AsyncTask内部的android.os.NetworkOnMainThreadException

我正在构建一个应用程序,并收到NetworkOnMainThreadException 内部 异步任务

电话:

new POST(this).execute("");

异步任务:

public class POST extends AsyncTask<String, Integer, HttpResponse>{
private MainActivity form;
public POST(MainActivity form){
    this.form = form;
}


@Override
protected HttpResponse doInBackground(String... params) {
try {
        HttpPost httppost = new HttpPost("http://diarwe.com:8080/account/login");
    List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(3);
    nameValuePairs.add(new BasicNameValuePair("email",((EditText)form.findViewById(R.id.in_email)).getText().toString()));
    //add more...
    httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
    return new DefaultHttpClient().execute(httppost);
} catch (Exception e) {
    Log.e("BackgroundError", e.toString());
}
return null;
}

@Override
protected void onPostExecute(HttpResponse result) {
super.onPostExecute(result);
try {
    Gson gSon = new GsonBuilder().setDateFormat("yyyy-MM-dd'T'HH:mm:ss").create();
    gSon.fromJson(IOUtils.toString(result.getEntity().getContent()), LogonInfo.class).fill(form);
} catch (Exception e) {
    Log.e("BackgroundError", e.toString());
}
}
}

日志类别:

BackgroundError | android.os.NetworkOnMainThreadException

我很困惑为什么这个异常会被抛出到AsyncTask的doInBackground中,有什么想法吗?