下面代码是一个 AsyncTask 应用的程序框架,请你根据已有代码在空白划线处填写所需代码。 private class DownloadFilesTask extends AsyncTask< ( 1 ) ______, Integer, ( 2 ) ______> { protected Long doInBackground(URL... urls) { int count = urls.length; long totalSize = 0; for (int i = 0; i < count; i++) { totalSize += Downloader.downloadFile(urls[i]); int progress = (int) ((i / (float) count) * 100); publishProgress(progress); // Escape early if cancel() is called if (isCancelled()) break; } return totalSize; } protected void onProgressUpdate( ( 3 ) ________________ ) { setProgressPercent(progress[0]); } protected void onPostExecute ( ( 4 ) ________________ ) { showDialog("Downloaded " + result + " bytes"); } } DownloadFilesTask task= new DownloadFilesTask(); task. ( 5 ) ________________ ( url1, url2, url3 );