bigdecimal运算

private double getConsumeRateAB(Long node_consumers, Long node_persons) {
    BigDecimal b1 = new BigDecimal(node_consumers);
    BigDecimal b2 = new BigDecimal(node_persons);
    int len = 2;
    boolean flag = (b2.compareTo(BigDecimal.ZERO) != 0) ? true : false;
    double doubleRes = 0D;
    if (flag){
        doubleRes = b1.divide(b2, len, BigDecimal.ROUND_HALF_UP).doubleValue();
    }
    return doubleRes;
}