Apache HttpComponents Proxy Config(v4.5.5)

ProxyConfig.java

try (ClosableHttpClient httpClient = HttpClients.createDefault()) {

    HttpHost proxy = new HttpHost("proxy host", 3128);

    RequestConfig config = RequestConfig.custom()
            .setProxy(proxy)
            .build();
  
    HttpGet httpget = new HttpGet("/path");
    httpget.setConfig(config);

    ...
    ...
    System.out.println("Executing request " + httpget.getRequestLine() + " to " + target + " via " + proxy);

}