HttpConnection htcon =
(HttpConnection)Connector.open(URL,Connector.READ_WRITE,true);
htcon.setRequestMethod(HttpConnection.POST);
htcon.setRequestProperty("Content-Type","application/x-www-form-urlencoded");
OutputStream htout = htcon.openOutputStream();
OutputStreamWriter htoutw = new OutputStreamWriter(htout);
htoutw.write(DATA)；
htoutw.close();
htout.close();
htcon.connect();
htcon.close();

これならどう？