Hibernater学习笔记（五）

上次学习一对多查询，今天学习多对多查询
场景：用户和角色的关系，一个用户可以是多个角色，一个角色可以有多个用户

• pojo类
  User.java

public class User {
   private int uid;
    private String username;
    private String password;
    private String address;
    /**
     *一个用户多个角色
     */
    private Set<Role> roles = new HashSet<Role>();
....省略get@set方法....
}

Role.java

public class Role {
    private Integer ro_id;
    private String ro_name;
    /**
     *角色描述
     */
    private String ro_memo;

    /**
     * 一个角色多个用户
     * @retu     */
    private Set<User> users = new HashSet<User>();
....省略get@set方法.....
}

• 配置文件
  User.hbm.xml

<?xml version="1.0" encoding="utf-8" ?>
    <!DOCTYPE hibernate-mapping PUBLIC
            "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
            "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
    <class name="com.study.entity.User" table="h_user">
        <id name="uid" column="uid">
            <generator class="native"></generator>
        </id>
        <property name="username" column="username"></property>
        <property name="password" column="password"></property>
        <property name="address" column="address"></property>
        <!--name:角色set集合名称  table属性：第三张表名称-->
        <set name="roles" table="user_role">
            <!--第三张表中的的外键名称-->
            <key column="userid"></key>
            <!--角色全路径和角色第三张表的外键名称-->
            <many-to-many class="com.study.entity.Role" column="roleid"></many-to-many>
        </set>
    </class>
</hibernate-mapping>

Role.hbm.xml

<?xml version="1.0" encoding="utf-8" ?>
    <!DOCTYPE hibernate-mapping PUBLIC
            "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
            "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
    <class name="com.study.entity.Role" table="h_role">
        <id name="ro_id" column="uid">
            <generator class="native"></generator>
        </id>
        <property name="ro_name" column="ro_name"></property>
        <property name="ro_memo" column="ro_memo"></property>
        <set name="users" table="user_role">
            <!--角色在第三章表中的外键-->
            <key column="roleid"></key>
            <many-to-many class="com.study.entity.User" column="userid"></many-to-many>
        </set>
    </class>
</hibernate-mapping>

创建成功

1.多对多级联保存

• 设置user用户配置文件

<set name="roles" table="user_role" cascade="save-update">
            <!--第三张表中的的外键名称-->
            <key column="userid"></key>
            <!--角色全路径和角色第三张表的外键名称-->
            <many-to-many class="com.study.entity.Role" column="roleid"></many-to-many>
        </set>

• 添加代码

public void TestMany_to_Many_add(){
        Session session = null;
        Transaction transaction=null;
        try{
            session = HibernateUtils.getSessionObject();
            transaction = session.beginTransaction();
            User user1 = new User();
            user1.setUsername("张用户");
            user1.setPassword("12345");
            user1.setAddress("西安");

            User user2 = new User();
            user2.setUsername("王用户");
            user2.setPassword("789456");
            user2.setAddress("广东");

            Role r1 = new Role();
            r1.setRo_name("总经理");
            r1.setRo_memo("总经理描述");
            Role r2 = new Role();
            r2.setRo_name("保安");
            r2.setRo_memo("保安描述");
            Role r3 = new Role();
            r3.setRo_name("司机");
            r3.setRo_memo("司机描述");
            //给用户1创建r1和r2的角色
            user1.getRoles().add(r1);
            user1.getRoles().add(r2);
            //给user2创建r2和r3的角色
            user2.getRoles().add(r2);
            user2.getRoles().add(r3);
            //保存用户
            session.save(user1);
            session.save(user2);
            transaction.commit();
        }catch(Exception e){
            e.printStackTrace();
            transaction.rollback();
        }finally {
            session.close();
        }
    }

多对多添加

2.维护第三张表

用户和惧色多对多关系，维护关系通过第三张表维护
场景：为某个用户添加某个角色

 @Test
    public void manyToManyTableTest(){
        Session session = null;
        Transaction transaction=null;
        try{
            session = HibernateUtils.getSessionObject();
            transaction = session.beginTransaction();
            User user =  session.get(User.class,3);
            Role role = session.get(Role.class,2);
            user.getRoles().add(role);
            transaction.commit();
        }catch(Exception e){
            e.printStackTrace();
            transaction.rollback();
        }finally {
            session.close();
        }
    }

删除用户和角色的关系

 @Test
    public void manyToManyDeleteTest(){
        Session session = null;
        Transaction transaction=null;
        try{
            session = HibernateUtils.getSessionObject();
            transaction = session.beginTransaction();
            User user =  session.get(User.class,2);
            Role role = session.get(Role.class,3)       ;
            //让用户移除某个操作
            user.getRoles().remove(role);
            transaction.commit();
        }catch(Exception e){
            e.printStackTrace();
            transaction.rollback();
        }finally {
            session.close();
        }
    }

删除用户和角色关系

---

上一篇：Hibernater学习笔记（四）

当前文集 :Hibernate框架学习

本笔记hibernate案例：github地址