第二章分类，推荐，搜索，评价，购物车开发 - 2.2 商品推荐 - 实现接口与联调 - 《Java 架构直通车》

在 foodie-dev-service 模块下的 CategoryService 接口添加 getSixNewItemsLazy 方法

package com.imooc.service;
import com.imooc.pojo.Category;
import com.imooc.pojo.vo.CategoryVO;
import com.imooc.pojo.vo.NewItemsVO;
import java.util.List;
/**
 * Created by 92578 on 2020/8/22 16:17
 **/
public interface CategoryService {
    /**
     * 查询所有一级分类
     *
     * @return
     */
    public List<Category> queryAllRootLevelCat();
    /**
     * 根据一级分类 id 查询子分类信息
     *
     * @param rootCatId
     * @return
     */
    public List<CategoryVO> getSubCatlist(Integer rootCatId);
    /**
     * 查询首页每个一级分类下的六条最新商品数据
     *
     * @param rootCatId
     * @return
     */
    public List<NewItemsVO> getSixNewItemsLazy(Integer rootCatId);
}

在 foodie-dev-mapper 模块下的 CategoryMapperCustom 接口添加 getSixNewItemsLazy 方法

package com.imooc.mapper;

import com.imooc.pojo.vo.CategoryVO;
import org.apache.ibatis.annotations.Param;

import java.util.List;
import java.util.Map;

public interface CategoryMapperCustom {

    public List<CategoryVO> getSubCatList(Integer rootCatId);

    public List getSixNewItemsLazy(@Param("paramsMap") Map<String, Object> map);
}

在 foodie-dev-pojo 模块下面 com.imooc.pojo.vo 包内新建 SimpleItemVO 类

package com.imooc.pojo.vo;

/**
 * 六个最新商品的简单数据类型
 * Created by 92578 on 2020/8/22 21:28
 **/
public class SimpleItemVO {

    private String itemId;
    private String itemName;
    private String itemUrl;

    public String getItemId() {
        return itemId;
    }

    public void setItemId(String itemId) {
        this.itemId = itemId;
    }

    public String getItemName() {
        return itemName;
    }

    public void setItemName(String itemName) {
        this.itemName = itemName;
    }

    public String getItemUrl() {
        return itemUrl;
    }

    public void setItemUrl(String itemUrl) {
        this.itemUrl = itemUrl;
    }
}

在 foodie-dev-pojo 模块下面 com.imooc.pojo.vo 包内新建 NewItemsVO 类

package com.imooc.pojo.vo;

import java.util.List;

/**
 * 最新商品 VO
 * Created by 92578 on 2020/8/22 19:57
 **/
public class NewItemsVO {

    private Integer rootCatId;
    private String rootCatName;
    private String slogan;
    private String catImage;
    private String bgColor;

    private List<SimpleItemVO> simpleItemList;

    public Integer getRootCatId() {
        return rootCatId;
    }

    public void setRootCatId(Integer rootCatId) {
        this.rootCatId = rootCatId;
    }

    public String getRootCatName() {
        return rootCatName;
    }

    public void setRootCatName(String rootCatName) {
        this.rootCatName = rootCatName;
    }

    public String getSlogan() {
        return slogan;
    }

    public void setSlogan(String slogan) {
        this.slogan = slogan;
    }

    public String getCatImage() {
        return catImage;
    }

    public void setCatImage(String catImage) {
        this.catImage = catImage;
    }

    public String getBgColor() {
        return bgColor;
    }

    public void setBgColor(String bgColor) {
        this.bgColor = bgColor;
    }

    public List<SimpleItemVO> getSimpleItemList() {
        return simpleItemList;
    }

    public void setSimpleItemList(List<SimpleItemVO> simpleItemList) {
        this.simpleItemList = simpleItemList;
    }
}

在 foodie-dev-mapper 模块下的 CategoryMapperCustom.xml 文件添加 getSixNewItemsLazy 查询方法

<?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>

    <resultMap id="myNewItemsVO" type="com.imooc.pojo.vo.NewItemsVO">
        <id column="rootCatId" property="rootCatId"/>
        <result column="rootCatName" property="rootCatName"/>
        <result column="slogan" property="slogan"/>
        <result column="catImage" property="catImage"/>
        <result column="bgColor" property="bgColor"/>

        <collection property="simpleItemList" ofType="com.imooc.pojo.vo.SimpleItemVO">
            <id column="itemId" property="itemId"/>
            <result column="itemName" property="itemName"/>
            <result column="itemUrl" property="itemUrl"/>
        </collection>
    </resultMap>

    <select id="getSixNewItemsLazy" resultMap="myNewItemsVO" parameterType="Map">
        SELECT
            f.id AS rootCatId,
            f.`name` AS rootCatName,
            f.slogan AS slogan,
            f.cat_image AS catImage,
            f.bg_color AS bgColor,
            i.id AS itemId,
            i.item_name AS itemName,
            ii.url AS itemUrl,
            i.created_time AS createdTime
        FROM
            category f
            LEFT JOIN items i ON f.id = i.root_cat_id
            LEFT JOIN items_img ii ON i.id = ii.item_id
        WHERE
            f.type = 1
            AND i.root_cat_id = #{paramsMap.rootCatId}
            AND ii.is_main = 1
        ORDER BY
            i.created_time DESC
            LIMIT 0,6
    </select>

</mapper>

在 foodie-dev-service 模块下的 CategoryServiceImpl 类中实现 getSixNewItemsLazy 接口

package com.imooc.service.impl;

import com.imooc.mapper.CategoryMapper;
import com.imooc.mapper.CategoryMapperCustom;
import com.imooc.pojo.Category;
import com.imooc.pojo.vo.CategoryVO;
import com.imooc.pojo.vo.NewItemsVO;
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.HashMap;
import java.util.List;
import java.util.Map;

/**
 * Created by 92578 on 2020/8/22 16:18
 **/
@Service
public class CategoryServiceImpl implements CategoryService {

    @Autowired
    private CategoryMapper categoryMapper;

    @Autowired
    private CategoryMapperCustom categoryMapperCustom;

    /**
     * 查询所有一级分类
     *
     * @return
     */
    @Transactional(propagation = Propagation.SUPPORTS)
    @Override
    public List<Category> queryAllRootLevelCat() {
        Example example = new Example(Category.class);
        Example.Criteria criteria = example.createCriteria();
        criteria.andEqualTo("type", 1);

        List<Category> result = categoryMapper.selectByExample(example);

        return result;
    }

    /**
     * 根据一级分类 id 查询子分类信息
     *
     * @param rootCatId
     * @return
     */
    @Transactional(propagation = Propagation.SUPPORTS)
    @Override
    public List<CategoryVO> getSubCatlist(Integer rootCatId) {
        return categoryMapperCustom.getSubCatList(rootCatId);
    }

    /**
     * 查询首页每个一级分类下的六条最新商品数据
     *
     * @param rootCatId
     * @return
     */
    @Transactional(propagation = Propagation.SUPPORTS)
    @Override
    public List<NewItemsVO> getSixNewItemsLazy(Integer rootCatId) {
        Map<String, Object> map = new HashMap<>();
        map.put("rootCatId", rootCatId);

        return categoryMapperCustom.getSixNewItemsLazy(map);
    }
}

在 foodie-dev-api 模块下的 IndexController 类添加 sixNewItems 方法

package com.imooc.controller;

import com.imooc.enums.YseOrNo;
import com.imooc.pojo.Carousel;
import com.imooc.pojo.Category;
import com.imooc.pojo.vo.CategoryVO;
import com.imooc.pojo.vo.NewItemsVO;
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.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 java.util.List;

/**
 * Created by 92578 on 2020/8/22 16:30
 **/
@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("/carousel")
    public IMOOCJSONResult carousel() {
        List<Carousel> list = carouselService.queryAll(YseOrNo.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.queryAllRootLevelCat();

        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);
    }

    @ApiOperation(value = "查询每个一级分类下的最新六条商品数据", notes = "查询每个一级分类下的最新六条商品数据", httpMethod = "GET")
    @GetMapping("/sixNewItems/{rootCatId}")
    public IMOOCJSONResult sixNewItems(
            @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<NewItemsVO> list = categoryService.getSixNewItemsLazy(rootCatId);

        return IMOOCJSONResult.ok(list);
    }
}

启动项目，打开浏览器，访问 http://localhost:8080/foodie-shop/index.html
向下滚动页面，发现图片已经懒加载出来了