用java生成写一段可以生成任意位数强密码的代码

您好，我可以回答这个问题。以下是一段可以生成任意位数强密码的 Java 代码：

import java.security.SecureRandom;
import java.util.Random;

public class PasswordGenerator {
    private static final String UPPER = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    private static final String LOWER = "abcdefghijklmnopqrstuvwxyz";
    private static final String DIGITS = "0123456789";
    private static final String PUNCTUATION = "!@#$%^&*()_+~`|}{[]\\:;?><,./-=";
    private static final String SYMBOLS = UPPER + LOWER + DIGITS + PUNCTUATION;

    private static SecureRandom random = new SecureRandom();

    public static String generate(int length) {
        if (length < 1) {
            throw new IllegalArgumentException("Length must be at least 1.");
        }

        StringBuilder sb = new StringBuilder(length);
        sb.append(randomChar(UPPER));
        sb.append(randomChar(LOWER));
        sb.append(randomChar(DIGITS));
        sb.append(randomChar(PUNCTUATION));

        for (int i = 4; i < length; i++) {
            sb.append(randomChar(SYMBOLS));
        }

        return shuffle(sb.toString());
    }

    private static char randomChar(String str) {
        int index = random.nextInt(str.length());
        return str.charAt(index);
    }

    private static String shuffle(String str) {
        char[] chars = str.toCharArray();
        for (int i = chars.length - 1; i > ; i--) {
            int index = random.nextInt(i + 1);
            char temp = chars[index];
            chars[index] = chars[i];
            chars[i] = temp;
        }
        return new String(chars);
    }
}

这段代码使用了安全随机数生成器和字符串操作来生成强密码。您可以调用 `PasswordGenerator.generate(length)` 方法来生成指定长度的密码。