java - 如何匹配字符串中的1个字符

Question

我正在为密码策略编写代码。

政策规定您不能拥有与已使用过的相同的字母。 例如:密码 - 您不能使用密码，因为它有两个 '

我怎样才能做到这一点？

编辑:

这是我的完整实现:​​

private static final String PASSWORD_DUPLICATE_CHARACTERS = "^(?:([a-zA-Z])(?!.*\\1))$";

pattern = Pattern.compile(PASSWORD_DUPLICATE_CHARACTERS);
this.checkForDuplicateLetters(LDAPNewUserPassword);

private boolean checkForDuplicateLetters(final String newPassword) throws LDAPException{
    LoggingEnt userEnt = new LoggingEnt();
    String userid = userEnt.getUseridCode();
    boolean foundDuplicate = false;

    matcher = pattern.matcher(newPassword);

    if (newPassword.matches(PASSWORD_DUPLICATE_LETTERS)){
        foundDuplicate = true;
        userEnt.setMsg1("Duplicate.");
        throw new LDAPException("Invalid password combination for " + userid, LDAPException.INVALID_CREDENTIALS);//BAristo
    } else {
        userEnt.setMsg1("Your password has been successfully changed.");
    }

    return matcher.matches();

}

Answer 1

使用这个正则表达式:

private static final String PASSWORD_PATTERN_LOWER_8 = "^(?:([a-zA-Z])(?!.*\\1))$";