public static void replaceSensitive(){
        // 卡号显示前6位和后4位，中间打*点, 卡号：16,19,19位都有可能
        String accountNumber = "6543211234567890";
        int encLength = accountNumber.length() - 10;
        String regex = "(\\d{6})\\d{" + encLength+ "}(\\w{4})";
        // $1表示匹配第一个{}的内容
        System.out.println("accountNumber:"+accountNumber.replaceAll(regex,"$1*********$2"));

        String userName = getUserName("杨柳依依");
        // 姓名 显示最后一个汉字，其他打*
        System.out.println("userName:"+userName);
        String mobile = "15529636659";
        // 手机号11位 中间四位展示 ****
        System.out.println("mobile:"+mobile.replaceAll("(\\d{3})\\d{4}(\\w{4})","$1****$2"));
        // 身份证号18位 只展示后四位
        String idCard = "612423199712116552";
        System.out.println("idCard:"+idCard.replaceAll("\\d{14}(\\w{4})","**************$1"));
    }

    private static String getUserName(String userName)
    {
        StringBuilder sb = new StringBuilder("");
        for (int i = 0; i < userName.length() - 1; i++)
        {
            sb.append("*");
        }
        sb.append(userName.substring(userName.length() - 1));
        return sb.toString();
    }