多对多组件映射介绍
不使用多对多关联映射的原因是为了提高数据库的运行性能，所以采用componenet映射，这个componenet类随着主类的消失而消失，不需要建立单独的映射文件。只能由主类看到componenet的信息。
component在表中没有对应的oid，
可以关联其它持久化类
component不能单独持久化（不能单独保存）
生命周期依赖于主类的生命周期
eg：
package com.bjpowernode.hibernate;
import java.util.HashSet;
import java.util.Set;
public class Monkey {
private Integer id;
private String name;
//是它身体的一部分
private Set monkeyAndTeacher = new HashSet();
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;
}
public Set getMonkeyAndTeacher() {
return monkeyAndTeacher;
}
public void setMonkeyAndTeacher(Set monkeyAndTeacher) {
this.monkeyAndTeacher = monkeyAndTeacher;
}
}
package com.bjpowernode.hibernate;
public class MonkeyAndTeacher {
private Monkey monkey;
private Teacher teacher;
private String gongfu ;
public Monkey getMonkey() {
return monkey;
}
public void setMonkey(Monkey monkey) {
this.monkey = monkey;
}
public Teacher getTeacher() {
return teacher;
}
public void setTeacher(Teacher teacher) {
this.teacher = teacher;
}
public String getGongfu() {
return gongfu;
}
public void setGongfu(String gongfu) {
this.gongfu = gongfu;
}
}
package com.bjpowernode.hibernate;
import java.util.HashSet;
import java.util.Set;
public class Teacher {
private Integer id;
private String name;
private Set monkeyAndTeacher = new HashSet();
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;
}
public Set getMonkeyAndTeacher() {
return monkeyAndTeacher;
}
public void setMonkeyAndTeacher(Set monkeyAndTeacher) {
this.monkeyAndTeacher = monkeyAndTeacher;
}
}
<?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> <class name="com.bjpowernode.hibernate.Monkey" table="t_monkey"> <id name="id"> <generator class="native"/> </id> <property name="name"/> <set name="monkeyAndTeacher" table="t_monkey_teacher" lazy="true"> <key column="monkey_id"/> <composite-element class="com.bjpowernode.hibernate.MonkeyAndTeacher"> <parent name="monkey"/> <many-to-one name="teacher" not-null="true" column="teacher_id" class="com.bjpowernode.hibernate.Teacher"/> <property name="gongfu" type="string" not-null="true"/> </composite-element> </set> </class> </hibernate-mapping>
<?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> <class name="com.bjpowernode.hibernate.Teacher" table="t_teacher"> <id name="id"> <generator class="native"/> </id> <property name="name"/> <set name="monkeyAndTeacher" table="t_monkey_teacher" lazy="true" inverse="true"> <key column="teacher_id"/> <composite-element class="com.bjpowernode.hibernate.MonkeyAndTeacher"> <parent name="teacher"/> <many-to-one name="monkey" not-null="true" column="monkey_id" class="com.bjpowernode.hibernate.Monkey"/> <property name="gongfu" type="string" not-null="true"/> </composite-element> </set> </class>
package com.bjpowernode.hibernate;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
import org.hibernate.Hibernate;
import org.hibernate.Session;
import junit.framework.TestCase;
public class Many2ManyTest extends TestCase {
public void testSave1() {
Session session = null;
try {
session = HibernateUtils.getSession();
session.beginTransaction();
Teacher t1 = new Teacher();
t1.setName("红孩儿");
session.save(t1);
Teacher t2 = new Teacher();
t2.setName("二郎神");
session.save(t2);
Monkey m = new Monkey();
m.setName("猴子一");
session.save(m);
MonkeyAndTeacher mt1= new MonkeyAndTeacher();
mt1.setTeacher(t1);
mt1.setGongfu("三位真火");
mt1.setMonkey(m);
MonkeyAndTeacher mt2= new MonkeyAndTeacher();
mt2.setTeacher(t2);
mt2.setGongfu("七十三变");
mt2.setMonkey(m);
m.getMonkeyAndTeacher().add(mt1);
m.getMonkeyAndTeacher().add(mt2);
session.save(m);
session.getTransaction().commit();
}catch(Exception e) {
e.printStackTrace();
session.getTransaction().rollback();
}finally {
HibernateUtils.closeSession(session);
}
}
public void testLoad1() {
Session session = null;
Monkey m = null;
try {
session = HibernateUtils.getSession();
session.beginTransaction();
m = (Monkey)session.load(Monkey.class, 1);
System.out.println(m.getName());
for (Iterator iter=m.getMonkeyAndTeacher().iterator(); iter.hasNext();) {
MonkeyAndTeacher role = (MonkeyAndTeacher)iter.next();
Hibernate.initialize(role.getTeacher());
//System.out.println(role.getName());
}
session.getTransaction().commit();
}catch(Exception e) {
e.printStackTrace();
session.getTransaction().rollback();
}finally {
HibernateUtils.closeSession(session);
}
System.out.println(m.getName());
for(Iterator i = m.getMonkeyAndTeacher().iterator();i.hasNext();){
MonkeyAndTeacher mt = (MonkeyAndTeacher)i.next();
System.out.println(mt.getTeacher().getName());
System.out.println("我的功夫是："+ mt.getGongfu());
}
}
}