防止精度丢失

// 2. 赠送礼物逻辑.
        BigDecimal price = new BigDecimal(ctx.getParam("price"));
        BigDecimal consumeTotal = price.multiply(new BigDecimal(ncount));//单价*个数
        BigDecimal buddyMoney = consumeTotal.divide(new BigDecimal(4));//consumeTotal总价的4分之一分给主播