Jakarta Commons HttpClientを利用したNTLM認証の方法です。
対象とするバージョンは4.3.3となります。

String userName = "test";
String password = "test";
HttpClientBuilder builder = HttpClientBuilder.create();
CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
credentialsProvider.setCredentials(AuthScope.ANY, new NTCredentials(userName + ":" + password));
builder.setDefaultCredentialsProvider(credentialsProvider);

HttpClient httpClient = builder.build();
HttpGet httpGet = new HttpGet("http://hogehoge");

try {
	HttpResponse response = httpClient.execute(httpGet);
	response.getEntity().writeTo(System.out);
} catch (ClientProtocolException e) {
	e.printStackTrace();
} catch (IOException e) {
	e.printStackTrace();
}