1 使用format，注意精度取舍

public static Double saveOneBitOneRound(Double d){
    String str = String.format("%.1f",d);
    double c = Double.parseDouble(str);
    return c;
}

2 使用BigDecimal

public static Double saveOneBitTwo(Double d){
     BigDecimal bd = new BigDecimal(d);
     Double tem = bd.setScale(2,BigDecimal.ROUND_FLOOR).doubleValue();
     return tem;
}