Configuring Spring RestTemplate

Question

Have the following code for getting calling the REST service

RestTemplate restTemplate = new RestTemplate(); 
HttpHeaders headers = new HttpHeaders();

String plainCreds = "test:test2";
byte[] plainCredsBytes = plainCreds.getBytes();
String base64Creds = DatatypeConverter.printBase64Binary(plainCredsBytes);
headers.add("Authorization", "Basic " + base64Creds);
headers.add("Content-type","application/x-www-form-urlencoded;charset=utf-8");

headers.set("Accept", MediaType.APPLICATION_XML_VALUE);
UriComponentsBuilder builder = UriComponentsBuilder.fromHttpUrl(baseUrl)
    .queryParam("id", "id1234"); 
HttpEntity<String> entity = new HttpEntity<>(headers);
ResponseEntity<String> response = restTemplate.exchange(
        builder.build().encode().toUri(),
        HttpMethod.GET, entity, String.class); 

Have the following doubts for this-

1. Can I use factory pattern for getting RestTemplate instead of using new. What will be the advantages and disadvantages of it.
2. Currently adding the credentials into headers in the above code. Is there some better way to achieve it(example in configuration or some other way that can be suitable for production code).

Thanks

Answer 1

1. The general usage pattern of RestTemplate is that you configure one in the way you want it and then reuse that througouht all your application. It is thread safe but can be expensive to create so creating as few as possible (ideally just one) and reusing them is what you should do.

2. There are ways of configuring the RestTemplate to automatically add basic authentication to all requests but IMO it's too complex to be worth it - you need to mess around a bit with Http Components and create your own request factory so I think the easiest solution is to just break out the manual step into a helper class.

--

public class RestTemplateUtils {

    public static final RestTemplate template;
    static {
        // Init the RestTemplate here
        template = new RestTemplate();
    }

    /**
     * Add basic authentication to some {@link HttpHeaders}.
     * @param headers The headers to add authentication to
     * @param username The username
     * @param password The password
     */
    public static HttpHeaders addBasicAuth(HttpHeaders headers, String username, String password) {
        String plainCreds = username + ":" + password;
        byte[] plainCredsBytes = plainCreds.getBytes();
        String base64Creds = DatatypeConverter.printBase64Binary(plainCredsBytes);
        headers.add("Authorization", "Basic " + base64Creds);
        return headers;
    }
}

Your code now turns into:

HttpHeaders headers = RestTemplateUtils.addBasicAuth(new HttpHeaders(),
        "test", "test");

headers.add("Content-type","application/x-www-form-urlencoded;charset=utf-8");
headers.set("Accept", MediaType.APPLICATION_XML_VALUE);

UriComponentsBuilder builder = UriComponentsBuilder.fromHttpUrl(baseUrl)
    .queryParam("id", "id1234"); 
HttpEntity<String> entity = new HttpEntity<>(headers);
ResponseEntity<String> response = RestTemplateUtils.template.exchange(
        builder.build().encode().toUri(),
        HttpMethod.GET, entity, String.class); 

Though I'd suggest adding a few more helper methods to create an entity and add any other standard headers to it.