Outh2 Access Token Exception - spring

Question

I am implementing Outh2 for authentication in spring boot application.I am getting the authorization code successfully but when i am making post request to token url by rest template it is giving me exception 400 bad Request.By this exception i am not able to identify the issue.Below is my code.
ResponseEntity<String> response = null;
System.out.println("Authorization Ccode------" + code);
RestTemplate restTemplate = new RestTemplate();
HttpHeaders headers = new HttpHeaders();
headers.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));
HttpEntity<String> request = new HttpEntity<String>(headers);
String access_token_url = "https://www.googleapis.com/oauth2/v3/token";
access_token_url += "?code=" + code;
access_token_url += "&client_id =487786082511-ta7fnptb8dnd4lbq9lphbtbpll9eo1it.apps.googleusercontent.com";
access_token_url += "&client_secret =fS4KHLUUMOm-lYu8QtDOFcDV";
access_token_url += "&grant_type=authorization_code";
access_token_url += "&redirect_uri=http://localhost:8080/salesgoal/googleOuth2Success";
try {
response = restTemplate.exchange(access_token_url, HttpMethod.POST, request, String.class);
}
catch(Exception e){
e.printStackTrace();
Please let me know what i am doing wrong.
Thanks

Answer 1

Following google's oauth2 documentation
Exchange code for access token and ID token
The response includes a code parameter, a one-time authorization code that your server can exchange for an access token and ID token. Your server makes this exchange by sending an HTTPS POST request. The POST request is sent to the token endpoint, which you should retrieve from the Discovery document using the token_endpoint metadata value. The following discussion assumes the endpoint is https://oauth2.googleapis.com/token. The request must include the following parameters in the POST body:
Follwing their documentation there could be validations on the url parameters (which yield the 400 Bad Request error code)
Please check the following:
The redirect_uri is URL_encoded (by using UrlEncoder)
Url parameters don't contain spaces ( checkclient_id and client_secret )
Later Edit:
Also try following oauth2 specification by using 'Content-Type', 'application/x-www-form-urlencoded' headers on the /token request