Mybatis返回值封装在Map集合中

ゝ一世哀愁。 2022-05-23 11:09 248阅读 0赞

数据库表:

CREATE TABLE `products` (
      `prod_id` char(10) COLLATE utf8_unicode_ci NOT NULL,
      `vend_id` char(10) COLLATE utf8_unicode_ci NOT NULL,
      `prod_name` char(255) COLLATE utf8_unicode_ci NOT NULL,
      `prod_price` decimal(8,2) NOT NULL,
      `prod_desc` text COLLATE utf8_unicode_ci,
      PRIMARY KEY (`prod_id`)
    ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

映射文件:

<?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.heiketu.testpackage.mapper.ProductsMapper">
    
    <select id="getResultUseMap" resultType="map">
        SELECT * FROM Products WHERE prod_id = #{prod_id}
    </select>
    </mapper>

/** 引入了lombok插件 */
    @Setter
    @Getter
    @ToString
    @AllArgsConstructor
    @NoArgsConstructor
    @EqualsAndHashCode
    public class Products { 
        private String prodId;
        private String vendId;
        private String prodName;
        private BigDecimal prodPrice;
        private String prodDesc;
    }

映射接口:

public interface ProductsMapper {
        //结果集以Map形式返回
        public Map<String,Object> getResultUseMap(@Param("prod_id") String productId);
    }

测试代码:

SqlSession sqlSession = null;
    
    try { 
        String configFile = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(configFile);
        SqlSessionFactory build = new SqlSessionFactoryBuilder().build(inputStream);
        sqlSession = build.openSession();
    
        //以Map形式返回
        ProductsMapper mapper = sqlSession.getMapper(ProductsMapper.class);
        Map<String, Object> useMap = mapper.getResultUseMap("BR03");
    
        //返回形式是key=字段名，value=字段的值
        System.out.println(useMap);
    
    } catch (IOException e) { 
        e.printStackTrace();
    }finally { 
        sqlSession.close();
    }

结果:

{ vend_id=BRS01, prod_desc=18 inch teddy bear, comes with cap and jacket, prod_price=11.99, prod_id=BR03, prod_name=18 inch teddy bear}

总结:  
`mybatis映射返回值封装成Map需要在映射文件中的resultType属性值设置为map(map为mybatis默认设置的Map集合类别名).`  
`封装的结果结构为: {key=字段名，value=字段的值,key=字段名，value=字段的值...}`