/**
* Download a JSON file from a server, parse the content and return the JSON object.
*
* @return result JSONObject containing the parsed representation.
*/
private JSONObject fetchJSONFromUrl(String urlString) {
InputStream is = null;
try {
URL url = new URL(urlString);
URLConnection urlConnection = url.openConnection();
is = new BufferedInputStream(urlConnection.getInputStream());
BufferedReader reader =
new BufferedReader(new InputStreamReader(urlConnection.getInputStream(), "iso-8859-1"));
StringBuilder sb = new StringBuilder();
String line;
while ((line = reader.readLine()) != null) {
sb.append(line);
}
return new JSONObject(sb.toString());
} catch (Exception e) {
LogHelper.e(TAG, "Failed to parse the json for media list", e);
return null;
} finally {
if (is != null) {
try {
is.close();
} catch (IOException e) {
// ignore
}
}
}
}
private synchronized void retrieveMedia() {
try {
if (mCurrentState == State.NON_INITIALIZED) {
mCurrentState = State.INITIALIZING;
int slashPos = CATALOG_URL.lastIndexOf('/');
String path = CATALOG_URL.substring(0, slashPos + 1);
JSONObject jsonObj = fetchJSONFromUrl(CATALOG_URL);
if (jsonObj == null) {
return;
}
JSONArray tracks = jsonObj.getJSONArray(JSON_MUSIC);
if (tracks != null) {
for (int j = 0; j < tracks.length(); j++) {
MediaMetadata item = buildFromJSON(tracks.getJSONObject(j), path);
String musicId = item.getString(MediaMetadata.METADATA_KEY_MEDIA_ID);
mMusicListById.put(musicId, new MutableMediaMetadata(musicId, item));
}
buildListsByGenre();
}
mCurrentState = State.INITIALIZED;
}
} catch (JSONException e) {
LogHelper.e(TAG, e, "Could not retrieve music list");
} finally {
if (mCurrentState != State.INITIALIZED) {
// Something bad happened, so we reset state to NON_INITIALIZED to allow
// retries (eg if the network connection is temporary unavailable)
mCurrentState = State.NON_INITIALIZED;
}
}
}
private MediaMetadata buildFromJSON(JSONObject json, String basePath) throws JSONException {
String title = json.getString(JSON_TITLE);
String album = json.getString(JSON_ALBUM);
String artist = json.getString(JSON_ARTIST);
String genre = json.getString(JSON_GENRE);
String source = json.getString(JSON_SOURCE);
String iconUrl = json.getString(JSON_IMAGE);
int trackNumber = json.getInt(JSON_TRACK_NUMBER);
int totalTrackCount = json.getInt(JSON_TOTAL_TRACK_COUNT);
int duration = json.getInt(JSON_DURATION) * 1000; // ms
LogHelper.d(TAG, "Found music track: ", json);
// Media is stored relative to JSON file
if (!source.startsWith("http")) {
source = basePath + source;
}
if (!iconUrl.startsWith("http")) {
iconUrl = basePath + iconUrl;
}
// Since we don't have a unique ID in the server, we fake one using the hashcode of
// the music source. In a real world app, this could come from the server.
String id = String.valueOf(source.hashCode());
// Adding the music source to the MediaMetadata (and consequently using it in the
// mediaSession.setMetadata) is not a good idea for a real world music app, because
// the session metadata can be accessed by notification listeners. This is done in this
// sample for convenience only.
return new MediaMetadata.Builder()
.putString(MediaMetadata.METADATA_KEY_MEDIA_ID, id)
.putString(CUSTOM_METADATA_TRACK_SOURCE, source)
.putString(MediaMetadata.METADATA_KEY_ALBUM, album)
.putString(MediaMetadata.METADATA_KEY_ARTIST, artist)
.putLong(MediaMetadata.METADATA_KEY_DURATION, duration)
.putString(MediaMetadata.METADATA_KEY_GENRE, genre)
.putString(MediaMetadata.METADATA_KEY_ALBUM_ART_URI, iconUrl)
.putString(MediaMetadata.METADATA_KEY_TITLE, title)
.putLong(MediaMetadata.METADATA_KEY_TRACK_NUMBER, trackNumber)
.putLong(MediaMetadata.METADATA_KEY_NUM_TRACKS, totalTrackCount)
.build();
}
/**
* Get the list of music tracks from a server and caches the track information for future
* reference, keying tracks by musicId and grouping by genre.
*/
public void retrieveMediaAsync(final Callback callback) {
LogHelper.d(TAG, "retrieveMediaAsync called");
if (mCurrentState == State.INITIALIZED) {
// Nothing to do, execute callback immediately
callback.onMusicCatalogReady(true);
return;
}
// Asynchronously load the music catalog in a separate thread
new AsyncTask<Void, Void, State>() {
@Override
protected State doInBackground(Void... params) {
retrieveMedia();
return mCurrentState;
}
@Override
protected void onPostExecute(State current) {
if (callback != null) {
callback.onMusicCatalogReady(current == State.INITIALIZED);
}
}
}.execute();
}
/** Utility class to get a list of MusicTrack's based on a server-side JSON configuration. */
public class MusicProvider {
private static final String TAG = LogHelper.makeLogTag(MusicProvider.class);
private static final String CATALOG_URL =
"http://storage.googleapis.com/automotive-media/music.json";
public static final String CUSTOM_METADATA_TRACK_SOURCE = "__SOURCE__";
private static final String JSON_MUSIC = "music";
private static final String JSON_TITLE = "title";
private static final String JSON_ALBUM = "album";
private static final String JSON_ARTIST = "artist";
private static final String JSON_GENRE = "genre";
private static final String JSON_SOURCE = "source";
private static final String JSON_IMAGE = "image";
private static final String JSON_TRACK_NUMBER = "trackNumber";
private static final String JSON_TOTAL_TRACK_COUNT = "totalTrackCount";
private static final String JSON_DURATION = "duration";
// Categorized caches for music track data:
private ConcurrentMap<String, List<MediaMetadata>> mMusicListByGenre;
private final ConcurrentMap<String, MutableMediaMetadata> mMusicListById;
private final Set<String> mFavoriteTracks;
enum State {
NON_INITIALIZED,
INITIALIZING,
INITIALIZED
}
private volatile State mCurrentState = State.NON_INITIALIZED;
public interface Callback {
void onMusicCatalogReady(boolean success);
}
public MusicProvider() {
mMusicListByGenre = new ConcurrentHashMap<>();
mMusicListById = new ConcurrentHashMap<>();
mFavoriteTracks = Collections.newSetFromMap(new ConcurrentHashMap<String, Boolean>());
}
/**
* Get an iterator over the list of genres
*
* @return genres
*/
public Iterable<String> getGenres() {
if (mCurrentState != State.INITIALIZED) {
return Collections.emptyList();
}
return mMusicListByGenre.keySet();
}
/** Get music tracks of the given genre */
public Iterable<MediaMetadata> getMusicsByGenre(String genre) {
if (mCurrentState != State.INITIALIZED || !mMusicListByGenre.containsKey(genre)) {
return Collections.emptyList();
}
return mMusicListByGenre.get(genre);
}
/**
* Very basic implementation of a search that filter music tracks which title containing the given
* query.
*/
public Iterable<MediaMetadata> searchMusic(String titleQuery) {
if (mCurrentState != State.INITIALIZED) {
return Collections.emptyList();
}
ArrayList<MediaMetadata> result = new ArrayList<>();
titleQuery = titleQuery.toLowerCase();
for (MutableMediaMetadata track : mMusicListById.values()) {
if (track
.metadata
.getString(MediaMetadata.METADATA_KEY_TITLE)
.toLowerCase()
.contains(titleQuery)) {
result.add(track.metadata);
}
}
return result;
}
/**
* Return the MediaMetadata for the given musicID.
*
* @param musicId The unique, non-hierarchical music ID.
*/
public MediaMetadata getMusic(String musicId) {
return mMusicListById.containsKey(musicId) ? mMusicListById.get(musicId).metadata : null;
}
public synchronized void updateMusic(String musicId, MediaMetadata metadata) {
MutableMediaMetadata track = mMusicListById.get(musicId);
if (track == null) {
return;
}
String oldGenre = track.metadata.getString(MediaMetadata.METADATA_KEY_GENRE);
String newGenre = metadata.getString(MediaMetadata.METADATA_KEY_GENRE);
track.metadata = metadata;
// if genre has changed, we need to rebuild the list by genre
if (!oldGenre.equals(newGenre)) {
buildListsByGenre();
}
}
public void setFavorite(String musicId, boolean favorite) {
if (favorite) {
mFavoriteTracks.add(musicId);
} else {
mFavoriteTracks.remove(musicId);
}
}
public boolean isFavorite(String musicId) {
return mFavoriteTracks.contains(musicId);
}
public boolean isInitialized() {
return mCurrentState == State.INITIALIZED;
}
/**
* Get the list of music tracks from a server and caches the track information for future
* reference, keying tracks by musicId and grouping by genre.
*/
public void retrieveMediaAsync(final Callback callback) {
LogHelper.d(TAG, "retrieveMediaAsync called");
if (mCurrentState == State.INITIALIZED) {
// Nothing to do, execute callback immediately
callback.onMusicCatalogReady(true);
return;
}
// Asynchronously load the music catalog in a separate thread
new AsyncTask<Void, Void, State>() {
@Override
protected State doInBackground(Void... params) {
retrieveMedia();
return mCurrentState;
}
@Override
protected void onPostExecute(State current) {
if (callback != null) {
callback.onMusicCatalogReady(current == State.INITIALIZED);
}
}
}.execute();
}
private synchronized void buildListsByGenre() {
ConcurrentMap<String, List<MediaMetadata>> newMusicListByGenre = new ConcurrentHashMap<>();
for (MutableMediaMetadata m : mMusicListById.values()) {
String genre = m.metadata.getString(MediaMetadata.METADATA_KEY_GENRE);
List<MediaMetadata> list = newMusicListByGenre.get(genre);
if (list == null) {
list = new ArrayList<>();
newMusicListByGenre.put(genre, list);
}
list.add(m.metadata);
}
mMusicListByGenre = newMusicListByGenre;
}
private synchronized void retrieveMedia() {
try {
if (mCurrentState == State.NON_INITIALIZED) {
mCurrentState = State.INITIALIZING;
int slashPos = CATALOG_URL.lastIndexOf('/');
String path = CATALOG_URL.substring(0, slashPos + 1);
JSONObject jsonObj = fetchJSONFromUrl(CATALOG_URL);
if (jsonObj == null) {
return;
}
JSONArray tracks = jsonObj.getJSONArray(JSON_MUSIC);
if (tracks != null) {
for (int j = 0; j < tracks.length(); j++) {
MediaMetadata item = buildFromJSON(tracks.getJSONObject(j), path);
String musicId = item.getString(MediaMetadata.METADATA_KEY_MEDIA_ID);
mMusicListById.put(musicId, new MutableMediaMetadata(musicId, item));
}
buildListsByGenre();
}
mCurrentState = State.INITIALIZED;
}
} catch (JSONException e) {
LogHelper.e(TAG, e, "Could not retrieve music list");
} finally {
if (mCurrentState != State.INITIALIZED) {
// Something bad happened, so we reset state to NON_INITIALIZED to allow
// retries (eg if the network connection is temporary unavailable)
mCurrentState = State.NON_INITIALIZED;
}
}
}
private MediaMetadata buildFromJSON(JSONObject json, String basePath) throws JSONException {
String title = json.getString(JSON_TITLE);
String album = json.getString(JSON_ALBUM);
String artist = json.getString(JSON_ARTIST);
String genre = json.getString(JSON_GENRE);
String source = json.getString(JSON_SOURCE);
String iconUrl = json.getString(JSON_IMAGE);
int trackNumber = json.getInt(JSON_TRACK_NUMBER);
int totalTrackCount = json.getInt(JSON_TOTAL_TRACK_COUNT);
int duration = json.getInt(JSON_DURATION) * 1000; // ms
LogHelper.d(TAG, "Found music track: ", json);
// Media is stored relative to JSON file
if (!source.startsWith("http")) {
source = basePath + source;
}
if (!iconUrl.startsWith("http")) {
iconUrl = basePath + iconUrl;
}
// Since we don't have a unique ID in the server, we fake one using the hashcode of
// the music source. In a real world app, this could come from the server.
String id = String.valueOf(source.hashCode());
// Adding the music source to the MediaMetadata (and consequently using it in the
// mediaSession.setMetadata) is not a good idea for a real world music app, because
// the session metadata can be accessed by notification listeners. This is done in this
// sample for convenience only.
return new MediaMetadata.Builder()
.putString(MediaMetadata.METADATA_KEY_MEDIA_ID, id)
.putString(CUSTOM_METADATA_TRACK_SOURCE, source)
.putString(MediaMetadata.METADATA_KEY_ALBUM, album)
.putString(MediaMetadata.METADATA_KEY_ARTIST, artist)
.putLong(MediaMetadata.METADATA_KEY_DURATION, duration)
.putString(MediaMetadata.METADATA_KEY_GENRE, genre)
.putString(MediaMetadata.METADATA_KEY_ALBUM_ART_URI, iconUrl)
.putString(MediaMetadata.METADATA_KEY_TITLE, title)
.putLong(MediaMetadata.METADATA_KEY_TRACK_NUMBER, trackNumber)
.putLong(MediaMetadata.METADATA_KEY_NUM_TRACKS, totalTrackCount)
.build();
}
/**
* Download a JSON file from a server, parse the content and return the JSON object.
*
* @return result JSONObject containing the parsed representation.
*/
private JSONObject fetchJSONFromUrl(String urlString) {
InputStream is = null;
try {
URL url = new URL(urlString);
URLConnection urlConnection = url.openConnection();
is = new BufferedInputStream(urlConnection.getInputStream());
BufferedReader reader =
new BufferedReader(new InputStreamReader(urlConnection.getInputStream(), "iso-8859-1"));
StringBuilder sb = new StringBuilder();
String line;
while ((line = reader.readLine()) != null) {
sb.append(line);
}
return new JSONObject(sb.toString());
} catch (Exception e) {
LogHelper.e(TAG, "Failed to parse the json for media list", e);
return null;
} finally {
if (is != null) {
try {
is.close();
} catch (IOException e) {
// ignore
}
}
}
}
}