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使用java如何生成随机的字母数字字符串?

java 随机字符串

使用java如何生成随机的字母数字字符串?


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2020-01-10

共1个答案

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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

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