public class SpringRestTemplateBasicAuthExample {

	public static void main(String... args){

		RestTemplate rt = new RestTemplate();
		rt.getMessageConverters().add(new MappingJackson2HttpMessageConverter());
		rt.getMessageConverters().add(new StringHttpMessageConverter());
		String uri = new String("https://some.api.provider.com/rest/authenticate");

		String plainCreds = "user@awesome.com:sfdfsdf$%&^$%4";
		byte[] plainCredsBytes = plainCreds.getBytes();
		byte[] base64CredsBytes = Base64.encodeBase64(plainCredsBytes);
		String base64Creds = new String(base64CredsBytes);

		HttpHeaders headers = new HttpHeaders();
		headers.add("Authorization", "Basic " + base64Creds);

		HttpEntity<String> request = new HttpEntity<String>(headers);
		ResponseEntity<String> response = rt.exchange(uri, HttpMethod.POST, request, String.class);
		log.info("Account Content:" + response.getBody());
	}
}