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401 unauthorized : [no body] with root cause in JAVA Spring

I'm creating my first REST API using JAVA Spring and when I'm making a rest call to an external API, I get
401 Unauthorized: [no body]
I think my problem is here:
requestParams.add("Grant_type", "client_credentials");
I saw some questions related to this but none well able to solve my problem.
Spring REST template - 401 Unauthorized error
Spring Boot Callable - 401 Unauthorized: [no body]
JAVA code:
public String getAuth(String client_id, String app_secret) {
String auth = client_id + ":" + app_secret;
return Base64.getEncoder().encodeToString(auth.getBytes());
}
#GetMapping(value = "/token")
public Object generateAccessToken() {
String auth = this.getAuth(
"CLIENT_ID",
"APP_SECRET"
);
RestTemplate restTemplate = new RestTemplate();
String base = "https://external-api.com";
HttpHeaders headers = new HttpHeaders();
headers.set("Authorization", "Basic " + auth);
MultiValueMap<String, String> requestParams = new LinkedMultiValueMap<>();
requestParams.add("Grant_type", "client_credentials");
ResponseEntity<Object> response = restTemplate.postForEntity(
base + "/v1/oauth2/token",
requestParams,
Object.class,
headers
);
return response.getBody();
}

Here's the solution to my own question.
This is what I had to change;
MultiValueMap<String, String> requestBody = new LinkedMultiValueMap<>();
requestBody.add("grant_type", "client_credentials");
HttpEntity<?> request = new HttpEntity<>(requestBody, headers);
ResponseEntity<String> response = restTemplate.postForEntity(
base +"/v1/oauth2/token",
request,
String.class
);
Here's the final solution:
public String generateAccessToken() {
String base = "example-api.com";
String auth = this.getAuth(
"client id",
"app_id"
);
// create an instance of RestTemplate
RestTemplate restTemplate = new RestTemplate();
// create headers
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_FORM_URLENCODED);
headers.set("Authorization", "Basic " + auth);
MultiValueMap<String, String> requestBody = new LinkedMultiValueMap<>();
requestBody.add("grant_type", "client_credentials");
HttpEntity<?> request = new HttpEntity<>(requestBody, headers);
ResponseEntity<String> response = restTemplate.postForEntity(
base +"/v1/oauth2/token",
request,
String.class
);
// check response
if (response.getStatusCode() == HttpStatus.OK) {
System.out.println("Request Successful");
System.out.println(response.getBody());
} else {
System.out.println("Request Failed");
System.out.println(response.getStatusCode());
}
JSONObject object = new JSONObject(response.getBody());
return object.getString("access_token");
}

Proper way to get Oath2 access token and call another service in Java Spring Boot

I want to get the oath2 access token and using this I want to call an another service.
Below code does the same it gets the access token and call an another API using that. Using the below code I am able to do what ever I want with the below code.
But I am new to Spring Security I just want to know if there is a better way to do this. Like rather than making a separate call to get the token and then call the service can i do it in a single call? Or Using any other class provided by Spring can I write this in a better way ?
public class TestAPIToken{
#RequestMapping(value = "/showEmployees", method = RequestMethod.GET)
public ModelAndView showEmployees(#RequestParam("code") String code) throws JsonProcessingException, IOException {
String accessToken = getAccessToken();
System.out.println("API Token ---------" + accessToken);
HttpEntity<String> response = getResponseByCallingWithToken(accessToken);
System.out.println("API Response ---------" + response.getBody());
return null;
}
private HttpEntity<String> getResponseByCallingWithToken(String accessToken) {
HttpHeaders headers = new HttpHeaders();
headers.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));
headers.add("Authorization", "Bearer " + accessToken);
UriComponentsBuilder builder = UriComponentsBuilder.fromHttpUrl(url)
.queryParam("msisdn", msisdn)
.queryParam("email", email);
HttpEntity<?> entity = new HttpEntity<>(headers);
HttpEntity<String> response = restTemplate.exchange(
builder.toUriString(),
HttpMethod.GET,
entity,
String.class);
reponse.getBody();
return response;
}
private String getAccessToken() {
ResponseEntity<String> response = null;
System.out.println("Authorization Code------" + code);
RestTemplate restTemplate = new RestTemplate();
// According OAuth documentation we need to send the client id and secret key in the header for authentication
String encodedCredentials = new String(Base64.encodeBase64(credentials.getBytes()));
HttpHeaders headers = new HttpHeaders();
headers.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));
headers.add("Authorization", "Basic " + encodedCredentials);
MultiValueMap<String, String> body = new LinkedMultiValueMap<>();
body.add("scope","scope,value");
body.add("grant_type","scope,value");
HttpEntity<String> request = new HttpEntity<String>(body, headers);
String access_token_url = "http://localhost:8080/oauth2/token";
ResponseEntity<TokenModel> response = restTemplate.exchange(access_token_url, HttpMethod.POST, request, TokenModel.class);
String accessToken = response.getBody().access_token;
return accessToken;
}
}
class TokenModel{
String access_token;
String scope;
String token_type;
String expires_in;
}
I am new to Spring security. Please help even if this seems simple to you
NB: This question does not have an exact duplicate

How to do GET API Request with URL params?

Client client = ClientBuilder.newClient();
urlApi="https://localhost:123/demo/api/v1/rows/search?";
WebTarget webTarget = client.target(urlApi);
for (Map.Entry<String, String> entry : queryParams.entrySet()) {
webTarget.queryParam(entry.getKey(), entry.getValue());
}
webTarget.queryParam("searchConditions",webTarget.queryParam("mobileNo","+9999999999"));
Invocation.Builder builder = webTarget.request();
builder.header("id", "ABC");
String asB64 = Base64.getEncoder().encodeToString("ABC:PWD".getBytes("utf-8"));
logger.debug("Calling API "+urlApi);
builder.header("Authorization", "Basic "+asB64);
builder.header("Content-type", MediaType.APPLICATION_JSON);
response = builder.get();
responseData = response.readEntity(String.class);
System.out.println(responseData);
I am trying to do GET request with searchCondition as Key and value as {mobileNo="+919999999999"}, I am unable to get this to work.
Apart from that, how can I print the Request "Headers" along with "Query params"? Thank you in advance

I think you need to encode the value inputs, something like this:
webTarget.queryParam("searchCondition", URLEncoder.encode("{mobileNo=\"+919999999999\"}", StandardCharsets.UTF_8.toString()));
UDPATE:
Example of the rest client with Spring:
#Test
public void testStack() throws Exception {
RestTemplate rest = new RestTemplate();
String fooResourceUrl="http://localhost:8080/usersParam?";
RestTemplate restTemplate = new RestTemplate();
String parameter = "{mobileNo=\"+919999999999\"}";
ResponseEntity<String> response = restTemplate.getForEntity(fooResourceUrl + "parameter=" + URLEncoder.encode(parameter, StandardCharsets.UTF_8.toString() ), String.class);
assertThat(response.getStatusCode()).isEqualTo(HttpStatus.OK);
}
And this would be the rest service:
#RequestMapping(method = RequestMethod.GET, value="/usersParam")
public User getUsersInfo(#RequestParam String parameter) throws UnsupportedEncodingException {
System.out.println(URLDecoder.decode(parameter, StandardCharsets.UTF_8.toString() ));
return null;
}

RestTemplate with encoded parameters

I need to send an HTTP request to an authentication provider (Auth0). I want to get one specific user by its email address.
The request has to go to:
curl -H "Authorization: Bearer ..." https://.../users?q=email%3A%22mymail%40abc.de%22&search_engine=v2
I tried my luck with RestTemplate (Spring):
public void doSomething() {
...
Map<String, String> requestMap = new HashMap<>();
requestMap.put("q", "email%3A%22mymail%40abc.de%22");
requestMap.put("search_engine", "v2");
RestTemplate restTemplate = getRestTemplateForRequestMap();
HttpHeaders headers = getHeaders();
HttpEntity<Map<String, String>> request = new HttpEntity<>(requestMap, headers);
ResponseEntity<UserInfo[]> response = restTemplate.exchange(URI.create(baseApiUrl + "users"), HttpMethod.GET, request, UserInfo[].class);
...
}
private RestTemplate getRestTemplateForRequestMap() {
RestTemplate restTemplate = new RestTemplate();
List messageConverters = new ArrayList<>();
messageConverters.add(new MappingJackson2HttpMessageConverter());
restTemplate.setMessageConverters(messageConverters);
return restTemplate;
}
Looks like the value of the q parameter needs to be encoded (they call it "Lucene query syntax"). I tried different variations. I even put them "hardcoded" encoded.
However it seems like the q parameter isn't working as the result includes not only the user with the specified email address but all users.
Headers are fine (otherwise I would get no user at all).

You can add the map of your request parameters on on an overloaded method of restTemplate.exchange :
ResponseEntity<UserInfo[]> response = restTemplate.exchange(URI.create(baseApiUrl + "users"), HttpMethod.GET,
request, UserInfo[].class,requestMap);

Works for me:
UriComponentsBuilder builder;
try {
String emailEncoded = URLEncoder.encode("email:" + email, "UTF-8");
builder = UriComponentsBuilder.fromHttpUrl(url)
.queryParam("include_fields", "true")
.queryParam("search_engine", "v3")
.queryParam("q", emailEncoded);
} catch (UnsupportedEncodingException e) {
.....
}
HttpEntity<?> httpEntity = HttpUtility.getHttpEntity(jwtToken);
ResponseEntity<String> response = restTemplate.exchange(builder.build().toUriString(), HttpMethod.GET, httpEntity, String.class);

Get STRING response from restTemplate.put

I'm having a problem using Spring restTemplate.
For now i'm sending a PUT request for a restful service and that restful service send me back important informations in response.
The question is that restTemplate.put are a void method and not a string so i can't see that response.
Following some answers i've change my method and now i'm using restTemplate.exchange, here are my method:
public String confirmAppointment(String clientMail, String appId)
{
String myJsonString = doLogin();
Response r = new Gson().fromJson(myJsonString, Response.class);
// MultiValueMap<String, String> map;
// map = new LinkedMultiValueMap<String, String>();
// JSONObject json;
// json = new JSONObject();
// json.put("status","1");
// map.add("data",json.toString());
String url = getApiUrl() + "company/" + getCompanyId() + "/appointment/" + appId + "?session_token=" + r.data.session_token;
String jsonp = "{\"data\":[{\"status\":\"1\"}]}";
RestTemplate rest = new RestTemplate();
HttpHeaders headers = new HttpHeaders();
headers.add("Content-Type", "application/json");
headers.add("Accept", "*/*");
HttpEntity<String> requestEntity = new HttpEntity<String>(jsonp, headers);
ResponseEntity<String> responseEntity =
rest.exchange(url, HttpMethod.PUT, requestEntity, String.class);
return responseEntity.getBody().toString();
}
Using the method above, i receive a 400 Bad Request
I know my parameters, url and so, are just fine, cause i can do a restTemplate.put request like this:
try {
restTemplate.put(getApiUrl() + "company/" + getCompanyId() + "/appointment/" + appId + "?session_token=" + r.data.session_token, map);
} catch(RestClientException j)
{
return j.toString();
}
The problem (like i said before) is that the try/catch above does not return any response but it gives me a 200 response.
So now i ask, what can be wrong?

Here's how you can check the response to a PUT. You have to use template.exchange(...) to have full control / inspection of the request/response.
String url = "http://localhost:9000/identities/{id}";
Long id = 2l;
String requestBody = "{\"status\":\"testStatus2\"}";
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);
HttpEntity<String> entity = new HttpEntity<String>(requestBody, headers);
ResponseEntity<String> response = template.exchange(url, HttpMethod.PUT, entity, String.class, id);
// check the response, e.g. Location header, Status, and body
response.getHeaders().getLocation();
response.getStatusCode();
String responseBody = response.getBody();

You can use the Header to send something in brief to your clients. Or else you can use the following approach as well.
restTemplate.exchange(url, HttpMethod.PUT, requestEntity, responseType, ...)
You will be able to get a Response Entity returned through that.

Had the same issue. And almost went nuts over it. Checked it in wireshark: The problem seems to be the escape characters from the request body:
String jsonp = "{\"data\":[{\"status\":\"1\"}]}";
The escape character (backslash) is not resolved. The String is sent with the backslashes, which is obviously not a valid json and therefore no valid request(-body).
I bypassed this by feeding everything in with an Object, that is mapping all the properties.