Java 些许公共工具类

public static String getNum(int length) {
        String val = "";
        Random random = new Random();
        for (int i = 0; i < length; i++) {
            val += String.valueOf(random.nextInt(10));
        }
        return val;
    }

public static String getCharAndNum(int length){
        String val = "";
        Random random = new Random();
        for(int i=0;i<length;i++){
            String charorNum = random.nextInt(2)% 2 ==0?"char":"num";
            if("char".equalsIgnoreCase(charorNum)){
                int choice = random.nextInt(2) % 2 ==0 ? 65 : 97;
                val +=(char) (choice + random.nextInt(26));
            }else if("num".equalsIgnoreCase(charorNum)){
                val +=String.valueOf(random.nextInt(10));
             }
        }
        return val;
    }

public static String hideName(String name) {
        if (name!=null) {
            String newName = name.substring(0, 1);
            int asteriskLen = name.length() - 1;
            for(int i=0;i<asteriskLen;i++){
                newName += "*";
            }
            return newName;
        }
        return name;
    }

public static String hidePhone(String phone){
        if(phone!="" && phone.length() == 11){
            return phone.substring(0, 3) + "*****" + phone.substring(8);
        }
        return  phone;
    }

public static String hideIdCard(String idCard){
        if(idCard!=null && idCard.length()>7){
            String part1 = idCard.substring(0,3);
            String part2 = idCard.substring(idCard.length()-4);
            StringBuffer part3 = new StringBuffer();
            for(int i=0;i<idCard.length()-7;i++){
                part3.append("*");
            }
            return part1+part3+part2;
        }
        return idCard;
    }