Person类：
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package
com.bjsxt.hibernate;
import
java.util.List;
import
javax.persistence.CascadeType;
import
javax.persistence.Entity;
import
javax.persistence.GeneratedValue;
import
javax.persistence.Id;
import
javax.persistence.ManyToOne;
@Entity
public
class
Person {
private
Integer id;
private
String name;
private
Group1 group1;
@ManyToOne
(cascade={CascadeType.MERGE,CascadeType.PERSIST,CascadeType.REFRESH})
public
Group1 getGroup1() {
return
group1;
}
public
void
setGroup1(Group1 group1) {
this
.group1 = group1;
}
@Id
@GeneratedValue
public
Integer getId() {
return
id;
}
public
void
setId(Integer id) {
this
.id = id;
}
public
String getName() {
return
name;
}
public
void
setName(String name) {
this
.name = name;
}
}
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Group1类(数据库中group是关键字，也可以做一个映射)：
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package
com.bjsxt.hibernate;
import
java.util.List;
import
javax.persistence.CascadeType;
import
javax.persistence.Entity;
import
javax.persistence.FetchType;
import
javax.persistence.GeneratedValue;
import
javax.persistence.Id;
import
javax.persistence.OneToMany;
@Entity
public
class
Group1 {
private
Integer id;
private
String name;
private
List<Person> persons;
@OneToMany
(mappedBy=
"group1"
,fetch=FetchType.EAGER,cascade={CascadeType.MERGE,CascadeType.REFRESH,CascadeType.REMOVE})
public
List<Person> getPersons() {
return
persons;
}
public
void
setPersons(List<Person> persons) {
this
.persons = persons;
}
@Id
@GeneratedValue
public
Integer getId() {
return
id;
}
public
void
setId(Integer id) {
this
.id = id;
}
public
String getName() {
return
name;
}
public
void
setName(String name) {
this
.name = name;
}
}
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测试类：
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package
com.bjsxt.hibernate;
import
java.util.ArrayList;
import
java.util.Iterator;
import
java.util.List;
import
org.hibernate.Session;
import
org.hibernate.SessionFactory;
import
org.hibernate.cfg.AnnotationConfiguration;
import
org.junit.Test;
public
class
TestPerson_group {
private
static
SessionFactory sessionFactory;
@Test
public
void
testAddPerson(){
sessionFactory=
new
AnnotationConfiguration().configure().buildSessionFactory();
Person person1=
new
Person();
person1.setName(
"person1"
);
Person person2=
new
Person();
person2.setName(
"person2"
);
Group1 group1=
new
Group1();
group1.setName(
"group1"
);
List<Person> persons=
new
ArrayList<Person>();
persons.add(person1);
persons.add(person2);
person1.setGroup1(group1);
person2.setGroup1(group1);
group1.setPersons(persons);
Session session=sessionFactory.getCurrentSession();
session.beginTransaction();
session.persist(group1);
session.getTransaction().commit();
}
@Test
public
void
deleteGroup1(){
sessionFactory=
new
AnnotationConfiguration().configure().buildSessionFactory();
Session session=sessionFactory.getCurrentSession();
session.beginTransaction();
Group1 group1=(Group1) session.get(Group1.
class
,
1
);
List<Person> persons=group1.getPersons();
Iterator<Person> iterator=persons.iterator();
if
(iterator.hasNext()){
Person person=iterator.next();
System.out.println(person.getName());
person.setGroup1(
null
);
}
session.update(group1);
/*
* 一定要先update一下group1，
* 将group1的每一个user的group设置为null，同步到数据库,否则group1对应于person的关联关系没有打破*/
group1.setPersons(null);
session.delete(group1);
session.getTransaction().commit();
System.out.println(group1.getName());
}
@Test
public void deleteUser(){
sessionFactory=new AnnotationConfiguration().configure().buildSessionFactory();
Session session=sessionFactory.getCurrentSession();
session.beginTransaction();
/*Person person=(Person) session.get(Person.class, 3);
person.setGroup1(null);
session.delete(person);*/
/*
* 或者直接写HQL删除*/
session.createQuery(
"delete from Person p where p.id=4"
).executeUpdate();
session.getTransaction().commit();
}
@Test
public
void
updatePerson(){
sessionFactory=
new
AnnotationConfiguration().configure().buildSessionFactory();
Session session=sessionFactory.getCurrentSession();
session.beginTransaction();
Person person=(Person) session.get(Person.
class
,
1
);
person.setGroup1(
null
);
session.update(person);
session.getTransaction().commit();
}
@Test
public
void
updateGroup1(){
sessionFactory=
new
AnnotationConfiguration().configure().buildSessionFactory();
Session session=sessionFactory.getCurrentSession();
session.beginTransaction();
Group1 group1=(Group1) session.get(Group1.
class
,
1
);
group1.setPersons(
null
);
session.update(group1);
session.getTransaction().commit();
}
}
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本文转自 matengbing 51CTO博客，原文链接:http://blog.51cto.com/matengbing/1879737
