Have you tried this (using HttpClient version 4):
String encoding = Base64Encoder.encode(user + ":" + pwd);
HttpPost httpPost = new HttpPost("http://host:post/test/login");
httpPost.setHeader(HttpHeaders.AUTHORIZATION, "Basic " + encoding);
System.out.println("executing request " + httpPost.getRequestLine());
HttpResponse response = httpClient.execute(httpPost);
HttpEntity entity = response.getEntity();