PoolingHttpClientConnectionManager connectionManager = new PoolingHttpClientConnectionManager(); CloseableHttpClient httpClient = HttpClients.custom() .setConnectionManager(connectionManager) .build(); HttpPost request = new HttpPost(url); request.setHeader("Accept-Encoding", "gzip, deflate"); CloseableHttpAsyncClient asyncHttpClient = HttpAsyncClients.createDefault(); asyncHttpClient.start(); HttpUriRequest request1 = RequestBuilder.get() .setUri(url1) .build(); asyncHttpClient.execute(request1, new FutureCallback<HttpResponse>() { @Override public void completed(HttpResponse response) { } @Override public void failed(Exception ex) { } @Override public void cancelled() { } }); HttpUriRequest request2 = RequestBuilder.get() .setUri(url2) .build(); asyncHttpClient.execute(request2, new FutureCallback<HttpResponse>() { // ... }); RequestConfig requestConfig = RequestConfig.custom() .build(); HttpGet request = new HttpGet(url); request.setConfig(requestConfig); HttpTransport transport = new JettyHttpTransport(); HttpClient client = HttpClient.newBuilder() .transport(transport) .build(); HttpRequest request = HttpRequest.newBuilder() .uri(URI.create(url)) .header("Accept", "application/json") .build(); HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());