hibernate多对多例子

1.建表

create   table  student(sid  varchar ( 32 )  not   null   primary   key ,sname  varchar ( 16 ),sage  varchar ( 16 ),)create   table  course(cid  varchar ( 32 )  not   null   primary   key ,cname  varchar ( 16 ))create   table  student_course_link(sid  varchar ( 32 )  not   null ,cid  varchar ( 32 )  not   null ,primary   key (sid,cid))

2.写VO
StudentVO2.写VO
StudentVO

package com.test;import java.util.Set;public class Student{    private String sid;    private String sname;    private String sage;    private Set course;    public Student()    {    }   //写上get setCourse vopackage com.test;import java.util.Set;public class Course{    private String cid;    private String cname;    private Set student;   //写上get set   

写配置文件
Student.hbm.xml

<?xml version="1.0"?><!DOCTYPE hibernate-mapping    PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN"    "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd"><hibernate-mapping>    <class name="com.test.Student" table="student" >        <id name="sid" type="string" unsaved-value="null" >            <column name="sid" sql-type="char(32)" not-null="true"/>            <generator class="uuid.hex"/>        </id>        <property name="sname">            <column name="sname" sql-type="varchar(16)" not-null="true"/>        </property>        <property name="sage">            <column name="sage" sql-type="varchar(16)" not-null="true"/>        </property>        <set name="course" table="student_course_link" cascade="all" outer-join="false">            <key column="sid"/>            <many-to-many class="com.test.Course" column="cid"/>        </set>       </class></hibernate-mapping>

Course.hbm.xml

<?xml version="1.0"?><!DOCTYPE hibernate-mapping    PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN"    "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd"><hibernate-mapping>    <class name="com.test.Course" table="course" >        <id name="cid" type="string" unsaved-value="null" >            <column name="cid" sql-type="char(32)" not-null="true"/>            <generator class="uuid.hex"/>        </id>        <property name="cname">            <column name="cname" sql-type="varchar(16)" not-null="true"/>        </property>        <set name="student" table="student_course_link" lazy="false" cascade="all">            <key column="cid"/>            <many-to-many class="com.test.Student" column="sid"/>        </set>       </class></hibernate-mapping>

 

接着把下面的hibernate.properties文件拷到classes目录下。。这里用的是mysql
hibernate.query.substitutions true 1, false 0, yes 'Y', no 'N'
## MySQL
hibernate.dialect net.sf.hibernate.dialect.MySQLDialect
hibernate.connection.driver_class org.gjt.mm.mysql.Driver
hibernate.connection.url jdbc:mysql://localhost:3306/wjcms
hibernate.connection.username root
hibernate.connection.password wujun
hibernate.connection.pool_size 1
hibernate.proxool.pool_alias pool1
hibernate.show_sql true
hibernate.jdbc.batch_size 0
hibernate.max_fetch_depth 1
hibernate.cache.use_query_cache true

写测试类了..

package com.test;import net.sf.hibernate.Session;import net.sf.hibernate.SessionFactory;import net.sf.hibernate.cfg.Configuration;import net.sf.hibernate.*;import java.util.Set;import java.util.HashSet;import java.sql.*;import java.util.List;import java.util.Iterator;public class TestManyToMany{    SessionFactory sf;    Session session;    public TestManyToMany()    {        try        {            Configuration cfg = new Configuration();            sf = cfg.addClass(Student.class).addClass(Course.class).buildSessionFactory();        }        catch(HibernateException ex)        {            ex.printStackTrace();        }    }    public void doCreate()    {        try        {            session = sf.openSession();            Student student = new Student();            student.setSname("小王");            student.setSage("22");            Set courseSet = new HashSet();            Course course = null;            for(int i=0;i<2;i++)            {                course = new Course();                if(i==0)                    course.setCname("c++");                else if(i==1)                    course.setCname("java");                courseSet.add(course);            }            student.setCourse(courseSet);                        session.save(student);            session.flush();            session.connection().commit();        }        catch(HibernateException ex)        {            ex.printStackTrace();        }        catch(SQLException ex1)        {            ex1.printStackTrace();        }        finally        {                try{                    session.close();                }                catch(HibernateException ex2){                }        }    }    public void doQuery()    {        try{            session = sf.openSession();            Query q = session.createQuery("select s from Student as s");            List l = q.list();            Student s = null;            Course course = null;            for(int i=0;i<l.size();i++)            {                s = (Student)l.get(i);                System.out.println("姓名： "+s.getSname());                System.out.println("年龄： "+s.getSage());                System.out.println("所选的课程：");                Iterator it = s.getCourse().iterator();                while(it.hasNext())                {                    course = (Course)it.next();                    System.out.println("课程名： "+course.getCname());                }            }        }        catch(HibernateException ex){            ex.printStackTrace();        }        finally{            try{                session.close();            }            catch(HibernateException ex2){            }        }    }    public static void main(String[] args)    {        TestManyToMany t = new TestManyToMany();        //t.doCreate();        t.doQuery();    }}