I am writing here the code that connects to a PHP page and sends some prameters to the page as POST and then it prints the whole HTML response from PHP page to console, I hope following code will help:

try{
      URL url = new URL("http://mywebsite:port/scripts/validate.php");
      HttpURLConnection urlConnection = (HttpURLConnection)url.openConnection();
      urlConnection.setRequestMethod("POST");
      urlConnection.setDoInput(true);
      urlConnection.setDoOutput(true);
      OutputStream os = urlConnection.getOutputStream();
      DataOutputStream dos = new DataOutputStream(os);
      String postString = "Name"+"="+"Yasir Khan"+
                          "&Email"+"="+"yasir.khan@ascertia.com";
      dos.writeBytes(postString);
      InputStream is = urlConnection.getInputStream();
      BufferedReader br = new BufferedReader(new InputStreamReader(is));
      String line= null;
      while( (line = br.readLine()) != null ){
        System.out.println(line);
      }
      System.out.println("line "+line);
      dos.close();
      br.close();
      urlConnection.disconnect();
    }
    catch(Exception ex) {
      ex.printStackTrace();
    }

Regards,

YK