Authenticate and Call the Azure AD Graph REST API from Java - Service to Service Authentication

Hello-Azure-AD-REST-API-Service-To-Service.java

import java.net.URI;
import java.util.ArrayList;
import java.util.List;

// https://hc.apache.org/
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.utils.URIBuilder;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;

// https://www.java2s.com/Code/JarDownload/java/java-json.jar.zip
import org.json.*;

public class HelloAzureAD {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		System.out.println("Hello, Java!");
		
		HttpClient httpclient = HttpClients.createDefault();

		try
		{
			// OAuth2 is required to access this API. For more information visit:
			// https://msdn.microsoft.com/en-us/office/office365/howto/common-app-authentication-tasks
			
			String azureADTenant = "00000000-dd34-4e90-9854-000000000000";
			
			String appId = "00000000-6486-476b-95d5-000000000000";
			String appKey = "kddjrhni49dkdne+efdRi+QyKPKYOCScpeObQyHngRgc=";
			
			String appIdUri = "https://graph.windows.net";
			
			
			System.out.println("Getting access_token token from Azure AD...");
			URIBuilder authTokenBuilder = new URIBuilder("https://login.microsoftonline.com/" + azureADTenant + "/oauth2/token");
			
			URI authTokenUri = authTokenBuilder.build();
			HttpPost authTokenRequest = new HttpPost(authTokenUri);
			
			List <NameValuePair> authTokenParamsArray = new ArrayList <NameValuePair>();
			authTokenParamsArray.add(new BasicNameValuePair("grant_type", "client_credentials"));
			authTokenParamsArray.add(new BasicNameValuePair("client_id", appId));
			authTokenParamsArray.add(new BasicNameValuePair("client_secret", appKey));
			authTokenParamsArray.add(new BasicNameValuePair("resource", appIdUri));
			authTokenRequest.setEntity(new UrlEncodedFormEntity(authTokenParamsArray));
						
			HttpResponse authTokenResponse = httpclient.execute(authTokenRequest);
			HttpEntity authTokenEntity = authTokenResponse.getEntity();
			if (authTokenEntity == null) {
				throw new Exception("authTokenEntity is null");
			}
			
			String authTokenJsonRaw = EntityUtils.toString(authTokenEntity);
			System.out.println("Raw JSON: " + authTokenJsonRaw);
			
			JSONObject authTokenJson = new JSONObject(authTokenJsonRaw);
					
			System.out.println("token_type: " + authTokenJson.getString("token_type"));
			System.out.println("expires_in: " + authTokenJson.getString("expires_in"));
			
			String access_token = authTokenJson.getString("access_token");
			System.out.println("access_token: " + access_token);
			
			
			
			
			
			
			
			System.out.println("");
			System.out.println("Calling Azure AD Graph API...");
			
			// Specify values for path parameters (shown as {...})
			URIBuilder builder = new URIBuilder("https://graph.windows.net/" + azureADTenant + "/users");
			
			// You can also look at the permission scopes set for this app by using this API endpoint:
			//   https://graph.windows.net/{tenant_id}/oauth2PermissionGrants
			// This can help to troubleshoot any permissions errors to double-check what permissions are configured.
						
			// Specify values for the following required parameters
			builder.setParameter("api-version", "1.6");
			URI uri = builder.build();
			HttpGet request = new HttpGet(uri);
			request.addHeader("Authorization", "Bearer " + access_token);
			HttpResponse response = httpclient.execute(request);
			
			System.out.println("HTTP Status Code: " + response.getStatusLine());
			HttpEntity entity = response.getEntity();
			if (entity != null) {
				System.out.println(EntityUtils.toString(entity));
			}
		}
		catch (Exception e)
		{
			System.out.println(e.getMessage());
		}
	}

}