cname;
}
public void setCname(String cname) {
this.cname = cname;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public Address getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
private Address address;
}Person.hbm.xml
<?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="cn.itcast.hiberate.sh.domain.onetoone.Person">
<id name="cid" length="5" type="java.lang.Long">
<generator class="foreign">
<param name="property">address</param>
</generator>
</id>
<property name="cname" length="20" type="java.lang.String"></property>
<property name="description" length="100" type="java.lang.String"></property>
<one-to-one name="address" class="cn.itcast.hiberate.sh.domain.onetoone.Address" constrained="true"></one-to-one>
</class>
</hibernate-mapping>注意constrained=”true”
adress.java与adress.hbm.xml
package cn.itcast.hiberate.sh.domain.onetoone;
import java.io.Serializable;
public class Address implements Serializable{
private Long sid;
private String sname;
private Person person;
public Person getPerson() {
return person;
}
public void setPerson(Person person) {
this.person = person;
}
public Long getSid() {
return sid;
}
public void setSid(Long sid) {
this.sid = sid;
}
public String getSname() {
return sname;
}
public void setSname(String sname) {
this.sname = sname;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
private String description;
}一般one-to-one只单向关联
<?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="cn.itcast.hiberate.sh.domain.onetoone.Address">
<id name="sid" length="5">
<generator class="increment"></generator>
</id>
<property name="sname" length="20"></property>
<property name="description" length="100"></property>
</class>
</hibernate-mapping>
