double 转 long 转 double 精度问题

double exchange = exchangeNumerator * 1d / exchangeDenominator;

            //获取到转换展示单位的值
            double baseValueDisplay = baseValue * exchange;
            BigDecimal baseValueDisplayBig = new BigDecimal(baseValueDisplay);
            baseValueDisplay = baseValueDisplayBig.setScale(6,BigDecimal.ROUND_HALF_UP).doubleValue();