【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>

巴特西

【Hibernate 多对多】

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