Java tutorial
/* This file is part of Subsonic. Subsonic 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. Subsonic 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 Subsonic. If not, see <http://www.gnu.org/licenses/>. Copyright 2009 (C) Sindre Mehus */ package net.sourceforge.kalimbaradio.androidapp.util; import android.app.Activity; import android.app.AlertDialog; import android.content.ComponentName; import android.content.Context; import android.content.DialogInterface; import android.content.Intent; import android.content.SharedPreferences; import android.content.pm.ApplicationInfo; import android.content.pm.PackageManager; import android.content.res.Resources; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.graphics.drawable.BitmapDrawable; import android.graphics.drawable.Drawable; import android.media.AudioManager; import android.net.ConnectivityManager; import android.net.NetworkInfo; import android.net.wifi.WifiManager; import android.os.Build; import android.os.Environment; import android.util.DisplayMetrics; import android.view.Gravity; import android.widget.Toast; import net.sourceforge.kalimbaradio.androidapp.domain.Version; import net.sourceforge.kalimbaradio.androidapp.receiver.MediaButtonIntentReceiver; import net.sourceforge.kalimbaradio.androidapp.R; import net.sourceforge.kalimbaradio.androidapp.domain.RepeatMode; import org.apache.http.HttpEntity; import java.io.ByteArrayOutputStream; import java.io.Closeable; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.io.UnsupportedEncodingException; import java.lang.reflect.Constructor; import java.lang.reflect.Method; import java.security.MessageDigest; import java.text.DecimalFormat; import java.text.NumberFormat; import java.util.List; import java.util.Map; import java.util.concurrent.ConcurrentHashMap; /** * @author Sindre Mehus * @version $Id: Util.java 4052 2014-05-26 15:17:55Z sindre_mehus $ */ public final class Util { private static final Logger LOG = new Logger(Util.class); private static final DecimalFormat GIGA_BYTE_FORMAT = new DecimalFormat("0.00 GB"); private static final DecimalFormat MEGA_BYTE_FORMAT = new DecimalFormat("0.00 MB"); private static final DecimalFormat KILO_BYTE_FORMAT = new DecimalFormat("0 KB"); private static DecimalFormat GIGA_BYTE_LOCALIZED_FORMAT = null; private static DecimalFormat MEGA_BYTE_LOCALIZED_FORMAT = null; private static DecimalFormat KILO_BYTE_LOCALIZED_FORMAT = null; private static DecimalFormat BYTE_LOCALIZED_FORMAT = null; private static final Map<Integer, Version> SERVER_REST_VERSIONS = new ConcurrentHashMap<Integer, Version>(); // Used by hexEncode() private static final char[] HEX_DIGITS = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' }; private static Toast toast; private Util() { } public static boolean isScreenLitOnDownload(Context context) { SharedPreferences prefs = getPreferences(context); return prefs.getBoolean(Constants.PREFERENCES_KEY_SCREEN_LIT_ON_DOWNLOAD, false); } public static RepeatMode getRepeatMode(Context context) { SharedPreferences prefs = getPreferences(context); return RepeatMode.valueOf(prefs.getString(Constants.PREFERENCES_KEY_REPEAT_MODE, RepeatMode.OFF.name())); } public static void setRepeatMode(Context context, RepeatMode repeatMode) { SharedPreferences prefs = getPreferences(context); SharedPreferences.Editor editor = prefs.edit(); editor.putString(Constants.PREFERENCES_KEY_REPEAT_MODE, repeatMode.name()); editor.commit(); } public static boolean isScrobblingEnabled(Context context) { if (isOffline(context)) { return false; } SharedPreferences prefs = getPreferences(context); return prefs.getBoolean(Constants.PREFERENCES_KEY_SCROBBLE, false); } public static boolean isOffline(Context context) { SharedPreferences prefs = getPreferences(context); return prefs.getBoolean(Constants.PREFERENCES_KEY_OFFLINE, false); } public static void setOffline(Context context, boolean offline) { SharedPreferences prefs = getPreferences(context); SharedPreferences.Editor editor = prefs.edit(); editor.putBoolean(Constants.PREFERENCES_KEY_OFFLINE, offline); editor.commit(); } public static ServerSettingsManager.ServerSettings getActiveServer(Context context) { return new ServerSettingsManager(context).getActiveServer(); } public static void setServerRestVersion(Context context, Version version) { SERVER_REST_VERSIONS.put(getActiveServer(context).getId(), version); } public static Version getServerRestVersion(Context context) { return SERVER_REST_VERSIONS.get(getActiveServer(context).getId()); } public static void setSelectedMusicFolderId(Context context, String musicFolderId) { int instance = getActiveServer(context).getId(); SharedPreferences prefs = getPreferences(context); SharedPreferences.Editor editor = prefs.edit(); editor.putString(Constants.PREFERENCES_KEY_MUSIC_FOLDER_ID + instance, musicFolderId); editor.commit(); } public static String getSelectedMusicFolderId(Context context) { SharedPreferences prefs = getPreferences(context); int instance = getActiveServer(context).getId(); return prefs.getString(Constants.PREFERENCES_KEY_MUSIC_FOLDER_ID + instance, null); } public static int getMaxBitrate(Context context) { ConnectivityManager manager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE); NetworkInfo networkInfo = manager.getActiveNetworkInfo(); if (networkInfo == null) { return 0; } boolean wifi = networkInfo.getType() == ConnectivityManager.TYPE_WIFI; SharedPreferences prefs = getPreferences(context); return Integer.parseInt(prefs.getString( wifi ? Constants.PREFERENCES_KEY_MAX_BITRATE_WIFI : Constants.PREFERENCES_KEY_MAX_BITRATE_MOBILE, "0")); } public static int getPreloadCount(Context context) { SharedPreferences prefs = getPreferences(context); int preloadCount = Integer.parseInt(prefs.getString(Constants.PREFERENCES_KEY_PRELOAD_COUNT, "-1")); return preloadCount == -1 ? 3 : preloadCount; } public static VideoPlayerType getVideoPlayerType(Context context) { SharedPreferences prefs = getPreferences(context); return VideoPlayerType .forKey(prefs.getString(Constants.PREFERENCES_KEY_VIDEO_PLAYER, VideoPlayerType.MX.getKey())); } public static int getCacheSizeMB(Context context) { SharedPreferences prefs = getPreferences(context); int cacheSize = Integer.parseInt(prefs.getString(Constants.PREFERENCES_KEY_CACHE_SIZE, "-1")); return cacheSize == -1 ? 50 : cacheSize; } public static String getRestUrl(Context context, String method) { StringBuilder builder = new StringBuilder(); ServerSettingsManager serverMgr = new ServerSettingsManager(context); ServerSettingsManager.ServerSettings server = serverMgr.getActiveServer(); String serverUrl = server.getUrl(); String username = server.getUsername(); String password = server.getPassword(); // Slightly obfuscate password password = "enc:" + Util.utf8HexEncode(password); builder.append(serverUrl); if (builder.charAt(builder.length() - 1) != '/') { builder.append("/"); } builder.append("rest/").append(method).append(".view"); builder.append("?u=").append(username); builder.append("&p=").append(password); builder.append("&v=").append(Constants.REST_PROTOCOL_VERSION); builder.append("&c=").append(Constants.REST_CLIENT_ID); return builder.toString(); } public static SharedPreferences getPreferences(Context context) { return context.getSharedPreferences(Constants.PREFERENCES_FILE_NAME, 0); } public static String getContentType(HttpEntity entity) { if (entity == null || entity.getContentType() == null) { return null; } return entity.getContentType().getValue(); } /** * Get the contents of an <code>InputStream</code> as a <code>byte[]</code>. * <p/> * This method buffers the input internally, so there is no need to use a * <code>BufferedInputStream</code>. * * @param input the <code>InputStream</code> to read from * @return the requested byte array * @throws NullPointerException if the input is null * @throws IOException if an I/O error occurs */ public static byte[] toByteArray(InputStream input) throws IOException { ByteArrayOutputStream output = new ByteArrayOutputStream(); copy(input, output); return output.toByteArray(); } public static long copy(InputStream input, OutputStream output) throws IOException { byte[] buffer = new byte[1024 * 4]; long count = 0; int n; while (-1 != (n = input.read(buffer))) { output.write(buffer, 0, n); count += n; } return count; } public static void atomicCopy(File from, File to) throws IOException { FileInputStream in = null; FileOutputStream out = null; File tmp = null; try { tmp = new File(to.getPath() + ".tmp"); in = new FileInputStream(from); out = new FileOutputStream(tmp); in.getChannel().transferTo(0, from.length(), out.getChannel()); out.close(); if (!tmp.renameTo(to)) { throw new IOException("Failed to rename " + tmp + " to " + to); } LOG.info("Copied " + from + " to " + to); } catch (IOException x) { close(out); delete(to); throw x; } finally { close(in); close(out); delete(tmp); } } public static void close(Closeable closeable) { try { if (closeable != null) { closeable.close(); } } catch (Throwable x) { // Ignored } } public static boolean delete(File file) { if (file != null && file.exists()) { if (!file.delete()) { LOG.warn("Failed to delete file " + file); return false; } LOG.info("Deleted file " + file); } return true; } public static void toast(Context context, int messageId) { toast(context, messageId, true); } public static void toast(Context context, int messageId, boolean shortDuration, Object... formatArgs) { toast(context, context.getString(messageId, formatArgs), shortDuration); } public static void toast(Context context, String message) { toast(context, message, true); } public static void toast(Context context, String message, boolean shortDuration) { if (toast == null) { toast = Toast.makeText(context, message, shortDuration ? Toast.LENGTH_SHORT : Toast.LENGTH_LONG); toast.setGravity(Gravity.CENTER, 0, 0); } else { toast.setText(message); toast.setDuration(shortDuration ? Toast.LENGTH_SHORT : Toast.LENGTH_LONG); } toast.show(); } /** * Converts a byte-count to a formatted string suitable for display to the user. * For instance: * <ul> * <li><code>format(918)</code> returns <em>"918 B"</em>.</li> * <li><code>format(98765)</code> returns <em>"96 KB"</em>.</li> * <li><code>format(1238476)</code> returns <em>"1.2 MB"</em>.</li> * </ul> * This method assumes that 1 KB is 1024 bytes. * To get a localized string, please use formatLocalizedBytes instead. * * @param byteCount The number of bytes. * @return The formatted string. */ public static synchronized String formatBytes(long byteCount) { // More than 1 GB? if (byteCount >= 1024 * 1024 * 1024) { NumberFormat gigaByteFormat = GIGA_BYTE_FORMAT; return gigaByteFormat.format((double) byteCount / (1024 * 1024 * 1024)); } // More than 1 MB? if (byteCount >= 1024 * 1024) { NumberFormat megaByteFormat = MEGA_BYTE_FORMAT; return megaByteFormat.format((double) byteCount / (1024 * 1024)); } // More than 1 KB? if (byteCount >= 1024) { NumberFormat kiloByteFormat = KILO_BYTE_FORMAT; return kiloByteFormat.format((double) byteCount / 1024); } return byteCount + " B"; } /** * Converts a byte-count to a formatted string suitable for display to the user. * For instance: * <ul> * <li><code>format(918)</code> returns <em>"918 B"</em>.</li> * <li><code>format(98765)</code> returns <em>"96 KB"</em>.</li> * <li><code>format(1238476)</code> returns <em>"1.2 MB"</em>.</li> * </ul> * This method assumes that 1 KB is 1024 bytes. * This version of the method returns a localized string. * * @param byteCount The number of bytes. * @return The formatted string. */ public static synchronized String formatLocalizedBytes(long byteCount, Context context) { // More than 1 GB? if (byteCount >= 1024 * 1024 * 1024) { if (GIGA_BYTE_LOCALIZED_FORMAT == null) { GIGA_BYTE_LOCALIZED_FORMAT = new DecimalFormat( context.getResources().getString(R.string.util_bytes_format_gigabyte)); } return GIGA_BYTE_LOCALIZED_FORMAT.format((double) byteCount / (1024 * 1024 * 1024)); } // More than 1 MB? if (byteCount >= 1024 * 1024) { if (MEGA_BYTE_LOCALIZED_FORMAT == null) { MEGA_BYTE_LOCALIZED_FORMAT = new DecimalFormat( context.getResources().getString(R.string.util_bytes_format_megabyte)); } return MEGA_BYTE_LOCALIZED_FORMAT.format((double) byteCount / (1024 * 1024)); } // More than 1 KB? if (byteCount >= 1024) { if (KILO_BYTE_LOCALIZED_FORMAT == null) { KILO_BYTE_LOCALIZED_FORMAT = new DecimalFormat( context.getResources().getString(R.string.util_bytes_format_kilobyte)); } return KILO_BYTE_LOCALIZED_FORMAT.format((double) byteCount / 1024); } if (BYTE_LOCALIZED_FORMAT == null) { BYTE_LOCALIZED_FORMAT = new DecimalFormat( context.getResources().getString(R.string.util_bytes_format_byte)); } return BYTE_LOCALIZED_FORMAT.format((double) byteCount); } public static String formatDuration(Integer seconds) { if (seconds == null) { return null; } int minutes = seconds / 60; int secs = seconds % 60; StringBuilder builder = new StringBuilder(6); builder.append(minutes).append(":"); if (secs < 10) { builder.append("0"); } builder.append(secs); return builder.toString(); } public static boolean equals(Object object1, Object object2) { if (object1 == object2) { return true; } if (object1 == null || object2 == null) { return false; } return object1.equals(object2); } /** * Encodes the given string by using the hexadecimal representation of its UTF-8 bytes. * * @param s The string to encode. * @return The encoded string. */ public static String utf8HexEncode(String s) { if (s == null) { return null; } byte[] utf8; try { utf8 = s.getBytes(Constants.UTF_8); } catch (UnsupportedEncodingException x) { throw new RuntimeException(x); } return hexEncode(utf8); } /** * Converts an array of bytes into an array of characters representing the hexadecimal values of each byte in order. * The returned array will be double the length of the passed array, as it takes two characters to represent any * given byte. * * @param data Bytes to convert to hexadecimal characters. * @return A string containing hexadecimal characters. */ public static String hexEncode(byte[] data) { int length = data.length; char[] out = new char[length << 1]; // two characters form the hex value. for (int i = 0, j = 0; i < length; i++) { out[j++] = HEX_DIGITS[(0xF0 & data[i]) >>> 4]; out[j++] = HEX_DIGITS[0x0F & data[i]]; } return new String(out); } /** * Calculates the MD5 digest and returns the value as a 32 character hex string. * * @param s Data to digest. * @return MD5 digest as a hex string. */ public static String md5Hex(String s) { if (s == null) { return null; } try { MessageDigest md5 = MessageDigest.getInstance("MD5"); return hexEncode(md5.digest(s.getBytes(Constants.UTF_8))); } catch (Exception x) { throw new RuntimeException(x.getMessage(), x); } } public static boolean isNetworkConnected(Context context) { ConnectivityManager manager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE); NetworkInfo networkInfo = manager.getActiveNetworkInfo(); boolean connected = networkInfo != null && networkInfo.isConnected(); boolean wifiConnected = connected && networkInfo.getType() == ConnectivityManager.TYPE_WIFI; boolean wifiRequired = isWifiRequiredForDownload(context); return connected && (!wifiRequired || wifiConnected); } public static boolean isExternalStoragePresent() { return Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState()); } private static boolean isWifiRequiredForDownload(Context context) { SharedPreferences prefs = getPreferences(context); return prefs.getBoolean(Constants.PREFERENCES_KEY_WIFI_REQUIRED_FOR_DOWNLOAD, false); } public static void info(Context context, int titleId, int messageId) { showDialog(context, android.R.drawable.ic_dialog_info, titleId, messageId); } private static void showDialog(Context context, int icon, int titleId, int messageId) { new AlertDialog.Builder(context).setIcon(icon).setTitle(titleId).setMessage(messageId) .setPositiveButton(R.string.common_ok, new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int i) { dialog.dismiss(); } }).show(); } public static boolean isPackageInstalled(Context context, String packageName) { PackageManager pm = context.getPackageManager(); List<ApplicationInfo> packages = pm.getInstalledApplications(0); for (ApplicationInfo packageInfo : packages) { if (packageInfo.packageName.equals(packageName)) { return true; } } return false; } public static void sleepQuietly(long millis) { try { Thread.sleep(millis); } catch (InterruptedException x) { LOG.warn("Interrupted from sleep.", x); } } public static void startActivityWithoutTransition(Activity currentActivity, Class<? extends Activity> newActivitiy) { startActivityWithoutTransition(currentActivity, new Intent(currentActivity, newActivitiy)); } public static void startActivityWithoutTransition(Activity currentActivity, Intent intent) { currentActivity.startActivity(intent); disablePendingTransition(currentActivity); } public static void disablePendingTransition(Activity activity) { // Activity.overridePendingTransition() was introduced in Android 2.0. Use reflection to maintain // compatibility with 1.5. try { Method method = Activity.class.getMethod("overridePendingTransition", int.class, int.class); method.invoke(activity, 0, 0); } catch (Throwable x) { // Ignored } } public static Drawable createDrawableFromBitmap(Context context, Bitmap bitmap) { // BitmapDrawable(Resources, Bitmap) was introduced in Android 1.6. Use reflection to maintain // compatibility with 1.5. try { Constructor<BitmapDrawable> constructor = BitmapDrawable.class.getConstructor(Resources.class, Bitmap.class); return constructor.newInstance(context.getResources(), bitmap); } catch (Throwable x) { return new BitmapDrawable(bitmap); } } public static void registerMediaButtonEventReceiver(Context context) { // Only do it if enabled in the settings. SharedPreferences prefs = getPreferences(context); boolean enabled = prefs.getBoolean(Constants.PREFERENCES_KEY_MEDIA_BUTTONS, true); if (enabled) { AudioManager audioManager = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE); ComponentName mediaButtonIntentReceiver = new ComponentName(context.getPackageName(), MediaButtonIntentReceiver.class.getName()); audioManager.registerMediaButtonEventReceiver(mediaButtonIntentReceiver); } } public static void unregisterMediaButtonEventReceiver(Context context) { AudioManager audioManager = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE); ComponentName mediaButtonIntentReceiver = new ComponentName(context.getPackageName(), MediaButtonIntentReceiver.class.getName()); audioManager.unregisterMediaButtonEventReceiver(mediaButtonIntentReceiver); } public static WifiManager.WifiLock createWifiLock(Context context, String tag) { WifiManager wm = (WifiManager) context.getSystemService(Context.WIFI_SERVICE); int lockType = WifiManager.WIFI_MODE_FULL; // Use WIFI_MODE_FULL_HIGH_PERF if API level 12 or higher. if (Build.VERSION.SDK_INT >= 12) { lockType = 3; // WifiManager.WIFI_MODE_FULL_HIGH_PERF } return wm.createWifiLock(lockType, tag); } /** * This method converts dp unit to equivalent pixels, depending on device density. * * @param dp A value in dp (density independent pixels) unit. Which we need to convert into pixels * @param context Context to get resources and device specific display metrics * @return A float value to represent px equivalent to dp depending on device density */ public static float convertDpToPixel(float dp, Context context) { Resources resources = context.getResources(); DisplayMetrics metrics = resources.getDisplayMetrics(); return dp * (metrics.densityDpi / (float) DisplayMetrics.DENSITY_MEDIUM); } /** * This method converts device specific pixels to density independent pixels. * * @param px A value in px (pixels) unit. Which we need to convert into db * @param context Context to get resources and device specific display metrics * @return A float value to represent dp equivalent to px value */ public static float convertPixelsToDp(float px, Context context) { Resources resources = context.getResources(); DisplayMetrics metrics = resources.getDisplayMetrics(); return px / (metrics.densityDpi / (float) DisplayMetrics.DENSITY_MEDIUM); } public static void setUncaughtExceptionHandler(Context context) { Thread.UncaughtExceptionHandler handler = Thread.getDefaultUncaughtExceptionHandler(); if (!(handler instanceof SubsonicUncaughtExceptionHandler)) { Thread.setDefaultUncaughtExceptionHandler(new SubsonicUncaughtExceptionHandler(context)); } } public static Bitmap decodeBitmap(Context context, int resourceId) { return BitmapFactory.decodeResource(context.getResources(), resourceId); } public static boolean isServerCompatibleTo(Context context, String version) { Version serverVersion = getServerRestVersion(context); Version requiredVersion = new Version(version); return serverVersion == null || serverVersion.compareTo(requiredVersion) >= 0; } }