Question

我对创建复杂的“Ex”并不感兴趣。我从另一个来源抄录了以下内容,以便在一定程度上强制执行一个附录的密码限制:

// 8 to 20 char, one digit, one letter
public static final String GOOD_PASSWORD_REGEX =
     "(^(?=.{8,20})(?=.*[a-zA-Z])(?=.*[\d]).*$)";

与此同时,这一单位测试失败了:

String tooLongPassword = "asdfghjkl123456789qwe";  // 21 characters
assertFalse(tooLongPassword.matches(ValidationContants.GOOD_PASSWORD_REGEX));

这是我针对这一“Ref”案,包括没有信件、没有数字的其他人以及所有其余通行证的少数类似测试案例之一。

错误在哪里?

Answer 1

In your version, the lookahead assertion only checks if it can match a string of 8-20 character length at the start of the string. This of course also succeeds in a string of length 21 and above.

So the $ needs to become part of the lookahead:

// 8 to 20 char, one digit, one letter
public static final String GOOD_PASSWORD_REGEX =
    "(^(?=.{8,20}$)(?=.*[a-zA-Z])(?=.*\d).*$)";

但是,为什么对密码规定最长期限? 另外,在<代码>d周围的<代码>[,不适用。

Furthermore, since you only need the regex to validate the password, not actually return it (because the way it s set up now it will return the entire input string), you can shorten the regex to:

"^(?=.{8,20}$)(?=.*[a-zA-Z])(?=.*\d)"

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