java 自定义数值保留小数工具类

直接上代码

/**
     * zn
     *
     * @param obj    待转换的数值 只允许为Integer或者Double
     * @param digits 保留小数的位数
     * @param boolea 是否开启四舍五入 true：开启四舍五入 false：舍去多余位数
     * @return
     * @throws Exception
     */
    public static String numFormat(Object obj, Integer digits, Boolean boolea) throws Exception {
        if (obj == null || digits == null || boolea == null || digits < 0) {
            throw new IllegalAccessException("参数列表有误");
        }
        Integer flag = obj instanceof Integer ? 1 : obj instanceof Double ? 2 : 3;
        StringBuffer str = new StringBuffer();
        switch (flag) {
            case 1:
                Integer integer = (Integer) obj;
                str.append(integer + ".");
                for (int i = 0; i < digits; i++) {
                    str.append(0);
                }
                break;
            case 2:
                Double aDouble = (Double) obj;
                String[] split = String.valueOf(aDouble).split("\\.");
                if (digits >= split[1].length()) {
                    str.append(split[0] + "." + split[1]);
                    for (int i = split[1].length(); i < digits; i++) {
                        str.append(0);
                    }
                } else {
                    if (boolea) {
                        int num = Integer.parseInt(split[0] + split[1].substring(0, digits));
                        num += (split[1].charAt(digits) - 48) > 4 ? 1 : 0;
                        String s = String.valueOf(num);
                        if (digits == 0) {
                            str.append(s.substring(0, s.length() - digits) + s.substring(s.length() - digits, s.length()));
                        } else {
                            str.append(s.substring(0, s.length() - digits) + "." + s.substring(s.length() - digits, s.length()));
                        }

                    } else {
                        if (digits == 0) {
                            str.append(split[0] + split[1].substring(0, digits));
                        } else {
                            str.append(split[0] + "." + split[1].substring(0, digits));
                        }
                    }
                }
                break;
            default:
                throw new NumberFormatException("转换参数类型错误");
        }
        return str.toString();
    }