HttpURLConnectionを使用してAndroidでPOSTデータを送信する方法?

public class CallAPI extends AsyncTask<String, String, String> {

    @Override
    protected String doInBackground(String... params) {
        String urlString = params[0];
        String data = params[1];
        OutputStream out = null;

        try {
            URL url = new URL(urlString);
            HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
            out = new BufferedOutputStream(urlConnection.getOutputStream());

            BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(out, "UTF-8"));
            writer.write(data);
            writer.flush();
            writer.close();
            out.close();

            urlConnection.connect();
        } catch (Exception e) {
            System.out.println(e.getMessage());
        }

        return null;
    }
}

public void postData() {
    HttpClient httpclient = new DefaultHttpClient();
    HttpPost httppost = new HttpPost("http://www.yoursite.com/script.php");

    List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
    nameValuePairs.add(new BasicNameValuePair("id", "12345"));
    nameValuePairs.add(new BasicNameValuePair("stringdata", "Hi"));
    httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));

    try {
        HttpResponse response = httpclient.execute(httppost);
    } catch (Exception e) {
        // Handle exceptions
    }
}