/** 扫描类型， 并将Song与Genre关联 */
public static ArrayList<Genre> scanGenres(Context context) {
LogUtils.v(TAG, "scanGenres() called");
ArrayList<Genre> genres = new ArrayList<>();
Cursor cursor =
context
.getContentResolver()
.query(
MediaStore.Audio.Genres.EXTERNAL_CONTENT_URI,
genreProjection,
null,
null,
MediaStore.Audio.Genres.NAME + " ASC");
LogUtils.v(TAG, cursor.getCount() + "");
for (int i = 0; i < cursor.getCount(); i++) {
cursor.moveToPosition(i);
int genreId = cursor.getInt(cursor.getColumnIndex(MediaStore.Audio.Genres._ID));
String genreName = cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Genres.NAME));
// LogUtils.v(TAG, "get genres : id = " + genreId + " name = " + genreName);
Genre genre = new Genre(genreId, genreName);
genres.add(genre);
// 将歌曲与类型关联
Cursor genreCursor =
context
.getContentResolver()
.query(
MediaStore.Audio.Genres.Members.getContentUri("external", genreId),
new String[] {MediaStore.Audio.Media._ID},
MediaStore.Audio.Media.IS_MUSIC + " != 0 ",
null,
null);
genreCursor.moveToFirst();
for (int j = 0; j < genreCursor.getCount(); j++) {
genreCursor.moveToPosition(j);
int index = genreCursor.getColumnIndex(MediaStore.Audio.Media._ID);
final Song song = findSongById(genreCursor.getInt(index));
if (song != null) {
song.setmGenreId(genreId);
}
}
genreCursor.close();
}
cursor.close();
return genres;
}
/**
* Builds a query that will return all the songs in the genre with the given id.
*
* @param id The id of the genre in MediaStore.Audio.Genres.
* @param projection The columns to query.
* @param selection The selection to pass to the query, or null.
* @param selectionArgs The arguments to substitute into the selection.
* @param sort The sort order.
* @param type The media type to query and return
* @param returnSongs returns matching songs instead of `type' if true
*/
public static QueryTask buildGenreQuery(
long id,
String[] projection,
String selection,
String[] selectionArgs,
String sort,
int type,
boolean returnSongs) {
// Note: This function works on a raw sql query with way too much internal
// knowledge about the mediaProvider SQL table layout. Yes: it's ugly.
// The reason for this mess is that android has a very crippled genre implementation
// and does, for example, not allow us to query the albumbs beloging to a genre.
Uri uri = MediaStore.Audio.Genres.Members.getContentUri("external", id);
String[] clonedProjection =
projection
.clone(); // we modify the projection, but this should not be visible to the caller
String sql = "";
String authority = "audio";
if (type == TYPE_ARTIST) authority = "artist_info";
if (type == TYPE_ALBUM) authority = "album_info";
// Our raw SQL query includes the album_info table (well: it's actually a view)
// which shares some columns with audio.
// This regexp should matche duplicate column names and forces them to use
// the audio table as a source
final String _FORCE_AUDIO_SRC = "(^|[ |,\\(])(_id|album(_\\w+)?|artist(_\\w+)?)";
// Prefix the SELECTed rows with the current table authority name
for (int i = 0; i < clonedProjection.length; i++) {
if (clonedProjection[i].equals("0") == false) // do not prefix fake rows
clonedProjection[i] = (returnSongs ? "audio" : authority) + "." + clonedProjection[i];
}
sql += TextUtils.join(", ", clonedProjection);
sql +=
" FROM audio_genres_map_noid, audio" + (authority.equals("audio") ? "" : ", " + authority);
sql += " WHERE(audio._id = audio_id AND genre_id=?)";
if (selection != null && selection.length() > 0)
sql += " AND(" + selection.replaceAll(_FORCE_AUDIO_SRC, "$1audio.$2") + ")";
if (type == TYPE_ARTIST)
sql +=
" AND(artist_info._id = audio.artist_id)"
+ (returnSongs ? "" : " GROUP BY artist_info._id");
if (type == TYPE_ALBUM)
sql +=
" AND(album_info._id = audio.album_id)" + (returnSongs ? "" : " GROUP BY album_info._id");
if (sort != null && sort.length() > 0)
sql += " ORDER BY " + sort.replaceAll(_FORCE_AUDIO_SRC, "$1audio.$2");
// We are now turning this into an sql injection. Fun times.
clonedProjection[0] = sql + " --";
QueryTask result = new QueryTask(uri, clonedProjection, selection, selectionArgs, sort);
result.type = TYPE_GENRE;
return result;
}