I developed a solution which looks easier that what has been posted here
private String executeGet(final String https_url, final String proxyName, final int port) {
String ret = "";
URL url;
try {
HttpsURLConnection con;
url = new URL(https_url);
if (proxyName.isEmpty()) {
con = (HttpsURLConnection) url.openConnection();
} else {
Proxy proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress(proxyName, port));
con = (HttpsURLConnection) url.openConnection(proxy);
Authenticator authenticator = new Authenticator() {
public PasswordAuthentication getPasswordAuthentication() {
return (new PasswordAuthentication(USERNAME, PASSWORD.toCharArray()));
}
};
Authenticator.setDefault(authenticator);
}
ret = getContent(con);
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return ret;
}