hibernate框架学习笔记11：Criteria查询详解

Posted 2020-10-24 xuyiqing

创建实体类对象：

package domain;

import java.util.HashSet;
import java.util.Set;

//客户实体
public class Customer {
    
    private Long cust_id;
    private String cust_name;
    private String cust_source;
    private String cust_industry;
    private String cust_level;
    private String cust_linkman;
    private String cust_phone;
    private String cust_mobile;
    //使用set集合,表达一对多关系
    private Set<LinkMan> linkMens = new HashSet<LinkMan>();

    public Set<LinkMan> getLinkMens() {
        return linkMens;
    }
    public void setLinkMens(Set<LinkMan> linkMens) {
        this.linkMens = linkMens;
    }
    public Long getCust_id() {
        return cust_id;
    }
    public void setCust_id(Long cust_id) {
        this.cust_id = cust_id;
    }
    public String getCust_name() {
        return cust_name;
    }
    public void setCust_name(String cust_name) {
        this.cust_name = cust_name;
    }
    public String getCust_source() {
        return cust_source;
    }
    public void setCust_source(String cust_source) {
        this.cust_source = cust_source;
    }
    public String getCust_industry() {
        return cust_industry;
    }
    public void setCust_industry(String cust_industry) {
        this.cust_industry = cust_industry;
    }
    public String getCust_level() {
        return cust_level;
    }
    public void setCust_level(String cust_level) {
        this.cust_level = cust_level;
    }
    public String getCust_linkman() {
        return cust_linkman;
    }
    public void setCust_linkman(String cust_linkman) {
        this.cust_linkman = cust_linkman;
    }
    public String getCust_phone() {
        return cust_phone;
    }
    public void setCust_phone(String cust_phone) {
        this.cust_phone = cust_phone;
    }
    public String getCust_mobile() {
        return cust_mobile;
    }
    public void setCust_mobile(String cust_mobile) {
        this.cust_mobile = cust_mobile;
    }
    @Override
    public String toString() {
        return "Customer [cust_id=" + cust_id + ", cust_name=" + cust_name + "]";
    }
}

View Code

 

自定义工具类：

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;
    }    
}

View Code

 

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();
        
    }
    
}