Hibernate之QBC检索和本地SQL检索

QBC查询就是通过使用Hibernate提供的Query By Criteria API来查询对象，这种API封装了SQL语句的动态拼装，对查询提供了更加面向对象的功能接口

本地SQL查询来完善HQL不能涵盖所有的查询特性。

 

====================代码区======================

测试类

package com.yl.hibernate.test;


import java.util.ArrayList;
import java.util.Arrays;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;

import oracle.net.aso.e;

import org.hibernate.Criteria;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.criterion.Conjunction;
import org.hibernate.criterion.Disjunction;
import org.hibernate.criterion.MatchMode;
import org.hibernate.criterion.Order;
import org.hibernate.criterion.Projection;
import org.hibernate.criterion.Projections;
import org.hibernate.criterion.Restrictions;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import com.yl.hibernate.entities.Department;
import com.yl.hibernate.entities.Employee;

public class HibernateTest {

    private SessionFactory sessionFactory;
    private Session session;
    private Transaction transaction;
    
    @Before
    public void init() {
        Configuration configuration = new Configuration().configure();
        ServiceRegistry serviceRegistry = 
                new ServiceRegistryBuilder().applySettings(configuration.getProperties())
                                            .buildServiceRegistry();

        sessionFactory = configuration.buildSessionFactory(serviceRegistry);
        
        session = sessionFactory.openSession();

        transaction = session.beginTransaction();
    }
    @After
    public void destory() {
        transaction.commit();
        
        session.close();
        
        sessionFactory.close();
    }
    
    
    @Test
    public void testQBC() {
        //1.创建一个Ctiteria对象
        Criteria criteria = session.createCriteria(Employee.class);
        //2.添加查询条件:在QBC中查询条件使用Criterion来表示
        //Criterion可以通过Restrictions 的静态方法得到
        criteria.add(Restrictions.eq("email", "PRESIDENT"));
        criteria.add(Restrictions.gt("salary", 500f));
        //3.执行查询
        Employee employee = (Employee) criteria.uniqueResult();
        System.out.println(employee);
    }
    
    @Test
    public void testQBC2() {
        
        Criteria criteria = session.createCriteria(Employee.class);
        //1.AND: 使用Conjunction表示
        //Conjunction 本身就是一个Criterion对象
        //且其中还可以添加Criterion对象
        Conjunction conjunction = Restrictions.conjunction();
        conjunction.add(Restrictions.like("name", "A", MatchMode.ANYWHERE));
        Department dept = new Department();
        dept.setId(20);
        conjunction.add(Restrictions.eq("dept", dept));
        System.out.println(conjunction);
        
        //2. OR
        Disjunction disjunction = Restrictions.disjunction();
        disjunction.add(Restrictions.ge("salary", 1000F));
        disjunction.add(Restrictions.isNotNull("email"));
        
        criteria.add(disjunction);
        criteria.add(conjunction);
        
        criteria.list();
        /**
         *  where
        (
            this_.SALARY>=? 
            or this_.EMAIL is not null
        ) 
        and (
            this_.NAME like ? 
            and this_.DEPT_ID=?
        )
         */
    }
    
    @Test
    public void testQBC3() {
        Criteria criteria = session.createCriteria(Employee.class);
        
        //统计查询： 使用Projection表示: 可以由Projections的静态方法得到
        criteria.setProjection(Projections.max("salary"));
        
        System.out.println(criteria.uniqueResult());
    }
    
    @Test
    public void testQBC4() {
        Criteria criteria = session.createCriteria(Employee.class);
        
        //1.添加排序
        criteria.addOrder(Order.asc("salary"));
        criteria.addOrder(Order.desc("email"));
        
        //2.添加分页
        int pageSize = 3;
        int pageNo = 2;
        criteria.setFirstResult((pageNo - 1) * pageSize)
                .setMaxResults(pageSize)
                .list();
        
    }
    
    @Test
    public void testNative() {
        String sql = "INSERT INTO YL_department VALUES(?, ?)";
        Query query = session.createSQLQuery(sql);
        
        query.setInteger(0, 50)
             .setString(1, "DEV")
             .executeUpdate();
    }
    
    @Test
    public void testHQLUpdate() {
        String hql = "DELETE FROM Department d WHERE d.id = :id";
        
        session.createQuery(hql).setInteger("id", 50)
                                .executeUpdate();
        
    }
}