千峰商城-springboot项目搭建-69-商品评论分页查询接口实现

一、流程分析

二、接口开发：改造商品评论列表接口(分页查询)

1.定义PageHelper：

@Data
@NoArgsConstructor
@AllArgsConstructor
public class PageHelper<T> {
    //总记录数
    private int count;
    
    //总页数
    private int pageCount;
    
    //分页数据
    private List<T> list;
    
}

2.改造数据库操作

ProductCommentsMapper ：

@Repository
public interface ProductCommentsMapper extends GeneralDAO<ProductComments> {
    //根据商品id分页查询评论信息
    public List<ProductCommentsVO> selectCommontsByProductId(@Param("productId") String productId, 
                                                             @Param("start") int start, 
                                                             @Param("limit") int limit);
}

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.qfedu.fmmall.dao.ProductCommentsMapper">
  <resultMap id="BaseResultMap" type="com.qfedu.fmmall.entity.ProductComments">

    <id column="comm_id" jdbcType="VARCHAR" property="commId" />
    <result column="product_id" jdbcType="VARCHAR" property="productId" />
    <result column="product_name" jdbcType="VARCHAR" property="productName" />
    <result column="order_item_id" jdbcType="VARCHAR" property="orderItemId" />
    <result column="user_id" jdbcType="VARCHAR" property="userId" />
    <result column="is_anonymous" jdbcType="INTEGER" property="isAnonymous" />
    <result column="comm_type" jdbcType="INTEGER" property="commType" />
    <result column="comm_level" jdbcType="INTEGER" property="commLevel" />
    <result column="comm_content" jdbcType="VARCHAR" property="commContent" />
    <result column="comm_imgs" jdbcType="VARCHAR" property="commImgs" />
    <result column="sepc_name" jdbcType="TIMESTAMP" property="sepcName" />
    <result column="reply_status" jdbcType="INTEGER" property="replyStatus" />
    <result column="reply_content" jdbcType="VARCHAR" property="replyContent" />
    <result column="reply_time" jdbcType="TIMESTAMP" property="replyTime" />
    <result column="is_show" jdbcType="INTEGER" property="isShow" />
  </resultMap>

  <resultMap id="ProductCommentsVOMap" type="com.qfedu.fmmall.entity.ProductCommentsVO">

    <id column="comm_id" jdbcType="VARCHAR" property="commId" />
    <result column="product_id" jdbcType="VARCHAR" property="productId" />
    <result column="product_name" jdbcType="VARCHAR" property="productName" />
    <result column="order_item_id" jdbcType="VARCHAR" property="orderItemId" />
    <result column="is_anonymous" jdbcType="INTEGER" property="isAnonymous" />
    <result column="comm_type" jdbcType="INTEGER" property="commType" />
    <result column="comm_level" jdbcType="INTEGER" property="commLevel" />
    <result column="comm_content" jdbcType="VARCHAR" property="commContent" />
    <result column="comm_imgs" jdbcType="VARCHAR" property="commImgs" />
    <result column="sepc_name" jdbcType="TIMESTAMP" property="sepcName" />
    <result column="reply_status" jdbcType="INTEGER" property="replyStatus" />
    <result column="reply_content" jdbcType="VARCHAR" property="replyContent" />
    <result column="reply_time" jdbcType="TIMESTAMP" property="replyTime" />
    <result column="is_show" jdbcType="INTEGER" property="isShow" />

    <result column="user_id" jdbcType="VARCHAR" property="userId" />
    <result column="username" jdbcType="VARCHAR" property="username" />
    <result column="nickname" jdbcType="VARCHAR" property="nickname" />
    <result column="user_img" jdbcType="VARCHAR" property="userImg" />

  </resultMap>

  <select id="selectCommontsByProductId" resultMap="ProductCommentsVOMap">
    SELECT u.nickname,
           u.user_img,
           u.username,
           c.comm_id,
           c.product_id,
           c.product_name,
           c.order_item_id,
           c.user_id,
           c.is_anonymous,
           c.comm_type,
           c.comm_level,
           c.comm_content,
           c.comm_imgs,
           c.sepc_name,
           c.reply_status,
           c.reply_content,
           c.reply_time,
           c.is_show
    FROM product_comments c
    INNER JOIN users u
    ON u.user_id = c.user_id
    WHERE c.product_id=#{productId}
    limit #{start},#{limit};
  </select>
</mapper>

3.改造业务逻辑层(将查询所有评论的业务改造为分页查询)

ProductCommentsService：

public interface ProductCommentsService {
    //根据商品id实现评论的分页查询
    //productId：商品id   pageNum：页码   limit：每页显示条数
    public ResultVO listCommentsByProductId(String productId,int pageNum,int limit);
}

ProductCommentsServiceImpl ：

@Service
public class ProductCommentsServiceImpl implements ProductCommentsService {

    @Autowired
    private ProductCommentsMapper productCommentsMapper;


    public ResultVO listCommentsByProductId(String productId,int pageNum,int limit) {
//        List<ProductCommentsVO> productCommentsVOS = productCommentsMapper.selectCommontsByProductId(productId);
//
//        ResultVO resultVO = new ResultVO(ResStatus.OK, "success", productCommentsVOS);

        //分页查询
        //1.根据商品id查询总记录数
        Example example = new Example(ProductComments.class);
        Example.Criteria criteria = example.createCriteria();
        criteria.andEqualTo("productId",productId);
        int count = productCommentsMapper.selectCountByExample(example);

        //2.计算出总页数(必须确定每页显示多少条 pageSize=limit)
        int pageCount = count%limit==0? count/limit : count/limit+1;

        //3.查询当前页的数据(因为评论中需要用户信息，因此需要联表查询---自定义)
        int start = (pageNum-1)*limit;
        List<ProductCommentsVO> list = productCommentsMapper.selectCommontsByProductId(productId, start, limit);

        ResultVO resultVO = new ResultVO(ResStatus.OK, "success", new PageHelper<ProductCommentsVO>(count,pageCount,list));
        return resultVO;
    }
}

4.改造控制层：

@RestController
@CrossOrigin
@RequestMapping("/product")
@Api(value = "提供商品信息相关的接口",tags = "商品管理")
public class ProductController {

    @Autowired
    private ProductService productService;
    @Autowired
    private ProductCommentsService productCommentsService;

    @ApiOperation("商品基本信息查询接口")
    @GetMapping("/detail-info/{pid}")
    public ResultVO getProductBasicInfo(@PathVariable("pid") String pid){
        return productService.getProductBasicInfo(pid);
    }

    @ApiOperation("商品参数信息查询接口")
    @GetMapping("/detail-params/{pid}")
    public ResultVO getProductParams(@PathVariable("pid") String pid){
        return productService.getProductParamsById(pid);
    }

    @ApiOperation("商品评论信息查询接口")
    @GetMapping("/detail-commonts/{pid}")
    @ApiImplicitParams({
            @ApiImplicitParam(dataType = "int",name = "pageNum",value = "当前页码",required = true),
            @ApiImplicitParam(dataType = "int",name = "limit",value = "每页显示条数",required = true)
    })
    public ResultVO getProductCommonts(@PathVariable("pid") String pid,int pageNum,int limit){
        return productCommentsService.listCommentsByProductId(pid,pageNum,limit);
    }
}

测试：