Question

我已阅读官方文档，但我无法理解该方法的作用：

@Override
public void onLoadChildren(final String parentMediaId,
final Result<List<MediaItem>> result) {

...
// Assume for example that the music catalog is already loaded/cached.

List<MediaItem> mediaItems = new ArrayList<>();

// Check if this is the root menu:
if (MY_MEDIA_ROOT_ID.equals(parentMediaId)) {

  // build the MediaItem objects for the top level,
  // and put them in the mediaItems list

  where is documented this part? how to build the media item?

} else {

  // examine the passed parentMediaId to see which submenu we're at,
  // and put the children of that menu in the mediaItems list
}
...
}

如果我想在手机上播放音乐，如何根据手机的音乐“建立媒体项目”？

Answer 1

我的回答有点晚，但我希望这有助于未来的疑虑。

在Service.java中

case MEDIA_ID_ROOT:
    for (MediaMetadataCompat track : mMusicProvider.getAllMusics()) {

        String mediaId = track.getDescription().getMediaId();
        //Artist song
        String title = String.valueOf(track.getDescription().getTitle());
        //Artist name
        String subTitle = String.valueOf(track.getDescription().getSubtitle());
        //Artist album
        String descriptin = String.valueOf(track.getDescription().getDescription());
        //Song duration
        Long duration = track.getLong(MediaMetadataCompat.METADATA_KEY_DURATION);

        Bundle songDuration = new Bundle();
        songDuration.putLong(MediaMetadataCompat.METADATA_KEY_DURATION, duration);

        MediaDescriptionCompat desc =
                new MediaDescriptionCompat.Builder()
                        .setMediaId(mediaId)
                        .setTitle(title)
                        .setSubtitle(subTitle)
                        .setDescription(descriptin)
                        .setExtras(songDuration)
                        .build();

        MediaBrowserCompat.MediaItem songList =
                new MediaBrowserCompat.MediaItem(desc,
                        MediaBrowserCompat.MediaItem.FLAG_PLAYABLE);
        mediaItems.add(songList);
    }
    break;

mMusicProvider是我模型的对象

在您的provider.java

中

// Categorized caches for music track data:                                     
   private final LinkedHashMap<String, MediaMetadataCompat> mMusicListById;

public Iterable<MediaMetadataCompat> getAllMusics() {

    if (mCurrentState != State.INITIALIZED || mMusicListById.isEmpty()) {
        return Collections.emptyList();
    }
    return mMusicListById.values();
}

MediaBrowserCompat.MediaItem基本上可以包含MediaId，Title，Subtitle，Description，IconBitmap，IconUri，Bundle。在我的情况下，我需要歌曲的持续时间，这就是为什么我作为额外的捆绑添加。您可以添加更多额外内容，如作曲家，年份，曲目编号等。

如果您不需要任何额外信息，可以直接调用getdescription（）。

for (MediaMetadataCompat track : mMusicProvider.getAllMusics()) {
    MediaBrowserCompat.MediaItem bItem =
            new MediaBrowserCompat.MediaItem(track.getDescription(),
                    MediaBrowserCompat.MediaItem.FLAG_PLAYABLE);

    mediaItems.add(bItem);

如何建立媒体项目？安卓

1 个答案: