Java tutorial
/* * Copyright (C) 2011 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package be.ugent.zeus.hydra.util.audiostream; import android.app.Notification; import android.app.NotificationManager; import android.app.PendingIntent; import android.app.Service; import android.content.ComponentName; import android.content.Context; import android.content.Intent; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.media.AudioManager; import android.media.MediaMetadataRetriever; import android.media.MediaPlayer; import android.media.MediaPlayer.OnCompletionListener; import android.media.MediaPlayer.OnErrorListener; import android.media.MediaPlayer.OnPreparedListener; import android.media.RemoteControlClient; import android.net.wifi.WifiManager; import android.net.wifi.WifiManager.WifiLock; import android.os.IBinder; import android.os.PowerManager; import android.support.v4.app.NotificationCompat; import android.util.Log; import android.widget.Toast; import be.ugent.zeus.hydra.R; import be.ugent.zeus.hydra.Urgent; import java.io.IOException; /** * Service that handles media playback. This is the Service through which we perform all the media * handling in our application. Upon initialization, it starts a {@link MusicRetriever} to scan the * user's media. Then, it waits for Intents (which come from our main activity, * {@link MainActivity}, which signal the service to perform specific operations: Play, Pause, * Rewind, Skip, etc. */ public class MusicService extends Service implements OnCompletionListener, OnPreparedListener, OnErrorListener, MusicFocusable { // Stream URL final static String URL = "http://urgent.stream.flumotion.com/urgent/high.mp3.m3u"; // The tag we put on debug messages final static String TAG = "Urgent.fm"; // These are the Intent actions that we are prepared to handle. Notice that the fact these // constants exist in our class is a mere convenience: what really defines the actions our // service can handle are the <action> tags in the <intent-filters> tag for our service in // AndroidManifest.xml. public static final String ACTION_TOGGLE_PLAYBACK = "be.ugent.zeus.hydra.util.audiostream.action.TOGGLE_PLAYBACK"; public static final String ACTION_PLAY = "be.ugent.zeus.hydra.util.audiostream.action.PLAY"; public static final String ACTION_PAUSE = "be.ugent.zeus.hydra.util.audiostream.action.PAUSE"; public static final String ACTION_STOP = "be.ugent.zeus.hydra.util.audiostream.action.STOP"; // The volume we set the media player to when we lose audio focus, but are allowed to reduce // the volume instead of stopping playback. public static final float DUCK_VOLUME = 0.1f; public static final boolean DEBUG = false; // our media player MediaPlayer mPlayer = null; // our AudioFocusHelper object, if it's available (it's available on SDK level >= 8) // If not available, this will be null. Always check for null before using! AudioFocusHelper mAudioFocusHelper = null; // indicates the state our service: public static enum State { Stopped, // media player is stopped and not prepared to play Preparing, // media player is preparing... Playing, // playback active (media player ready!). (but the media player may actually be // paused in this state if we don't have audio focus. But we stay in this state // so that we know we have to resume playback once we get focus back) Paused // playback paused (media player ready!) }; public static State mState = State.Stopped; // if in Retrieving mode, this flag indicates whether we should start playing immediately // when we are ready or not. boolean mStartPlayingAfterRetrieve = false; enum PauseReason { UserRequest, // paused by user request FocusLoss, // paused because of audio focus loss }; // why did we pause? (only relevant if mState == State.Paused) PauseReason mPauseReason = PauseReason.UserRequest; // do we have audio focus? enum AudioFocus { NoFocusNoDuck, // we don't have audio focus, and can't duck NoFocusCanDuck, // we don't have focus, but can play at a low volume ("ducking") Focused // we have full audio focus } AudioFocus mAudioFocus = AudioFocus.NoFocusNoDuck; // title of the song we are currently playing String mSongTitle = ""; // whether the song we are playing is streaming from the network boolean mIsStreaming = false; // Wifi lock that we hold when streaming files from the internet, in order to prevent the // device from shutting off the Wifi radio WifiLock mWifiLock; // The ID we use for the notification (the onscreen alert that appears at the notification // area at the top of the screen as an icon -- and as text as well if the user expands the // notification area). final int NOTIFICATION_ID = 1; // our RemoteControlClient object, which will use remote control APIs available in // SDK level >= 14, if they're available. RemoteControlClientCompat mRemoteControlClientCompat; // Dummy album art we will pass to the remote control (if the APIs are available). Bitmap mDummyAlbumArt; // The component name of MusicIntentReceiver, for use with media button and remote control // APIs ComponentName mMediaButtonReceiverComponent; AudioManager mAudioManager; NotificationManager mNotificationManager; Notification mNotification = null; /** * Makes sure the media player exists and has been reset. This will create the media player if * needed, or reset the existing media player if one already exists. */ void createMediaPlayerIfNeeded() { if (mPlayer == null) { mPlayer = new MediaPlayer(); // Make sure the media player will acquire a wake-lock while playing. If we don't do // that, the CPU might go to sleep while the song is playing, causing playback to stop. // // Remember that to use this, we have to declare the android.permission.WAKE_LOCK // permission in AndroidManifest.xml. mPlayer.setWakeMode(getApplicationContext(), PowerManager.PARTIAL_WAKE_LOCK); // we want the media player to notify us when it's ready preparing, and when it's done // playing: mPlayer.setOnPreparedListener(this); mPlayer.setOnCompletionListener(this); mPlayer.setOnErrorListener(this); } else { mPlayer.reset(); } } @Override public void onCreate() { Log.i(TAG, "debug: Creating service"); // Create the Wifi lock (this does not acquire the lock, this just creates it) mWifiLock = ((WifiManager) getSystemService(Context.WIFI_SERVICE)) .createWifiLock(WifiManager.WIFI_MODE_FULL, "mylock"); mNotificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE); mAudioManager = (AudioManager) getSystemService(AUDIO_SERVICE); if (mStartPlayingAfterRetrieve) { tryToGetAudioFocus(); playStream(); } // create the Audio Focus Helper, if the Audio Focus feature is available (SDK 8 or above) if (android.os.Build.VERSION.SDK_INT >= 8) { mAudioFocusHelper = new AudioFocusHelper(getApplicationContext(), this); } else { mAudioFocus = AudioFocus.Focused; // no focus feature, so we always "have" audio focus } mDummyAlbumArt = BitmapFactory.decodeResource(getResources(), R.drawable.urgent_lockart); mMediaButtonReceiverComponent = new ComponentName(this, MusicIntentReceiver.class); } /** * Called when we receive an Intent. When we receive an intent sent to us via startService(), * this is the method that gets called. So here we react appropriately depending on the Intent's * action, which specifies what is being requested of us. */ @Override public int onStartCommand(Intent intent, int flags, int startId) { String action = intent.getAction(); if (action.equals(ACTION_TOGGLE_PLAYBACK)) { processTogglePlaybackRequest(); } else if (action.equals(ACTION_PLAY)) { processPlayRequest(); } else if (action.equals(ACTION_PAUSE)) { processPauseRequest(); } else if (action.equals(ACTION_STOP)) { processStopRequest(); } return START_NOT_STICKY; // Means we started the service, but don't want it to // restart in case it's killed. } void processTogglePlaybackRequest() { if (mState == State.Paused || mState == State.Stopped) { processPlayRequest(); } else { processPauseRequest(); } } void processPlayRequest() { tryToGetAudioFocus(); // actually play the song if (mState == State.Stopped) { // If we're stopped, just go ahead to the next song and start playing playStream(); } else if (mState == State.Paused) { // If we're paused, just continue playback and restore the 'foreground service' state. mState = State.Playing; setUpAsForeground(mSongTitle + " (playing)"); configAndStartMediaPlayer(); } // Tell any remote controls that our playback state is 'playing'. if (mRemoteControlClientCompat != null) { mRemoteControlClientCompat.setPlaybackState(RemoteControlClient.PLAYSTATE_PLAYING); } } void processPauseRequest() { if (mState == State.Playing) { // Pause media player and cancel the 'foreground service' state. mState = State.Paused; mPlayer.pause(); relaxResources(false); // while paused, we always retain the MediaPlayer // do not give up audio focus } // Tell any remote controls that our playback state is 'paused'. if (mRemoteControlClientCompat != null) { mRemoteControlClientCompat.setPlaybackState(RemoteControlClient.PLAYSTATE_PAUSED); } } void processStopRequest() { processStopRequest(false); } void processStopRequest(boolean force) { if (mState == State.Playing || mState == State.Paused || force) { mState = State.Stopped; // let go of all resources... relaxResources(true); giveUpAudioFocus(); // Tell any remote controls that our playback state is 'paused'. if (mRemoteControlClientCompat != null) { mRemoteControlClientCompat.setPlaybackState(RemoteControlClient.PLAYSTATE_STOPPED); } // service is no longer necessary. Will be started again if needed. stopSelf(); } } /** * Releases resources used by the service for playback. This includes the "foreground service" * status and notification, the wake locks and possibly the MediaPlayer. * * @param releaseMediaPlayer Indicates whether the Media Player should also be released or not */ void relaxResources(boolean releaseMediaPlayer) { // stop being a foreground service stopForeground(true); // stop and release the Media Player, if it's available if (releaseMediaPlayer && mPlayer != null) { mPlayer.reset(); mPlayer.release(); mPlayer = null; } // we can also release the Wifi lock, if we're holding it if (mWifiLock.isHeld()) { mWifiLock.release(); } } void giveUpAudioFocus() { if (mAudioFocus == AudioFocus.Focused && mAudioFocusHelper != null && mAudioFocusHelper.abandonFocus()) { mAudioFocus = AudioFocus.NoFocusNoDuck; } } /** * Reconfigures MediaPlayer according to audio focus settings and starts/restarts it. This * method starts/restarts the MediaPlayer respecting the current audio focus state. So if we * have focus, it will play normally; if we don't have focus, it will either leave the * MediaPlayer paused or set it to a low volume, depending on what is allowed by the current * focus settings. This method assumes mPlayer != null, so if you are calling it, you have to do * so from a context where you are sure this is the case. */ void configAndStartMediaPlayer() { if (mAudioFocus == AudioFocus.NoFocusNoDuck) { // If we don't have audio focus and can't duck, we have to pause, even if mState // is State.Playing. But we stay in the Playing state so that we know we have to resume // playback once we get the focus back. if (mPlayer.isPlaying()) { mPlayer.pause(); } return; } else if (mAudioFocus == AudioFocus.NoFocusCanDuck) { mPlayer.setVolume(DUCK_VOLUME, DUCK_VOLUME); } // we'll be relatively quiet else { mPlayer.setVolume(1.0f, 1.0f); } // we can be loud if (!mPlayer.isPlaying()) { mPlayer.start(); } } void tryToGetAudioFocus() { if (mAudioFocus != AudioFocus.Focused && mAudioFocusHelper != null && mAudioFocusHelper.requestFocus()) { mAudioFocus = AudioFocus.Focused; } } void playStream() { new ParseStreamAsyncTask(this).execute(URL); } /** * Starts playing the next song. If manualUrl is null, the next song will be randomly selected * from our Media Retriever (that is, it will be a random song in the user's device). If * manualUrl is non-null, then it specifies the URL or path to the song that will be played * next. */ void playmp3(String mp3url) { mState = State.Stopped; relaxResources(false); // release everything except MediaPlayer try { // set the source of the media player to a manual URL or path createMediaPlayerIfNeeded(); mPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC); mPlayer.setDataSource(mp3url); mIsStreaming = true; mSongTitle = "Urgent.fm"; mState = State.Preparing; setUpAsForeground(mSongTitle + " (loading)"); // Use the media button APIs (if available) to register ourselves for media button // events MediaButtonHelper.registerMediaButtonEventReceiverCompat(mAudioManager, mMediaButtonReceiverComponent); // Use the remote control APIs (if available) to set the playback state if (mRemoteControlClientCompat == null) { Intent intent = new Intent(Intent.ACTION_MEDIA_BUTTON); intent.setComponent(mMediaButtonReceiverComponent); mRemoteControlClientCompat = new RemoteControlClientCompat(PendingIntent.getBroadcast( this /*context*/, 0 /*requestCode, ignored*/, intent /*intent*/, 0 /*flags*/)); RemoteControlHelper.registerRemoteControlClient(mAudioManager, mRemoteControlClientCompat); } mRemoteControlClientCompat.setPlaybackState(RemoteControlClient.PLAYSTATE_PLAYING); mRemoteControlClientCompat.setTransportControlFlags(RemoteControlClient.FLAG_KEY_MEDIA_PLAY | RemoteControlClient.FLAG_KEY_MEDIA_PAUSE | RemoteControlClient.FLAG_KEY_MEDIA_STOP); // Update the remote controls mRemoteControlClientCompat.editMetadata(true) .putString(MediaMetadataRetriever.METADATA_KEY_TITLE, "Urgent.fm") .putBitmap(RemoteControlClientCompat.MetadataEditorCompat.METADATA_KEY_ARTWORK, mDummyAlbumArt) .apply(); // starts preparing the media player in the background. When it's done, it will call // our OnPreparedListener (that is, the onPrepared() method on this class, since we set // the listener to 'this'). // // Until the media player is prepared, we *cannot* call start() on it! mPlayer.prepareAsync(); // If we are streaming from the internet, we want to hold a Wifi lock, which prevents // the Wifi radio from going to sleep while the song is playing. If, on the other hand, // we are *not* streaming, we want to release the lock if we were holding it before. if (mIsStreaming) { mWifiLock.acquire(); } else if (mWifiLock.isHeld()) { mWifiLock.release(); } } catch (IOException ex) { Log.e("MusicService", "IOException playing next song: " + ex.getMessage()); ex.printStackTrace(); } } /** * Called when media player is done playing current song. */ public void onCompletion(MediaPlayer player) { // The media player finished playing the current song, so we go ahead and start the next. playStream(); } /** * Called when media player is done preparing. */ public void onPrepared(MediaPlayer player) { // The media player is done preparing. That means we can start playing! mState = State.Playing; updateNotification(mSongTitle + " (playing)"); configAndStartMediaPlayer(); } /** * Updates the notification. */ void updateNotification(String text) { PendingIntent pi = PendingIntent.getActivity(getApplicationContext(), 0, new Intent(getApplicationContext(), Urgent.class), PendingIntent.FLAG_UPDATE_CURRENT); mNotification.setLatestEventInfo(getApplicationContext(), "Urgent.fm", text, pi); mNotificationManager.notify(NOTIFICATION_ID, mNotification); } /** * Configures service as a foreground service. A foreground service is a service that's doing * something the user is actively aware of (such as playing music), and must appear to the user * as a notification. That's why we create the notification here. */ void setUpAsForeground(String text) { PendingIntent pi = PendingIntent.getActivity(getApplicationContext(), 0, new Intent(getApplicationContext(), Urgent.class), PendingIntent.FLAG_UPDATE_CURRENT); mNotification = new NotificationCompat.Builder(getApplicationContext()).setSmallIcon(R.drawable.urgent_icon) .setTicker(text).setContentTitle("Urgent.fm livestream").setContentText(text).setContentIntent(pi) .build(); mNotification.flags |= Notification.FLAG_ONGOING_EVENT; startForeground(NOTIFICATION_ID, mNotification); } /** * Called when there's an error playing media. When this happens, the media player goes to the * Error state. We warn the user about the error and reset the media player. */ public boolean onError(MediaPlayer mp, int what, int extra) { Toast.makeText(getApplicationContext(), "Media player error! Resetting.", Toast.LENGTH_SHORT).show(); Log.e(TAG, "Error: what=" + String.valueOf(what) + ", extra=" + String.valueOf(extra)); mState = State.Stopped; relaxResources(true); giveUpAudioFocus(); return true; // true indicates we handled the error } public void onGainedAudioFocus() { if (MusicService.DEBUG) { Toast.makeText(getApplicationContext(), "gained audio focus.", Toast.LENGTH_SHORT).show(); } mAudioFocus = AudioFocus.Focused; // restart media player with new focus settings if (mState == State.Playing) { configAndStartMediaPlayer(); } } public void onLostAudioFocus(boolean canDuck) { mAudioFocus = canDuck ? AudioFocus.NoFocusCanDuck : AudioFocus.NoFocusNoDuck; // start/restart/pause media player with new focus settings if (mPlayer != null && mPlayer.isPlaying()) { configAndStartMediaPlayer(); } } @Override public void onDestroy() { // Service is being killed, so make sure we release our resources mState = State.Stopped; relaxResources(true); giveUpAudioFocus(); } @Override public IBinder onBind(Intent arg0) { return null; } }