【mybatis】06 -查询查看详情

news/2024/7/5 2:54:51

学习mybatis的获取参数的一种方式

编写mapper接口

package com.ljh.mapper;

import com.ljh.pojo.Brand;

import java.util.List;

public interface BrandMapper {
//    1. 获取id，返回对应的公司详情
    public Brand selectById(int id);
}

生成mapper语句

<?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.ljh.mapper.BrandMapper">
<!--    利用resultMap进行属性值和数据库字段进行映射-->
    <resultMap id="brandResultMap" type="brand">
        <result column="brand_name" property="brandName"></result>
        <result column="company_name" property="companyName"></result>
    </resultMap>
    <!--注意：此处要用resultMap属性绑定resultMap字段-->
    <select id="selectById" resultMap="brandResultMap">
        select *
        from tb_brand where id = #{id};
    </select>
</mapper>

app测试

package com.ljh.test;

import com.ljh.mapper.BrandMapper;
import com.ljh.pojo.Brand;
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 java.io.IOException;
import java.io.InputStream;
import java.util.List;

public class MybatisTest {
    @Test
    public void testSelectAll() throws IOException {
        //1.获取session工厂
        String resource = "mybatis-config";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        //2.获取session
        SqlSession sqlSession = sqlSessionFactory.openSession();
        //3.获取mapper
        BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);
        //4.执行sql
        //接收数据
        int id = 1;
        Brand brand = mapper.selectById(id);
        System.out.println(brand);
        //5.关闭资源
        sqlSession.close();
    }
}