public List<String> getPointIotStrByProcessIds(@RequestParam List<Integer> processIds){
        LambdaQueryWrapper<Point> lambdaQueryWrapper =  new QueryWrapper<Point>().lambda();
        lambdaQueryWrapper.select(Point::getIotStr);
        lambdaQueryWrapper.in(Point::getProcessId,processIds);
        Function<Object,String> f = (o -> o.toString()) ;


        return pointService.listObjs(lambdaQueryWrapper,f);
    }

返回的是iot_str字符串集合