Hibernate_映射_继承结构映射2_另外两种映射方式-蒲公英云

package cn.itcast.j_hbm_extends;
import java.util.Date;
/**
 * 文章
 * 
 * @author 风清杨
 * @version V1.0
 */
public class Article {
    private Integer id;
    private String title;
    private String content;
    private Date postTime;
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getTitle() {
        return title;
    }
    public void setTitle(String title) {
        this.title = title;
    }
    public String getContent() {
        return content;
    }
    public void setContent(String content) {
        this.content = content;
    }
    public Date getPostTime() {
        return postTime;
    }
    public void setPostTime(Date postTime) {
        this.postTime = postTime;
    }
}
package cn.itcast.j_hbm_extends;
/**
 * 主题
 * 
 * @author 风清杨
 * @version V1.0
 */
public class Topic extends Article {
    private Integer type;// 精华、置顶...
    public Integer getType() {
        return type;
    }
    public void setType(Integer type) {
        this.type = type;
    }
}
package cn.itcast.j_hbm_extends;
/**
 * 回贴
 * 
 * @author 风清杨
 * @version V1.0
 */
public class Reply extends Article {
    private Integer floor;// 楼层
    public Integer getFloor() {
        return floor;
    }
    public void setFloor(Integer floor) {
        this.floor = floor;
    }
}
package cn.itcast.j_hbm_extends;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.junit.Test;
/**
 * 应用程序操作类
 * 
 * @author 风清杨
 * @version V1.0
 * 
 */
public class App {
    private static SessionFactory sessionFactory = new Configuration()//
            .configure()//
            .addClass(Article.class)//
            .buildSessionFactory();
    // 保存,有关联关系
    @Test
    public void testSave() throws Exception {
        Session session = sessionFactory.openSession();
        Transaction tx = null;
        try {
            tx = session.beginTransaction();
            // ------------------------------------
            // 新键对象
            Article article = new Article();
            article.setTitle("这是一个Article");
            Topic topic = new Topic();
            topic.setTitle("这是一个Topic");
            Reply reply = new Reply();
            reply.setTitle("这是一个Reply");
            // 保存
            session.save(article);
            session.save(topic);
            session.save(reply);
            // ------------------------------------
            tx.commit();
        } catch (RuntimeException e) {
            tx.rollback();
            throw e;
        } finally {
            session.close();
        }
    }
    // 获取,可以获取到关联的对方
    @Test
    public void testGet() throws Exception {
        Session session = sessionFactory.openSession();
        Transaction tx = null;
        try {
            tx = session.beginTransaction();
            // ------------------------------------
            // 获取
            Article article = (Article) session.get(Article.class, 1);
            Topic topic = (Topic) session.get(Topic.class, 2);
            Reply reply = (Reply) session.get(Reply.class, 3);
            System.out.println(article);
            System.out.println(topic);
            System.out.println(reply);
            System.out.println();
            Article article1 = (Article) session.get(Article.class, 2);
            Article article2 = (Article) session.get(Article.class, 3);
            System.out.println(article1);
            System.out.println(article2);
            // ------------------------------------
            tx.commit();
        } catch (RuntimeException e) {
            tx.rollback();
            throw e;
        } finally {
            session.close();
        }
    }
}

方式1

Center

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- 导入包 -->
<hibernate-mapping package="cn.itcast.j_hbm_extends2">
    <!-- 采用每个类一张表的方式,抽象类也对应表 -->
    <class name="Article" table="t_article">
        <id name="id" type="integer" column="id_">
            <generator class="native" />
        </id>
        <property name="title" type="string" column="title_" />
        <property name="content" type="text" length="10000" column="content_"></property>
        <property name="postTime" type="timestamp" column="postTime_"></property>
        <!-- 子类：Topic -->
        <joined-subclass name="Topic" table="t_topic">
            <key column="articleId"></key>
            <property name="type" type="integer" column="type_"/>
        </joined-subclass>
        <!-- 子类：Reply -->
        <joined-subclass name="Reply" table="t_reply">
            <key column="articleId"></key>
            <property name="floor" type="integer" column="floor_"/>
        </joined-subclass>
    </class>
</hibernate-mapping>

方式2

Center 1

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- 导入包 -->
<hibernate-mapping package="cn.itcast.j_hbm_extends3">
    <!-- 采用每个具体类一张表的方式,抽象类不对应表 
        abstract默认为false,设为true表示本类不对应表(类可以不是abstract的),这时就会忽略table属性。
    -->
    <class name="Article" abstract="false">
        <id name="id" type="integer" column="id_">
        <!-- 
            当使用每个具体类一张表的方式时,主键生成策略不能是identity。 
            因为在整个继承结构中,主键值是不能重复的。
        -->
            <generator class="hilo">
                <param name="table">hi_value</param>
                <param name="column">next_value</param>
                <param name="max_lo">100</param>
            </generator>
        </id>
        <property name="title" type="string" column="title_" />
        <property name="content" type="text" length="10000" column="content_"></property>
        <property name="postTime" type="timestamp" column="postTime_"></property>
        <!-- 子类：Topic -->
        <union-subclass name="Topic" table="t_topic">
            <property name="type" type="integer" column="type_"/>
        </union-subclass>
        <!-- 子类：Reply -->
        <union-subclass name="Reply" table="t_reply">
            <property name="floor" type="integer" column="floor_"/>
        </union-subclass>
    </class>
</hibernate-mapping>