如何在android中爲音樂播放器創建縮略圖播放列表？

Question

我在android中開發了一個簡單的媒體播放器應用程序。它有一個列表視圖來加載SD卡中的所有歌曲，查找欄和播放按鈕。我需要爲我的應用創建專輯藝術畫廊（如在谷歌播放音樂應用）。我用這個代碼從SD卡中的所有歌曲，

public ArrayList<String> GetFiles(String DirectoryPath) { 
     ArrayList<String> MyFiles = new ArrayList<String>(); 
     File f = new File(DirectoryPath); 
     f.mkdirs(); 
     File[] files = f.listFiles(); 
     if (files.length == 0) { 
      return null; 
     }else { 
      for (int i=0; i<files.length; i++) 
       MyFiles.add(files[i].getName()); 
     } 

     return MyFiles; 
    } 

1. 如何改善這種代碼返回歌曲名稱和專輯藝術？

2. 如何爲每首歌曲創建縮略圖視圖？

   _________ 
   |   | 
   | image | 
   |   | 
   |_________| 
   | title | 
   |_________| 
   

Answer 1

您需要使用內容解析器。

---

Uri uri = android.provider.MediaStore.Audio.Media.EXTERNAL_CONTENT_URI; 
      // Perform a query on the content resolver. The URI we're passing specifies that we 
      // want to query for all audio media on external storage (e.g. SD card) 
      Cursor cur = contentResolver.query(uri, null, 
        MediaStore.Audio.Media.IS_MUSIC + " = 1", null, null); 
      if (cur == null) { 
       Log.e(TAG, "Failed to retrieve music: cursor is null :-("); 
       subscriber.onError(new Throwable("Failed to retrieve music: cursor is null :-(")); 
       return; 
      } 
      if (!cur.moveToFirst()) { 
       subscriber.onError(new Throwable("No results. :(Add some tracks!")); 

       Log.e(TAG, "Failed to move cursor to first row (no query results)."); 
       return; 
      } 
      int artistColumn = cur.getColumnIndex(MediaStore.Audio.Media.ARTIST); 
      int titleColumn = cur.getColumnIndex(MediaStore.Audio.Media.TITLE); 
      int albumColumn = cur.getColumnIndex(MediaStore.Audio.Media.ALBUM_ID); 
      int durationColumn = cur.getColumnIndex(MediaStore.Audio.Media.DURATION); 
      int idColumn = cur.getColumnIndex(MediaStore.Audio.Media._ID); 
      int dataColumn = cur.getColumnIndex(MediaStore.Audio.Media.DATA); 
      ArrayList<LocalTrack> tracks = new ArrayList<>(); 

      do { 
       Log.i(TAG, "ID: " + cur.getString(idColumn) + " Title: " + cur.getString(titleColumn)); 
       tracks.add(new LocalTrack(
         cur.getLong(idColumn), 
         cur.getString(artistColumn), 
         cur.getString(titleColumn), 
         cur.getLong(albumColumn), 
         cur.getLong(durationColumn), 
         cur.getString(dataColumn))); 
      } while (cur.moveToNext()); 
      Log.i(TAG, "Done querying media. MusicRetriever is ready."); 
      cur.close(); 


      for (LocalTrack localTrack : tracks) { 
       localTrack.setArtPath(findAlbumArt(localTrack)); 
      } 
      subscriber.onNext(tracks); 

---

public String findAlbumArt(LocalTrack localTrack) { 
    Cursor cursor = contentResolver.query(MediaStore.Audio.Albums.EXTERNAL_CONTENT_URI, 
      new String[]{MediaStore.Audio.Albums._ID, MediaStore.Audio.Albums.ALBUM_ART}, 
      MediaStore.Audio.Albums._ID + "=?", 
      new String[]{String.valueOf(localTrack.getAlbum())}, 
      null); 

    String path = null; 
    if (cursor != null) { 
     if (cursor.moveToFirst()) { 
      path = cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Albums.ALBUM_ART)); 
      // do whatever you need to do 
      cursor.close(); 
     } 
    } 

    return path; 
}