hibernate框架学习笔记11：Criteria查询详解

创建实体类对象：

package utils;

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

public class HibernateUtils {
private static SessionFactory sf;

static{
//1 创建,调用空参构造
Configuration conf = new Configuration().configure();
//2 根据配置信息,创建 SessionFactory对象
sf = conf.buildSessionFactory();
}

//获得session => 获得全新session
public static Session openSession(){
//3 获得session
Session session = sf.openSession();

return session;

}
//获得session => 获得与线程绑定的session
public static Session getCurrentSession(){
//3 获得session
Session session = sf.getCurrentSession();

return session;
}
}

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测试类示例：

基本语法：

package criteria;

import java.util.List;

import org.hibernate.Criteria;
import org.hibernate.Session;
import org.hibernate.Transaction;
import org.hibernate.criterion.Order;
import org.hibernate.criterion.Projections;
import org.hibernate.criterion.Restrictions;
import org.junit.Test;

import domain.Customer;
import utils.HibernateUtils;

//学习Criteria语法
public class Demo {

@Test
//基本语法
public void fun1(){
Session session = HibernateUtils.openSession();
Transaction tx = session.beginTransaction();
//----------------------------------------------------

Criteria c = session.createCriteria(Customer.class);

List<Customer> list = c.list();

System.out.println(list);

//----------------------------------------------------
tx.commit();
session.close();

}

@Test
//条件语法
// >                 gt
// >=                ge
// <                lt
// <=                le
// ==                eq
// !=                ne
// in                in
// between and        between
// like             like
// is not null         isNotNull
// is null            isNull
// or                or
// and                and
public void fun2(){
Session session = HibernateUtils.openSession();
Transaction tx = session.beginTransaction();
//----------------------------------------------------

Criteria c = session.createCriteria(Customer.class);

//        c.add(Restrictions.idEq(2l));
c.add(Restrictions.eq("cust_id",2l));

List<Customer> list = c.list();

System.out.println(list);

//----------------------------------------------------
tx.commit();
session.close();

}

@Test
//分页语法 - 与HQL一样
public void fun3(){
Session session = HibernateUtils.openSession();
Transaction tx = session.beginTransaction();
//----------------------------------------------------

Criteria c = session.createCriteria(Customer.class);
//limit ?,?
c.setFirstResult(0);
c.setMaxResults(2);

List<Customer> list = c.list();

System.out.println(list);

//----------------------------------------------------
tx.commit();
session.close();

}

@Test
//排序语法
public void fun4(){
Session session = HibernateUtils.openSession();
Transaction tx = session.beginTransaction();
//----------------------------------------------------

Criteria c = session.createCriteria(Customer.class);

c.addOrder(Order.asc("cust_id"));//升序
//c.addOrder(Order.desc("cust_id"));降序

List<Customer> list = c.list();

System.out.println(list);

//----------------------------------------------------
tx.commit();
session.close();

}

@Test
//统计语法
public void fun5(){
Session session = HibernateUtils.openSession();
Transaction tx = session.beginTransaction();
//----------------------------------------------------

Criteria c = session.createCriteria(Customer.class);

//设置查询目标（聚合函数）
c.setProjection(Projections.rowCount());

List list = c.list();

System.out.println(list);

//----------------------------------------------------
tx.commit();
session.close();

}

}

离线查询：

传统criteria对象创建依赖于session，前端传递查询条件依次经过WEB、SERVICE层到DAO层，

在DAO层组装查询条件到criteria后执行查询

离线的criteria对象，于session无关，凭空创建，可以在WEB层创建criteria对象并组装查询条件，

这时候直接传递criteria对象到DAO层查询即可，这时候就做到了一个DAO方法适用于所有查询

package criteria;

import java.util.List;

import org.hibernate.Criteria;
import org.hibernate.Session;
import org.hibernate.Transaction;
import org.hibernate.criterion.DetachedCriteria;
import org.hibernate.criterion.Order;
import org.hibernate.criterion.Projections;
import org.hibernate.criterion.Restrictions;
import org.junit.Test;

import domain.Customer;
import utils.HibernateUtils;

//学习离线Criteria
public class Demo2 {

@Test
public void fun1(){
//Service/web层
DetachedCriteria dc  = DetachedCriteria.forClass(Customer.class);

dc.add(Restrictions.idEq(5l));//拼装条件(全部与普通Criteria一致)

//----------------------------------------------------
Session session = HibernateUtils.openSession();
Transaction tx = session.beginTransaction();
//----------------------------------------------------
//Dao层
Criteria c = dc.getExecutableCriteria(session);

List list = c.list();

System.out.println(list);
//----------------------------------------------------
tx.commit();
session.close();

}

}