java double/float转BigDecimal,精度问

double/float 转BigDecimal，会有精度问题。
所以需要转String类型，然后再转BigDecimal

/**
     * object -> BigDecimal 转换.
     * @param value
     * @return
     */
    public static BigDecimal getBigDecimal(Object value) {
        BigDecimal ret = null;
        if (value != null) {
            if (value instanceof BigDecimal) {
                ret = (BigDecimal) value;
            } else if (value instanceof String) {
                ret = new BigDecimal((String) value);
            } else if (value instanceof BigInteger) {
                ret = new BigDecimal((BigInteger) value);
            } else if (value instanceof Number) {
                //转成String类型，然后new
                ret = new BigDecimal(((Number) value).toString());
            } else {
                throw new ClassCastException("Not possible to coerce [" + value + "] from class " 
                        + value.getClass() + " into a BigDecimal.");
            }
        }
        return ret;
    }