Making authenticated POST requests with Spring RestTemplate for Android

I have a RESTful API I'm trying to connect with via Android and RestTemplate. All requests to the API are authenticated with HTTP Authentication, through setting the headers of the HttpEntity and then using RestTemplate's exchange() method.

All GET requests work great this way, but I cannot figure out how to accomplish authenticated POST requests. postForObject and postForEntity handle POSTs, but have no easy way to set the Authentication headers.

So for GETs, this works great:

HttpAuthentication httpAuthentication = new HttpBasicAuthentication("username", "password");
HttpHeaders requestHeaders = new HttpHeaders();
requestHeaders.setAuthorization(httpAuthentication);

HttpEntity<?> httpEntity = new HttpEntity<Object>(requestHeaders);

MyModel[] models = restTemplate.exchange("/api/url", HttpMethod.GET, httpEntity, MyModel[].class);

But POSTs apparently don't work with exchange() as it never sends the customized headers and I don't see how to set the request body using exchange().

What is the easiest way to make authenticated POST requests from RestTemplate?

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);

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);
    }
}

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());