java - 用符号、数字、字母（大写和小写）在 Java 中生成密码

Question

java - 如何在java中生成包含大小写字母、数字和特殊符号的随机字符串（密码），长度为6

我的代码如下：

package pw;

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

public class PasswordBuilder {

    private static final Random RANDOM = new SecureRandom();

    public static void main(String[] args) {
        System.out.println(generateRandomPassword());
    }

    public static String generateRandomPassword() {
        String letters = "abcdefghjkmnpqrstuvwxyzABCDEFGHJKMNPQRSTUVWXYZ0123456789!@#$%^&*()_-+";

        String pw = "";
        for (int i = 0; i < 6; i++) {
            int index = (int) (RANDOM.nextDouble() * letters.length());
            pw += letters.substring(index, index + 1);
        }
        return pw;
    }

}

Answer 1

使用安全随机，您可以决定字符串中所需的字符、数字和字母。

public class RandomGenerator {
      private static SecureRandom prng;
      private static final Logger LOG = LoggerFactory
                .getLogger(AuthTokenGenerator.class);
        static {
            try {
                // Initialize SecureRandom
                prng = SecureRandom.getInstance("SHA1PRNG");
            } catch (NoSuchAlgorithmException e) {
                LOG.info("ERROR while intantiating Secure Random:   " + prng);
        }
    }
    /**
     * @return
     */
    public static String getToken() {
        try {
            LOG.info("About to Generate Token in getToken()");
            String token;
            // generate a random number
            String randomNum = Integer.toString(prng.nextInt());
            // get its digest
            MessageDigest sha = MessageDigest.getInstance("SHA-1");
            byte[] result = sha.digest(randomNum.getBytes());
            token = hexEncode(result);
            LOG.info("Token in getToken():   " + token);
            return token;
        } catch (NoSuchAlgorithmException ex) {
            return null;
        }
    }
    /**
     * @param aInput
     * @return
     */
    private static String hexEncode(byte[] aInput) {
        StringBuilder result = new StringBuilder();
        char[] digits = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h',
                'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z' };
        for (byte b : aInput) {
            result.append(digits[(b & 0xf0) >> 4]);
            result.append(digits[b & 0x0f]);
        }
        return result.toString();
    }

}