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.IntentService; import android.app.Notification; import android.content.Context; import android.content.Intent; import android.content.SharedPreferences; import android.preference.PreferenceManager; import android.support.v4.app.NotificationCompat; import android.util.Log; 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; import java.text.SimpleDateFormat; import java.util.Date; public class ServiceExternal extends IntentService { private static final String TAG = "NetGuard.External"; private static final String ACTION_DOWNLOAD_HOSTS_FILE = "eu.faircode.netguard.DOWNLOAD_HOSTS_FILE"; // am startservice -a eu.faircode.netguard.DOWNLOAD_HOSTS_FILE public ServiceExternal() { super(TAG); } @Override protected void onHandleIntent(Intent intent) { try { startForeground(ServiceSinkhole.NOTIFY_EXTERNAL, getForegroundNotification(this)); Log.i(TAG, "Received " + intent); Util.logExtras(intent); if (ACTION_DOWNLOAD_HOSTS_FILE.equals(intent.getAction())) { final SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this); String hosts_url = prefs.getString("hosts_url", null); File tmp = new File(getFilesDir(), "hosts.tmp"); File hosts = new File(getFilesDir(), "hosts.txt"); InputStream in = null; OutputStream out = null; URLConnection connection = null; try { URL url = new URL(hosts_url); 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(tmp); long size = 0; byte buffer[] = new byte[4096]; int bytes; while ((bytes = in.read(buffer)) != -1) { out.write(buffer, 0, bytes); size += bytes; } Log.i(TAG, "Downloaded size=" + size); if (hosts.exists()) hosts.delete(); tmp.renameTo(hosts); String last = SimpleDateFormat.getDateTimeInstance().format(new Date().getTime()); prefs.edit().putString("hosts_last_download", last).apply(); ServiceSinkhole.reload("hosts file download", this, false); } catch (Throwable ex) { Log.e(TAG, ex.toString() + "\n" + Log.getStackTraceString(ex)); if (tmp.exists()) tmp.delete(); } 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(); } } } finally { stopForeground(true); } } private static Notification getForegroundNotification(Context context) { NotificationCompat.Builder builder = new NotificationCompat.Builder(context, "foreground"); builder.setSmallIcon(R.drawable.ic_hourglass_empty_white_24dp); builder.setPriority(NotificationCompat.PRIORITY_MIN); builder.setCategory(NotificationCompat.CATEGORY_STATUS); builder.setVisibility(NotificationCompat.VISIBILITY_PUBLIC); builder.setContentTitle(context.getString(R.string.app_name)); return builder.build(); } }