Hibernate提供的多种查询方式

注意：每种查询方式又含有多种重载的方法，这里只列出基础的一种。

Hibernate提供了多种查询方式：

1. Hibernate查询方式一：get查询
2. Hibernate查询方式二：load延迟加载
3. Hibernate查询方式三：HQL之createQuery，返回多条数据
4. Hibernate查询方式四：createCriteria查询，返回多条数据
5. Hibernate查询方式五：HQL之createSQLQuery，根据SQL语句返回数据

package com.ckinghan.test;

import java.util.List;

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

import com.ckinghan.bean.User;

/**
 * Hibernate提供了多种查询方式
 * @author ckinghan
 */
public class HibernateQueryTest {

    /**
     * Hibernate查询方式一：get
     */
    @Test
    public void HibernateGetQuery(){
        Configuration configuration = new Configuration().configure();
        SessionFactory buildSessionFactory = configuration.buildSessionFactory();
        Session currentSession = buildSessionFactory.getCurrentSession();
        Transaction transaction = currentSession.beginTransaction();
        Object object = currentSession.get(User.class, );
        if(object != null && !"".equals(object)){
            User user = (User) object;
            System.out.println(user);
        }
        transaction.commit();
        buildSessionFactory.close();
    }

    /**
     * Hibernate查询方式二：load延迟加载
     */
    @Test
    public void hibernateLoadQuery(){
        Configuration configuration = new Configuration().configure();
        SessionFactory buildSessionFactory = configuration.buildSessionFactory();
        Session currentSession = buildSessionFactory.getCurrentSession();
        Transaction transaction = currentSession.beginTransaction();
        Object load = currentSession.load(User.class, );
        if(load != null && !"".equals(load)){
            User user = (User) load;
            System.out.println(user);
        }
        transaction.commit();
        buildSessionFactory.close();
    }

    /**
     * Hibernate查询方式三：HQL之createQuery，返回多条数据
     */
    @Test
    public void hibernateHqlQuery(){
        Configuration configuration = new Configuration().configure();
        SessionFactory buildSessionFactory = configuration.buildSessionFactory();
        Session currentSession = buildSessionFactory.getCurrentSession();
        Transaction transaction = currentSession.beginTransaction();
        //注意：这里传的参数中的User是实体类名
        Query createQuery = currentSession.createQuery("from User");
        //通过Query类中的list()方法返回list结果集
        List<User> users = createQuery.list();
        System.out.println(users);
        transaction.commit();
        buildSessionFactory.close();
    }

    /**
     * Hibernate查询方式四：createCriteria查询，返回多条数据
     */
    @Test
    public void hibernateCriteriaQuery(){
        Configuration configuration = new Configuration().configure();
        SessionFactory buildSessionFactory = configuration.buildSessionFactory();
        Session currentSession = buildSessionFactory.getCurrentSession();
        Transaction transaction = currentSession.beginTransaction();
        //通过实体类，将对应的数据库表中的数据全部返回
        Criteria createCriteria = currentSession.createCriteria(User.class);
        //通过Criteria类提供的list()方法将数据转换为List<User>类型
        List<User> list = createCriteria.list();
        System.out.println(list);
        transaction.commit();
        buildSessionFactory.close();
    }

    /**
     * Hibernate查询方式五：HQL之createSQLQuery，根据SQL语句返回数据
     */
    @Test
    public void hibernateHqlCreateSqlQuery(){
        Configuration configuration = new Configuration().configure();
        SessionFactory buildSessionFactory = configuration.buildSessionFactory();
        Session currentSession = buildSessionFactory.getCurrentSession();
        Transaction transaction = currentSession.beginTransaction();
        //传入要查询的SQL语句 
        SQLQuery query = currentSession.createSQLQuery("select * from user");
        //将查询到的数据封装到User实体中
        query.addEntity(User.class);
        //通过Query的list()方法，返回List<User>
        List<User> list = query.list();
        System.out.println(list);
        transaction.commit();
        buildSessionFactory.close();
    }

}