Hibernate实现数据库增、删、改、查

时间：2022-12-11 21:23:30

1.导入hibernate jar包和mysql jar包，修改配置文件hibernate.cfg.xml

 

<?xml version="1.0" encoding="gbk"?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
<session-factory name="foo">
<!-- 配置数据库信息 --> 
<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="connection.url">jdbc:mysql:///hibernate1</property>
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.username">root</property>
<property name="hibernate.connection.password">123</property>

<!-- 其他配置 -->
<property name="hibernate.show_sql">true</property>

<!-- 导入映射文件 

-->
<mapping resource="demo/User.hbm.xml"/>



</session-factory>
</hibernate-configuration>
2.创建数据库中的表，根据表创建实体对象 

package demo;

public class User {
private int id;
private String name;
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;
}
@Override
public String toString() {
// TODO Auto-generated method stub
return "id="+id+" name="+name;
}
}

3.根据表和对象，配置映射关系 User.hbm.xml 

<?xml version="1.0" encoding="gbk"?>
<!DOCTYPE hibernate-mapping PUBLIC 
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<!-- 

  This mapping demonstrates 

     (1) a table-per-subclass mapping strategy

     (2) a simple component mapping

     (3) recursive associations withing an inheritance tree

-->

<hibernate-mapping 
package="demo">

<class name="User" table="t_user">

<id name="id" type="int" column="id" >
<generator class="native"/> <!--表示自动增长-->
</id>

        <property name="name" type="string" column="name" />

</class>


</hibernate-mapping>

4.写个HIbernate小工具，方便快速得到SessionFactory，得到session 

package demo;


import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;

public class HibernateUtils {
private static SessionFactory sessionFactory;

//初始化SessionFactory
static{
//Configuration cfg=new Configuration();
//cfg.configure();//读取默认的配置文件hibernate.cfg.xml
//cfg.configure("hibernate.cfg.xml");
//sessionFactory=cfg.buildSessionFactory();
sessionFactory=new Configuration()
.configure()
.buildSessionFactory();
}
/**
 * 获取全局唯一的SessionFactory
 * @return
 */
public static SessionFactory getSessionFactory() {

return sessionFactory;
}
/**
 * 从全局唯一的SessionFactory打开session
 * @return
 */
public static Session openSession() {
return sessionFactory.openSession();

}
}

5.在UserDao中完成具体功能 

package demo;

import java.util.List;

import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.Transaction;

public class UserDao {
/**
 * 增
 * @param user
 */
public void add(User user){
Session session=HibernateUtils.openSession();
Transaction tx=null;
try{
tx=session.beginTransaction();
session.save(user);
tx.commit();
} catch (Exception e) {
tx.rollback();
throw new RuntimeException(e);
} finally{
session.close();
}
}
/**
 * 删
 * @param user
 */
public void delete(int id){
Session session=HibernateUtils.openSession();
Transaction tx=null;
try{
tx=session.beginTransaction();
session.delete(session.get(User.class, id));
tx.commit();
} catch (Exception e) {
tx.rollback();
throw new RuntimeException(e);
} finally{
session.close();
}
}
/**
 * 改
 * @param user
 */
public void update(User user){
Session session=HibernateUtils.openSession();
Transaction tx=null;
try{
tx=session.beginTransaction();
session.update(user);
tx.commit();
} catch (Exception e) {
tx.rollback();
throw new RuntimeException(e);
} finally{
session.close();
}
}
/**
 * 查
 * @param id
 */
public User getById(int id){
Session session=HibernateUtils.openSession();
Transaction tx=null;
try{
tx=session.beginTransaction();
User user=(User) session.get(User.class, id);
tx.commit();
return user;
} catch (Exception e) {
tx.rollback();
throw new RuntimeException(e);
} finally{
session.close();
}
}

public List<User> findAll(){
Session session=HibernateUtils.openSession();
Transaction tx=null;
try{
tx=session.beginTransaction();
List<User> list=session.createQuery( //使用HQL查询
"FROM User")
.list();//根据条件得到list
tx.commit();
return list;
} catch (Exception e) {
tx.rollback();
throw new RuntimeException(e);
} finally{
session.close();
}

}

/**
 * 分页，返回一页的数据列表
 * @param firstResult 从结果列表中的那个索引开始取数据
 * @param maxResults 最多取多少条数据
 * @return  list+count返回的条数
 */
public QueryResult findAll(int firstResult, int maxResults){
Session session=HibernateUtils.openSession();
Transaction tx=null;
try{
tx=session.beginTransaction();
//查询一页的数据列表
//方式一
//Query query=session.createQuery("FROM User");
//query.setFirstResult(firstResult);
//query.setMaxResults(maxResults);
//List<User> list=query.list();
//方式二
List<User> list=session.createQuery("FROM User")
.setFirstResult(firstResult)
.setMaxResults(maxResults)
.list();
//查询总记录数
Long count=(Long)session.createQuery("SELECT COUNT(*) FROM User")
.uniqueResult();
tx.commit();
return new QueryResult(count.intValue(),list);
} catch (Exception e) {
tx.rollback();
throw new RuntimeException(e);
} finally{
session.close();
}
}
}

6.右击包名-new-Junit Test Case，也可以一一测试，对UserDao进行测试  

package demo;

import static org.junit.Assert.*;

import java.util.List;

import org.hibernate.SessionFactory;
import org.junit.Test;

public class UserDaoTest {
private UserDao userDao=new UserDao();
@Test
public void testAdd() {
User user=new User();
user.setName("Lily");
userDao.add(user);

}

@Test
public void testAdd_25() {
for(int i=1;i<=25;i++){
User user=new User();
user.setName("test_"+i);
userDao.add(user);
}

}

@Test
public void testDelete() {
userDao.delete(1);
}

@Test
public void testUpdate() {
//从数据库中获取一条已存在的数据
User user=userDao.getById(1);
user.setName("haha");
userDao.update(user);
}

@Test
public void testGetById() {
User user =userDao.getById(1);
System.out.println(user);
}

@Test
public void testFindAll() {
List<User> users=userDao.findAll();
for(User user:users){
System.out.println(user);
}
}

@Test
public void testFindAllIntInt() {
//QueryResult qr=userDao.findAll(0,10); //第1页，每页10条
//QueryResult qr=userDao.findAll(10,10);
QueryResult qr=userDao.findAll(20,10);

//显示结果
System.out.println("总记录数："+qr.getCount());
for(Object user:qr.getList()){
System.out.println(user);
}
}

}


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