Mybatis学习第19节 -- 嵌套查询一对多的配置

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一对多和多对多是一样的.
而多对多是指 A对于B来说是一对多的关系, 同时B对于A来说也是一对多的关系, 互为一对多,即为多对多.
比如说一个标签下面有多篇文章,一篇文章也可能有多个标签
 
Shop实体类设计
List<Product> productList;
Product实体类设计
public class Product implements Serializable{

    Integer id;
    String name;
    String desc;
    String imgAddr;
    String normalPrice;
    String promotionPrice;
    Integer priority;
    Date createTime;
    Date lastEditTime;
    Integer enableStatus;
ProductMapper接口
List<Product> getProductListByShopID(Integer id);
Product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="io.github.coinsjack.dao.ProductMapper">
    <cache/>
    <resultMap id="productResultMap" type="Product">
        <result column="product_id" property="id"/>
        <result column="product_name" property="name"/>
        <result column="product_desc" property="desc"/>
        <result column="img_addr" property="imgAddr"/>
        <result column="normal_price" property="normalPrice"/>
        <result column="promotion_price" property="promotionPrice"/>
        <result column="create_time" property="createTime"/>
        <result column="last_edit_time" property="lastEditTime"/>
        <result column="enable_status" property="enableStatus"/>
        <result column="product_category_id" property="categoryID"/>
        <result column="shop_id" property="shopID"/>
    </resultMap>

    <select id="getProductListByShopID" resultMap="productResultMap">
        select * from tb_product
        WHERE `shop_id` = #{id};
    </select>
</mapper>
测试使用Product
public class ProductMapperTest {
    @Test
    public void test_getProductByID() {
        SqlSession sqlSession = MyBatisUtil.getSqlSession();
        ProductMapper productMapper= sqlSession.getMapper(ProductMapper.class);

        System.out.printf("查询结果: %s%n", productMapper.getProductListByShopID(29));;
    }
}
测试Product
略
ShopMapper配置文件
<resultMap id="simpleResultMap" type="Shop">
    <id column="shop_id" property="id" ></id>
    <result column="owner_id" property="ownerId" ></result>
    <result column="shop_category_id" property="categoryId" ></result>
    <result column="shop_name" property="name"></result>
    <result column="shop_desc" property="desc"></result>
    <result column="shop_addr" property="addr"></result>
    <result column="phone" property="phone"></result>
    <result column="shop_img" property="image"></result>
    <result column="priority" property="priority"></result>
    <result column="create_time" property="createTime"></result>
    <result column="last_edit_time" property="lastEditTime"></result>
    <result column="enable_status" property="enableStatus"></result>
    <association property="area" column="area_id" javaType="Area"
                 select="io.github.coinsjack.dao.AreaMapper.getAreaById"/>
    <collection property="productList" column="shop_id"
                select="io.github.coinsjack.dao.ProductMapper.getProductListByShopID" javaType="ArrayList" ofType="Product" >
    </collection>
</resultMap>
id, result, association, collection的顺序不能错, 因为有Mapper对应的构造器的原因, association的column属性用来给select指定的方法进行参数传入, collection也是一样

测试查询Shop中的所有商品

@Test
public void testGetShopById() {
    SqlSession session = MyBatisUtil.getSqlSession();
    ShopMapper mapper = session.getMapper(ShopMapper.class);
    System.out.println(mapper.getShopById(29));
    session.close();
}

测试结果

Shop{id=29, ownerId=1, area=Area{id=3, name=‘长治学院‘, priority=2, createTime=null, lastEditTime=null}, categoryId=22, name=‘暴漫奶茶店‘, desc=‘过来喝喝就知道啦，你是我的奶茶‘, addr=‘西苑1号‘, phone=‘1211334565‘, image=‘/upload/images/item/shop/29/2017092601054939287.jpg‘, priority=40, createTime=2017-09-26, lastEditTime=2017-09-26, enableStatus=1, advice=‘null‘, productList=[Product{id=1, name=‘大黄人‘, desc=‘我是大黄人‘, imgAddr=‘upload/images/item/shop/29/2017092601204036435.jpg‘, normalPrice=‘2‘, promotionPrice=‘1‘, priority=100, createTime=Tue Sep 26 09:20:40 CST 2017, lastEditTime=Tue Sep 26 09:20:40 CST 2017, enableStatus=1, CategoryID=3, shopID=29}
, Product{id=2, name=‘小黄人‘, desc=‘我是小黄人‘, imgAddr=‘upload/images/item/shop/29/2017092601212211185.jpg‘, normalPrice=‘3‘, promotionPrice=‘2‘, priority=90, createTime=Tue Sep 26 09:21:22 CST 2017, lastEditTime=Tue Sep 26 09:21:22 CST 2017, enableStatus=1, CategoryID=2, shopID=29}
, Product{id=3, name=‘暴漫人‘, desc=‘开心了‘, imgAddr=‘upload/images/item/shop/29/2017092601220059819.jpg‘, normalPrice=‘3‘, promotionPrice=‘2‘, priority=80, createTime=Tue Sep 26 09:22:00 CST 2017, lastEditTime=Tue Sep 26 09:22:00 CST 2017, enableStatus=1, CategoryID=3, shopID=29}
, Product{id=4, name=‘宇宙第一‘, desc=‘宇宙无敌‘, imgAddr=‘upload/images/item/shop/29/2017092601224389939.jpg‘, normalPrice=‘5‘, promotionPrice=‘2‘, priority=70, createTime=Tue Sep 26 09:22:43 CST 2017, lastEditTime=Tue Sep 26 09:22:43 CST 2017, enableStatus=1, CategoryID=3, shopID=29}
, Product{id=5, name=‘眼凸凸‘, desc=‘宇宙无敌‘, imgAddr=‘upload/images/item/shop/29/2017092601231570458.jpg‘, normalPrice=‘3‘, promotionPrice=‘2‘, priority=60, createTime=Tue Sep 26 09:23:15 CST 2017, lastEditTime=Tue Sep 26 09:23:15 CST 2017, enableStatus=1, CategoryID=3, shopID=29}
, Product{id=6, name=‘笑眯眯‘, desc=‘笑眯眯 甜蜜蜜‘, imgAddr=‘upload/images/item/shop/29/2017092601234922140.jpg‘, normalPrice=‘2‘, promotionPrice=‘2‘, priority=50, createTime=Tue Sep 26 09:23:49 CST 2017, lastEditTime=Tue Sep 26 09:23:49 CST 2017, enableStatus=1, CategoryID=3, shopID=29}
]}
 

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