hibernate開發(fā)步驟
- 創(chuàng)建hibernate配置文件
- 創(chuàng)建實(shí)體類
- 創(chuàng)建對(duì)象-關(guān)系映射文件
- 通過(guò)hibernate訪問(wèn)數(shù)據(jù)庫(kù)
下面提供一個(gè)簡(jiǎn)單地示例
hibernate配置文件
<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD//EN"
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<!-- 配置連接數(shù)據(jù)庫(kù)信息 -->
<property name="connection.url">jdbc:mysql://localhost:3306/studyhibernate</property>
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.username">root</property>
<property name="connection.password">123456</property>
<!-- 配置hibernate的基本信息 -->
<!-- hibernate方言 -->
<property name="dialect">org.hibernate.dialect.MySQL5InnoDBDialect</property>
<!-- 執(zhí)行操作時(shí)是否在控制臺(tái)打印 -->
<property name="show_sql">true</property>
<!-- 是否對(duì)SQL進(jìn)行格式化 -->
<property name="format_sql">true</property>
<!-- 指定自動(dòng)生成數(shù)據(jù)表的策略 -->
<property name="hibernate.hbm2ddl.auto">update</property>
<!-- 指定關(guān)聯(lián)的映射文件 -->
<mapping resource="User.hbm.xml"/>
</session-factory>
</hibernate-configuration>
實(shí)體類
- 提供一個(gè)無(wú)參構(gòu)造器：hibernate使用Constructor.newInstance()來(lái)實(shí)例化
- 提供一個(gè)主鍵字段
- 實(shí)體類的字段要聲明get/set方法：hibernate通過(guò)get/set方法來(lái)獲取字段
- 使用非final的類：如果沒(méi)有實(shí)現(xiàn)接口的話仲锄，hibernate會(huì)使用cglib來(lái)生成代理蛀骇，final類不可以生成cglib代理
package com.zhanghe.study.model;
/**
* @author zh
* @date 2020/12/4 10:26
*/
public class User {
private int id;
private String name;
private int age;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
}
hibernate映射文件
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<!-- name為實(shí)體類 table為表名 -->
<class name="com.zhanghe.study.model.User" table="user">
<!-- name為字段名 type為類型 column為表的字段名 -->
<id name="id" type="java.lang.Integer">
<column name="id"/>
<!-- 指定主鍵生成方式 navive 使用數(shù)據(jù)庫(kù)本地方式 -->
<generator class="native"/>
</id>
<property name="name" type="java.lang.String">
<column name="name"/>
</property>
<property name="age" type="java.lang.Integer">
<column name="age"/>
</property>
</class>
</hibernate-mapping>
hibernate訪問(wèn)數(shù)據(jù)庫(kù)
package com.zhanghe.study;
import com.zhanghe.study.model.User;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
/**
* @author zh
* @date 2020/12/4 10:00
*/
public class Main {
private static final SessionFactory sessionFactory;
// 創(chuàng)建sessionFactory對(duì)象
static {
try {
// 對(duì)應(yīng)的hibernate基本配置信息和對(duì)象關(guān)系映射信息
Configuration configuration = new Configuration();
// 找到hibernate.cfg.xml配置文件,如果沒(méi)有會(huì)報(bào)錯(cuò) 當(dāng)然也可以調(diào)用configure(String resource)有參的方法，自己指定配置文件名稱及位置
configuration.configure();
// 4.0之前不需要使用serviceRegistry 直接構(gòu)建sessionFactory configuration.buildSessionFactory()
// 4.0之后創(chuàng)建serviceRegistry,所有的配置和服務(wù)都要在該對(duì)象中注冊(cè)才可以生效
// 4.3之前使用該方式new ServiceRegistryBuilder().applySettings(configuration.getProperties()).buildServiceRegistry();
ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder().applySettings(configuration.getProperties()).build();
sessionFactory = configuration.buildSessionFactory(serviceRegistry);
} catch (Throwable ex) {
throw new ExceptionInInitializerError(ex);
}
}
// 創(chuàng)建session對(duì)象
public static Session getSession() throws HibernateException {
return sessionFactory.openSession();
}
public static void main(final String[] args) throws Exception {
final Session session = getSession();
// 開啟事務(wù)
Transaction transaction = session.beginTransaction();
try {
User user = new User();
user.setAge(20);
user.setName("張三");
session.save(user);
transaction.commit();
} catch (Exception e){
transaction.rollback();
e.printStackTrace();
} finally {
session.close();
}
}
}
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