MusicDemo/src/main/java/com/example/android/musicservicedemo/model/MusicProvider.java - platform/developers/demos - Git at Google

 /*
  * Copyright (C) 2014 Google Inc. All Rights Reserved.
  *
  * 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 com.example.android.musicservicedemo.model;

 import android.media.MediaMetadata;
 import android.os.AsyncTask;

 import com.example.android.musicservicedemo.utils.LogHelper;

 import org.json.JSONArray;
 import org.json.JSONException;
 import org.json.JSONObject;

 import java.io.BufferedInputStream;
 import java.io.BufferedReader;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.net.URLConnection;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
 import java.util.concurrent.locks.ReentrantLock;

 /**
  * Utility class to get a list of MusicTrack's based on a server-side JSON
  * configuration.
  */
 public class MusicProvider {

     private static final String TAG = "MusicProvider";

     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 String JSON_MUSIC = "music";
     private static String JSON_TITLE = "title";
     private static String JSON_ALBUM = "album";
     private static String JSON_ARTIST = "artist";
     private static String JSON_GENRE = "genre";
     private static String JSON_SOURCE = "source";
     private static String JSON_IMAGE = "image";
     private static String JSON_TRACK_NUMBER = "trackNumber";
     private static String JSON_TOTAL_TRACK_COUNT = "totalTrackCount";
     private static String JSON_DURATION = "duration";

     private final ReentrantLock initializationLock = new ReentrantLock();

     // Categorized caches for music track data:
     private final HashMap<String, List<MediaMetadata>> mMusicListByGenre;
     private final HashMap<String, MediaMetadata> mMusicListById;

     private final HashSet<String> mFavoriteTracks;

     enum State {
         NON_INITIALIZED, INITIALIZING, INITIALIZED;
     }

     private State mCurrentState = State.NON_INITIALIZED;


     public interface Callback {
         void onMusicCatalogReady(boolean success);
     }

     public MusicProvider() {
         mMusicListByGenre = new HashMap<>();
         mMusicListById = new HashMap<>();
         mFavoriteTracks = new HashSet<>();
     }

     /**
      * Get an iterator over the list of genres
      *
      * @return
      */
     public Iterable<String> getGenres() {
         if (mCurrentState != State.INITIALIZED) {
             return new ArrayList<String>(0);
         }
         return mMusicListByGenre.keySet();
     }

     /**
      * Get music tracks of the given genre
      *
      * @return
      */
     public Iterable<MediaMetadata> getMusicsByGenre(String genre) {
         if (mCurrentState != State.INITIALIZED || !mMusicListByGenre.containsKey(genre)) {
             return new ArrayList<MediaMetadata>();
         }
         return mMusicListByGenre.get(genre);
     }

     /**
      * Very basic implementation of a search that filter music tracks which title containing
      * the given query.
      *
      * @return
      */
     public Iterable<MediaMetadata> searchMusics(String titleQuery) {
         ArrayList<MediaMetadata> result = new ArrayList<>();
         if (mCurrentState != State.INITIALIZED) {
             return result;
         }
         titleQuery = titleQuery.toLowerCase();
         for (MediaMetadata track: mMusicListById.values()) {
             if (track.getString(MediaMetadata.METADATA_KEY_TITLE).toLowerCase()
                     .contains(titleQuery)) {
                 result.add(track);
             }
         }
         return result;
     }

     public MediaMetadata getMusic(String mediaId) {
         return mMusicListById.get(mediaId);
     }

     public void setFavorite(String mediaId, boolean favorite) {
         if (favorite) {
             mFavoriteTracks.add(mediaId);
         } else {
             mFavoriteTracks.remove(mediaId);
         }
     }

     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 mediaId and grouping by genre.
      *
      * @return
      */
     public void retrieveMedia(final Callback callback) {

         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() {
             @Override
             protected Object doInBackground(Object[] objects) {
                 retrieveMediaAsync(callback);
                 return null;
             }
         }.execute();
     }

     private void retrieveMediaAsync(Callback callback) {
         initializationLock.lock();

         try {
             if (mCurrentState == State.NON_INITIALIZED) {
                 mCurrentState = State.INITIALIZING;

                 int slashPos = CATALOG_URL.lastIndexOf('/');
                 String path = CATALOG_URL.substring(0, slashPos + 1);
                 JSONObject jsonObj = parseUrl(CATALOG_URL);

                 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 genre = item.getString(MediaMetadata.METADATA_KEY_GENRE);
                         List<MediaMetadata> list = mMusicListByGenre.get(genre);
                         if (list == null) {
                             list = new ArrayList<>();
                         }
                         list.add(item);
                         mMusicListByGenre.put(genre, list);
                         mMusicListById.put(item.getString(MediaMetadata.METADATA_KEY_MEDIA_ID),
                                 item);
                     }
                 }
                 mCurrentState = State.INITIALIZED;
             }
         } catch (RuntimeException | 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;
             }
             initializationLock.unlock();
             if (callback != null) {
                 callback.onMusicCatalogReady(mCurrentState == State.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.
      *
      * @param urlString
      * @return
      */
     private JSONObject parseUrl(String urlString) {
         InputStream is = null;
         try {
             java.net.URL url = new java.net.URL(urlString);
             URLConnection urlConnection = url.openConnection();
             is = new BufferedInputStream(urlConnection.getInputStream());
             BufferedReader reader = new BufferedReader(new InputStreamReader(
                     urlConnection.getInputStream(), "iso-8859-1"), 8);
             StringBuilder sb = new StringBuilder();
             String line = null;
             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
                 }
             }
         }
     }
 }
	/*
	* Copyright (C) 2014 Google Inc. All Rights Reserved.
	*
	* 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 com.example.android.musicservicedemo.model;

	import android.media.MediaMetadata;
	import android.os.AsyncTask;

	import com.example.android.musicservicedemo.utils.LogHelper;

	import org.json.JSONArray;
	import org.json.JSONException;
	import org.json.JSONObject;

	import java.io.BufferedInputStream;
	import java.io.BufferedReader;
	import java.io.IOException;
	import java.io.InputStream;
	import java.io.InputStreamReader;
	import java.net.URLConnection;
	import java.util.ArrayList;
	import java.util.HashMap;
	import java.util.HashSet;
	import java.util.List;
	import java.util.concurrent.locks.ReentrantLock;

	/**
	* Utility class to get a list of MusicTrack's based on a server-side JSON
	* configuration.
	*/
	public class MusicProvider {

	private static final String TAG = "MusicProvider";

	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 String JSON_MUSIC = "music";
	private static String JSON_TITLE = "title";
	private static String JSON_ALBUM = "album";
	private static String JSON_ARTIST = "artist";
	private static String JSON_GENRE = "genre";
	private static String JSON_SOURCE = "source";
	private static String JSON_IMAGE = "image";
	private static String JSON_TRACK_NUMBER = "trackNumber";
	private static String JSON_TOTAL_TRACK_COUNT = "totalTrackCount";
	private static String JSON_DURATION = "duration";

	private final ReentrantLock initializationLock = new ReentrantLock();

	// Categorized caches for music track data:
	private final HashMap<String, List<MediaMetadata>> mMusicListByGenre;
	private final HashMap<String, MediaMetadata> mMusicListById;

	private final HashSet<String> mFavoriteTracks;

	enum State {
	NON_INITIALIZED, INITIALIZING, INITIALIZED;
	}

	private State mCurrentState = State.NON_INITIALIZED;


	public interface Callback {
	void onMusicCatalogReady(boolean success);
	}

	public MusicProvider() {
	mMusicListByGenre = new HashMap<>();
	mMusicListById = new HashMap<>();
	mFavoriteTracks = new HashSet<>();
	}

	/**
	* Get an iterator over the list of genres
	*
	* @return
	*/
	public Iterable<String> getGenres() {
	if (mCurrentState != State.INITIALIZED) {
	return new ArrayList<String>(0);
	}
	return mMusicListByGenre.keySet();
	}

	/**
	* Get music tracks of the given genre
	*
	* @return
	*/
	public Iterable<MediaMetadata> getMusicsByGenre(String genre) {
	if (mCurrentState != State.INITIALIZED \|\| !mMusicListByGenre.containsKey(genre)) {
	return new ArrayList<MediaMetadata>();
	}
	return mMusicListByGenre.get(genre);
	}

	/**
	* Very basic implementation of a search that filter music tracks which title containing
	* the given query.
	*
	* @return
	*/
	public Iterable<MediaMetadata> searchMusics(String titleQuery) {
	ArrayList<MediaMetadata> result = new ArrayList<>();
	if (mCurrentState != State.INITIALIZED) {
	return result;
	}
	titleQuery = titleQuery.toLowerCase();
	for (MediaMetadata track: mMusicListById.values()) {
	if (track.getString(MediaMetadata.METADATA_KEY_TITLE).toLowerCase()
	.contains(titleQuery)) {
	result.add(track);
	}
	}
	return result;
	}

	public MediaMetadata getMusic(String mediaId) {
	return mMusicListById.get(mediaId);
	}

	public void setFavorite(String mediaId, boolean favorite) {
	if (favorite) {
	mFavoriteTracks.add(mediaId);
	} else {
	mFavoriteTracks.remove(mediaId);
	}
	}

	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 mediaId and grouping by genre.
	*
	* @return
	*/
	public void retrieveMedia(final Callback callback) {

	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() {
	@Override
	protected Object doInBackground(Object[] objects) {
	retrieveMediaAsync(callback);
	return null;
	}
	}.execute();
	}

	private void retrieveMediaAsync(Callback callback) {
	initializationLock.lock();

	try {
	if (mCurrentState == State.NON_INITIALIZED) {
	mCurrentState = State.INITIALIZING;

	int slashPos = CATALOG_URL.lastIndexOf('/');
	String path = CATALOG_URL.substring(0, slashPos + 1);
	JSONObject jsonObj = parseUrl(CATALOG_URL);

	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 genre = item.getString(MediaMetadata.METADATA_KEY_GENRE);
	List<MediaMetadata> list = mMusicListByGenre.get(genre);
	if (list == null) {
	list = new ArrayList<>();
	}
	list.add(item);
	mMusicListByGenre.put(genre, list);
	mMusicListById.put(item.getString(MediaMetadata.METADATA_KEY_MEDIA_ID),
	item);
	}
	}
	mCurrentState = State.INITIALIZED;
	}
	} catch (RuntimeException \| 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;
	}
	initializationLock.unlock();
	if (callback != null) {
	callback.onMusicCatalogReady(mCurrentState == State.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.
	*
	* @param urlString
	* @return
	*/
	private JSONObject parseUrl(String urlString) {
	InputStream is = null;
	try {
	java.net.URL url = new java.net.URL(urlString);
	URLConnection urlConnection = url.openConnection();
	is = new BufferedInputStream(urlConnection.getInputStream());
	BufferedReader reader = new BufferedReader(new InputStreamReader(
	urlConnection.getInputStream(), "iso-8859-1"), 8);
	StringBuilder sb = new StringBuilder();
	String line = null;
	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
	}
	}
	}
	}
	}