小编典典

算法

要生成随机字符串，请连接从可接受的符号集中随机抽取的字符，直到字符串达到所需的长度为止。

实例

这是一些相当简单且非常灵活的代码，用于生成随机标识符。阅读以下信息以获取重要的应用笔记。

public class RandomString {

/**

* Generate a random string.

*/

public String nextString() {

for (int idx = 0; idx < buf.length; ++idx)

buf[idx] = symbols[random.nextInt(symbols.length)];

return new String(buf);

}

public static final String upper = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

public static final String lower = upper.toLowerCase(Locale.ROOT);

public static final String digits = "0123456789";

public static final String alphanum = upper + lower + digits;

private final Random random;

private final char[] symbols;

private final char[] buf;

public RandomString(int length, Random random, String symbols) {

if (length < 1) throw new IllegalArgumentException();

if (symbols.length() < 2) throw new IllegalArgumentException();

this.random = Objects.requireNonNull(random);

this.symbols = symbols.toCharArray();

this.buf = new char[length];

}

/**

* Create an alphanumeric string generator.

*/

public RandomString(int length, Random random) {

this(length, random, alphanum);

}

/**

* Create an alphanumeric strings from a secure generator.

*/

public RandomString(int length) {

this(length, new SecureRandom());

}

/**

* Create session identifiers.

*/

public RandomString() {

this(21);

}

}

用法示例

为8个字符的标识符创建不安全的生成器：

RandomString gen = new RandomString(8, ThreadLocalRandom.current());

为会话标识符创建一个安全的生成器：

RandomString session = new RandomString();

创建具有易于阅读的代码的生成器以进行打印。字符串比完整的字母数字字符串长，以补偿使用较少的符号：

String easy = RandomString.digits + "ACEFGHJKLMNPQRUVWXYabcdefhijkprstuvwx";

RandomString tickets = new RandomString(23, new SecureRandom(), easy);

2020-01-10