实现一个音乐播放器

1、显示歌曲名，艺人，专辑。页面有mini条包含暂停恢复，上下首按钮，可以显示歌曲信息。
2、点击后启动播放，使用后出通知栏提醒。
3、可以从service拿到播放信息更新ui
4、通知栏效果可以参考常见音乐播放器排版。

public class MusicActivity extends AppCompatActivity implements View.OnClickListener {    private Button mPrevious,mPlay,mNext,mPause;    private ComponentName component;    private MyReceiver receiver;    private TextView textView;    private ListView listView;    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        receiver=new MyReceiver();        IntentFilter intentFilter = new IntentFilter();        intentFilter.addAction("com.skyl.RECEIVER");        registerReceiver(receiver,intentFilter);        setupViews();    }    //初始化    public void setupViews(){        listView= (ListView) findViewById(R.id.listview);        component = new ComponentName(this,                MusicService.class);        textView= (TextView) findViewById(R.id.textView);        mPrevious = (Button)findViewById(R.id.previous);        mPlay = (Button)findViewById(R.id.play);        mNext = (Button)findViewById(R.id.next);        mPause = (Button)findViewById(R.id.pause);        mPrevious.setOnClickListener(this);        mPlay.setOnClickListener(this);        mNext.setOnClickListener(this);        mPause.setOnClickListener(this);    }    public void onClick(View v) {        if(v == mPrevious){            Intent mIntent = new Intent(MusicService.PREVIOUS_ACTION);            mIntent.setComponent(component);            startService(mIntent);        }else if(v == mPlay){            Intent mIntent = new Intent(MusicService.PLAY_ACTION);            mIntent.setComponent(component);            startService(mIntent);        }else if(v == mNext){            Intent mIntent = new Intent(MusicService.NEXT_ACTION);            mIntent.setComponent(component);            startService(mIntent);        }else{            Intent mIntent = new Intent(MusicService.PAUSE_ACTION);            mIntent.setComponent(component);            startService(mIntent);        }    }    public class MyReceiver extends BroadcastReceiver{        @Override        public void onReceive(Context context, Intent intent) {            String info =intent.getStringExtra("info");            textView.setText(info);            ArrayList<String> musiclist = intent.getStringArrayListExtra("MusitList");            listView.setAdapter(new ArrayAdapter<String>(MusicActivity.this,android.R.layout.simple_list_item_1,musiclist));        }    }    @Override    protected void onDestroy() {        super.onDestroy();        unregisterReceiver(receiver);    }

public class MusicService extends Service {    String[] mCursorCols = new String[] {            "audio._id AS _id",            MediaStore.Audio.Media.ARTIST, MediaStore.Audio.Media.ALBUM,            MediaStore.Audio.Media.TITLE, MediaStore.Audio.Media.DATA,            MediaStore.Audio.Media.MIME_TYPE, MediaStore.Audio.Media.ALBUM_ID,            MediaStore.Audio.Media.ARTIST_ID, MediaStore.Audio.Media.DURATION    };    private MediaPlayer mMediaPlayer;    private Cursor mCursor;    private int mPlayPosition = 0;    ArrayList<String> list;    public static final String PLAY_ACTION = "com.skyl.music.PLAY_ACTION";    public static final String PAUSE_ACTION = "com.skyl.music.PAUSE_ACTION";    public static final String NEXT_ACTION = "com.skyl.music.NEXT_ACTION";    public static final String PREVIOUS_ACTION = "com.skyl.music.PREVIOUS_ACTION";    @Override    public IBinder onBind(Intent arg0) {        // TODO Auto-generated method stub        return null;    }    @Override    public void onCreate() {        super.onCreate();        mMediaPlayer = new MediaPlayer();        //通过一个URI可以获取所有音频文件默认大于10秒的可以看作是歌        Uri MUSIC_URL = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;        mCursor = getContentResolver().query(MUSIC_URL, mCursorCols, "duration > 10000", null, null);        list=new ArrayList<>();//        发送广播更新UI        while(mCursor.moveToNext()){            int titleColumn = mCursor.getColumnIndex(MediaStore.Audio.Media.TITLE);            String titleName=mCursor.getString(titleColumn);            list.add(titleName);        }    }    @Override    public int onStartCommand(Intent intent, int flags, int startId) {        String action = intent.getAction();        if(action.equals(PLAY_ACTION)){            play();        }else if(action.equals(PAUSE_ACTION)){            pause();        }else if(action.equals(NEXT_ACTION)){            next();        }else if(action.equals(PREVIOUS_ACTION)){            previous();        }        return super.onStartCommand(intent, flags, startId);    }    //play the music    public void play() {        inite();    }    //暂停时，结束服务    public void pause() {        stopSelf();    }    //上一首    public void previous() {        if (mPlayPosition == 0) {            mPlayPosition = mCursor.getCount() - 1;        } else {            mPlayPosition--;        }        inite();    }    //下一首    public void next() {        if (mPlayPosition == mCursor.getCount() - 1) {            mPlayPosition = 0;        } else {            mPlayPosition++;        }        inite();    }    //初始化    public void inite() {        mMediaPlayer.reset();        String dataSource = getDateByPosition(mCursor, mPlayPosition);        String info = getInfoByPosition(mCursor, mPlayPosition);        Intent intent =new Intent("com.skyl.RECEIVER");        intent.putExtra("info",info);        intent.putStringArrayListExtra("MusitList",list);        sendBroadcast(intent);        //开启通知栏        startForeground(1,onCreateNotifi(info));        try {            mMediaPlayer.setDataSource(dataSource);            mMediaPlayer.prepare();            mMediaPlayer.start();        } catch (IllegalArgumentException e1) {            e1.printStackTrace();        } catch (IllegalStateException e1) {            e1.printStackTrace();        } catch (IOException e1) {            e1.printStackTrace();        }    }    //根据位置来获取歌曲位置    public String getDateByPosition(Cursor c,int position){        c.moveToPosition(position);        int dataColumn = c.getColumnIndex(MediaStore.Audio.Media.DATA);        String data = c.getString(dataColumn);        return data;    }    //获取当前播放歌曲演唱者、歌名及专辑名    public String getInfoByPosition(Cursor c,int position){        c.moveToPosition(position);        int titleColumn = c.getColumnIndex(MediaStore.Audio.Media.TITLE);        int artistColumn = c.getColumnIndex(MediaStore.Audio.Media.ARTIST);        int albumColumn=c.getColumnIndex(MediaStore.Audio.Media.ALBUM);        String info = "歌手名："+c.getString(artistColumn)+"  歌曲名：" + c.getString(titleColumn)+"  专辑名："+c.getString(albumColumn);        return info;    }    //服务结束时释放MediaPlayer    public void onDestroy() {        super.onDestroy();        mMediaPlayer.release();    }    //创建通知栏    public Notification onCreateNotifi(String info){        RemoteViews remoteViews=new RemoteViews(getPackageName(),R.layout.list_item_notification);        remoteViews.setTextViewText(R.id.tv_nofitication_singname,info);        //注册上一首点击事件        Intent previous =new Intent(this,MusicService.class);        previous.setAction(PREVIOUS_ACTION);        PendingIntent previousIntent=PendingIntent.getService(this,200,previous,PendingIntent.FLAG_UPDATE_CURRENT);        remoteViews.setOnClickPendingIntent(R.id.iv_nofitication_kzhi_previous,                previousIntent);        //注册播放事件        Intent play=new Intent(this,MusicService.class);        play.setAction(PLAY_ACTION);        PendingIntent playIntent=PendingIntent.getService(this,200,play,PendingIntent.FLAG_UPDATE_CURRENT);        remoteViews.setOnClickPendingIntent(R.id.iv_nofitication_kzhi_play,                playIntent);        //注册下一首事件        Intent next=new Intent(this,MusicService.class);        play.setAction(NEXT_ACTION);        PendingIntent nextIntent=PendingIntent.getService(this,200,play,PendingIntent.FLAG_UPDATE_CURRENT);        remoteViews.setOnClickPendingIntent(R.id.iv_nofitication_kzhi_next,                nextIntent);        //注册暂停事件        Intent pause=new Intent(this,MusicService.class);        play.setAction(PAUSE_ACTION);        PendingIntent pauseIntent=PendingIntent.getService(this,200,play,PendingIntent.FLAG_UPDATE_CURRENT);        remoteViews.setOnClickPendingIntent(R.id.iv_nofitication_kzhi_colse,                pauseIntent);        Notification notification=new NotificationCompat.Builder(this)                .setSmallIcon(R.drawable.ic_launcher)                .setTicker(info)                .setContent(remoteViews)                .build();        return notification;    }}