Making authenticated POST requests with Spring RestTemplate for Android

Slightly different approach:

MultiValueMap<String, String> headers = new LinkedMultiValueMap<String, String>();
headers.add("HeaderName", "value");
headers.add("Content-Type", "application/json");

RestTemplate restTemplate = new RestTemplate();
restTemplate.getMessageConverters().add(new MappingJackson2HttpMessageConverter());

HttpEntity<ObjectToPass> request = new HttpEntity<ObjectToPass>(objectToPass, headers);

restTemplate.postForObject(url, request, ClassWhateverYourControllerReturns.class);

I was recently dealing with an issue when I was trying to get past authentication while making a REST call from Java, and while the answers in this thread (and other threads) helped, there was still a bit of trial and error involved in getting it working.

What worked for me was encoding credentials in Base64 and adding them as Basic Authorization headers. I then added them as an HttpEntity to restTemplate.postForEntity, which gave me the response I needed.

Here's the class I wrote for this in full (extending RestTemplate):

public class AuthorizedRestTemplate extends RestTemplate{

    private String username;
    private String password;

    public AuthorizedRestTemplate(String username, String password){
        this.username = username;
        this.password = password;
    }

    public String getForObject(String url, Object... urlVariables){
        return authorizedRestCall(this, url, urlVariables);
    }

    private String authorizedRestCall(RestTemplate restTemplate, 
            String url, Object... urlVariables){
        HttpEntity<String> request = getRequest();
        ResponseEntity<String> entity = restTemplate.postForEntity(url, 
                request, String.class, urlVariables);
        return entity.getBody();
    }

    private HttpEntity<String> getRequest(){
        HttpHeaders headers = new HttpHeaders();
        headers.add("Authorization", "Basic " + getBase64Credentials());
        return new HttpEntity<String>(headers);
    }

    private String getBase64Credentials(){
        String plainCreds = username + ":" + password;
        byte[] plainCredsBytes = plainCreds.getBytes();
        byte[] base64CredsBytes = Base64.encodeBase64(plainCredsBytes);
        return new String(base64CredsBytes);
    }
}

Ok found the answer. exchange() is the best way. Oddly the HttpEntity class doesn't have a setBody() method (it has getBody()), but it is still possible to set the request body, via the constructor.

// Create the request body as a MultiValueMap
MultiValueMap<String, String> body = new LinkedMultiValueMap<String, String>();     

body.add("field", "value");

// Note the body object as first parameter!
HttpEntity<?> httpEntity = new HttpEntity<Object>(body, requestHeaders);

ResponseEntity<MyModel> response = restTemplate.exchange("/api/url", HttpMethod.POST, httpEntity, MyModel.class);

Very useful I had a slightly different scenario where I the request xml was itself the body of the POST and not a param. For that the following code can be used - Posting as an answer just in case anyone else having similar issue will benefit.

    final HttpHeaders headers = new HttpHeaders();
    headers.add("header1", "9998");
    headers.add("username", "xxxxx");
    headers.add("password", "xxxxx");
    headers.add("header2", "yyyyyy");
    headers.add("header3", "zzzzz");
    headers.setContentType(MediaType.APPLICATION_XML);
    headers.setAccept(Arrays.asList(MediaType.APPLICATION_XML));
    final HttpEntity<MyXmlbeansRequestDocument> httpEntity = new HttpEntity<MyXmlbeansRequestDocument>(
            MyXmlbeansRequestDocument.Factory.parse(request), headers);
    final ResponseEntity<MyXmlbeansResponseDocument> responseEntity = restTemplate.exchange(url, HttpMethod.POST, httpEntity,MyXmlbeansResponseDocument.class);
    log.info(responseEntity.getBody());