音樂服務始終返回null

-1

我已經和音樂列表和服務在後臺播放音樂，但是當我從列表中的音樂單擊它總是返回null音樂服務始終返回null

我從來沒有與音樂服務工作前，所以我也許在這裏做錯了我是否在採用者或其他方面通過錯誤的立場？

服務

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

    //media player 
    private MediaPlayer player; 
    //song list 
    private ArrayList<SongModel> songs; 
    //current position 
    private int songPosn; 
    //binder 
    private final IBinder musicBind = new MusicBinder(); 
    //title of current song 
    private String songTitle = ""; 
    //notification id 
    private static final int NOTIFY_ID = 1; 
    //shuffle flag and random 
    private boolean shuffle = false; 
    private Random rand; 

    public void onCreate() { 
     //create the service 
     super.onCreate(); 
     //initialize position 
     songPosn = 0; 
     //random 
     rand = new Random(); 
     //create player 
     player = new MediaPlayer(); 
     //initialize 
     initMusicPlayer(); 
    } 

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

    //pass song list 
    public void setList(ArrayList<SongModel> theSongs) { 
     songs = theSongs; 
    } 

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

    //activity will bind to service 
    @Override 
    public IBinder onBind(Intent intent) { 
     return musicBind; 
    } 

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

    //play a song 
    public void playSong() { 
     //play 
     player.reset(); 
     //get song 
     SongModel playSong = songs.get(songPosn); 
     //get title 
     songTitle = playSong.getSongTitle(); 
     //get id 
     long currSong = playSong.getmSongID(); 
     //set uri 
     Uri trackUri = ContentUris.withAppendedId(
       android.provider.MediaStore.Audio.Media.EXTERNAL_CONTENT_URI, 
       currSong); 
     //set the data source 
     try { 
      player.setDataSource(getApplicationContext(), trackUri); 
     } catch (Exception e) { 
      Log.e("MUSIC SERVICE", "Error setting data source", e); 
     } 
     player.prepareAsync(); 
    } 

    //set the song 
    public void setSong(int songIndex) { 
     Log.e("click", " service" + songIndex); 
     for (int i = 0; i < songs.size(); i++) { 
      Log.e("click", songs.get(i).getArtistname() + " " + songs.get(i).getmSongID()); 
     } 
     songPosn = songIndex; 
    } 

    @Override 
    public void onCompletion(MediaPlayer mp) { 
     //check if playback has reached the end of a track 
     if (player.getCurrentPosition() > 0) { 
      mp.reset(); 
      playNext(); 
     } 
    } 

    @Override 
    public boolean onError(MediaPlayer mp, int what, int extra) { 
     Log.v("MUSIC PLAYER", "Playback Error"); 
     mp.reset(); 
     return false; 
    } 

    @Override 
    public void onPrepared(MediaPlayer mp) { 
     //start playback 
     mp.start(); 
     //notification 
     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.mipmap.ic_play_circle_filled_black_24dp) 
       .setTicker(songTitle) 
       .setOngoing(true) 
       .setContentTitle("Playing") 
       .setContentText(songTitle); 
     Notification not = builder.build(); 
     startForeground(NOTIFY_ID, not); 
    } 

    //playback methods 
    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(); 
    } 

    //skip to previous track 
    public void playPrev() { 
     songPosn--; 
     if (songPosn < 0) songPosn = songs.size() - 1; 
     playSong(); 
    } 

    //skip to next 
    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(); 
    } 

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

    //toggle shuffle 
    public void setShuffle() { 
     if (shuffle) shuffle = false; 
     else shuffle = true; 
    }}

活動類

public static MusicService musicSrv; 
    private Intent playIntent; 
    private boolean musicBound=false; 

    public static ArrayList<SongModel> songList; 
    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 

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

private ServiceConnection musicConnection = new ServiceConnection() { 

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

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

    private void initLayout() { 
     final Uri uri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI; 
     final String[] cursor_cols = {MediaStore.Audio.Media._ID, 
       MediaStore.Audio.Media.ARTIST, MediaStore.Audio.Media.ALBUM, 
       MediaStore.Audio.Media.TITLE, MediaStore.Audio.Media.DATA, 
       MediaStore.Audio.Media.ALBUM_ID, 
       MediaStore.Audio.Media.DURATION}; 
     final String where = MediaStore.Audio.Media.IS_MUSIC + "=1"; 
     final Cursor cursor = getContentResolver().query(uri, 
       cursor_cols, where, null, null); 


     while (cursor.moveToNext()) { 
      String artist = cursor.getString(cursor 
        .getColumnIndexOrThrow(MediaStore.Audio.Media.ARTIST)); 
      String album = cursor.getString(cursor 
        .getColumnIndexOrThrow(MediaStore.Audio.Media.ALBUM)); 
      String track = cursor.getString(cursor 
        .getColumnIndexOrThrow(MediaStore.Audio.Media.TITLE)); 
      String data = cursor.getString(cursor 
        .getColumnIndexOrThrow(MediaStore.Audio.Media.DATA)); 
      Long albumId = cursor.getLong(cursor 
        .getColumnIndexOrThrow(MediaStore.Audio.Media.ALBUM_ID)); 

      int duration = cursor.getInt(cursor 
        .getColumnIndexOrThrow(MediaStore.Audio.Media.DURATION)); 

      Uri sArtworkUri = Uri 
        .parse("content://media/external/audio/albumart"); 
      Uri albumArtUri = ContentUris.withAppendedId(sArtworkUri, albumId); 

      Log.e("art", albumArtUri.toString()); 
      /*Bitmap bitmap = null; 
      try { 
       bitmap = MediaStore.Images.Media.getBitmap(
         getActivity().getContentResolver(), albumArtUri); 
       bitmap = Bitmap.createScaledBitmap(bitmap, 30, 30, true); 

      } catch (FileNotFoundException exception) { 
       exception.printStackTrace(); 
       bitmap = BitmapFactory.decodeResource(getActivity().getResources(), 
         R.mipmap.ic_music_note_black_24dp); 
      } catch (IOException e) { 

       e.printStackTrace(); 
      }*/ 

      SongModel audioListModel = new SongModel(); 
      audioListModel.setArtistname(artist); 
      // audioListModel.setBitmap(bitmap); 
      audioListModel.setmSongTitle(album); 
      audioListModel.setmSongTitle(track); 
      audioListModel.setData(data); 
      audioListModel.setmSongID(albumId); 
      audioListModel.setSongLength(String.valueOf(duration)); 
      audioListModel.setUri(String.valueOf(albumArtUri)); 
      Log.e("data", "artist :" + artist + " album " + album + " track " + track + " data " + data + " " + "albumId " + albumId 
        + " " + "duration " + duration + " art: " + albumArtUri); 

      songList.add(audioListModel); 

     } 

    } 


    private class GetAudioListAsynkTask extends AsyncTask<Void, Void, Boolean> { 

     private Context context; 

     public GetAudioListAsynkTask(Context context) { 

      this.context = context; 
     } 

     @Override 
     protected void onPreExecute() { 
      super.onPreExecute(); 

     } 

     @Override 
     protected Boolean doInBackground(Void... params) { 
      try { 
       initLayout(); 

       return true; 
      } catch (Exception e) { 
       return false; 

      } 

     } 

     @Override 
     protected void onPostExecute(Boolean result) { 
      Collections.sort(songList, new Comparator<SongModel>() { 
       public int compare(SongModel a, SongModel b) { 
        return a.getSongTitle().compareTo(b.getSongTitle()); 
       } 
      }); 

     } 
    } 

    public void load() { 
     songList = new ArrayList<>(); 
     new GetAudioListAsynkTask(this).execute((Void) null); 


    }

適配器類

@Override 
public void onBindViewHolder(final Holder holder, final int position) { 
    final SongModel songModel = list.get(holder.getAdapterPosition()); 
    Glide.with(holder.itemView.getContext()).load(songModel.getUri()).error(R.mipmap.ic_music_note_black_24dp).into(holder.imageView); 
    holder.imageView.setImageURI(Uri.parse(songModel.getUri())); 
    holder.artistname.setText(songModel.getArtistname()); 
    holder.duration.setText(songModel.getSongLength()); 
    holder.songname.setText(songModel.getSongTitle()); 
    holder.itemView.setTag(position); 

    holder.itemView.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 

      songPicked(position); 
     } 
    }); 


} 
private void songPicked(int position) { 
    musicSrv.setSong(position); 
    musicSrv.playSong(); 
}

錯誤日誌

04-21 19:01:37.847 3983-29870/? E/DatabaseUtils: Writing exception to parcel 
               java.lang.SecurityException: Permission Denial: reading com.android.providers.media.MediaProvider uri content://media/external/audio/media/1 from pid=2608, uid=1000 requires android.permission.READ_EXTERNAL_STORAGE, or grantUriPermission() 
                at android.content.ContentProvider.enforceReadPermissionInner(ContentProvider.java:646) 
                at android.content.ContentProvider$Transport.enforceReadPermission(ContentProvider.java:493) 
                at android.content.ContentProvider$Transport.enforceFilePermission(ContentProvider.java:484) 
                at android.content.ContentProvider$Transport.openFile(ContentProvider.java:380) 
                at android.content.ContentProviderNative.onTransact(ContentProviderNative.java:240) 
                at android.os.Binder.execTransact(Binder.java:453) 


               [ 04-21 19:01:37.847 2264:16266 D/   ] 
               openContentUri(content://media/external/audio/media/1) caught exception -1 
04-21 19:01:37.847 2264-16266/? E/MediaPlayerService: Couldn't open fd for content://media/external/audio/media/1 
04-21 19:01:37.847 19273-19273/? E/MediaPlayer: Unable to create media player 
04-21 19:01:37.847 19273-19273/? E/MUSIC SERVICE: Error setting data source 
                java.io.IOException: setDataSource failed.: status=0x80000000 
                 at android.media.MediaPlayer.nativeSetDataSource(Native Method) 
                 at android.media.MediaPlayer.setDataSource(MediaPlayer.java:1231) 
                 at android.media.MediaPlayer.setDataSource(MediaPlayer.java:1215) 
                 at android.media.MediaPlayer.setDataSource(MediaPlayer.java:1169) 
                 at android.media.MediaPlayer.setDataSource(MediaPlayer.java:1105) 
                 at com.nowsip.musicplayer.service.MusicService.playSong(MusicService.java:118) 
                 at com.nowsip.musicplayer.adapter.SongAdapter.songPicked(SongAdapter.java:86) 
                 at com.nowsip.musicplayer.adapter.SongAdapter.access$000(SongAdapter.java:24) 
                 at com.nowsip.musicplayer.adapter.SongAdapter$1.onClick(SongAdapter.java:52) 
                 at android.view.View.performClick(View.java:5721) 
                 at android.view.View$PerformClick.run(View.java:22620) 
                 at android.os.Handler.handleCallback(Handler.java:739) 
                 at android.os.Handler.dispatchMessage(Handler.java:95) 
                 at android.os.Looper.loop(Looper.java:148) 
                 at android.app.ActivityThread.main(ActivityThread.java:7409) 
                 at java.lang.reflect.Method.invoke(Native Method) 
                 at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230) 
                 at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120) 
04-21 19:01:37.847 19273-19273/? E/MediaPlayer: prepareAsync called in state 1 
04-21 19:01:37.847 19273-19273/? E/AndroidRuntime: FATAL EXCEPTION: main 
                Process: com.nowsip.musicplayer, PID: 19273 
                java.lang.IllegalStateException 
                 at android.media.MediaPlayer.prepareAsync(Native Method) 
                 at com.nowsip.musicplayer.service.MusicService.playSong(MusicService.java:122) 
                 at com.nowsip.musicplayer.adapter.SongAdapter.songPicked(SongAdapter.java:86) 
                 at com.nowsip.musicplayer.adapter.SongAdapter.access$000(SongAdapter.java:24) 
                 at com.nowsip.musicplayer.adapter.SongAdapter$1.onClick(SongAdapter.java:52) 
                 at android.view.View.performClick(View.java:5721) 
                 at android.view.View$PerformClick.run(View.java:22620) 
                 at android.os.Handler.handleCallback(Handler.java:739) 
                 at android.os.Handler.dispatchMessage(Handler.java:95) 
                 at android.os.Looper.loop(Looper.java:148) 
                 at android.app.ActivityThread.main(ActivityThread.java:7409) 
                 at java.lang.reflect.Method.invoke(Native Method) 
                 at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230) 
                 at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120) 
04-21 19:01:37.887 19790-19790/? E/Zygote: v2 
04-21 19:01:37.887 2608-19795/? E/android.os.Debug: ro.product_ship = true 
04-21 19:01:37.887 2608-19795/? E/android.os.Debug: ro.debug_level = 0x4f4c 
04-21 19:01:37.887 2608-19795/? E/android.os.Debug: sys.mobilecare.preload = false 
04-21 19:01:37.897 19790-19790/? E/Zygote: accessInfo : 0 
04-21 19:01:37.897 2608-2803/? E/Qmage: isQIO : stream is not a QIO file 
04-21 19:01:38.457 11589-11589/? E/Qmage: isQIO : stream is not a QIO file 
04-21 19:01:38.497 11589-11589/? E/Qmage: isQIO : stream is not a QIO file 
04-21 19:01:38.497 11589-11589/? E/Qmage: isQIO : stream is not a QIO file

來源

2017-04-21 androidpie

*音樂服務始終返回null *它不會自動的設置爲不爲空，並在你的代碼沒有分配新建分配FY – Selvin

@Selvin讓我怎麼設置u能告訴我 – androidpie

像往常一樣（和因爲它是在無數的教程/問題中說明）讓活頁夾在正確的位置，從活頁夾得到服務，分配 – Selvin

確認時叫你的onServiceConnected方法和設置歌曲列表中的服務，在那個時候你songList是prapared與否？

我的意思是你的歌曲列表可能爲空，當你撥打下面的線。

//pass list 
    musicSrv.setList(songList);

在當你initLayout方法之前完成業務接入的情況下。

更新

根據以下線的錯誤日誌，你需要在你的清單文件中添加READ_EXTERNAL_STORAGE權限。

java.lang.SecurityException異常：權限拒絕：讀取 com.android.providers.media.MediaProvider URI 內容：//媒體/外部/音頻/媒體/ 1從PID = 2608，UID = 1000 需要android.permission.READ_EXTERNAL_STORAGE，或 grantUriPermission（）使用文件FileDescriptor

集的數據源：

//play a song 
public void playSong() { 
    //play 
    player.reset(); 
    //get song 
    SongModel playSong = songs.get(songPosn); 
    //get title 
    songTitle = playSong.getSongTitle(); 
    //get id 
    long currSong = playSong.getmSongID(); 
    //set uri 
    Uri trackUri = ContentUris.withAppendedId(
      android.provider.MediaStore.Audio.Media.EXTERNAL_CONTENT_URI, 
      currSong); 
    //set the data source 
    try { 
     String filePath = getPathFromContentUri(context, trackUri); 
     File file = new File(filePath); 
     FileInputStream inputStream = new FileInputStream(file);  
     player.setDataSource(inputStream.getFD()); 
     inputStream.close(); 
    } catch (Exception e) { 
     Log.e("MUSIC SERVICE", "Error setting data source", e); 
    } 
    player.prepareAsync(); 
} 


public static String getPathFromContentUri(Context context, Uri contentUri) { 
    String[] proj = { MediaStore.Audio.Media.DATA }; 
    Cursor cursor = context.getContentResolver().query(contentUri, 
      proj, null, null, null); 
    cursor.moveToFirst(); 

    String path = cursor.getString(cursor 
      .getColumnIndexOrThrow(MediaStore.Audio.Media.DATA)); 

    cursor.close(); 
    return path; 
}

結帳this answer瞭解更多信息。這可能對你有所幫助。

來源

2017-04-21 12:54:36

我試過同樣的錯誤 – androidpie

O n您正在使用哪個設備和Android操作系統版本進行測試？ –

M和KITKAT測試 – androidpie

這不是音樂服務的問題就是權限問題

首先你需要給服務名爲Android清單像

後，如果您在運行6。0或更多，那麼當第一次運行應用程序在棒棒糖或套件kat或其他在安裝時給予許可但在棉花糖或更多的手動請求用戶

檢查了這一點 Storage permission error in Marshmallow

來源

2018-01-21 09:05:31

音樂服務始終返回null

回答

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