怎么用hibernate对数据库增删改查
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发布时间：2022-04-08 02:09
共2个回答
懂视网
时间：2022-04-08 06:30
配置过程省略。
数据库连接的公共类HibernateUtils.java
package test.hibernate.dao;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
public class HibernateUtils {
private static SessionFactory sessionFactory;
static {
// Configuration configuration=new Configuration();
// configuration.configure();//读取默认的文件hibernate.cfg.xml
// // configuration.configure("hibernate.cfg.xml");读取指定文件
// sessionFactory=configuration.buildSessionFactory();
sessionFactory = new Configuration()//
.configure()//
.buildSessionFactory();
}
/*
* 获得一个全局唯一的SessionFactory
*
* @return
*/
public static SessionFactory getSessionFactory() {
return sessionFactory;
}
/*
* 从全局SessionFactory中打开一个Session
*/
public static Session openSession() {
return sessionFactory.openSession();
}
public static void setSessionFactory(SessionFactory sessionFactory) {
HibernateUtils.sessionFactory = sessionFactory;
}
}
QueryResult.java
package test.hibernate.dao;
import java.util.List;
public class QueryResult {
private int count;
private List list;
public QueryResult(int count, List list) {
this.count = count;
this.list = list;
}
public int getCount() {
return count;
}
public void setCount(int count) {
this.count = count;
}
public List getList() {
return list;
}
public void setList(List list) {
this.list = list;
}
}
业务实现类UserDao.javapackage test.hibernate.dao;
import java.util.List;
import org.hibernate.Criteria;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.Transaction;
import org.hibernate.criterion.Order;
import org.hibernate.criterion.Restrictions;
import test.hibernate.domain.User;
/**
* @author LinDL
*
*/
public class UserDao {
public void save(User user) {
Session session = HibernateUtils.openSession();
Transaction transaction = null;
try {
transaction = session.beginTransaction();
session.save(user);
transaction.commit();
} catch (RuntimeException e) {
// TODO: handle exception
transaction.rollback();
throw e;
} finally {
}
session.close();
}
public void update(User user) {
Session session = HibernateUtils.openSession();
Transaction transaction = null;
try {
transaction = session.beginTransaction();
session.update(user);
transaction.commit();
} catch (RuntimeException e) {
// TODO: handle exception
transaction.rollback();
throw e;
} finally {
}
session.close();
}
public void delete(int id) {
Session session = HibernateUtils.openSession();
Transaction transaction = null;
try {
transaction = session.beginTransaction();
User user = (User) session.get(User.class, id);// 要先获取到实体对象
session.delete(user);// 删除的是实体对象
transaction.commit();
} catch (RuntimeException e) {
// TODO: handle exception
transaction.rollback();
throw e;
} finally {
}
session.close();
}
/**
* @param id
* @return
*/
public User getById(int id) {
Session session = HibernateUtils.openSession();
Transaction transaction = null;
try {
transaction = session.beginTransaction();
User user = (User) session.get(User.class, id);
transaction.commit();
return user;
} catch (RuntimeException e) {
// TODO: handle exception
transaction.rollback();
throw e;
} finally {
session.close();
}
}
/**
* @return
*/
public List<User> findAll() {
Session session = HibernateUtils.openSession();
Transaction transaction = null;
try {
transaction = session.beginTransaction();
// 使用HQL查询
// List<User> all = session.createQuery("from User").list();
// 使用面向对象的方式查询
Criteria criteria = session.createCriteria(User.class);
// criteria.add(Restrictions.eq("id", 5));// 添加限制条件，查询id等于5的记录
// criteria.add(Restrictions.ge("id", 6));//
// 查询id大于等于6的记录，lt表小于,le表小于等于
// criteria.addOrder(Order.asc("id"));// 添加排序条件
List<User> all = criteria.list();
transaction.commit();
return all;
} catch (RuntimeException e) {
// TODO: handle exception
transaction.rollback();
throw e;
} finally {
session.close();
}
}
/**
* @param firstResult
* @param maxResult
* @return
*/
@SuppressWarnings("unchecked")
public QueryResult findAll(int firstResult, int maxResult) {
Session session = HibernateUtils.openSession();
Transaction transaction = null;
try {
transaction = session.beginTransaction();
// 使用HQL查询
// Query query = (Query) session.createQuery("from User");
// query.setFirstResult(firstResult);
// query.setMaxResults(maxResult);
// List<User> all = query.list();
List<User> all = session.createQuery("from User")
.setFirstResult(firstResult)//
.setMaxResults(maxResult)//
.list();
// 查询总记录数
Long count = (Long) session
.createQuery("select count(*) from User").uniqueResult();
transaction.commit();
return new QueryResult(count.intValue(), all);
} catch (RuntimeException e) {
// TODO: handle exception
transaction.rollback();
throw e;
} finally {
session.close();
}
}
}
测试类
package test.hibernate.dao;
import static org.junit.Assert.*;
import java.util.List;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import test.hibernate.domain.User;
public class UserDaoTest {
UserDao userDao = new UserDao();
@Test
public void testSave() {
User user = new User();
// user.setName("张三");
// userDao.save(user);
for (int i = 1; i < 30; i++) {
user.setId(i);
user.setName("test" + i);
userDao.save(user);
}
}
@Test
public void testUpdate() {
User user = userDao.getById(2);
user.setName("历史");
userDao.update(user);
}
@Test
public void testDelete() {
userDao.delete(2);
}
@Test
public void testGetById() {
User user = userDao.getById(1);
System.out.println(user);
}
@Test
public void testFindAll() {
List<User> list = userDao.findAll();
for (User user : list) {
System.out.println(user);
}
}
@Test
public void testFindAllIntInt() {
// QueryResult queryResult = userDao.findAll(0, 10);
// QueryResult queryResult=userDao.findAll(10, 10);
QueryResult queryResult = userDao.findAll(20, 10);
System.out.println("总记录数" + queryResult.getCount());
for (Object user : queryResult.getList()) {
System.out.println(user);
}
}
}
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Hibernate之实现数据库的基本操作
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热心网友
时间：2022-04-08 03:38
首先，我们要对Hibernate在eclipse环境下进行布局配置。 详情请看Hibernate配置。
其次，我们了解几个查询的用法。
一、Criteria Query
Criteria Query通过面向对象化的设计，将数据查询条件封装为一个对象，换句话讲Criteria Query可以看作是传统SQL的对象化表示。如： Criteria criteria = session.createCriteria(TUser.class);
criteria.add(Expression.eq(“name”,”Erica”));
criteria.add(Expression.eq(“sex”,new Integer(1)));
1. Criteria查询表达式
Criteria本身只是一个查询器，具体的查询条件需要通过Criteria.add方法添加到Criteria实例中。 如前面的例子所示，Expression对象具体描述了查询条件。针对SQL语法，Expression提供了对应的查询限定机制。
