spring - Get specific response value from the API in SpringBoot

Question

I am calling one post call and getting the response like below :

Now I want to get the value of the access token and do some logic. How to get the value from the response? Can anyone please help. Service code of the API.

public String getToken(User user) throws JsonMappingException, JsonProcessingException {
        ObjectMapper mapper = new ObjectMapper();
        System.out.println(clientId+clientPass);
        String plainCreds = clientId+":"+clientPass;
        byte[] plainCredsBytes = plainCreds.getBytes();
        byte[] base64CredsBytes = Base64.getEncoder().encode(plainCredsBytes);
        String base64Creds = new String(base64CredsBytes);
        HttpHeaders headers = new HttpHeaders();
        headers.add("Authorization", "Basic " + base64Creds);
        HttpEntity<String> request=new HttpEntity<String>(headers);
        String uri = url+ user.getUser_id()
                + "&password=" + user.getPassword();
        RestTemplate restTemplate = new RestTemplate();
        
        ResponseEntity<String> result = restTemplate.exchange(uri, HttpMethod.POST, request, String.class) ;
        JsonNode newNode = mapper.readTree(result.getBody());
        ObjectNode node = ((ObjectNode) newNode).put("Authentication", "Successful");
        
        return mapper.writerWithDefaultPrettyPrinter().writeValueAsString(node);
    }

Answer 1

You can write DTO for response:

public class ResponseSample {
   @JsonProperty("access_token")
   String accessToken;
   ....
}

(or deserialize to Map) and instead calling ResponseEntity<String> result = restTemplate.exchange(...) you can call

ResponseEntity<ResponseSample> result = restTemplate.exchange(..., ResponseSample.class)