功能使用说明.首页加载分类数据的方式
(1)先渲染一级分类
(2)懒加载二级分类，（如鼠标hover一级分类时才开始加载对应的二级数据）
一、数据库表结构 category 分类表
create table `foodie-shop-dev`.category ( id int auto_increment comment '主键' primary key, name varchar(32) not null comment '分类名称', type int not null comment '分类类型', father_id int not null comment '父id', logo varchar(64) null comment '图标', slogan varchar(64) null comment '口号', cat_image varchar(64) null comment '分类图', bg_color varchar(32) null comment '背景颜色' ) comment '商品分类 ' charset = utf8mb4;
INSERT INTO `category` VALUES (1, '甜点/蛋糕', 1, 0, 'img/cake.png', '每一道甜品都能打开你的味蕾', 'http://localhost:88/foodie/category/cake.png', '#fe7a65'); INSERT INTO `category` VALUES (2, '饼干/膨化', 1, 0, 'img/cookies.png', '嘎嘣脆，一听到声音就开吃', 'http://localhost:88/foodie/category/cookies.png', '#f59cec'); INSERT INTO `category` VALUES (3, '熟食/肉类', 1, 0, 'img/meat.png', '食肉者最爱绝佳美食', 'http://localhost:88/foodie/category/meat.png', '#b474fe'); INSERT INTO `category` VALUES (4, '素食/卤味', 1, 0, 'img/luwei.png', '香辣甜辣麻辣，辣了才有味', 'http://localhost:88/foodie/category/duck.png', '#82ceff'); INSERT INTO `category` VALUES (5, '坚果/炒货', 1, 0, 'img/jianguo.png', '酥脆无比，休闲最佳', 'http://localhost:88/foodie/category/nut.png', '#c6a868'); INSERT INTO `category` VALUES (6, '糖果/蜜饯', 1, 0, 'img/sweet.png', '甜味是爱美者的最爱', 'http://localhost:88/foodie/category/mango.png', '#6bdea7'); INSERT INTO `category` VALUES (7, '巧克力', 1, 0, 'img/chocolate.png', '美容养颜，男女都爱', 'http://localhost:88/foodie/category/chocolate.png', '#f8c375'); INSERT INTO `category` VALUES (8, '海鲜/海味', 1, 0, 'img/lobster.png', '吃货们怎么能少了海鲜呢？', 'http://localhost:88/foodie/category/crab.png', '#84affe'); INSERT INTO `category` VALUES (9, '花茶/果茶', 1, 0, 'img/tea.png', '绿茶红茶怎能少得了', 'http://localhost:88/foodie/category/tea.png', '#ff9229'); INSERT INTO `category` VALUES (10, '生鲜/蔬果', 1, 0, 'img/food.png', '新鲜少不了，每日蔬果生鲜', 'http://localhost:88/foodie/category/meat2.png', '#6cc67c'); INSERT INTO `category` VALUES (11, '蛋糕', 2, 1, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (12, '点心', 2, 1, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (13, '饼干', 2, 2, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (14, '薯片', 2, 2, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (15, '虾条', 2, 2, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (16, '肉铺', 2, 3, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (17, '肉松', 2, 3, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (18, '香肠', 2, 3, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (19, '豆干', 2, 4, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (20, '干笋', 2, 4, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (21, '鸭脖', 2, 4, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (22, '坚果', 2, 5, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (23, '锅巴', 2, 5, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (24, '糖果', 2, 6, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (25, '蜜饯', 2, 6, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (26, '巧克力', 2, 7, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (27, '果冻', 2, 7, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (29, '海鲜', 2, 8, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (30, '海味', 2, 8, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (31, '茶叶', 2, 9, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (32, '奶茶', 2, 9, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (33, '果茶', 2, 9, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (34, '蔬菜', 2, 10, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (35, '水果', 2, 10, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (36, '肉类', 2, 10, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (37, '蒸蛋糕', 3, 11, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (38, '软面包', 3, 11, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (39, '脱水蛋糕', 3, 11, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (40, '马卡龙', 3, 11, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (41, '甜甜圈', 3, 11, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (42, '三明治', 3, 11, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (43, '铜锣烧', 3, 11, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (44, '肉松饼', 3, 12, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (45, '华夫饼', 3, 12, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (46, '沙琪玛', 3, 12, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (47, '鸡蛋卷', 3, 12, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (48, '蛋饼', 3, 12, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (49, '凤梨酥', 3, 12, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (50, '手撕面包', 3, 12, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (51, '苏打饼干', 3, 13, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (52, '夹心饼干', 3, 13, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (53, '闲饼干', 3, 13, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (54, '甜饼干', 3, 13, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (55, '威化饼干', 3, 13, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (56, '酥饼干', 3, 13, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (57, '曲奇', 3, 13, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (58, '无糖饼干', 3, 13, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (59, '早餐饼干', 3, 13, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (60, '薯条', 3, 14, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (61, '薯片', 3, 14, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (62, '山药薯片', 3, 14, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (63, '网红薯片', 3, 14, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (64, '蛋黄薯片', 3, 14, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (65, '虾条', 3, 15, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (66, '怀旧虾条', 3, 15, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (67, '8090后虾条', 3, 15, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (68, '进口虾条', 3, 15, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (69, 'DIY虾条', 3, 15, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (73, '猪肉脯', 3, 16, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (74, '牛肉脯', 3, 16, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (75, '鸡肉脯', 3, 16, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (76, '散装肉脯', 3, 16, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (77, '猪肉干', 3, 16, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (78, '牛肉干', 3, 16, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (79, '牛肉粒', 3, 16, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (80, '牛肉松', 3, 17, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (81, '猪肉松', 3, 17, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (82, '儿童肉松', 3, 17, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (83, '腊味香肠', 3, 18, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (84, '广式香肠', 3, 18, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (85, '火腿肠', 3, 18, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (86, '烤肠', 3, 18, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (87, '鸡肉肠', 3, 18, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (88, '鱼肠', 3, 18, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (89, '酒味香肠', 3, 18, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (90, '香菇', 3, 19, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (91, '零食', 3, 19, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (92, '豆腐干', 3, 19, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (93, '辣条', 3, 19, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (94, '泡椒脆笋', 3, 20, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (95, '野生笋干', 3, 20, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (96, '扁尖笋', 3, 20, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (97, '农家笋', 3, 20, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (98, '卤味鸭脖', 3, 21, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (99, '麻辣鸭脖', 3, 21, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (100, '武汉鸭脖', 3, 21, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (101, '鸭锁骨', 3, 21, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (102, '鸭胗', 3, 21, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (103, '鸭翅', 3, 21, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (104, '网红坚果', 3, 22, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (105, '瓜子', 3, 22, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (106, '碧根果', 3, 22, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (107, '松子', 3, 22, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (108, '山核桃', 3, 22, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (109, '开心果', 3, 22, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (110, '腰果', 3, 22, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (111, '网红锅巴', 3, 23, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (112, '蛋黄锅巴', 3, 23, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (113, '水果糖', 3, 24, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (114, '薄荷糖', 3, 24, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (115, '夹心糖', 3, 24, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (116, '奶糖', 3, 24, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (117, '喜糖', 3, 24, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (118, '麦芽糖', 3, 24, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (119, '话梅', 3, 25, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (120, '果干', 3, 25, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (121, '草莓干', 3, 25, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (122, '芒果干', 3, 25, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (123, '菠萝干', 3, 25, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (124, '山楂糕', 3, 25, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (125, '黑巧克力', 3, 26, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (126, '白巧克力', 3, 26, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (127, '夹心巧克力', 3, 26, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (128, '榛果巧克力', 3, 26, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (129, '日本生巧', 3, 26, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (130, '果肉布丁', 3, 27, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (131, '果冻碎碎冰', 3, 27, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (132, '果汁果冻', 3, 27, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (133, '帝王蟹', 3, 29, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (134, '大龙虾', 3, 29, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (135, '鲍鱼', 3, 29, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (136, '海参', 3, 29, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (137, '鱿鱼', 3, 29, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (138, '三文鱼', 3, 29, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (139, '扇贝', 3, 29, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (140, '干贝', 3, 30, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (141, '海苔', 3, 30, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (142, '虾仁', 3, 30, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (143, '海鱼干', 3, 30, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (144, '水蜜桃茶', 3, 33, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (145, '白桃乌龙茶', 3, 33, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (146, '柠檬片', 3, 33, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (147, '白茶', 3, 31, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (148, '红茶', 3, 31, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (149, '绿茶', 3, 31, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (150, '铁观音', 3, 31, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (151, '胖大海', 3, 31, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (152, '碧螺春', 3, 31, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (153, '速冲奶茶', 3, 32, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (154, '珍珠奶茶', 3, 32, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (155, '袋装奶茶', 3, 32, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (156, '英式奶茶', 3, 32, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (157, '黄瓜', 3, 34, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (158, '芋头', 3, 34, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (159, '玉米', 3, 34, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (160, '南瓜', 3, 34, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (161, '荸荠', 3, 34, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (162, '山药', 3, 34, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (163, '秋葵', 3, 34, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (164, '红薯/紫薯', 3, 34, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (165, '土豆', 3, 34, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (166, '水蜜桃', 3, 35, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (167, '西瓜', 3, 35, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (168, '苹果', 3, 35, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (169, '凤梨', 3, 35, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (170, '草莓', 3, 35, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (171, '葡萄', 3, 35, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (172, '杨梅', 3, 35, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (173, '牛排', 3, 36, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (174, '鸡肉', 3, 36, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (175, '猪肉', 3, 36, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (176, '羊肉', 3, 36, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (177, '蹄子', 3, 36, NULL, NULL, NULL, NULL); INSERT INTO `category` VALUES (178, '糖醋排骨', 3, 36, NULL, NULL, NULL, NULL);
二、根据一级分类查询子分类语句
SELECT f.id AS id, f.`name` AS `name`, f.type AS type, f.father_id AS fatherId, c.id AS subId, c.NAME AS subName, c.type AS subType, c.father_id AS subFatherId FROM category f LEFT JOIN category c ON f.id = c.father_id WHERE f.father_id =1
三、Mapper实现
1、新增vo对象 CategoryVO （目录：com/imooc/pojo/vo/CategoryVO.java）
package com.imooc.pojo.vo; import java.util.List; /** * 二级分类 VO （view） */ public class CategoryVO { private Integer id; private String name; private String type; private Integer fatherId; //三级分类vo list private List<SubCategoryVO> subCatList; public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getType() { return type; } public void setType(String type) { this.type = type; } public Integer getFatherId() { return fatherId; } public void setFatherId(Integer fatherId) { this.fatherId = fatherId; } public List<SubCategoryVO> getSubCatList() { return subCatList; } public void setSubCatList(List<SubCategoryVO> subCatList) { this.subCatList = subCatList; } }
2、新增vo对象 SubCategoryVO.java（目录：com/imooc/pojo/vo/SubCategoryVO.java）
package com.imooc.pojo.vo; import java.util.List; /** * 二级分类 VO （view） */ public class CategoryVO { private Integer id; private String name; private String type; private Integer fatherId; //三级分类vo list private List<SubCategoryVO> subCatList; public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getType() { return type; } public void setType(String type) { this.type = type; } public Integer getFatherId() { return fatherId; } public void setFatherId(Integer fatherId) { this.fatherId = fatherId; } public List<SubCategoryVO> getSubCatList() { return subCatList; } public void setSubCatList(List<SubCategoryVO> subCatList) { this.subCatList = subCatList; } }
3、新增定制接口 CategoryMapperCustom （目录：com/imooc/mapper/CategoryMapperCustom.java）
package com.imooc.mapper; import com.imooc.pojo.vo.CategoryVO; import java.util.List; public interface CategoryMapperCustom { public List<CategoryVO> getSubCatList(Integer rootCatId); }
4、新增 CategoryMapperCustom.xml （目录：src/main/resources/mapper/CategoryMapperCustom.xml）
(1)自定义mapper，注意在xml中mapper的namespace一定要跟mapper接口名相同
(2)resultMap的type参数对应的vo类，如果有构造函数，一定要加上无参构造函数
（3）mapper.xml 中拼接SQL时
## mapper.xml 中拼接SQL时 - 单个情况判断用 <if></if> - 多个情况判断用 <choose> <when></when> <when></when> <otherwise> </otherwise> </choose> - 拼接字符串时用 ${} 不用 #{} - 单引号要转义 "
<?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.imooc.mapper.CategoryMapperCustom" >
<resultMap id="myCategoryVO" type="com.imooc.pojo.vo.CategoryVO">
<id column="id" property="id"/>
<result column="name" property="name"/>
<result column="type" property="type"/>
<result column="fatherId" property="fatherId"/>
<!--
collection 标签：用于定义关联的list集合类型的封装规则
property：对应三级分类的list属性名
ofType：集合的类型，三级分类的vo
-->
<collection property="subCatList" ofType="com.imooc.pojo.vo.SubCategoryVO">
<id column="subId" property="subId"/>
<result column="subName" property="subName"/>
<result column="subType" property="subType"/>
<result column="subFatherId" property="subFatherId"/>
</collection>
</resultMap>
<select id="getSubCatList" resultMap="myCategoryVO" parameterType="int">
SELECT
f.id AS id,
f.`name` AS `name`,
f.type AS type,
f.father_id AS fatherId,
c.id AS subId,
c.NAME AS subName,
c.type AS subType,
c.father_id AS subFatherId
FROM
category f
LEFT JOIN
category c
ON
f.id = c.father_id
WHERE
f.father_id = #{rootCatId}
</select>
</mapper>
四、service接口
（1）接口方法定义
package com.imooc.service; import com.imooc.pojo.Carousel; import com.imooc.pojo.Category; import com.imooc.pojo.vo.CategoryVO; import java.util.List; public interface CategoryService { /** *查询所有一级分类 * @return */ public List<Category> queryAllRootLeverCat(); /**根据一级分类查询 * * @param rootCatId * @return */ public List<CategoryVO> getSubCatList(Integer rootCatId); }
（2）接口实现
package com.imooc.service.impl; import com.imooc.mapper.CarouselMapper; import com.imooc.mapper.CategoryMapper; import com.imooc.mapper.CategoryMapperCustom; import com.imooc.pojo.Carousel; import com.imooc.pojo.Category; import com.imooc.pojo.vo.CategoryVO; import com.imooc.service.CarouselService; import com.imooc.service.CategoryService; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; import org.springframework.transaction.annotation.Propagation; import org.springframework.transaction.annotation.Transactional; import tk.mybatis.mapper.entity.Example; import java.util.List; @Service public class CategoryServiceImpl implements CategoryService { @Autowired private CategoryMapper categoryMapper; @Autowired private CategoryMapperCustom categoryMapperCustom; @Transactional(propagation = Propagation.SUPPORTS) @Override public List<CategoryVO> getSubCatList(Integer rootCatId) { return categoryMapperCustom.getSubCatList(rootCatId); } @Transactional(propagation = Propagation.SUPPORTS) @Override public List<Category> queryAllRootLeverCat() { Example example = new Example(Carousel.class); Example.Criteria criteria = example.createCriteria(); criteria.andEqualTo("type",1); List<Category> resList= categoryMapper.selectByExample(example); return resList; } }
五、api接口实现（目录com/imooc/controller/IndexController.java）
前端：
axios.get(serverUrl + '/index/subCat/' + rootCatId, {})
使用@PathVariable注解获取URL中的参数，@getMapping（）中要以路径形式 使用{ }注明值的位置
package com.imooc.controller; import com.imooc.enums.YesOrNo; import com.imooc.pojo.Carousel; import com.imooc.pojo.Category; import com.imooc.pojo.vo.CategoryVO; import com.imooc.service.CarouselService; import com.imooc.service.CategoryService; import com.imooc.utils.IMOOCJSONResult; import io.swagger.annotations.Api; import io.swagger.annotations.ApiOperation; import io.swagger.annotations.ApiParam; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; import springfox.documentation.annotations.ApiIgnore; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpSession; import java.util.List; @Api(value = "首页",tags = "首页展示的相关接口") @RestController @RequestMapping("index") public class IndexController { @Autowired private CarouselService carouselService; @Autowired private CategoryService categoryService; @ApiOperation(value="获取首页轮播图列表",notes = "获取首页轮播图列表",httpMethod = "GET") @GetMapping("/carouse") public IMOOCJSONResult carouse() { List<Carousel> list= carouselService.queryAll(YesOrNo.YES.type); return IMOOCJSONResult.ok(list); } @ApiOperation(value="获取商品分类(一级分类)",notes = "获取商品分类(一级分类)",httpMethod = "GET") @GetMapping("/cats") public IMOOCJSONResult cats() { List<Category> list= categoryService.queryAllRootLeverCat(); return IMOOCJSONResult.ok(list); } @ApiOperation(value="获取商品子分类",notes = "获取商品子分类",httpMethod = "GET") @GetMapping("/subCat/{rootCatId}") public IMOOCJSONResult subCat( @ApiParam(name="rootCatId",value = "一级分类id",required = true) @PathVariable Integer rootCatId) { if(rootCatId ==null){ return IMOOCJSONResult.errorMsg("分类不存在"); } List<CategoryVO> list= categoryService.getSubCatList(rootCatId); return IMOOCJSONResult.ok(list); } }
分类:
Java架构师
【推荐】国内首个AI IDE，深度理解中文开发场景，立即下载体验Trae
【推荐】编程新体验，更懂你的AI，立即体验豆包MarsCode编程助手
【推荐】抖音旗下AI助手豆包，你的智能百科全书，全免费不限次数
【推荐】轻量又高性能的 SSH 工具 IShell：AI 加持，快人一步
· AI与.NET技术实操系列：向量存储与相似性搜索在 .NET 中的实现
· 基于Microsoft.Extensions.AI核心库实现RAG应用
· Linux系列：如何用heaptrack跟踪.NET程序的非托管内存泄露
· 开发者必知的日志记录最佳实践
· SQL Server 2025 AI相关能力初探
· winform 绘制太阳，地球，月球 运作规律
· 震惊！C++程序真的从main开始吗？99%的程序员都答错了
· AI与.NET技术实操系列（五）：向量存储与相似性搜索在 .NET 中的实现
· 超详细：普通电脑也行Windows部署deepseek R1训练数据并当服务器共享给他人
· 【硬核科普】Trae如何「偷看」你的代码？零基础破解AI编程运行原理