Good afternoon. Tell me how you can implement Downloading and saving the file to the device’s memory or if there is an SD card then there is it.

    2 answers 2

    If necessary via HTTP , like this:

    public void saveUrl(final String filename, final String urlString) throws MalformedURLException, IOException { BufferedInputStream in = null; FileOutputStream fout = null; try { in = new BufferedInputStream(new URL(urlString).openStream()); fout = new FileOutputStream(filename); final byte data[] = new byte[1024]; int count; while ((count = in.read(data, 0, 1024)) != -1) { fout.write(data, 0, count); } } finally { if (in != null) { in.close(); } if (fout != null) { fout.close(); } } }

    Then:

     try{ saveUrl(Environment.getExternalStorageDirectory() + "...", "..."); } catch(Exception e){ //Обработайте ошибку }

    getExternalStorageDirectory () will return what the phone manufacturer called the "external storage" (external storage). To check the availability of a memory card, use getExternalStorageState () .

    PS Do not forget to add to the manifest:

     <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> <uses-permission android:name="android.permission.INTERNET" />

      Use AsyncTask and show progress downloading in the dialog box.

      This method allows processes to run in the background.

      Example:

       // declare the dialog as a member field of your activity ProgressDialog mProgressDialog; // instantiate it within the onCreate method mProgressDialog = new ProgressDialog(YourActivity.this); mProgressDialog.setMessage("A message"); mProgressDialog.setIndeterminate(true); mProgressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL); mProgressDialog.setCancelable(true); // execute this when the downloader must be fired final DownloadTask downloadTask = new DownloadTask(YourActivity.this); downloadTask.execute("the url to the file you want to download"); mProgressDialog.setOnCancelListener(new DialogInterface.OnCancelListener() { @Override public void onCancel(DialogInterface dialog) { downloadTask.cancel(true); } }); AsyncTask выглядит следующим образом: // usually, subclasses of AsyncTask are declared inside the activity class. // that way, you can easily modify the UI thread from here private class DownloadTask extends AsyncTask<String, Integer, String> { private Context context; private PowerManager.WakeLock mWakeLock; public DownloadTask(Context context) { this.context = context; } @Override protected String doInBackground(String... sUrl) { InputStream input = null; OutputStream output = null; HttpURLConnection connection = null; try { URL url = new URL(sUrl[0]); connection = (HttpURLConnection) url.openConnection(); connection.connect(); // expect HTTP 200 OK, so we don't mistakenly save error report // instead of the file if (connection.getResponseCode() != HttpURLConnection.HTTP_OK) { return "Server returned HTTP " + connection.getResponseCode() + " " + connection.getResponseMessage(); } // this will be useful to display download percentage // might be -1: server did not report the length int fileLength = connection.getContentLength(); // download the file input = connection.getInputStream(); output = new FileOutputStream("/sdcard/file_name.extension"); byte data[] = new byte[4096]; long total = 0; int count; while ((count = input.read(data)) != -1) { // allow canceling with back button if (isCancelled()) { input.close(); return null; } total += count; // publishing the progress.... if (fileLength > 0) // only if total length is known publishProgress((int) (total * 100 / fileLength)); output.write(data, 0, count); } } catch (Exception e) { return e.toString(); } finally { try { if (output != null) output.close(); if (input != null) input.close(); } catch (IOException ignored) { } if (connection != null) connection.disconnect(); } return null; }

      The doInBackground method always works in the background. You should not do any operations related to the program interface. For this there is onProgressUpdate and onPreExecute .

       @Override protected void onPreExecute() { super.onPreExecute(); // take CPU lock to prevent CPU from going off if the user // presses the power button during download PowerManager pm = (PowerManager) context.getSystemService(Context.POWER_SERVICE); mWakeLock = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, getClass().getName()); mWakeLock.acquire(); mProgressDialog.show(); } @Override protected void onProgressUpdate(Integer... progress) { super.onProgressUpdate(progress); // if we get here, length is known, now set indeterminate to false mProgressDialog.setIndeterminate(false); mProgressDialog.setMax(100); mProgressDialog.setProgress(progress[0]); } @Override protected void onPostExecute(String result) { mWakeLock.release(); mProgressDialog.dismiss(); if (result != null) Toast.makeText(context,"Download error: "+result, Toast.LENGTH_LONG).show(); else Toast.makeText(context,"File downloaded", Toast.LENGTH_SHORT).show(); }

      Don't forget to add AndroidManifest.xml

       <uses-permission android:name="android.permission.WAKE_LOCK" />

      There are other methods , but I liked the above.