hibernate多对多关联--单双向

前几篇文章分别介绍了一对一、一对多的关联，下面我们来看下多对多的关联。多对多关联也分为单向和双向两种。

单向关联示例

Role类

public class Role {private int id;private String name;private Set<Function> functions=new HashSet<Function>();//省略get/set}

Function类

public class Function {private int id;private String name;private String code;private String url;//省略get/set方法public Function(){}public Function(String name, String code, String url) {super();this.name = name;this.code = code;this.url = url;}}

Role.hbm.xml配置文件

<hibernate-mapping package="com.test.pojo"><class name="Role"><id name="id"><generator class="native"></generator></id><property name="name" /><!-- 多对多 --><set name="functions" table="role_func" cascade="save-update"><!-- 表示当前类映射到关系表中的列 --><key column="rid"/><!-- 所对应的另一方在关系表中的列 --><many-to-many column="fid" class="Function"/></set></class></hibernate-mapping>

Function.hbm.xml配置文件

<hibernate-mapping package="com.test.pojo"><class name="Function"><id name="id"><generator class="native"></generator></id><property name="name" /><property name="code"/><property name="url"/></class></hibernate-mapping>

测试类

public class HibernateTest {@Testpublic void testCreateDB(){Configuration cfg=new Configuration().configure();SchemaExport se=new SchemaExport(cfg);//第一个参数表示是否生成ddl脚本，第二个参数表示是否执行到数据库中se.create(true, true);}/** * 保存数据 */@Testpublic void save(){Session session=null;Transaction tx=null;try{session=HibernateUtil.getSession();tx=session.beginTransaction();Function f1=new Function("用户管理", "user_mag", "userAction");Function f2=new Function("角色管理", "role_mag", "roleAction");Function f3=new Function("系统管理", "sys_mag", "sysAction");Function f4=new Function("权限管理", "prev_mag", "prevAction");Role r1=new Role();r1.setName("admin");r1.getFunctions().add(f1);r1.getFunctions().add(f2);r1.getFunctions().add(f3);r1.getFunctions().add(f4);Role r2=new Role();r2.setName("vip");r2.getFunctions().add(f1);r2.getFunctions().add(f2);session.save(r1);session.save(r2);tx.commit();}catch(Exception e){if(tx!=null)tx.rollback();e.printStackTrace();}finally{HibernateUtil.closeSession();}}@Testpublic void testGet(){Session session=null;Transaction tx=null;try{session=HibernateUtil.getSession();tx=session.beginTransaction();Role role=(Role) session.get(Role.class, 1);System.out.println("角色名："+role.getName());System.out.println("该角色所对应权限：");for(Iterator<Function> iter=role.getFunctions().iterator();iter.hasNext();){Function func=iter.next();System.out.println(func.getName());}tx.commit();}catch(Exception e){if(tx!=null)tx.rollback();e.printStackTrace();}finally{HibernateUtil.closeSession();}}}

执行testCreateDB控制台打印信息如下：

alter table role_func         drop         foreign key FK_234akokjkyam2j9tvadytgu76alter table role_func         drop         foreign key FK_g07mqbgd657ui8qqsho6bcw01drop table if exists Function    drop table if exists Role    drop table if exists role_func    create table Function (        id integer not null auto_increment,        name varchar(255),        code varchar(255),        url varchar(255),        primary key (id)    )    create table Role (        id integer not null auto_increment,        name varchar(255),        primary key (id)    )    create table role_func (        rid integer not null,        fid integer not null,        primary key (rid, fid)    )    alter table role_func         add constraint FK_234akokjkyam2j9tvadytgu76         foreign key (fid)         references Function (id)    alter table role_func         add constraint FK_g07mqbgd657ui8qqsho6bcw01         foreign key (rid)         references Role (id)

执行save控制台打印信息如下：

Hibernate:     insert     into        Role        (name)     values        (?)Hibernate:     insert     into        Function        (name, code, url)     values        (?, ?, ?)Hibernate:     insert     into        Function        (name, code, url)     values        (?, ?, ?)Hibernate:     insert     into        Function        (name, code, url)     values        (?, ?, ?)Hibernate:     insert     into        Function        (name, code, url)     values        (?, ?, ?)Hibernate:     insert     into        Role        (name)     values        (?)Hibernate:     insert     into        role_func        (rid, fid)     values        (?, ?)Hibernate:     insert     into        role_func        (rid, fid)     values        (?, ?)Hibernate:     insert     into        role_func        (rid, fid)     values        (?, ?)Hibernate:     insert     into        role_func        (rid, fid)     values        (?, ?)Hibernate:     insert     into        role_func        (rid, fid)     values        (?, ?)Hibernate:     insert     into        role_func        (rid, fid)     values        (?, ?)

执行testGet控制台打印信息如下：

Hibernate:     select        role0_.id as id1_1_0_,        role0_.name as name2_1_0_     from        Role role0_     where        role0_.id=?角色名：admin该角色所对应权限：Hibernate:     select        functions0_.rid as rid1_1_0_,        functions0_.fid as fid2_2_0_,        function1_.id as id1_0_1_,        function1_.name as name2_0_1_,        function1_.code as code3_0_1_,        function1_.url as url4_0_1_     from        role_func functions0_     inner join        Function function1_             on functions0_.fid=function1_.id     where        functions0_.rid=?系统管理用户管理角色管理权限管理

数据库表信息如下：

         

双向关联示例（只展示与单向关联不同的地方）

Function类

public class Function {private int id;private String name;private String code;private String url;private Set<Role> roles=new HashSet<Role>();//省略get/set方法public Function(){}public Function(String name, String code, String url) {super();this.name = name;this.code = code;this.url = url;}}

Function.hbm.xml配置文件

<hibernate-mapping package="com.test.pojo"><class name="Function"><id name="id"><generator class="native"></generator></id><property name="name" /><property name="code"/><property name="url"/><set name="roles" inverse="true" table="role_func"><key column="fid"/><many-to-many column="rid" class="Role"/></set></class></hibernate-mapping>

测试类

@Testpublic void testGet(){Session session=null;Transaction tx=null;try{session=HibernateUtil.getSession();tx=session.beginTransaction();Role role=(Role) session.get(Role.class, 1);System.out.println("角色名："+role.getName());System.out.println("该角色所对应权限：");for(Iterator<Function> iter=role.getFunctions().iterator();iter.hasNext();){Function func=iter.next();System.out.println(func.getName());}System.out.println("=============");Function func=(Function) session.get(Function.class, 4);System.out.println("功能名称："+func.getName());System.out.println("该功能所对应的角色：");for(Iterator<Role> iter=func.getRoles().iterator();iter.hasNext();){System.out.println(iter.next().getName());}tx.commit();}catch(Exception e){if(tx!=null)tx.rollback();e.printStackTrace();}finally{HibernateUtil.closeSession();}}@Testpublic void testDelete(){Session session=null;Transaction tx=null;try{session=HibernateUtil.getSession();tx=session.beginTransaction();Role role=(Role) session.get(Role.class, 1);session.delete(role);tx.commit();}catch(Exception e){if(tx!=null)tx.rollback();e.printStackTrace();}finally{HibernateUtil.closeSession();}}

具体执行结果在此不做展示，有兴趣的可以自己演示。