TokenGenerator.java

import org.apache.commons.codec.binary.Base64;
import javax.crypto.KeyGenerator;
import java.security.NoSuchAlgorithmException;

public class TokenGenerator {

    private final KeyGenerator keyGenerator;

    public TokenGenerator(){
        try {
            this.keyGenerator = KeyGenerator.getInstance("AES");
            keyGenerator.init(256);
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException("Failed to initialise KeyGenerator in TokenGenerator", e);
        }
    }

    public String generateToken(){
        return getUrlSafeAesSecretKeyAsBase64String();
    }

    private String getUrlSafeAesSecretKeyAsBase64String(){
        return new String(Base64.encodeBase64URLSafe(keyGenerator.generateKey().getEncoded()));
    }
}