Hibernate多对多单向关联（2个一对多）

把多对多分割成2个一对多，一般情况下，单向关联比较多！

 

分割的话则生成的持久类需要3个，包括关联表！

 

学生类，和关联表一对多，

<?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"><!-- Mapping file autogenerated by MyEclipse Persistence Tools--><hibernate-mapping> <class name="com.pojo.Student" table="STUDENT" schema="ZM"> <id name="id" type="java.lang.Long"> <column name="ID" precision="4" scale="0" /> <generator class="increment" /> </id> <property name="name" type="java.lang.String"> <column name="NAME" length="100" /> </property> <property name="age" type="java.lang.Long"> <column name="AGE" precision="4" scale="0" /> </property> <property name="sex" type="java.lang.String"> <column name="SEX" length="100" /> </property> </class></hibernate-mapping>

 

老师类，和学生以及关联表都是一对多的关系

 

<?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"><!-- Mapping file autogenerated by MyEclipse Persistence Tools--><hibernate-mapping> <class name="com.pojo.Teacher" table="TEACHER" schema="ZM"> <id name="id" type="java.lang.Long"> <column name="ID" precision="4" scale="0" /> <generator class="increment" /> </id> <property name="name" type="java.lang.String"> <column name="NAME" length="100" /> </property> <property name="sourcename" type="java.lang.String"> <column name="SOURCENAME" length="100" /> </property> <!-- 一对多关系 --> <set name="stuteas" inverse="true" cascade="save-update"> <key> <column name="TEACHER_ID" precision="4" scale="0" not-null="true" /> </key> <one-to-many class="com.pojo.Stutea" /> </set> </class></hibernate-mapping>

 

关联表，由于关联表没有ID主键，而是符合主键。

 

<?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"><!-- Mapping file autogenerated by MyEclipse Persistence Tools--><hibernate-mapping> <class name="com.pojo.Stutea" table="STUTEA" schema="ZM"> <composite-id> <!-- 组合主键 --> <key-many-to-one name="student" class="com.pojo.Student"> <column name="STUDENT_ID" precision="4" scale="0" /> </key-many-to-one> <key-many-to-one name="teacher" class="com.pojo.Teacher"> <column name="TEACHER_ID" precision="4" scale="0" /> </key-many-to-one> <key-property name="stunumber" type="java.lang.Long"> <column name="STUNUMBER" precision="4" scale="0" /> </key-property> </composite-id> </class></hibernate-mapping>

 

测试类：

package com.test;import java.util.HashSet;import java.util.Set;import org.hibernate.Session;import com.pojo.Student;import com.pojo.Stutea;import com.pojo.Teacher;import com.util.HibernateManager;public class Test4 {public static void main(String[] args) {Test4.addPerson();}public static void addPerson() {Session session = HibernateManager.openSession();//老师Teacher t = new Teacher() ;t.setName("王老师") ;t.setSourcename("语文老师") ;//获取2个学生对象Student s1 = (Student)session.get(Student.class, new Long(1)) ;Student s2 = (Student)session.get(Student.class, new Long(2)) ;Stutea sa1 = new Stutea() ;Stutea sa2 = new Stutea() ;//学生和关联表sa1.setStudent(s1) ;sa1.setTeacher(t) ;sa1.setStunumber(new Long(100)) ;sa2.setStudent(s2) ;sa2.setTeacher(t) ;sa2.setStunumber(new Long(100)) ;Set<Stutea> st = new HashSet<Stutea>() ;st.add(sa1) ;st.add(sa2) ;//老师和关联表t.setStuteas(st) ;try {//只需要save teacher,因为设置了cascade="save-update" 级联操作session.save(t);HibernateManager.closeSession();} catch (Exception e) {e.printStackTrace();HibernateManager.rollbackTransaction();}}}