问题
I'm attempting to create a new Playlist, using Android's ContentResolver, that will be added to music player's playlists, but when the code runs, the insert into the playlist returns null (for the Uri) and when I check the music player's playlists, my new Playlist entry isn't there. I suspect that the reason that the insert() returns null is because I haven't created the Playlist correctly. Could someone clarify how to dynamically create a new playlist, given that my code doesn't work. (In my searching, I've found several way to query playlists, but nothing actually creates a new one)
Here's my code...
ContentResolver resolver = getActivity().getContentResolver();
Uri playlists = MediaStore.Audio.Playlists.EXTERNAL_CONTENT_URI;
Log.d(A.TAG, "Checking for existing playlist for " + chart.getName());
Cursor c = resolver.query(playlists, new String[] {"*"}, null, null, null);
long playlistId = 0;
c.moveToFirst();
do {
String plname = c.getString(c.getColumnIndex(MediaStore.Audio.Playlists.NAME));
if (plname.equalsIgnoreCase(chart.getName())) {
playlistId = c.getLong(c.getColumnIndex(MediaStore.Audio.Playlists._ID));
break;
}
} while (c.moveToNext());
c.close();
if (playlistId!=0) {
Uri deleteUri = ContentUris.withAppendedId(playlists, playlistId);
Log.d(A.TAG, "REMOVING Existing Playlist: " + playlistId);
// delete the playlist
resolver.delete(deleteUri, null, null);
}
Log.d(A.TAG, "CREATING PLAYLIST: " + chart.getName());
ContentValues v = new ContentValues();
v.put(MediaStore.Audio.Playlists.NAME, chart.getName());
v.put(MediaStore.Audio.Playlists.DATE_MODIFIED, System.currentTimeMillis());
Uri newpl = resolver.insert(playlists, v);
Log.d(A.TAG, "Added PlayLIst: " + newpl);
Uri insUri = Uri.withAppendedPath(newpl, MediaStore.Audio.Playlists.Members.CONTENT_DIRECTORY);
int order = 1;
Log.d(A.TAG, "Playlist Members Url: " + insUri);
c = getContentManager().queryWhere(getActivity(), Song.class, Song.Fields.LIBRARYID + " != 0 and " + Song.Fields.CHARTID + " = " + chart.getId(), (String[])null);
if (c.moveToFirst()) {
Log.d(A.TAG, "Adding Songs to PlayList **");
do {
long id = c.getLong(c.getColumnIndex(Song.Fields.LIBRARYID));
ContentValues cv = new ContentValues();
cv.put(MediaStore.Audio.Playlists.Members.PLAY_ORDER, order++);
cv.put(MediaStore.Audio.Playlists.Members.AUDIO_ID, id);
Uri u = resolver.insert(insUri, cv);
Log.d(A.TAG, "Added Playlist Item: " + u + " for AUDIO_ID " + id);
} while (c.moveToNext());
}
c.close();
UPDATE: Partially Solved **
The above code does correctly add a new Playlist on 4.0.3, but not on 2.3. The only problem areas for 4.0.3 was that I needed to make sure the DATE_MODIFIED was set on the Playlist and that PLAY_ORDER was set on the Playlist item.
I still have no idea why it would not create a playlist on 2.x, so if anyone has any thoughts on that, I'd like to know.
回答1:
This is the code I use in a custom built AsyncTask and it works on 2.3, 3.1, and 4.03:
ContentValues mInserts = new ContentValues();
mInserts.put(MediaStore.Audio.Playlists.NAME, mPrefs.getString(AM.MEDIASTORECHANGE_NEWPLAYLISTNAME, "New Playlist"));
mInserts.put(MediaStore.Audio.Playlists.DATE_ADDED, System.currentTimeMillis());
mInserts.put(MediaStore.Audio.Playlists.DATE_MODIFIED, System.currentTimeMillis());
mUri = mCR.insert(MediaStore.Audio.Playlists.EXTERNAL_CONTENT_URI, mInserts);
if (mUri != null) {
mPlaylistId = -1;
mResult = FM.SUCCESS;
c = mCR.query(mUri, PROJECTION_PLAYLIST, null, null, null);
if (c != null) {
// Save the newly created ID so it can be selected. Names are allowed to be duplicated,
// but IDs can never be.
mPlaylistId = c.getInt(c.getColumnIndex(MediaStore.Audio.Playlists._ID));
c.close();
}
if (DBG.AUDIO) {
Log.d(TAG, "PLAYLIST_ADD - mPlaylistId: " + mPlaylistId
+ " mSelectString: " + mSelectString + " mUri: "+ mUri.toString());
}
}
public static final String[] PROJECTION_PLAYLIST = new String[] {
MediaStore.Audio.Playlists._ID,
MediaStore.Audio.Playlists.NAME,
MediaStore.Audio.Playlists.DATA
};
To get the correct Uri to add playlist members, you need the Id. To add songs to the playlist, you also need to know the current high water mark of PLAYORDER in the playlist's current state. Otherwise the MediaStore ContentResolver will gag because you are trying to insert playlist members with the same play order. So, you need to query the Playlist Uri first to get the highest PLAYORDER value, and use that as the starting point for your ContentValues inserts.
I have only tried inserting one playlist member at a time, though in theory you might be able to do a bulk insert. The code below is set up to convert to a bulk insert in the future, but currently only does one insert at a time. It takes a cursor of MediaStore.Audio.Media songs and inserts them into a playlist Id that has been stored in SharedPreferences.
private void addSongsInCursorToPlaylist(Cursor c) {
int mIdCol;
int mCount;
int mPercent = 0;
ContentResolver mCR = mContext.getContentResolver();
ContentProviderClient mCRC = null;
try {
mCount = c.getCount();
mIdCol = c.getColumnIndex(MediaStore.Audio.Media._ID);
ContentValues[] mInsertList = new ContentValues[1];
mInsertList[0] = new ContentValues();
int mPlaylistId = mPrefs.getInt(AM.PLAYLIST_NOWPLAYING_ID, AM.PLAYLIST_ID_DEFAULT);
Uri mUri = MediaStore.Audio.Playlists.Members.getContentUri("external", mPlaylistId);
Cursor c2 = mCR.query(mUri,
PROJECTION_PLAYLISTMEMBERS_PLAYORDER, null, null, MediaStore.Audio.Playlists.Members.PLAY_ORDER + " DESC ");
int mPlayOrder = 1;
if (c2 != null) {
if (c2.moveToFirst()) {
mPlayOrder = (c2.getInt(c2.getColumnIndex(MediaStore.Audio.Playlists.Members.PLAY_ORDER))) + 1;
}
c2.close();
}
mCRC = mCR.acquireContentProviderClient(mUri);
if (DBG.AUDIO) {
Log.d(TAG, "addSongsInCursorToPlaylist -Content Uri: " + mUri.toString()
+ " PlaylistID: " + mPlaylistId + " mPlayOrder: " + mPlayOrder);
}
for (int i=0; i< mCount; i++) {
if (c.moveToPosition(i)) {
// Don't pollute with progress messages..has to be at least 1% increments
int mTemp = (i * 100) / (mCount );
if (mTemp > mPercent) {
mPercent = mTemp;
publishProgress(mPercent);
}
mInsertList[0].put(MediaStore.Audio.Playlists.Members.AUDIO_ID, c.getLong(mIdCol));
mInsertList[0].put(MediaStore.Audio.Playlists.Members.PLAY_ORDER, mPlayOrder++);
mCR.insert(mUri, mInsertList[0]);
if (DBG.AUDIO) {
Log.d(TAG, "addSongsInCursorToPlaylist -Adding AudioID: " + c.getLong(mIdCol) + " to Uri: " + mUri.toString() );
}
}
mCRC.release();
}
} catch (Throwable t) {
t.printStackTrace();
}
}
// Projection to get high water mark of PLAY_ORDER in a particular playlist
public static final String[] PROJECTION_PLAYLISTMEMBERS_PLAYORDER = new String[] {
MediaStore.Audio.Playlists.Members._ID,
MediaStore.Audio.Playlists.Members.PLAY_ORDER
};
// Projection to get the list of song IDs to be added to a playlist
public static final String[] PROJECTION_SONGS_ADDTOPLAYLIST = new String[] {
MediaStore.Audio.Media._ID,
};
来源：https://stackoverflow.com/questions/10969281/how-to-create-a-new-playlist-using-contentresolver