mybatis学习（五）——增删改查及自增主键的获取

一、mybatis的增删改查

1、修改hotelMapper接口

package com.pjf.mybatis.dao;

import com.pjf.mybatis.po.Hotel;

public interface HotelMapper {

    public Hotel getHotel(Integer i);

    public void updateHotel(Hotel hotel);

    public void insertHotel(Hotel hotel);

    public void deleteHotel(Integer i);
}

2、修改hotelMapper.xml文件

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="com.pjf.mybatis.dao.HotelMapper">
    <!-- public Hotel getHotel(Integer i); -->
    <select id="getHotel" resultType="com.pjf.mybatis.po.Hotel">
        select id,hotel_name as
        hotelName, hotel_address as hotelAddress, price from hotel
        where
        id=#{id}
    </select>
    <!-- public void updateHotel(Hotel hotel); -->
    <update id="updateHotel" parameterType="com.pjf.mybatis.po.Hotel">
        update hotel set
        price=#{price} where id =#{id}
    </update>
    <!-- public void insertHotel(Hotel hotel); -->
    <insert id="insertHotel" parameterType="com.pjf.mybatis.po.Hotel">
        insert into hotel(id,hotel_name,hotel_address,price)
        value(#{id},#{hotelName},#{hotelAddress},#{price})
    </insert>
    <!-- public void deleteHotel(Integer i); -->
    <delete id="deleteHotel">
        delete from hotel where id=#{id}
    </delete>

</mapper>

3、测试类

package com.pjf.mybatis;

import java.io.IOException;
import java.io.InputStream;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Test;

import com.pjf.mybatis.dao.HotelMapper;
import com.pjf.mybatis.po.Hotel;

public class TestHotel {

    public SqlSessionFactory sqlSessionFactory() throws IOException {
        // mybatis的配置文件
        String resource = "mybatis_config.xml";
        // 使用类加载器加载mybatis的配置文件（它也加载关联的映射文件）TestHotel.class.getClassLoader()
        InputStream is = Resources.getResourceAsStream(resource);
        // 构建sqlSession的工厂
        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);
        return sessionFactory;
    }

    // 查
    @Test
    public void getHotel() throws IOException {

        SqlSessionFactory sessionFactory = sqlSessionFactory();
        SqlSession session = sessionFactory.openSession();
        HotelMapper hotelMapper = session.getMapper(HotelMapper.class);
        System.out.println(hotelMapper.getClass());
        Hotel hotel = hotelMapper.getHotel(1001);
        System.out.println(hotel);
        session.close();
    }

    // 改
    @Test
    public void updateHotel() throws IOException {
        SqlSessionFactory sessionFactory = sqlSessionFactory();
        //注：这里使用sessionFactory.openSession();需要手动提交sql：session.commit();
        //如果这里使用sessionFactory.openSession(true);就可以自动提交
        SqlSession session = sessionFactory.openSession();
        HotelMapper hotelMapper = session.getMapper(HotelMapper.class);
        Hotel hotel = new Hotel(1001, "南京玄武饭店", "鼓楼区中央路193号", 997);
        hotelMapper.updateHotel(hotel);
        session.commit();
        session.close();
    }

    // 增
    @Test
    public void insertHotel() throws IOException {
        SqlSessionFactory sessionFactory = sqlSessionFactory();
        SqlSession session = sessionFactory.openSession();
        HotelMapper hotelMapper = session.getMapper(HotelMapper.class);
        Hotel hotel = new Hotel(1005, "南京饭店", "鼓楼区中央路001号", 997);
        hotelMapper.insertHotel(hotel);
        session.commit();
        session.close();
    }

    // 删
    @Test
    public void deleteHotel() throws IOException {
        SqlSessionFactory sessionFactory = sqlSessionFactory();
        SqlSession session = sessionFactory.openSession();
        HotelMapper hotelMapper = session.getMapper(HotelMapper.class);
        hotelMapper.deleteHotel(1005);
        session.commit();
        session.close();
    }
}

这样就可以实现增删改查了

二、自增主键的获取

修改hotelMapper.xml文件

指定useGeneratedKeys 使用自增主键获得主键值策略，keyProperty 指定对应的主键属性值，也就是mybatis获得主键值后，会传给javaBean中的属性

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="com.pjf.mybatis.dao.HotelMapper">
    <!-- public Hotel getHotel(Integer i); -->
    <select id="getHotel" resultType="com.pjf.mybatis.po.Hotel">
        select id,hotel_name as
        hotelName, hotel_address as hotelAddress, price from hotel
        where
        id=#{id}
    </select>
    <!-- public void updateHotel(Hotel hotel); -->
    <update id="updateHotel" parameterType="com.pjf.mybatis.po.Hotel">
        update hotel set
        price=#{price} where id =#{id}
    </update>
    <!-- public void insertHotel(Hotel hotel); -->
    <!-- useGeneratedKeys 使用自增主键获得主键值策略
         keyProperty  指定对应的主键属性值，也就是mybatis获得主键值后，会传给javaBean中的属性
     -->
    <insert id="insertHotel" parameterType="com.pjf.mybatis.po.Hotel" useGeneratedKeys="true" keyProperty="id">
        insert into hotel(id,hotel_name,hotel_address,price)
        value(#{id},#{hotelName},#{hotelAddress},#{price})
    </insert>
    <!-- public void deleteHotel(Integer i); -->
    <delete id="deleteHotel">
        delete from hotel where id=#{id}
    </delete>

</mapper>

测试

package com.pjf.mybatis;

import java.io.IOException;
import java.io.InputStream;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Test;

import com.pjf.mybatis.dao.HotelMapper;
import com.pjf.mybatis.po.Hotel;

public class TestHotel {

    public SqlSessionFactory sqlSessionFactory() throws IOException {
        // mybatis的配置文件
        String resource = "mybatis_config.xml";
        // 使用类加载器加载mybatis的配置文件（它也加载关联的映射文件）TestHotel.class.getClassLoader()
        InputStream is = Resources.getResourceAsStream(resource);
        // 构建sqlSession的工厂
        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);
        return sessionFactory;
    }
    // 增
    @Test
    public void insertHotel() throws IOException {
        SqlSessionFactory sessionFactory = sqlSessionFactory();
        SqlSession session = sessionFactory.openSession();
        HotelMapper hotelMapper = session.getMapper(HotelMapper.class);
        Hotel hotel = new Hotel(bull, "南京饭店", "鼓楼区中央路001号", 997);
        hotelMapper.insertHotel(hotel);
        //直接打印出自增主键的值
        System.out.println(hotel.getId());
        session.commit();
        session.close();
    }
}