什麼是MediaStore.Audio.Playlists.Members.getContentUri引用的字符串'volumeName'參數？

Question

我想查詢給定播放列表的成員。我有正確的播放列表ID，並且希望使用managedQuery（）查看相關播放列表成員。

什麼我是這樣的：

private String [] columns = { 
    MediaStore.Audio.Playlists.Members.PLAYLIST_ID, 
    MediaStore.Audio.Playlists.Members.TITLE, 
    }; 
Uri membersUri = MediaStore.Audio.Playlists.Members.getContentUri(volume, playlistId); 
Cursor tCursor = managedQuery(membersUri, columns, null, null, null); 

我不知道是什麼的體積參數必須是。我試過這個： MediaStore.Audio.Playlists.EXTERNAL_CONTENT_URI.toString()爲「卷」參數。

這讓我回一個有效的內容URI，看起來像：

content://media/external/audio/playlists/2/members 

然而，我的光標回來空。我可能離基地很遠 - 我知道我想要做的事很簡單。

Answer 1

字符串「外部」的作品作爲MediaStore.Audio.Playlists.Members.getContentUri(volume, playlistId)

體積這項活動將打印在Android的歌曲，播放列表，以及它們的內容。

import android.app.Activity; 
import android.database.Cursor; 
import android.net.Uri; 
import android.os.Bundle; 
import android.provider.MediaStore; 
import android.util.Log; 

public class PlaylistActivity extends Activity { 
    private final String [] STAR= {"*"}; 
    private final String TAG= "list"; 

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

     Log.i(TAG, "All the titles"); 
     Uri allaudio_uri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI; 
     Cursor ca= managedQuery(allaudio_uri, STAR, null,null,null); 
     for(ca.moveToFirst(); !ca.isAfterLast(); ca.moveToNext()){ 
      if(ca.isFirst()){ // print all the fields of the first song 
       for(int k= 0; k<ca.getColumnCount(); k++) 
        Log.i(TAG, " "+ca.getColumnName(k)+"="+ca.getString(k)); 
      }else{    // but just the titles of the res 
       Log.i(TAG, ca.getString(ca.getColumnIndex("title"))); 
      } 
     } 
     Log.i(TAG, "--------------------------"); 
     Log.i(TAG, "All the playlists"); 
     Uri playlist_uri= MediaStore.Audio.Playlists.EXTERNAL_CONTENT_URI;  
     Cursor cursor= managedQuery(playlist_uri, STAR, null,null,null); 
     cursor.moveToFirst(); 
     for(int r= 0; r<cursor.getCount(); r++, cursor.moveToNext()){ 
      Log.i(TAG, "-----"); 
      Log.i(TAG, "Playlist " + cursor.getString(cursor.getColumnIndex("name"))); 
      for(int k= 0; k<cursor.getColumnCount(); k++)   
       Log.i(TAG, cursor.getColumnName(k)+"="+cursor.getString(k)); 

      // the members of this playlist 
      int id= cursor.getInt(0); 
      Uri membersUri = MediaStore.Audio.Playlists.Members.getContentUri("external", id); 
      Cursor membersCursor = managedQuery(membersUri, STAR, null, null, null); 
      membersCursor.moveToFirst(); 
      for(int s= 0; s<membersCursor.getCount(); s++, membersCursor.moveToNext()) 
       Log.i(TAG, " "+membersCursor.getString(membersCursor.getColumnIndex("title"))); 
      membersCursor.close(); 
     } 
     cursor.close(); 
    } 
}