面临问题无法使用异步下载队列中的文件

Question

我通过创建 Async 类来处理这个问题，然后将 URL 列表传递给该类。在 Async 类内部，循环下载队列中的文件

Answer 1

class DownloadFileAsync extends AsyncTask<ArrayList<String>, String, String>
 {

       int index = 0;

        @Override
        protected String doInBackground(ArrayList<String>... arrayLists) {

            int count;

            for (String fileUrl : allFileUrls) {
                ++index;
                String fileName = fileUrl.substring(fileUrl.lastIndexOf('/') + 1, fileUrl.length());
                File dir = new File(getFilesDir().getAbsolutePath() + "/" + fileName);

                if (!dir.exists()) {

                    try {
                        URL url = new URL(fileUrl);
                        URLConnection conexion = url.openConnection();
                        conexion.connect();

                        int lenghtOfFile = conexion.getContentLength();


                        InputStream input = new BufferedInputStream(url.openStream());
                        OutputStream output = new FileOutputStream(dir);

                        byte data[] = new byte[1024];

                        long total = 0;

                        while ((count = input.read(data)) != -1) {
                            total += count;
                            publishProgress("" + (int) ((total * 100) / lenghtOfFile), String.valueOf(index));
                            output.write(data, 0, count);
                        }

                        output.flush();
                        output.close();
                        input.close();
                    } catch (Exception e) {
                        Log.d("ANDRO_ASYNC error", e.getMessage());

                    }

                }
            }


            return null;
        }

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            pDialog = new ProgressDialog(SyncActivity.this);
            pDialog.setTitle("Please wait");
            pDialog.setMessage("Starting download..");
            pDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
            pDialog.setCancelable(false);
            pDialog.show();
        }

        protected void onProgressUpdate(String... progress) {

            pDialog.setMessage(" Downloading the File : " + index);
            pDialog.setProgress(Integer.parseInt(progress[0]));

        }


        @Override
        protected void onPostExecute(String unused) {
            pDialog.dismiss();
        }

    }