电商学习笔记

使用PageHelper插件分页

 public ServerResponse<PageInfo> getGoodsList(int pageNum, int pageSize){
        //startPage--start，开始初始化，注意是使用pagehelper.startpage属性的填入起始页和每页的数量
        PageHelper.startPage(pageNum,pageSize);
        //填充自己的sql查询逻辑，即查询所有数据
        List<Goods> goodsList = goodsMapper.selectList();
        //遍历goodsList,使其转为VO的list，VOlist的含义是根据goodlist里的元素和自己定义的元素集成封装的一个value object
        List<GoodsListVo> goodsListVoList = Lists.newArrayList();
        for(Goods goodsItem : goodsList){
            GoodsListVo goodsListVo = assembleGoodsListVo(goodsItem);
            goodsListVoList.add(goodsListVo);
        }
        //pageHelper-收尾
        PageInfo pageResult = new PageInfo(goodsList);//收尾使用pageinfo实例化一个pageresult对象
        pageResult.setList(goodsListVoList);//注意，还有一步使用的是pageresult设置list集合，且对象为封装好的VOlist,而不是goodlist
        return ServerResponse.createBySuccess(pageResult);
    }

递归获取商品结点及子元素节点

 //查询同层次结点ID      即输入一个父节点（默认商品分类的根父节点为“0”）  则查找父节点为0的所有节点，称为同层次结点
    public ServerResponse<List<Category>> selectParalleCategory(Integer parentId){
        if(parentId==null){
            return  ServerResponse.createByErrorMessage("品类参数错误");
        }
        List<Category> categoyList=categoryMapper.selectParalleCategoryByParentId(parentId);
        if(CollectionUtils.isEmpty(categoyList)){
            logger.info("未找到当前分类的子分类");
        }
        return ServerResponse.createBySuccess(categoyList);

    }

    //查询本节点ID及孩子结点ID
    public ServerResponse selectCategoryAndChildren(Integer categoryId){
        Set<Category> categorySet= Sets.newHashSet();//初始化set，作用是加入查询结点结合并根据查询结点查询子节点，根据子节点循环遍历递归查询子节点的子节点（如果有的话）
        findChildCategory(categorySet,categoryId);//将
        List<Integer> categoryIdList= Lists.newArrayList();//
        if(categoryId!=null){
            for(Category categoryItem:categorySet){
                categoryIdList.add(categoryItem.getId());
            }
        }
        return ServerResponse.createBySuccess(categoryIdList);
    }
    //递归查找子节点   
    private  Set<Category> findChildCategory(Set<Category> categorySet,Integer categoryId){
        Category category=categoryMapper.selectByPrimaryKey(categoryId);

        if(category!=null){//递归的判断条件
            categorySet.add(category);
        }
        List<Category> categoryList=categoryMapper.selectParalleCategoryByParentId(categoryId);
        for(Category categoryItem:categoryList){
            findChildCategory(categorySet,categoryItem.getId());
        }
        return categorySet;//出口
    }

mybaits查询技巧

/*当要查询或者操作的元素是大量的或者在集合时，用到foreach*/
<delete id="deleteByUserIdGoodsIds" parameterType="map">
    delete from cart
    where uid = #{userId}
    <if test="goodsIdList != null">
      and goods_id in
      <foreach collection="goodsIdList" item="item" index="index" open="(" separator="," close=")">
        #{item}
      </foreach> 
    </if>
  </delete>

/**/
<select id="selectLogin" parameterType="map" resultType="com.xiaoyitao.entity.User">
    SELECT <include refid="Base_Column_List" />
    FROM user
    WHERE uid=#{uid} and password=#{password}
  </select>

//当遇到一种情况，如果查询条件有一方为空，或者两者都为空，则会变成只有selt 。。。 form goods where 空。。。此时程序会报错。为了解决这个问题，使用<where></where>标签，自动判断，如果两者都为空，则不加入where，且会判断是否加入and 标签 而且使用include标签选择属性list数组可以避免冗长的代码
<select id="selectByNameAndGoodsId" resultMap="BaseResultMap" parameterType="map">
    SELECT
    <include refid="Base_Column_List" />
    FROM goods
    <where>
      <if test="goodsName != null">
        goods_name like #{goodsName}
      </if>
      <if test="goodsId != null">
        and id = #{goodsId}
      </if>
    </where>
  </select>

/*通过assemblegoodslistvo组装goodslist的vo对象，vo里有goodlistd的基本属性，再扩展了很多其他属性*/
    public ServerResponse<PageInfo> getGoodsList(int pageNum, int pageSize){
        //startPage--start
        PageHelper.startPage(pageNum,pageSize);
        //填充自己的sql查询逻辑
        List<Goods> goodsList = goodsMapper.selectList();
        //遍历goodsList,使其转为VO的list
        List<GoodsListVo> goodsListVoList = Lists.newArrayList();
        for(Goods goodsItem : goodsList){
            GoodsListVo goodsListVo = assembleGoodsListVo(goodsItem);
            goodsListVoList.add(goodsListVo);
        }
        //pageHelper-收尾
        PageInfo pageResult = new PageInfo(goodsList);
        pageResult.setList(goodsListVoList);
        return ServerResponse.createBySuccess(pageResult);
    }

    //pojo -> VO 的组装方法
    private GoodsListVo assembleGoodsListVo(Goods goods){
        GoodsListVo goodsListVo = new GoodsListVo();
        goodsListVo.setId(goods.getId());
        goodsListVo.setGoodsName(goods.getGoodsName());
        goodsListVo.setStatus(goods.getStatus());
        goodsListVo.setPrice(goods.getPrice());
        goodsListVo.setCategory(goods.getCategory());
        goodsListVo.setGoodsAddress(goods.getGoodsAddress());
        goodsListVo.setUid(goods.getUid());
        goodsListVo.setAmount(goods.getAmount());
        goodsListVo.setMainImage(goods.getMainImage());

        goodsListVo.setImageHost(PropertiesUtil.getProperty("ftp.server.http.prefix","http://img.happymmall.com/"));

        return goodsListVo;
    }

controller控制器的写法

@Controller  //在控制器类上添加controller注解
@RequestMapping("/manage/category")//添加request请求路径

  @Autowired//使用MVC模式，添加service注解
    private IUserService iUserService;

  @Autowired
    private ICategoryService iCategoryService;

//首先添加requestmapping 里面添加value和method，添加responsebody注解
@RequestMapping(value="upload.do",method = RequestMethod.POST)
    @ResponseBody
    public ServerResponse upload(HttpSession session, @RequestParam(value = "upload_file",required = false) MultipartFile file, HttpServletRequest request){
        //检查文件大小
        if (file.getSize() <= 0) {
            return ServerResponse.createByErrorCodeMessage(ResponseCode.ERROR.getCode(),"上传失败:文件为空");
        }
        //验证用户登录模块
        User user = (User)session.getAttribute(Const.CURRENT_USER);
        if(user == null){
            return ServerResponse.createByErrorCodeMessage(ResponseCode.NEED_LOGIN.getCode(),"用户未登录,请登录管理员");
        }
        //检查是否拥有管理员权限
        if(iUserService.checkAdminRole(user).isSuccess()){
            //填充商品业务逻辑
            //获取路径，webapp下的upload文件夹
            String path = request.getSession().getServletContext().getRealPath("upload");
            //上传文件到ftp，返回保存在ftp里的随机文件名
            String targetFileName = iFileService.goodsImgUpload(file,path,user.getUid());
            if(StringUtils.isBlank(targetFileName)){
                return ServerResponse.createByErrorCodeMessage(ResponseCode.ERROR.getCode(),"上传文件异常或不支持的图片文件格式");
            }
            //从xiaoyitao.properties配置文件中读取url
            //url+文件名就得到了一个保存在图片服务器上的图片完整url地址
            String url = PropertiesUtil.getProperty("ftp.server.http.prefix")+targetFileName;

            Map fileMap = Maps.newHashMap();
            fileMap.put("uri",targetFileName);
            fileMap.put("url",url);
            //返回一个文件在ftp上的url
            return ServerResponse.createBySuccess(fileMap);
        }else{
            return ServerResponse.createByErrorMessage("无权限操作");
        }
    }