Java 在Android中发送POST数据

public class CallAPI extends AsyncTask<String, String, String> {       public CallAPI(){//set context variables if required       }       @Override       protected void onPreExecute() {super.onPreExecute();       }        @Override        protected String doInBackground(String... params) {String urlString = params[0]; // URL to callString data = params[1]; //data to postOutputStream 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());}       }   }