SOLUCIONADO, asi funciona
Código:
try {
// Construct data
String data = URLEncoder.encode("login", "UTF-8") + "=" + URLEncoder.encode(ptf_login, "UTF-8");
data += "&" + URLEncoder.encode("firstname", "UTF-8") + "=" + URLEncoder.encode(ptf_firstname, "UTF-8");
URL url = new URL("http://direcccionserver");
URLConnection conn = url.openConnection();
conn.setDoOutput(true);
OutputStreamWriter wr = new OutputStreamWriter(conn.getOutputStream());
wr.write(data);
wr.flush();
System.out.println(data);
// Get the response
System.out.println("cogiendo la respuesta..");
BufferedReader rd = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String line;
int i=0;
while ((line = rd.readLine()) != null) {
// Process line...
System.out.println("linea"+i+""+line);
i++;
}
wr.close();
rd.close();
System.out.println("FIN");
} catch (Exception e) {
System.out.println("EXCEPCION..");
}