Java tutorial
package org.schabi.newpipe; import android.app.NotificationManager; import android.content.Context; import android.content.SharedPreferences; import android.graphics.drawable.BitmapDrawable; import android.graphics.drawable.Drawable; import android.os.AsyncTask; import android.preference.PreferenceManager; import android.support.v4.app.NotificationCompat; import android.util.Log; import java.io.BufferedInputStream; import java.io.BufferedReader; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.net.HttpURLConnection; import java.net.URL; import java.net.UnknownHostException; import javax.net.ssl.HttpsURLConnection; import info.guardianproject.netcipher.NetCipher; /** * Created by Christian Schabesberger on 14.08.15. * * Copyright (C) Christian Schabesberger 2015 <chris.schabesberger@mailbox.org> * Downloader.java is part of NewPipe. * * NewPipe 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. * * NewPipe 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 NewPipe. If not, see <http://www.gnu.org/licenses/>. */ public class Downloader extends AsyncTask<Void, Integer, Void> { public static final String TAG = "Downloader"; private static final String USER_AGENT = "Mozilla/5.0"; private NotificationManager nm; private NotificationCompat.Builder builder; private int notifyId = 0x1234; private int fileSize = 0xffffffff; private final Context context; private final String fileURL; private final File saveFilePath; private final String title; private final String debugContext; public Downloader(Context context, String fileURL, File saveFilePath, String title) { this.context = context; this.fileURL = fileURL; this.saveFilePath = saveFilePath; this.title = title; this.debugContext = "'" + fileURL + "' => '" + saveFilePath + "'"; } /**Download the text file at the supplied URL as in download(String), * but set the HTTP header field "Accept-Language" to the supplied string. * @param siteUrl the URL of the text file to return the contents of * @param language the language (usually a 2-character code) to set as the preferred language * @return the contents of the specified text file*/ public static String download(String siteUrl, String language) { String ret = ""; try { URL url = new URL(siteUrl); HttpsURLConnection con = (HttpsURLConnection) url.openConnection(); con.setRequestProperty("Accept-Language", language); ret = dl(con); } catch (Exception e) { e.printStackTrace(); } return ret; } /**Common functionality between download(String url) and download(String url, String language)*/ private static String dl(HttpsURLConnection con) throws IOException { StringBuilder response = new StringBuilder(); try { con.setRequestMethod("GET"); con.setRequestProperty("User-Agent", USER_AGENT); BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream())); String inputLine; while ((inputLine = in.readLine()) != null) { response.append(inputLine); } in.close(); } catch (UnknownHostException uhe) {//thrown when there's no internet connection uhe.printStackTrace(); //Toast.makeText(getActivity(), uhe.getMessage(), Toast.LENGTH_LONG).show(); } return response.toString(); } /**Download (via HTTP) the text file located at the supplied URL, and return its contents. * Primarily intended for downloading web pages. * @param siteUrl the URL of the text file to download * @return the contents of the specified text file*/ public static String download(String siteUrl) { String ret = ""; try { URL url = new URL(siteUrl); HttpsURLConnection con = NetCipher.getHttpsURLConnection(url); ret = dl(con); } catch (Exception e) { e.printStackTrace(); } return ret; } /** * Downloads a file from a URL in the background using an {@link AsyncTask}. * * @param fileURL HTTP URL of the file to be downloaded * @param saveFilePath path of the directory to save the file * @param title * @throws IOException */ public static void downloadFile(final Context context, final String fileURL, final File saveFilePath, String title) { new Downloader(context, fileURL, saveFilePath, title).execute(); } /** AsyncTask impl: executed in gui thread */ @Override protected void onPreExecute() { super.onPreExecute(); nm = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE); Drawable icon = context.getResources().getDrawable(R.mipmap.ic_launcher); builder = new NotificationCompat.Builder(context).setSmallIcon(android.R.drawable.stat_sys_download) .setLargeIcon(((BitmapDrawable) icon).getBitmap()).setContentTitle(saveFilePath.getName()) .setContentText(saveFilePath.getAbsolutePath()).setProgress(fileSize, 0, false); nm.notify(notifyId, builder.build()); } /** AsyncTask impl: executed in background thread does the download */ @Override protected Void doInBackground(Void... voids) { HttpsURLConnection con = null; InputStream inputStream = null; FileOutputStream outputStream = null; try { con = NetCipher.getHttpsURLConnection(fileURL); int responseCode = con.getResponseCode(); // always check HTTP response code first if (responseCode == HttpURLConnection.HTTP_OK) { fileSize = con.getContentLength(); inputStream = new BufferedInputStream(con.getInputStream()); outputStream = new FileOutputStream(saveFilePath); int bufferSize = 8192; int downloaded = 0; int bytesRead = -1; byte[] buffer = new byte[bufferSize]; while ((bytesRead = inputStream.read(buffer)) != -1) { outputStream.write(buffer, 0, bytesRead); downloaded += bytesRead; if (downloaded % 50000 < bufferSize) { publishProgress(downloaded); } } publishProgress(bufferSize); } else { Log.i(TAG, "No file to download. Server replied HTTP code: " + responseCode); } } catch (IOException e) { Log.e(TAG, "No file to download. Server replied HTTP code: ", e); e.printStackTrace(); } finally { try { if (outputStream != null) { outputStream.close(); outputStream = null; } if (inputStream != null) { inputStream.close(); inputStream = null; } } catch (IOException e) { e.printStackTrace(); } if (con != null) { con.disconnect(); con = null; } } return null; } @Override protected void onProgressUpdate(Integer... progress) { builder.setProgress(fileSize, progress[0], false); nm.notify(notifyId, builder.build()); } @Override protected void onPostExecute(Void aVoid) { super.onPostExecute(aVoid); nm.cancel(notifyId); } }