Java tutorial
/* * Copyright (C) 2014 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 org.copticchurchlibrary.arabicreader.playback; import android.content.BroadcastReceiver; import android.content.Context; import android.content.Intent; import android.content.IntentFilter; import android.media.AudioManager; import android.media.MediaPlayer; import android.net.wifi.WifiManager; import android.os.PowerManager; import android.support.v4.media.MediaMetadataCompat; import android.support.v4.media.session.PlaybackStateCompat; import android.text.TextUtils; import org.copticchurchlibrary.arabicreader.MusicService; import org.copticchurchlibrary.arabicreader.model.MusicProvider; import org.copticchurchlibrary.arabicreader.model.MusicProviderSource; import org.copticchurchlibrary.arabicreader.utils.LogHelper; import org.copticchurchlibrary.arabicreader.utils.MediaIDHelper; import java.io.IOException; import static android.media.MediaPlayer.OnCompletionListener; import static android.media.MediaPlayer.OnErrorListener; import static android.media.MediaPlayer.OnPreparedListener; import static android.media.MediaPlayer.OnSeekCompleteListener; import static android.support.v4.media.session.MediaSessionCompat.QueueItem; /** * A class that implements local media playback using {@link android.media.MediaPlayer} */ public class LocalPlayback implements Playback, AudioManager.OnAudioFocusChangeListener, OnCompletionListener, OnErrorListener, OnPreparedListener, OnSeekCompleteListener { private static final String TAG = LogHelper.makeLogTag(LocalPlayback.class); // 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 VOLUME_DUCK = 0.2f; // The volume we set the media player when we have audio focus. public static final float VOLUME_NORMAL = 1.0f; // we don't have audio focus, and can't duck (play at a low volume) private static final int AUDIO_NO_FOCUS_NO_DUCK = 0; // we don't have focus, but can duck (play at a low volume) private static final int AUDIO_NO_FOCUS_CAN_DUCK = 1; // we have full audio focus private static final int AUDIO_FOCUSED = 2; private final Context mContext; private final WifiManager.WifiLock mWifiLock; private int mState; private boolean mPlayOnFocusGain; private Callback mCallback; private final MusicProvider mMusicProvider; private volatile boolean mAudioNoisyReceiverRegistered; private volatile int mCurrentPosition; private volatile String mCurrentMediaId; // Type of audio focus we have: private int mAudioFocus = AUDIO_NO_FOCUS_NO_DUCK; private final AudioManager mAudioManager; private MediaPlayer mMediaPlayer; private final IntentFilter mAudioNoisyIntentFilter = new IntentFilter(AudioManager.ACTION_AUDIO_BECOMING_NOISY); private final BroadcastReceiver mAudioNoisyReceiver = new BroadcastReceiver() { @Override public void onReceive(Context context, Intent intent) { if (AudioManager.ACTION_AUDIO_BECOMING_NOISY.equals(intent.getAction())) { LogHelper.d(TAG, "Headphones disconnected."); if (isPlaying()) { Intent i = new Intent(context, MusicService.class); i.setAction(MusicService.ACTION_CMD); i.putExtra(MusicService.CMD_NAME, MusicService.CMD_PAUSE); mContext.startService(i); } } } }; public LocalPlayback(Context context, MusicProvider musicProvider) { this.mContext = context; this.mMusicProvider = musicProvider; this.mAudioManager = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE); // Create the Wifi lock (this does not acquire the lock, this just creates it) this.mWifiLock = ((WifiManager) context.getSystemService(Context.WIFI_SERVICE)) .createWifiLock(WifiManager.WIFI_MODE_FULL, "uAmp_lock"); this.mState = PlaybackStateCompat.STATE_NONE; } @Override public void start() { } @Override public void stop(boolean notifyListeners) { mState = PlaybackStateCompat.STATE_STOPPED; if (notifyListeners && mCallback != null) { mCallback.onPlaybackStatusChanged(mState); } mCurrentPosition = getCurrentStreamPosition(); // Give up Audio focus giveUpAudioFocus(); unregisterAudioNoisyReceiver(); // Relax all resources relaxResources(true); } @Override public void setState(int state) { this.mState = state; } @Override public int getState() { return mState; } @Override public boolean isConnected() { return true; } @Override public boolean isPlaying() { return mPlayOnFocusGain || (mMediaPlayer != null && mMediaPlayer.isPlaying()); } @Override public int getCurrentStreamPosition() { return mMediaPlayer != null ? mMediaPlayer.getCurrentPosition() : mCurrentPosition; } @Override public void updateLastKnownStreamPosition() { if (mMediaPlayer != null) { mCurrentPosition = mMediaPlayer.getCurrentPosition(); } } @Override public void play(QueueItem item) { mPlayOnFocusGain = true; tryToGetAudioFocus(); registerAudioNoisyReceiver(); String mediaId = item.getDescription().getMediaId(); boolean mediaHasChanged = !TextUtils.equals(mediaId, mCurrentMediaId); if (mediaHasChanged) { mCurrentPosition = 0; mCurrentMediaId = mediaId; } if (mState == PlaybackStateCompat.STATE_PAUSED && !mediaHasChanged && mMediaPlayer != null) { configMediaPlayerState(); } else { mState = PlaybackStateCompat.STATE_STOPPED; relaxResources(false); // release everything except MediaPlayer MediaMetadataCompat track = mMusicProvider .getMusic(MediaIDHelper.extractMusicIDFromMediaID(item.getDescription().getMediaId())); //noinspection ResourceType String source = track.getString(MusicProviderSource.CUSTOM_METADATA_TRACK_SOURCE); try { createMediaPlayerIfNeeded(); mState = PlaybackStateCompat.STATE_BUFFERING; mMediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC); mMediaPlayer.setDataSource(source); // 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! mMediaPlayer.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. mWifiLock.acquire(); if (mCallback != null) { mCallback.onPlaybackStatusChanged(mState); } } catch (IOException ex) { LogHelper.e(TAG, ex, "Exception playing song"); if (mCallback != null) { mCallback.onError(ex.getMessage()); } } } } @Override public void pause() { if (mState == PlaybackStateCompat.STATE_PLAYING) { // Pause media player and cancel the 'foreground service' state. if (mMediaPlayer != null && mMediaPlayer.isPlaying()) { mMediaPlayer.pause(); mCurrentPosition = mMediaPlayer.getCurrentPosition(); } // while paused, retain the MediaPlayer but give up audio focus relaxResources(false); giveUpAudioFocus(); } mState = PlaybackStateCompat.STATE_PAUSED; if (mCallback != null) { mCallback.onPlaybackStatusChanged(mState); } unregisterAudioNoisyReceiver(); } @Override public void seekTo(int position) { LogHelper.d(TAG, "seekTo called with ", position); if (mMediaPlayer == null) { // If we do not have a current media player, simply update the current position mCurrentPosition = position; } else { if (mMediaPlayer.isPlaying()) { mState = PlaybackStateCompat.STATE_BUFFERING; } mMediaPlayer.seekTo(position); if (mCallback != null) { mCallback.onPlaybackStatusChanged(mState); } } } @Override public void setCallback(Callback callback) { this.mCallback = callback; } @Override public void setCurrentStreamPosition(int pos) { this.mCurrentPosition = pos; } @Override public void setCurrentMediaId(String mediaId) { this.mCurrentMediaId = mediaId; } @Override public String getCurrentMediaId() { return mCurrentMediaId; } /** * Try to get the system audio focus. */ private void tryToGetAudioFocus() { LogHelper.d(TAG, "tryToGetAudioFocus"); if (mAudioFocus != AUDIO_FOCUSED) { int result = mAudioManager.requestAudioFocus(this, AudioManager.STREAM_MUSIC, AudioManager.AUDIOFOCUS_GAIN); if (result == AudioManager.AUDIOFOCUS_REQUEST_GRANTED) { mAudioFocus = AUDIO_FOCUSED; } } } /** * Give up the audio focus. */ private void giveUpAudioFocus() { LogHelper.d(TAG, "giveUpAudioFocus"); if (mAudioFocus == AUDIO_FOCUSED) { if (mAudioManager.abandonAudioFocus(this) == AudioManager.AUDIOFOCUS_REQUEST_GRANTED) { mAudioFocus = AUDIO_NO_FOCUS_NO_DUCK; } } } /** * 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. */ private void configMediaPlayerState() { LogHelper.d(TAG, "configMediaPlayerState. mAudioFocus=", mAudioFocus); if (mAudioFocus == AUDIO_NO_FOCUS_NO_DUCK) { // If we don't have audio focus and can't duck, we have to pause, if (mState == PlaybackStateCompat.STATE_PLAYING) { pause(); } } else { // we have audio focus: if (mAudioFocus == AUDIO_NO_FOCUS_CAN_DUCK) { mMediaPlayer.setVolume(VOLUME_DUCK, VOLUME_DUCK); // we'll be relatively quiet } else { if (mMediaPlayer != null) { mMediaPlayer.setVolume(VOLUME_NORMAL, VOLUME_NORMAL); // we can be loud again } // else do something for remote client. } // If we were playing when we lost focus, we need to resume playing. if (mPlayOnFocusGain) { if (mMediaPlayer != null && !mMediaPlayer.isPlaying()) { LogHelper.d(TAG, "configMediaPlayerState startMediaPlayer. seeking to ", mCurrentPosition); if (mCurrentPosition == mMediaPlayer.getCurrentPosition()) { mMediaPlayer.start(); mState = PlaybackStateCompat.STATE_PLAYING; } else { mMediaPlayer.seekTo(mCurrentPosition); mState = PlaybackStateCompat.STATE_BUFFERING; } } mPlayOnFocusGain = false; } } if (mCallback != null) { mCallback.onPlaybackStatusChanged(mState); } } /** * Called by AudioManager on audio focus changes. * Implementation of {@link android.media.AudioManager.OnAudioFocusChangeListener} */ @Override public void onAudioFocusChange(int focusChange) { LogHelper.d(TAG, "onAudioFocusChange. focusChange=", focusChange); if (focusChange == AudioManager.AUDIOFOCUS_GAIN) { // We have gained focus: mAudioFocus = AUDIO_FOCUSED; } else if (focusChange == AudioManager.AUDIOFOCUS_LOSS || focusChange == AudioManager.AUDIOFOCUS_LOSS_TRANSIENT || focusChange == AudioManager.AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK) { // We have lost focus. If we can duck (low playback volume), we can keep playing. // Otherwise, we need to pause the playback. boolean canDuck = focusChange == AudioManager.AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK; mAudioFocus = canDuck ? AUDIO_NO_FOCUS_CAN_DUCK : AUDIO_NO_FOCUS_NO_DUCK; // If we are playing, we need to reset media player by calling configMediaPlayerState // with mAudioFocus properly set. if (mState == PlaybackStateCompat.STATE_PLAYING && !canDuck) { // If we don't have audio focus and can't duck, we save the information that // we were playing, so that we can resume playback once we get the focus back. mPlayOnFocusGain = true; } } else { LogHelper.e(TAG, "onAudioFocusChange: Ignoring unsupported focusChange: ", focusChange); } configMediaPlayerState(); } /** * Called when MediaPlayer has completed a seek * * @see OnSeekCompleteListener */ @Override public void onSeekComplete(MediaPlayer mp) { LogHelper.d(TAG, "onSeekComplete from MediaPlayer:", mp.getCurrentPosition()); mCurrentPosition = mp.getCurrentPosition(); if (mState == PlaybackStateCompat.STATE_BUFFERING) { mMediaPlayer.start(); mState = PlaybackStateCompat.STATE_PLAYING; } if (mCallback != null) { mCallback.onPlaybackStatusChanged(mState); } } /** * Called when media player is done playing current song. * * @see OnCompletionListener */ @Override public void onCompletion(MediaPlayer player) { LogHelper.d(TAG, "onCompletion from MediaPlayer"); // The media player finished playing the current song, so we go ahead // and start the next. if (mCallback != null) { mCallback.onCompletion(); } } /** * Called when media player is done preparing. * * @see OnPreparedListener */ @Override public void onPrepared(MediaPlayer player) { LogHelper.d(TAG, "onPrepared from MediaPlayer"); // The media player is done preparing. That means we can start playing if we // have audio focus. configMediaPlayerState(); } /** * 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. * * @see OnErrorListener */ @Override public boolean onError(MediaPlayer mp, int what, int extra) { LogHelper.e(TAG, "Media player error: what=" + what + ", extra=" + extra); if (mCallback != null) { mCallback.onError("MediaPlayer error " + what + " (" + extra + ")"); } return true; // true indicates we handled the error } /** * 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. */ private void createMediaPlayerIfNeeded() { LogHelper.d(TAG, "createMediaPlayerIfNeeded. needed? ", (mMediaPlayer == null)); if (mMediaPlayer == null) { mMediaPlayer = 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. mMediaPlayer.setWakeMode(mContext.getApplicationContext(), PowerManager.PARTIAL_WAKE_LOCK); // we want the media player to notify us when it's ready preparing, // and when it's done playing: mMediaPlayer.setOnPreparedListener(this); mMediaPlayer.setOnCompletionListener(this); mMediaPlayer.setOnErrorListener(this); mMediaPlayer.setOnSeekCompleteListener(this); } else { mMediaPlayer.reset(); } } /** * Releases resources used by the service for playback. This includes the * "foreground service" status, the wake locks and possibly the MediaPlayer. * * @param releaseMediaPlayer Indicates whether the Media Player should also * be released or not */ private void relaxResources(boolean releaseMediaPlayer) { LogHelper.d(TAG, "relaxResources. releaseMediaPlayer=", releaseMediaPlayer); // stop and release the Media Player, if it's available if (releaseMediaPlayer && mMediaPlayer != null) { mMediaPlayer.reset(); mMediaPlayer.release(); mMediaPlayer = null; } // we can also release the Wifi lock, if we're holding it if (mWifiLock.isHeld()) { mWifiLock.release(); } } private void registerAudioNoisyReceiver() { if (!mAudioNoisyReceiverRegistered) { mContext.registerReceiver(mAudioNoisyReceiver, mAudioNoisyIntentFilter); mAudioNoisyReceiverRegistered = true; } } private void unregisterAudioNoisyReceiver() { if (mAudioNoisyReceiverRegistered) { mContext.unregisterReceiver(mAudioNoisyReceiver); mAudioNoisyReceiverRegistered = false; } } }