无法在Android上发出简单的http请求，没有错误只是没有工作

Question

我尝试构建一个简单的应用程序，它将发送一个http post请求来控制某个程序。这是我用于调用请求的AsyncTask类。

class CallURL extends AsyncTask<String,Void,Void>{
    protected Void doInBackground(String... command) {
        URL url;
        HttpURLConnection conn = null;
        try {
            url= new URL("http://192.168.1.20:13579/command.html");
            conn = (HttpURLConnection)url.openConnection();
            conn.setReadTimeout(10000 /* milliseconds */);
            conn.setConnectTimeout(15000 /* milliseconds */);
            conn.setRequestMethod("POST");
            conn.setDoOutput(true);
            conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");

            String query = URLEncoder.encode("wm_command="+command[0],"UTF-8");
            OutputStream os = conn.getOutputStream();
            BufferedWriter writer = new BufferedWriter(
                    new OutputStreamWriter(os, "UTF-8"));
            writer.write(query);
            writer.flush();
            writer.close();
            os.close();

            urlConnection.connect();
        } catch (Exception e){
            e.printStackTrace();
        }
        return null;
    }
}

应用程序可以构建并运行得很好但是当我点击按钮时，它只是给我这个

10-12 18:27:08.167 8484-8484/com.example.nattawit.myapplication I/ViewRootImpl: ViewRoot's Touch Event : ACTION_DOWN
10-12 18:27:08.257 8484-8484/com.example.nattawit.myapplication I/ViewRootImpl: ViewRoot's Touch Event : ACTION_UP
10-12 18:27:08.274 8484-9196/com.example.nattawit.myapplication D/libc-netbsd: [getaddrinfo]: hostname=xxxxx; servname=(null); cache_mode=(null), netid=0; mark=0
10-12 18:27:08.274 8484-9196/com.example.nattawit.myapplication D/libc-netbsd: [getaddrinfo]: ai_addrlen=0; ai_canonname=xxxxx; ai_flags=4; ai_family=0
10-12 18:27:08.310 8484-9196/com.example.nattawit.myapplication D/libc-netbsd: [getaddrinfo]: hostname=xxxxx; servname=(null); cache_mode=(null), netid=0; mark=0
10-12 18:27:08.310 8484-9196/com.example.nattawit.myapplication D/libc-netbsd: [getaddrinfo]: ai_addrlen=0; ai_canonname=xxxxx; ai_flags=4; ai_family=0

没有例外或错误或任何事情。不知道我需要修理什么。 （另外，我已将<uses-permission android:name="android.permission.INTERNET"/>放入我的清单中）