Hibernate_映射_继承结构映射2_另外两种映射方式

╰半夏微凉° 2022-06-16 08:07 219阅读 0赞

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">
    
    <hibernate-mapping package="cn.itcast.j_hbm_extends2">
    	
    	<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>
    
    		
    		<joined-subclass name="Topic" table="t_topic">
    			<key column="articleId"></key>
    			<property name="type" type="integer" column="type_"/>
    		</joined-subclass>
    
    		
    		<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">
    
    <hibernate-mapping package="cn.itcast.j_hbm_extends3">
    	
    	<class name="Article" abstract="false">
    		<id name="id" type="integer" column="id_">
    		
    		
    			<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>
    
    		
    		<union-subclass name="Topic" table="t_topic">
    			<property name="type" type="integer" column="type_"/>
    		</union-subclass>
    
    		
    		<union-subclass name="Reply" table="t_reply">
    			<property name="floor" type="integer" column="floor_"/>
    		</union-subclass>
    	</class>
    </hibernate-mapping>

[Center]: /images/20220616/fd60ee1962594b6d98c467a5dd9e27ce.png
[Center 1]: /images/20220616/6bca3441ede84db68327c085fbee1900.png