gistfile1.txt

import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpMethod;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.client.RestTemplate;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;

import java.util.HashMap;
import java.util.Map;

public class OAuth2TokenGenerator {

    private static final String TOKEN_URL = "https://your-auth-server.com/oauth/token";
    private static final String CLIENT_ID = "your-client-id";
    private static final String CLIENT_SECRET = "your-client-secret";
    private static final String GRANT_TYPE = "client_credentials"; // or other grant types
    private static final String SCOPE = "your-scope";

    public static void main(String[] args) {
        RestTemplate restTemplate = new RestTemplate();
        ObjectMapper objectMapper = new ObjectMapper();

        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.APPLICATION_FORM_URLENCODED);

        Map<String, String> params = new HashMap<>();
        params.put("client_id", CLIENT_ID);
        params.put("client_secret", CLIENT_SECRET);
        params.put("grant_type", GRANT_TYPE);
        params.put("scope", SCOPE);

        StringBuilder requestBody = new StringBuilder();
        params.forEach((key, value) -> requestBody.append(key).append("=").append(value).append("&"));
        requestBody.deleteCharAt(requestBody.length() - 1); // Remove trailing '&'

        HttpEntity<String> entity = new HttpEntity<>(requestBody.toString(), headers);

        ResponseEntity<String> response = restTemplate.exchange(
            TOKEN_URL,
            HttpMethod.POST,
            entity,
            String.class
        );

        if (response.getStatusCode().is2xxSuccessful()) {
            try {
                JsonNode jsonResponse = objectMapper.readTree(response.getBody());
                String accessToken = jsonResponse.get("access_token").asText();
                System.out.println("Access Token: " + accessToken);
            } catch (Exception e) {
                e.printStackTrace();
            }
        } else {
            System.out.println("Error: " + response.getStatusCode());
        }
    }
}