【Hibernate 多对多】

HibernateManytoMany

public class HibernateManytoMany {

    //演示维护第三张表
    @Test
    public void testTable2() {
        SessionFactory sessionFactory = null;
        Session session = null;
        Transaction tx = null;
        try {
            //得到sessionFactory
            sessionFactory = HibernateUtils.getSessionFactory();
            //得到session
            session = sessionFactory.openSession();
            //开启事务
            tx = session.beginTransaction();

            // 让某个用户没有有某个角色
            User user = session.get(User.class, 2);
            Role role = session.get(Role.class, 3);

            //2 从用户里面把角色去掉
            user.getSetRole().remove(role);

            //提交事务
            tx.commit();

        } catch (Exception e) {
            tx.rollback();
        } finally {
            session.close();
            //sessionFactory不需要关闭
            sessionFactory.close();
        }
    }

    //演示维护第三张表
    @Test
    public void testTable1() {
        SessionFactory sessionFactory = null;
        Session session = null;
        Transaction tx = null;
        try {
            //得到sessionFactory
            sessionFactory = HibernateUtils.getSessionFactory();
            //得到session
            session = sessionFactory.openSession();
            //开启事务
            tx = session.beginTransaction();

            // 让某个用户有某个角色
            //让lucy有经纪人角色
            //1 查询lucy和经纪人
            User lucy = session.get(User.class, 2);
            Role role = session.get(Role.class, 5);

            //2 把角色放到用户的set集合里面
            lucy.getSetRole().add(role);

            //提交事务
            tx.commit();

        } catch (Exception e) {
            tx.rollback();
        } finally {
            session.close();
            //sessionFactory不需要关闭
            sessionFactory.close();
        }
    }

    //演示多对多修级联保存
    @Test
    public void testDelete() {
        SessionFactory sessionFactory = null;
        Session session = null;
        Transaction tx = null;
        try {
            //得到sessionFactory
            sessionFactory = HibernateUtils.getSessionFactory();
            //得到session
            session = sessionFactory.openSession();
            //开启事务
            tx = session.beginTransaction();

            User user = session.get(User.class, 4);
            session.delete(user);
            //提交事务
            tx.commit();

        } catch (Exception e) {
            tx.rollback();
        } finally {
            session.close();
            //sessionFactory不需要关闭
            sessionFactory.close();
        }
    }

    //演示多对多修级联保存
    @Test
    public void testSave() {
        SessionFactory sessionFactory = null;
        Session session = null;
        Transaction tx = null;
        try {
            //得到sessionFactory
            sessionFactory = HibernateUtils.getSessionFactory();
            //得到session
            session = sessionFactory.openSession();
            //开启事务
            tx = session.beginTransaction();

            //添加两个用户，为每个用户添加两个角色
            //1 创建对象
            User user1 = new User();
            user1.setUser_name("lucy");
            user1.setUser_password("123");

            User user2 = new User();
            user2.setUser_name("mary");
            user2.setUser_password("456");

            Role r1 = new Role();
            r1.setRole_name("总经理");
            r1.setRole_memo("总经理");

            Role r2 = new Role();
            r2.setRole_name("秘书");
            r2.setRole_memo("秘书");

            Role r3 = new Role();
            r3.setRole_name("保安");
            r3.setRole_memo("保安");

            //2 建立关系，把角色放到用户里面
            // user1 -- r1/r2
            user1.getSetRole().add(r1);
            user1.getSetRole().add(r2);

            // user2 -- r2/r3
            user2.getSetRole().add(r2);
            user2.getSetRole().add(r3);

            //3 保存用户
            session.save(user1);
            session.save(user2);

            //提交事务
            tx.commit();

        } catch (Exception e) {
            tx.rollback();
        } finally {
            session.close();
            //sessionFactory不需要关闭
            sessionFactory.close();
        }
    }
}

 User

public class User {
    private Integer user_id;//用户id
    private String user_name;//用户名称
    private String user_password;//用户密码

    public Set<Role> getSetRole() {
        return setRole;
    }

    public void setSetRole(Set<Role> setRole) {
        this.setRole = setRole;
    }

    private Set<Role> setRole = new HashSet<>();

    public Integer getUser_id() {
        return user_id;
    }

    public void setUser_id(Integer user_id) {
        this.user_id = user_id;
    }

    public String getUser_name() {
        return user_name;
    }

    public void setUser_name(String user_name) {
        this.user_name = user_name;
    }

    public String getUser_password() {
        return user_password;
    }

    public void setUser_password(String user_password) {
        this.user_password = user_password;
    }
}

User.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="k.manytomany.User" table="t_user">
        <id name="user_id" column="user_id">
            <generator class="native"></generator>
        </id>
        <property name="user_name" column="user_name"></property>
        <property name="user_password" column="user_password"></property>
        <set name="setRole" table="user_role" cascade="save-update,delete">
            <key column="userid"></key>
            <many-to-many class="k.manytomany.Role" column="roleid"></many-to-many>
        </set>
    </class>
</hibernate-mapping>

Role

public class Role {
    private Integer role_id;//角色id
    private String role_name;//角色名称
    private String role_memo;//角色描述
    private Set<User> setUser = new HashSet<>();

    public Set<User> getSetUser() {
        return setUser;
    }

    public void setSetUser(Set<User> setUser) {
        this.setUser = setUser;
    }

    public Integer getRole_id() {
        return role_id;
    }

    public void setRole_id(Integer role_id) {
        this.role_id = role_id;
    }

    public String getRole_name() {
        return role_name;
    }

    public void setRole_name(String role_name) {
        this.role_name = role_name;
    }

    public String getRole_memo() {
        return role_memo;
    }

    public void setRole_memo(String role_memo) {
        this.role_memo = role_memo;
    }
}

Role.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="k.manytomany.Role" table="t_role">
        <id name="role_id" column="role_id">
            <generator class="native"></generator>
        </id>
        <property name="role_name" column="role_name"></property>
        <property name="role_memo" column="role_memo"></property>
        <set name="setUser" table="user_role" >
            <key column="roleid"></key>
            <many-to-many class="k.manytomany.User" column="userid"></many-to-many>
        </set>
    </class>
</hibernate-mapping>

HibernateUtils

public class HibernateUtils {

    static Configuration cfg = null;
    static SessionFactory sessionFactory = null;
    //静态代码块实现
    static {
        //加载核心配置文件
        cfg = new Configuration();
        cfg.configure();
        sessionFactory = cfg.buildSessionFactory();
    }

    //提供返回与本地线程帮的session的方法
    public static Session getSessionobject() {
        return sessionFactory.getCurrentSession();
    }

    //提供方法返回sessionFactory
    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }

    public static void main(String[] args) {

    }
}

hibernate.cfg.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
    "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <!-- 第一部分： 配置数据库信息 必须的 -->
        <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="hibernate.connection.url">jdbc:mysql:///hibernate_day01</property>
        <property name="hibernate.connection.useUnicode">true</property>
        <property name="hibernate.connection.characterEncoding">UTF-8</property>
        <property name="hibernate.connection.username">root</property>
        <property name="hibernate.connection.password">root3306</property>
        
        <!-- 第二部分： 配置hibernate信息  可选的-->
        <!-- 输出底层sql语句 -->
        <property name="hibernate.show_sql">true</property>
        <!-- 输出底层sql语句格式 -->
        <property name="hibernate.format_sql">true</property>
        <!-- hibernate帮创建表，需要配置之后 
            update: 如果已经有表，更新，如果没有，创建
        -->
        <property name="hibernate.hbm2ddl.auto">update</property>
        <!-- 配置数据库方言
            在mysql里面实现分页 关键字 limit，只能使用mysql里面
            在oracle数据库，实现分页rownum
            让hibernate框架识别不同数据库的自己特有的语句
         -->
        <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
        
        <!-- 第三部分： 把映射文件放到核心配置文件中 必须的-->
        <!--<mapping resource="k/entity/User.hbm.xml"/>-->
        <mapping resource="k/manytomany/User.xml"/>
        <mapping resource="k/manytomany/Role.xml"/>
    </session-factory>
</hibernate-configuration>