String postData = String.format("username=%s&password=%s",
        URLEncoder.encode(username, "UTF-8"),
        URLEncoder.encode(password, "UTF-8"));

URL url = new URL("http://example.com/login.php");
HttpURLConnection connection =
        (HttpURLConnection) url.openConnection(createTorProxy());
connection.setRequestMethod("POST");
connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
connection.setRequestProperty("Content-Length", String.valueOf(postData.length()));
connection.setDoOutput(true);

OutputStreamWriter writer = new OutputStreamWriter(connection.getOutputStream());
writer.write(postData);
writer.flush();
writer.close();

Log.d(TAG, String.format("Login result: %d", connection.getResponseCode()));