MyBatis的SUM映射问题及解决

// Mapper层
<select id="selectInfoByTest" resultType="map">
    SELECT SUM(flag) as flags,taskid FROM qcdata GROUP BY taskid
</select>
// 接口
List<HashMap<String, Object>> selectInfoByTest();
 
// 调用代码
List<HashMap<String, Object>> result = qcDao.selectInfoByTest();
int flags=(Integer)result.get(0).get("flags"); // 报错
return JSONResult.ok(flags);

    public JSONResult test() {
        List<HashMap<String, Object>> result = qcDao.selectInfoByTest();  
        // toString
        int flags=Integer.parseInt(result.get(0).get("flags").toString()); 
        // String.valueOf
        int flags2=Integer.parseInt(String.valueOf(result.get(0).get("flags")));
        // 空字符串
        int flags3=Integer.parseInt(result.get(0).get("flags")+"");
        return JSONResult.ok(flags+flags2+flags3);
    }

 <select id="pieChart"    resultType="map">
       select   sum(com.thinkmoney*ord.commnumber)  as totalPrice , com.category as  category  from commodity com,orders ord
        where com.commid=ord.commid and ord.orderstatus=1
        GROUP BY com.category
 </select>

 private static final long serialVersionUID = 1L;
    /**
     * 订单id
     */
	private String id;
    /**
     * 订单编号
     */
	private String ordernumber;
    /**
     * 下单时间
     */
	private Date ordertime;
    /**
     * 商品名
     */
	private String commname;
    /**
     * 商品id
     */
    private String commid;
    /**
     * 商品描述
     */
    private String commdesc;
    /**
     * 购买数量
     */
	private Integer commnumber;
    /**
     * 商品单价
     */
	private BigDecimal price;
    /**
     * 收货地址
     */
	private String useraddress;
    /**
     * 订单状态 0未支付 1正常 2删除
     */
	private Integer orderstatus;
    /**
     * 收货人
     */
	private String username;
    /**
     * 收货人手机号
     */
	private String mobilephone;
    /**
     * 发货状态 0未发货 1已发货 2确认收货
     */
	private Integer kdstatus;
    /**
     * 快递编号
     */
	private String kdnumber;
    /**
     * 买家id
     */
	private String buyuserid;
    /**
     * 卖家id
     */
	private String selluserid;
	private  Commodity commodity;
	private  BigDecimal  totalPrice;

 /**
     * 管理员首页 饼图
     * */
    @GetMapping("/echars/piechart")
    public String piechart(HttpSession  session,HttpServletRequest request){
        List<HashMap<String,Object>>  result =ordersService.pieChart();
        List<String>  totalPriceList= new ArrayList<String>();
        List<String>  categoryList= new ArrayList<String>();
        for( Map<String, Object> mapList : result ) {
            totalPriceList.add(mapList.get("totalPrice").toString());
            categoryList.add(mapList.get("category").toString());
        }
        session = request.getSession();
        System.out.println("totalPriceList:"+totalPriceList+",categoryList:"+categoryList);
        session.setAttribute("totalPriceList",totalPriceList);
        session.setAttribute("categoryList",categoryList);
        return "/admin/echars/piechart";
    }