//load privatekey data
//change it with YOUR payplug private key (see in payplug documentation)
byte[] keyBytes = Files.readAllBytes(Paths.get("./yourPrivateKey"));
PaymentUrl payplug = new PaymentUrl(baseUrl);
payplug.loadPrivateKey(keyBytes);
payplug.addParam("amount", "142"); //amount in cents : 1,42€ here
payplug.addParam("currency","EUR");
payplug.addParam("ipn_url","http://test.test.com/ipn.php");
payplug.addParam("return_url","http://www.google.com/");
payplug.addParam("email","joen.do@test.com");
payplug.addParam("firstname","Joen");
payplug.addParam("lastname","Do");
payplug.addParam("customer","42");
payplug.addParam("order","198");
payplug.addParam("custom_datas","product_id=2|ip_address=88.161.117.16");
String url = payplug.getUrl();
System.out.println("url : " + url);
} catch (NoSuchAlgorithmException e) {
// TODO Auto-generated catch block
e.printStackTrace();