SQL(MY SQL):create table tgroup ( group_id int not null auto_increment, name varchar(16) not null default '', primary key (group_id)) type=innodb;

create table trole ( role_id int not null auto_increment, name varchar(16) not null default '', primary key (role_id)) type=innodb;

create table tgroup_role ( group_id int not null, role_id int not null, primary key(group_id, role_id), index (group_id), foreign key (group_id) references tgroup(group_id), index (role_id), foreign key (role_id) references trole(role_id)) type=innodb;

Group 类：package ivan.hibernate.many2many;public class Group { private int id; private String name; private Set roles = new HashSet(); ...}

Group.hbm.xml：

Role 类：package ivan.hibernate.many2many;public class Role { private int id; private String name; private Set groups = new HashSet(); ...}

Role.hbm.xml：

hibernate.cfg.xml 同前面的例子差不多。

public class Test { public static void main(String[] args) throws HibernateException { Role role1 = new Role(); role1.setName("Role1"); Role role2 = new Role(); role2.setName("Role2"); Role role3 = new Role(); role3.setName("Role3"); Group group1 = new Group(); group1.setName("group1"); Group group2 = new Group(); group2.setName("group2"); Group group3 = new Group(); group3.setName("group3"); group1.getRoles().add(role1); group1.getRoles().add(role2); group2.getRoles().add(role2); group2.getRoles().add(role3); group3.getRoles().add(role1); group3.getRoles().add(role3); role1.getGroups().add(group1); role1.getGroups().add(group3); role2.getGroups().add(group1); role2.getGroups().add(group2); role3.getGroups().add(group2); role3.getGroups().add(group3); SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory(); Session session = sessionFactory.openSession(); Transaction tx= session.beginTransaction(); session.save(role1); session.save(role2); session.save(role3); session.save(group1); session.save(group2); session.save(group3); tx.commit(); session.close(); sessionFactory.close(); }}