hibernate 查询

获取Session

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.boot.MetadataSources;
import org.hibernate.boot.registry.StandardServiceRegistry;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;

public class HibernateSessionUtil {

    private static SessionFactory sessionFactory;

    static {
        final StandardServiceRegistry registry = new StandardServiceRegistryBuilder()
                .configure() //默认值:hibernate.cfg.xml
                .build();
        try {
            sessionFactory = new MetadataSources( registry ).buildMetadata().buildSessionFactory();
        }
        catch (Exception e) {
            StandardServiceRegistryBuilder.destroy( registry );
        }
    }


    public static Session createSession(){
        return sessionFactory.openSession();
    }
}

获取Query对象

session = HibernateSessionUtil.createSession();
//Query对象
Query query = session.createQuery("");
//NativeQuery对象
NativeQuery nativeQuery = session.createNativeQuery("");

NativeQuery对象方法

//将查询结果放入实体
addEntity();

Query对象方法

//给占位符设置值
setParameter()
//将查询结果加入List集合中
list()
//查询单个结果
uniqueResult()
//执行更新或删除
executeUpdate()

hql

-- 查询并将查询结果注入到实体中
select t from PersonEntity as p;
-- 简写方式
from PersonEntity;

-- 带条件的查询
from PersonEntity where p_id=?;

-- 查询多列,注入到多个数组
-- [personId,personName]
select personId,personName from PersonEntity;

-- 使用DTO的构造器
select new com.dto.personDTO(personId,personName) from PersonEntity;

-- 使用map
select new map(personId,personName) form PersonEntity;

-- 连表查询
-- e.g. Person 和 Room
select new map(p.personId,r.roomName) from PersonEntity p left join p.roomList r where p.personName=?

-- 删除
delete from PersonEntity where personName=?

-- 修改
update PersonEntity set personName=? where personId=?