Hibernate——以面向物件的思維操作關係資料庫(一)
阿新 • • 發佈:2019-02-07
Hibernate是一個輕量級的ORM開源框架。Hibernate解脫了面對繁瑣的JDBC的開發者,使得變成更加面向物件化,將之前的連線語句,增刪改查等語句進行了很好的封裝,使得業務邏輯等的編寫更加的容易;使移植資料庫也變得十分的容易,即根據不同的資料庫配置configuration.cfg.xml就可以輕鬆改變資料庫;下面以一個程式碼段稍作解釋:
一 :每個相對應的實體都會有相對應的對映檔案,對映檔案的作用主要是維護實體間的關係。
實體類User:
package com.bjpowernode.hibernate; import java.util.Date; public class User { private String id; private String name; private String password; private Date createTime; private Date expireTime; public String getId() { return id; } public void setId(String id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } public Date getCreateTime() { return createTime; } public void setCreateTime(Date createTime) { this.createTime = createTime; } public Date getExpireTime() { return expireTime; } public void setExpireTime(Date expireTime) { this.expireTime = expireTime; } }
對映檔案:
<?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> <class name="com.bjpowernode.hibernate.User"> <id name="id"> <generator class="uuid"/> </id> <property name="name"/> <property name="password"/> <property name="createTime"/> <property name="expireTime"/> </class> </hibernate-mapping>
將對映檔案生成dll檔案:
package com.bjpowernode.hibernate; import org.hibernate.cfg.Configuration; import org.hibernate.tool.hbm2ddl.SchemaExport; /** * 將hbm生成ddl * @author Administrator * */ public class ExportDB { public static void main(String[] args) { //預設讀取hibernate.cfg.xml檔案 Configuration cfg = new Configuration().configure(); SchemaExport export = new SchemaExport(cfg); export.create(true, true); } }
二 :在configuration.cfg.xml中配置基本資訊,並將對映檔案資訊配置到configuration.cfg.xml中
configuration.cfg.xml配置檔案:
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/hibernate_first</property>
<property name="hibernate.connection.username">root</property>
<property name="hibernate.connection.password">bjpowernode</property>
<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="hibernate.show_sql">true</property>
<mapping resource="com/bjpowernode/hibernate/User.hbm.xml"/>
</session-factory>
</hibernate-configuration>
三:建立客戶端類Client,新增使用者資料到資料庫
package com.bjpowernode.hibernate;
import java.util.Date;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
public class Client {
public static void main(String[] args) {
//讀取hibernate.cfg.xml檔案
Configuration cfg = new Configuration().configure();
//建立SessionFactory
SessionFactory factory = cfg.buildSessionFactory();
//取得session
Session session = null;
try {
session = factory.openSession();
//開啟事務
session.beginTransaction();
User user = new User();
user.setName("張三");
user.setPassword("123");
user.setCreateTime(new Date());
user.setExpireTime(new Date());
//儲存User物件
session.save(user);
//提交事務
session.getTransaction().commit();
}catch(Exception e) {
e.printStackTrace();
//回滾事務
session.getTransaction().rollback();
}finally {
if (session != null) {
if (session.isOpen()) {
//關閉session
session.close();
}
}
}
}
}
總結:上面只是一個小例子,但是從小例子中我們依稀可以感受到那種封裝給我們帶來的便捷了。