Generate Server to Server Token From Java

In Java, you can use the java.security.SecureRandom class to generate secure random numbers for creating a token generator. Here is an example of a Java method:

import java.security.SecureRandom;

public class TokenGenerator {

    public static String generateToken(int length, boolean uppercase, boolean lowercase, boolean numbers) {
        StringBuilder token = new StringBuilder();
        String charset = "";

        if (uppercase) {
            charset += "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        }
        if (lowercase) {
            charset += "abcdefghijklmnopqrstuvwxyz";
        }
        if (numbers) {
            charset += "0123456789";
        }

        if (charset.length() == 0) {
            throw new IllegalArgumentException("At least one character set must be selected.");
        }

        SecureRandom random = new SecureRandom();
        for (int i = 0; i < length; i++) {
            int index = random.nextInt(charset.length());
            token.append(charset.charAt(index));
        }

        return token.toString();
    }

    public static void main(String[] args) {
        // Example usage:
        String token = generateToken(16, true, true, true);
        System.out.println("Generated token: " + token);
    }
}

In this Java method, generateToken accepts four parameters: length (the length of the token), and three boolean parameters uppercase, lowercase, and numbers, which respectively indicate whether to include uppercase letters, lowercase letters, and numbers. Inside the method, a character set charset is constructed, and then the SecureRandom class is used to generate secure random numbers. For each character of the token, a random index is generated and used to select a character from charset.

Please note that SecureRandom is a cryptographically secure random number generator provided by Java, suitable for scenarios requiring high security. This class is more appropriate for security-sensitive applications than java.util.Random because it provides stronger randomness and can resist predictive attacks.

In the main method, we provide an example usage and print the generated token. You can adjust the parameters of the generateToken method to generate tokens of different lengths and character sets as needed.