java 部分隐藏字段

        //利用正则表达式匹配替换字符串
        String email = "young452wer@gamil.com";
        Pattern p = Pattern.compile("(\\w{3})(\\w+)(\\w{3})");
        Matcher m = p.matcher(email);
        System.out.println(m.replaceAll("$1***$3"));


        email = "you";
        String aa="";
        for (int i=0;i<email.length()-6;i++){
            aa+="*";
        }
        String pa="$1"+aa+"$3";
        System.out.println(email.replaceAll(regex, pa));
        return null;

        System.out.println(StringUtils.rightPad("", 10, "*"));//输出10个*号