Java tutorial
package eu.faircode.netguard; /* This file is part of NetGuard. NetGuard is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. NetGuard is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with NetGuard. If not, see <http://www.gnu.org/licenses/>. Copyright 2015-2017 by Marcel Bokhorst (M66B) */ import android.app.Activity; import android.app.PendingIntent; import android.content.Context; import android.content.Intent; import android.os.AsyncTask; import android.os.Build; import android.os.PowerManager; import android.support.v4.app.NotificationCompat; import android.support.v4.app.NotificationManagerCompat; import android.util.Log; import android.util.TypedValue; import android.widget.Toast; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.net.HttpURLConnection; import java.net.URL; import java.net.URLConnection; public class DownloadTask extends AsyncTask<Object, Integer, Object> { private static final String TAG = "NetGuard.Download"; private Context context; private URL url; private File file; private Listener listener; private PowerManager.WakeLock wakeLock; public interface Listener { void onCompleted(); void onCancelled(); void onException(Throwable ex); } public DownloadTask(Activity context, URL url, File file, Listener listener) { this.context = context; this.url = url; this.file = file; this.listener = listener; } @Override protected void onPreExecute() { PowerManager pm = (PowerManager) context.getSystemService(Context.POWER_SERVICE); wakeLock = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, getClass().getName()); wakeLock.acquire(); showNotification(0); Toast.makeText(context, context.getString(R.string.msg_downloading, url.toString()), Toast.LENGTH_SHORT) .show(); } @Override protected Object doInBackground(Object... args) { Log.i(TAG, "Downloading " + url + " into " + file); InputStream in = null; OutputStream out = null; URLConnection connection = null; try { connection = url.openConnection(); connection.connect(); if (connection instanceof HttpURLConnection) { HttpURLConnection httpConnection = (HttpURLConnection) connection; if (httpConnection.getResponseCode() != HttpURLConnection.HTTP_OK) throw new IOException( httpConnection.getResponseCode() + " " + httpConnection.getResponseMessage()); } int contentLength = connection.getContentLength(); Log.i(TAG, "Content length=" + contentLength); in = connection.getInputStream(); out = new FileOutputStream(file); long size = 0; byte buffer[] = new byte[4096]; int bytes; while (!isCancelled() && (bytes = in.read(buffer)) != -1) { out.write(buffer, 0, bytes); size += bytes; if (contentLength > 0) publishProgress((int) (size * 100 / contentLength)); } Log.i(TAG, "Downloaded size=" + size); return null; } catch (Throwable ex) { return ex; } finally { try { if (out != null) out.close(); } catch (IOException ex) { Log.e(TAG, ex.toString() + "\n" + Log.getStackTraceString(ex)); } try { if (in != null) in.close(); } catch (IOException ex) { Log.e(TAG, ex.toString() + "\n" + Log.getStackTraceString(ex)); } if (connection instanceof HttpURLConnection) ((HttpURLConnection) connection).disconnect(); } } @Override protected void onProgressUpdate(Integer... progress) { super.onProgressUpdate(progress); showNotification(progress[0]); } @Override protected void onCancelled() { super.onCancelled(); Log.i(TAG, "Cancelled"); listener.onCancelled(); } @Override protected void onPostExecute(Object result) { wakeLock.release(); NotificationManagerCompat.from(context).cancel(ServiceSinkhole.NOTIFY_DOWNLOAD); if (result instanceof Throwable) { Log.e(TAG, result.toString() + "\n" + Log.getStackTraceString((Throwable) result)); listener.onException((Throwable) result); } else listener.onCompleted(); } private void showNotification(int progress) { Intent main = new Intent(context, ActivitySettings.class); PendingIntent pi = PendingIntent.getActivity(context, ServiceSinkhole.NOTIFY_DOWNLOAD, main, PendingIntent.FLAG_UPDATE_CURRENT); TypedValue tv = new TypedValue(); context.getTheme().resolveAttribute(R.attr.colorOff, tv, true); NotificationCompat.Builder builder = new NotificationCompat.Builder(context, "notify"); builder.setSmallIcon(R.drawable.ic_file_download_white_24dp) .setContentTitle(context.getString(R.string.app_name)) .setContentText(context.getString(R.string.msg_downloading, url.toString())).setContentIntent(pi) .setProgress(100, progress, false).setColor(tv.data).setOngoing(true).setAutoCancel(false); if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) builder.setCategory(NotificationCompat.CATEGORY_STATUS) .setVisibility(NotificationCompat.VISIBILITY_SECRET); NotificationManagerCompat.from(context).notify(ServiceSinkhole.NOTIFY_DOWNLOAD, builder.build()); } }