hibernate_day02_14_Query对象查询所有记录

14_Query对象查询所有记录

Query对象

1 使用query对象，不需要写sql语句，但是写hql语句

（1）hql：hibernate query language，hibernate提供查询语言，这个hql语句和普通sql语句很相似

（2）hql和sql语句区别：

- 使用sql操作表和表字段

- 使用hql操作实体类和属性

2 查询所有hql语句：

（1）from 实体类名称

3 Query对象使用

（1）创建Query对象

（2）调用query对象里面的方法得到结果

 

package com.hlg.hibernatetest;

import java.util.List;

import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.junit.Test;

import com.hlg.entity.User;
import com.hlg.utils.HibernateUtils;

public class HibernateQueryData {

@Test
public void testQuery(){
SessionFactory sessionFactory = null;
Session session = null;
Transaction tx = null;

try{
sessionFactory = HibernateUtils.getSessionFactory();
session = sessionFactory.openSession();
tx = session.beginTransaction();

//1 创建Query对象
Query query = session.createQuery("from User");

List<User> list = query.list();

for(User user:list){
System.out.println(user);
}

//提交事务
tx.commit();

}catch(Exception e){
//回滚事务
tx.rollback();
}finally{
//关闭
session.close();
sessionFactory.close();
}

}
}

Criteria对象

1 使用这个对象查询操作，但是使用这个对象时候，不需要写语句，直接调用方法实现

 

2 实现过程

（1）创建criteria对象

（2）调用对象里面的方法得到结果

@Test
public void testCriteria(){
SessionFactory sessionFactory = null;
Session session = null;
Transaction tx = null;

try{
sessionFactory = HibernateUtils.getSessionFactory();
session = sessionFactory.openSession();
tx = session.beginTransaction();

//1 创建Criteria对象
Criteria criteria = session.createCriteria(User.class);

List<User> list = criteria.list();

for (User user : list) {
System.out.println(user);
}

//提交事务
tx.commit();

}catch(Exception e){
//回滚事务
tx.rollback();
}finally{
//关闭
session.close();
sessionFactory.close();
}

}

16_SQLQuery对象查询所有记录

package com.hlg.hibernatetest;

import java.util.Arrays;
import java.util.List;

import org.hibernate.Criteria;
import org.hibernate.Query;
import org.hibernate.SQLQuery;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.junit.Test;

import com.hlg.entity.User;
import com.hlg.utils.HibernateUtils;

public class HibernateQueryData {

@Test
public void testQuery(){
SessionFactory sessionFactory = null;
Session session = null;
Transaction tx = null;

try{
sessionFactory = HibernateUtils.getSessionFactory();
session = sessionFactory.openSession();
tx = session.beginTransaction();

//1 创建Query对象
Query query = session.createQuery("from User");

List<User> list = query.list();

for(User user:list){
System.out.println(user);
}

//提交事务
tx.commit();

}catch(Exception e){
//回滚事务
tx.rollback();
}finally{
//关闭
session.close();
sessionFactory.close();
}

}

@Test
public void testCriteria(){
SessionFactory sessionFactory = null;
Session session = null;
Transaction tx = null;

try{
sessionFactory = HibernateUtils.getSessionFactory();
session = sessionFactory.openSession();
tx = session.beginTransaction();

//1 创建Criteria对象
Criteria criteria = session.createCriteria(User.class);

List<User> list = criteria.list();

for (User user : list) {
System.out.println(user);
}

//提交事务
tx.commit();

}catch(Exception e){
//回滚事务
tx.rollback();
}finally{
//关闭
session.close();
sessionFactory.close();
}

}

@Test
public void testSQLQuery(){
SessionFactory sessionFactory = null;
Session session = null;
Transaction tx = null;

try{
sessionFactory = HibernateUtils.getSessionFactory();
session = sessionFactory.openSession();
tx = session.beginTransaction();

//1 创建对象
//参数是普通的sql语句
SQLQuery sqlQuery = session.createSQLQuery("select * from t_user");
//返回List集合 ,默认每部分是数组结构
List<Object[]> list = sqlQuery.list();

for (Object[] objects : list) {
//Arrays.toString() 让数组以字符串形式输出
System.out.println(Arrays.toString(objects));
}

//提交事务
tx.commit();

}catch(Exception e){
//回滚事务
tx.rollback();
}finally{
//关闭
session.close();
sessionFactory.close();
}

}
}

返回list中每部分是对象形式

//1 创建对象
//参数是普通的sql语句
SQLQuery sqlQuery = session.createSQLQuery("select * from t_user");
//返回List集合 的每部分是对象形式

sqlQuery.addEntity(User.class);

//
List<User> list =  sqlQuery.list();
for (User user : list) {
System.out.println(user);
}

package com.hlg.hibernatetest;

import java.util.Arrays;
import java.util.List;

import org.hibernate.Criteria;
import org.hibernate.Query;
import org.hibernate.SQLQuery;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.junit.Test;

import com.hlg.entity.User;
import com.hlg.utils.HibernateUtils;

public class HibernateQueryData {

@Test
public void testQuery(){
SessionFactory sessionFactory = null;
Session session = null;
Transaction tx = null;

try{
sessionFactory = HibernateUtils.getSessionFactory();
session = sessionFactory.openSession();
tx = session.beginTransaction();

//1 创建Query对象
Query query = session.createQuery("from User");

List<User> list = query.list();

for(User user:list){
System.out.println(user);
}

//提交事务
tx.commit();

}catch(Exception e){
//回滚事务
tx.rollback();
}finally{
//关闭
session.close();
sessionFactory.close();
}

}

@Test
public void testCriteria(){
SessionFactory sessionFactory = null;
Session session = null;
Transaction tx = null;

try{
sessionFactory = HibernateUtils.getSessionFactory();
session = sessionFactory.openSession();
tx = session.beginTransaction();

//1 创建Criteria对象
Criteria criteria = session.createCriteria(User.class);

List<User> list = criteria.list();

for (User user : list) {
System.out.println(user);
}

//提交事务
tx.commit();

}catch(Exception e){
//回滚事务
tx.rollback();
}finally{
//关闭
session.close();
sessionFactory.close();
}

}

@Test
public void testSQLQuery(){
SessionFactory sessionFactory = null;
Session session = null;
Transaction tx = null;

try{
sessionFactory = HibernateUtils.getSessionFactory();
session = sessionFactory.openSession();
tx = session.beginTransaction();

//1 创建对象
//参数是普通的sql语句
SQLQuery sqlQuery = session.createSQLQuery("select * from t_user");
//返回List集合 的每部分是对象形式

sqlQuery.addEntity(User.class);

//
List<User> list =  sqlQuery.list();
for (User user : list) {
System.out.println(user);
}

//			List<Object[]> list = sqlQuery.list();
//
//			for (Object[] objects : list) {
//				//Arrays.toString() 让数组以字符串形式输出
//				System.out.println(Arrays.toString(objects));
//			}

//提交事务
tx.commit();

}catch(Exception e){
//回滚事务
tx.rollback();
}finally{
//关闭
session.close();
sessionFactory.close();
}

}
}