Android HTTP POST请求到服务器（需要说明）

Question

        URL url = new URL("url");
        URLConnection conn = url.openConnection();
        conn.setDoOutput(true);
        conn.setDoInput(true);// i can delete this nothing happens
        OutputStreamWriter wr = new OutputStreamWriter(conn.getOutputStream());
        wr.write(valueIWantToSend);
        wr.flush();
        wr.close();
        Reader in = new BufferedReader(new InputStreamReader(conn.getInputStream(),"UTF-8"));

This code above post my value: valueIWantToSend to my server. Everything is working fine, but i want to ask: Why then i remove this line:

 Reader in = new BufferedReader(new InputStreamReader(conn.getInputStream(),"UTF-8"));

Nothing is shown on my server, but then i add this line everything is working great, but why ? I am not using Reader in this connection so what i miss understood?

Answer 1

I think u should call urlConnection.connect()

    urlConnection = (HttpURLConnection) url.openConnection();
        urlConnection.setRequestMethod("POST");
        urlConnection.connect();