refactor(mall): 优化订单计算中的 BigDecimal 除法和舍入操作

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2025-05-20 2ffbbd151994d9a9bc7933d6b3b632036f2df8e9

refactor(mall): 优化订单计算中的 BigDecimal 除法和舍入操作

- 将 RoundingMode.DOWN 更改为 RoundingMode.HALF_DOWN，以提高计算精度
- 修改了多处 BigDecimal 的 divide 和 setScale 方法调用，统一使用新的舍入模式
- 优化了满减计算逻辑，提高了计算结果的准确性

 src/main/java/cc/mrbird/febs/mall/service/impl/ApiMallOrderInfoServiceImpl.java

@@ -477,7 +477,7 @@
        if (MallGoodsCoupon.TYPE_ONE == type) {
            realAmount = mallGoodsCoupon.getRealAmount();
        } else if (MallGoodsCoupon.TYPE_TWO == type) {
            BigDecimal divideTime = totalAmount.divide(costAmount, 0, RoundingMode.DOWN); // 累计减免次数
            BigDecimal divideTime = totalAmount.divide(costAmount, 0, RoundingMode.HALF_DOWN); // 累计减免次数
            realAmount = divideTime.multiply(realAmount); // 实际减免金额
        }

@@ -489,17 +489,17 @@
        for (Map.Entry<Long, BigDecimal> entry : skuMap.entrySet()) {
            Long keySkuId = entry.getKey();
            BigDecimal valueSkuAmount = entry.getValue();
            BigDecimal divide = valueSkuAmount.divide(totalAmount, 4, RoundingMode.DOWN); // 每个商品占符合满减的总额的比例
            BigDecimal divide = valueSkuAmount.divide(totalAmount, 4, RoundingMode.HALF_DOWN); // 每个商品占符合满减的总额的比例
            BigDecimal skuRealAmount = BigDecimal.ZERO;
            if (MallGoodsCoupon.TYPE_ONE == type) {
                BigDecimal bigDecimalOne = realAmount.multiply(divide).setScale(2, RoundingMode.DOWN); // 每个SKU的减免金额(比例*减免金额)
                skuRealAmount = valueSkuAmount.subtract(bigDecimalOne.max(BigDecimal.ZERO)).setScale(2, RoundingMode.DOWN);
                BigDecimal bigDecimalOne = realAmount.multiply(divide).setScale(2, RoundingMode.HALF_DOWN); // 每个SKU的减免金额(比例*减免金额)
                skuRealAmount = valueSkuAmount.subtract(bigDecimalOne.max(BigDecimal.ZERO)).setScale(2, RoundingMode.HALF_DOWN);
                totalDiscount = totalDiscount.add(bigDecimalOne);
            } else if (MallGoodsCoupon.TYPE_TWO == type) {
                BigDecimal divideTime = totalAmount.divide(costAmount, 0, RoundingMode.DOWN); // 累计减免次数
                BigDecimal divideTime = totalAmount.divide(costAmount, 0, RoundingMode.HALF_DOWN); // 累计减免次数
                BigDecimal multiply = divideTime.multiply(realAmount); // 实际减免金额
                BigDecimal bigDecimalTwo = multiply.multiply(divide).setScale(2, RoundingMode.DOWN); // 每个SKU的减免金额(比例*实际减免金额)
                skuRealAmount = valueSkuAmount.subtract(bigDecimalTwo.max(BigDecimal.ZERO)).setScale(2, RoundingMode.DOWN);
                BigDecimal bigDecimalTwo = multiply.multiply(divide).setScale(2, RoundingMode.HALF_DOWN); // 每个SKU的减免金额(比例*实际减免金额)
                skuRealAmount = valueSkuAmount.subtract(bigDecimalTwo.max(BigDecimal.ZERO)).setScale(2, RoundingMode.HALF_DOWN);
                totalDiscount = totalDiscount.add(bigDecimalTwo);
            }
            couponAmountMap.put(keySkuId, skuRealAmount);
@@ -511,7 +511,7 @@
            for (Map.Entry<Long, BigDecimal> entry : couponAmountMap.entrySet()) {
                Long keySkuId = entry.getKey();
                BigDecimal skuRealAmount = entry.getValue();
                BigDecimal newSkuRealAmount = skuRealAmount.subtract(difference).setScale(2, RoundingMode.DOWN);
                BigDecimal newSkuRealAmount = skuRealAmount.subtract(difference).setScale(2, RoundingMode.HALF_DOWN);
                couponAmountMap.put(keySkuId, newSkuRealAmount);
                break; // 调整最后一个商品的减免金额
            }