java - 如何生成20个字符的随机字符串

Question

Possible Duplicate:
How to generate a random String in Java

我想在不使用 apache 类的情况下生成 20 个字符的随机字符串。我真的不在乎是否是字母数字。另外，我稍后会将其转换为字节数组。

谢谢，

Answer 1

给你。只需在第一行指定要允许的字符即可。

char[] chars = "abcdefghijklmnopqrstuvwxyz".toCharArray();
StringBuilder sb = new StringBuilder(20);
Random random = new Random();
for (int i = 0; i < 20; i++) {
    char c = chars[random.nextInt(chars.length)];
    sb.append(c);
}
String output = sb.toString();
System.out.println(output);

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If you are using this to generate something sensitive like a password reset URL or session ID cookie or temporary password reset, be sure to use java.security.SecureRandom instead. Values produced by java.util.Random and java.util.concurrent.ThreadLocalRandom are mathematically predictable.