simple mp3-player android (service example)

gistfile1.txt

MainActivity.java: (CREATE NEW EMPTY ACTIVITY PROJECT!)

package com.alex.player;

import package com.alex.player.MusicService.MusicBinder;

import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.os.IBinder;
import android.content.ComponentName;
import android.content.Context;
import android.content.ServiceConnection;
import android.view.MenuItem;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import android.net.Uri;
import android.content.ContentResolver;
import android.database.Cursor;
import android.widget.ListView;
import android.widget.MediaController;
import android.widget.MediaController.MediaPlayerControl;

import com.karumi.dexter.Dexter;
import com.karumi.dexter.MultiplePermissionsReport;
import com.karumi.dexter.PermissionToken;
import com.karumi.dexter.listener.PermissionRequest;
import com.karumi.dexter.listener.multi.MultiplePermissionsListener;

public class MainActivity extends AppCompatActivity implements MediaPlayerControl {

    private boolean paused;
    private boolean playbackPaused;
    private MediaController controller;
    private MusicService musicSrv;
    private Intent playIntent;
    private boolean musicBound = false;
    private ArrayList<Song> songList;

    @Override
    protected void onPause() {
        super.onPause();
        paused = true;
    }

    @Override
    protected void onResume() {
        super.onResume();
        if (paused) {
            setController();
            paused = false;
        }
    }

    @Override
    protected void onStop() {
        controller.hide();
        super.onStop();
    }

    private void setController() {
        controller = new MediaController(this);
        controller.setPrevNextListeners(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                playNext();
            }
        }, new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                playPrev();
            }
        });

        controller.setMediaPlayer(this);
        controller.setAnchorView(findViewById(R.id.song_list));
        controller.setEnabled(true);
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // https://github.com/Karumi/Dexter
        Dexter.withActivity(this)
                .withPermissions(Manifest.permission.READ_EXTERNAL_STORAGE,
                        Manifest.permission.WAKE_LOCK)
                .withListener(new MultiplePermissionsListener() {
                    @Override
                    public void onPermissionsChecked(MultiplePermissionsReport report) {
                        // Toast.makeText(MainActivity.this, "OK", Toast.LENGTH_SHORT).show();
                    }

                    @Override
                    public void onPermissionRationaleShouldBeShown(List<PermissionRequest> permissions, PermissionToken token) {
                        
                    }
                }).check();
                
        ListView songView = findViewById(R.id.song_list);
        songList = new ArrayList<>();

        getSongList();

        Collections.sort(songList, new Comparator<Song>() {
            public int compare(Song a, Song b) {
                return a.getTitle().compareTo(b.getTitle());
            }
        });

        SongAdapter songAdt = new SongAdapter(this, songList);
        songView.setAdapter(songAdt);

        setController();
    }

    private void playNext() {
        musicSrv.playNext();
        if (playbackPaused) {
            setController();
            playbackPaused = false;
        }
        controller.show(0);
    }

    private void playPrev() {
        musicSrv.playPrev();
        if (playbackPaused) {
            setController();
            playbackPaused = false;
        }
        controller.show(0);
    }

    public void getSongList() {
        ContentResolver musicResolver = getContentResolver();
        Uri musicUri = android.provider.MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
        Cursor musicCursor = musicResolver.query(musicUri, null, null, null, null);

         if (musicCursor != null && musicCursor.moveToFirst()) {
            int titleColumn = musicCursor.getColumnIndex
                    (android.provider.MediaStore.Audio.Media.TITLE);
            int idColumn = musicCursor.getColumnIndex
                    (android.provider.MediaStore.Audio.Media._ID);
            int artistColumn = musicCursor.getColumnIndex
                    (android.provider.MediaStore.Audio.Media.ARTIST);

            do {
                long thisId = musicCursor.getLong(idColumn);
                String thisTitle = musicCursor.getString(titleColumn);
                String thisArtist = musicCursor.getString(artistColumn);
                songList.add(new Song(thisId, thisTitle, thisArtist));
            }
            while (musicCursor.moveToNext());
        }
    }

    private ServiceConnection musicConnection = new ServiceConnection() {

        @Override
        public void onServiceConnected(ComponentName name, IBinder service) {
            MusicBinder binder = (MusicBinder) service;
            musicSrv = binder.getService();
            musicSrv.setList(songList);
            musicBound = true;
        }

        @Override
        public void onServiceDisconnected(ComponentName name) {
            musicBound = false;
        }
    };

    public void songPicked(View view) {
        musicSrv.setSong(Integer.parseInt(view.getTag().toString()));
        musicSrv.playSong();
        if (playbackPaused) {
            setController();
            playbackPaused = false;
        }
        controller.show(0);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.action_shuffle:
                musicSrv.setShuffle();
                break;
            case R.id.action_end:
                stopService(playIntent);
                musicSrv = null;
                System.exit(0);
                break;
        }
        return super.onOptionsItemSelected(item);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    protected void onStart() {
        super.onStart();
        if (playIntent == null) {
            playIntent = new Intent(this, MusicService.class);
            bindService(playIntent, musicConnection, Context.BIND_AUTO_CREATE);
            startService(playIntent);
        }
    }

    @Override
    protected void onDestroy() {
        stopService(playIntent);
        musicSrv = null;
        super.onDestroy();
    }

    @Override
    public void pause() {
        playbackPaused = true;
        musicSrv.pausePlayer();
    }

    @Override
    public void seekTo(int pos) {
        musicSrv.seek(pos);
    }

    @Override
    public void start() {
        musicSrv.go();
    }

    @Override
    public int getDuration() {
        if (musicSrv != null && musicBound && musicSrv.isPng())
            return musicSrv.getDur();
        else return 0;
    }

    @Override
    public int getCurrentPosition() {
        if (musicSrv != null && musicBound && musicSrv.isPng())
            return musicSrv.getPosn();
        else return 0;
    }

    @Override
    public boolean isPlaying() {
        return musicSrv != null && musicBound && musicSrv.isPng();
    }

    @Override
    public int getBufferPercentage() {
        return 0;
    }

    @Override
    public boolean canPause() {
        return true;
    }

    @Override
    public boolean canSeekBackward() {
        return true;
    }

    @Override
    public boolean canSeekForward() {
        return true;
    }

    @Override
    public int getAudioSessionId() {
        return 0;
    }
}

==================================================================================================================================

MusicService.java:

package com.alex.player;

import android.app.Service;
import android.content.Intent;
import android.media.MediaPlayer;
import android.os.IBinder;
import java.util.ArrayList;
import android.content.ContentUris;
import android.media.AudioManager;
import android.net.Uri;
import android.os.Binder;
import android.os.PowerManager;
import android.util.Log;

import java.util.Random;

import android.app.Notification;
import android.app.PendingIntent;

public class MusicService extends Service implements MediaPlayer.OnPreparedListener, MediaPlayer.OnErrorListener,
        MediaPlayer.OnCompletionListener {

    private boolean shuffle = false;
    private Random rand;
    private String songTitle = "";
    private static final int NOTIFY_ID = 1;
    private MediaPlayer player;
    private ArrayList<Song> songs;
    private int songPosn;
    private final IBinder musicBind = new MusicBinder();

    public void setShuffle() {
        shuffle = !shuffle;
    }

    public void onCreate() {
        super.onCreate();
        rand = new Random();
        songPosn = 0;
        player = new MediaPlayer();
        initMusicPlayer();
    }

    public void initMusicPlayer() {
        player.setWakeMode(getApplicationContext(), PowerManager.PARTIAL_WAKE_LOCK);
        player.setAudioStreamType(AudioManager.STREAM_MUSIC);
        player.setOnPreparedListener(this);
        player.setOnCompletionListener(this);
        player.setOnErrorListener(this);
    }

    public void setList(ArrayList<Song> theSongs) {
        songs = theSongs;
    }

    public class MusicBinder extends Binder {
        MusicService getService() {
            return MusicService.this;
        }
    }

    @Override
    public IBinder onBind(Intent intent) {
        return musicBind;
    }

    @Override
    public boolean onUnbind(Intent intent) {
        player.stop();
        player.release();
        return false;
    }

    public void playSong() {
        player.reset();
        Song playSong = songs.get(songPosn);
        songTitle = playSong.getTitle();
        long currSong = playSong.getID();
        Uri trackUri = ContentUris.withAppendedId(
                android.provider.MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,
                currSong);
        try {
            player.setDataSource(getApplicationContext(), trackUri);
        } catch (Exception e) {
            Log.e("MUSIC SERVICE", "Error setting data source", e);
        }

        player.prepareAsync();
    }

    @Override
    public void onDestroy() {
        stopForeground(true);
    }

    @Override
    public void onCompletion(MediaPlayer mp) {
        if (player.getCurrentPosition() > 0) {
            mp.reset();
            playNext();
        }
    }

    @Override
    public boolean onError(MediaPlayer mp, int what, int extra) {
        mp.reset();
        return false;
    }

    public void setSong(int songIndex) {
        songPosn = songIndex;
    }

    @Override
    public void onPrepared(MediaPlayer mp) {
        mp.start();
        Intent notIntent = new Intent(this, MainActivity.class);
        notIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        PendingIntent pendInt = PendingIntent.getActivity(this, 0, notIntent, PendingIntent.FLAG_UPDATE_CURRENT);

        Notification.Builder builder = new Notification.Builder(this);

        builder.setContentIntent(pendInt)
                .setSmallIcon(R.drawable.play)
                .setTicker(songTitle)
                .setOngoing(true)
                .setContentTitle("Playing")
                .setContentText(songTitle);
        Notification not = builder.build();

        startForeground(NOTIFY_ID, not);
    }

    public int getPosn() {
        return player.getCurrentPosition();
    }

    public int getDur() {
        return player.getDuration();
    }

    public boolean isPng() {
        return player.isPlaying();
    }

    public void pausePlayer() {
        player.pause();
    }

    public void seek(int posn) {
        player.seekTo(posn);
    }

    public void go() {
        player.start();
    }

    public void playPrev() {
        songPosn--;
        if (songPosn < 0) songPosn = songs.size() - 1;
        playSong();
    }

    public void playNext() {
        if (shuffle) {
            int newSong = songPosn;
            while (newSong == songPosn) {
                newSong = rand.nextInt(songs.size());
            }
            songPosn = newSong;
        } else {
            songPosn++;
            if (songPosn >= songs.size()) songPosn = 0;
        }
        playSong();
    }
}

==================================================================================================================================

Song.java: 

package com.alex.player;

class Song {
    private long id;
    private String title;
    private String artist;

    Song(long songID, String songTitle, String songArtist) {
        id = songID;
        title = songTitle;
        artist = songArtist;
    }

    long getID() {
        return id;
    }

    String getTitle() {
        return title;
    }

    String getArtist() {
        return artist;
    }
}

==================================================================================================================================

SongAdapter.java:

package com.alex.player;

import java.util.ArrayList;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.BaseAdapter;

class SongAdapter extends BaseAdapter {

    private ArrayList<Song> songs;
    private LayoutInflater songInf;

    SongAdapter(Context c, ArrayList<Song> theSongs) {
        songs = theSongs;
        songInf = LayoutInflater.from(c);
    }

    @Override
    public int getCount() {
        return songs.size();
    }

    @Override
    public Object getItem(int arg0) {
        return null;
    }

    @Override
    public long getItemId(int arg0) {
        return 0;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        LinearLayout songLay = (LinearLayout) songInf.inflate
                (R.layout.song, parent, false);
        TextView songView = (TextView) songLay.findViewById(R.id.song_title);
        TextView artistView = (TextView) songLay.findViewById(R.id.song_artist);
        Song currSong = songs.get(position);
        songView.setText(currSong.getTitle());
        artistView.setText(currSong.getArtist());
        songLay.setTag(position);
        return songLay;
    }
}

==================================================================================================================================

drawable: end, play, rand

==================================================================================================================================

layout / activity_main.xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="#FF000000"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <ListView
        android:id="@+id/song_list"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

</LinearLayout>

==================================================================================================================================

layout / song.xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:onClick="songPicked"
    android:orientation="vertical"
    android:padding="5dp" >

    <TextView
        android:id="@+id/song_title"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textColor="#FFFFFFFF"
        android:textSize="20sp"
        android:textStyle="bold" />

    <TextView
        android:id="@+id/song_artist"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textColor="#FFAAAAAA"
        android:textSize="18sp" />

</LinearLayout>

==================================================================================================================================

menu / menu_main.xml:

<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <item
        android:id="@+id/action_shuffle"
        android:icon="@drawable/rand"
        android:orderInCategory="1"
        app:showAsAction="ifRoom"
        android:title="Shuffle"/>

    <item
        android:id="@+id/action_end"
        android:icon="@drawable/end"
        android:orderInCategory="2"
        app:showAsAction="ifRoom"
        android:title="End"/>

</menu>

==================================================================================================================================

AndroidManifest.xml: (check service!)

...
    <uses-permission android:name="android.permission.WAKE_LOCK" />
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
...

==================================================================================================================================

build.gradle (Module:app):

dependencies {
    ...
    implementation 'com.karumi:dexter:5.0.0'
}