首页 > 代码库 > hibernate用注解的方式实现orm

hibernate用注解的方式实现orm

hibernate 有两种方式实现把一张表映射成一个对象,一种是配置文件的方式,一种是注解的方式。这里用hibernate提供的注解的方式实现一个对象和一张表之间的对应。

思路:

首先在hibernate.cfg.xml文件中配置如下内容:数据库,方言,是否显示sql,加载映射类:注意这个hibernate.cfg.xml位置在src下。

因为new Configuration().configure()。这个configure()函数打开源码默认的hiberante.cfg.xml就在src下。

hibernate.cfg.xml的配置的代码如下所示:

 1 <?xml version=‘1.0‘ encoding=‘utf-8‘?>
 2 <!--
 3   ~ Hibernate, Relational Persistence for Idiomatic Java
 4   ~
 5   ~ License: GNU Lesser General Public License (LGPL), version 2.1 or later.
 6   ~ See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
 7   -->
 8 <!DOCTYPE hibernate-configuration PUBLIC
 9         "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
10         "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
11 
12 <hibernate-configuration>
13 
14     <session-factory>
15 
16         <!-- Database connection settings -->
17         <property name="connection.driver_class">oracle.jdbc.OracleDriver</property>
18         <property name="connection.url">jdbc:oracle:thin:@localhost:1521:orcl</property>
19         <property name="connection.username">scott</property>
20         <property name="connection.password">a123456</property>
21 
22         <!-- JDBC connection pool (use the built-in) -->
23         <property name="connection.pool_size">10</property>
24 
25         <!-- SQL dialect -->
26         <property name="dialect">org.hibernate.dialect.Oracle10gDialect</property>
27         <!-- Echo all executed SQL to stdout -->
28         <property name="show_sql">true</property>
29 
30         <!-- Drop and re-create the database schema on startup -->
31      <!--   <property name="hbm2ddl.auto">create</property>-->
32 
33         <!-- Names the annotated entity class -->
34              <mapping class="com.qls.domain.DiaoChan"/>
35     </session-factory>
36 
37 </hibernate-configuration>

然后再oracle数据库中创建diaoChan这张表:

sql语句如下:

1 create table diaoChan(
2  id number(2) primary key not null,
3  name varchar2(30) ,
4    height number(2)
5   );

然后再oracle数据库创建一个序列,用于主键生成策略用的。

sql语句如下:

1 create sequence sixi start with 1 increment by 1;

 写一个hibernate的domain对象:

代码如下:

package com.qls.domain;

import javax.persistence.*;

/**
 * Created by 秦林森 on 2017/5/20.
 */
@Entity
@Table(name = "diaoChan")
public class DiaoChan {
    private int id;
    private String name;
    private int height;
 
   @Id
   @GeneratedValue(strategy = GenerationType.SEQUENCE,generator = "people")
//其中上行的generator中的内容必须和下面这行的name表示一致。
   @SequenceGenerator(name = "people",sequenceName = "sixi",initialValue = http://www.mamicode.com/1,allocationSize = 1)"name")
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
    @Column(name = "height")
    public int getHeight() {
        return height;
    }

    public void setHeight(int height) {
        this.height = height;
    }
}

然后写一个Test类主要是向表中插入一条数据:

代码如下:

 1 package com.qls.test;
 2 
 3 import com.qls.domain.DiaoChan;
 4 import org.hibernate.Session;
 5 import org.hibernate.SessionFactory;
 6 import org.hibernate.Transaction;
 7 import org.hibernate.cfg.Configuration;
 8 
 9 /**
10  * Created by 秦林森 on 2017/5/20.
11  */
12 public class Test2 {
13     public static void main(String[] args) {
14         SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
15         Session session = sessionFactory.openSession();
16         DiaoChan diaoChan = new DiaoChan();
17         diaoChan.setName("崇祯");
18         diaoChan.setHeight(10);
19         Transaction tx = session.beginTransaction();//开启事务。
20         session.save(diaoChan);
21         tx.commit();//提交事务。
22         session.close();//关闭会话。
23     }
24 }

 

运行Test2之后就会在diaoChan这张表中插入一条数据:

查询结果如下所示:

1 SQL> select *from diaochan;
2  
3  ID NAME                           HEIGHT
4 --- ------------------------------ ------
5   3 貂蝉                               12
6   4 崇祯                               10

上面的结果是因为我运行了两次的原因。

 

hibernate用注解的方式实现orm