MediaBrowserService 音乐播放项目，本项目主要有如下功能：
（1）：支持播放在线音乐
（2）：按住home键退出页面后显示通知栏部分播放提示，
 (3) : 支持切换上下首歌曲
本项目来自：https://github.com/googlesamples/android-MediaBrowserService
 首先配置如下服务：
 <service
        android:name=".service.MusicService"
        android:exported="true">
      <intent-filter>
         <action android:name="android.media.browse.MediaBrowserService" />
      </intent-filter>
    </service>

主要代码如下：

public class BrowseFragment extends Fragment {

private static final String TAG = LogHelper.makeLogTag(BrowseFragment.class.getSimpleName());

public static final String ARG_MEDIA_ID = "media_id";

public static interface FragmentDataHelper {
        void onMediaItemSelected(MediaBrowser.MediaItem item);
    }

// The mediaId to be used for subscribing for children using the MediaBrowser.
    private String mMediaId;

private MediaBrowser mMediaBrowser;
    private BrowseAdapter mBrowserAdapter;

private MediaBrowser.SubscriptionCallback mSubscriptionCallback = new MediaBrowser.SubscriptionCallback() {

@Override
        public void onChildrenLoaded(String parentId, List<MediaBrowser.MediaItem> children) {
            mBrowserAdapter.clear();
            mBrowserAdapter.notifyDataSetInvalidated();
            for (MediaBrowser.MediaItem item : children) {
                mBrowserAdapter.add(item);
            }
            mBrowserAdapter.notifyDataSetChanged();
        }

@Override
        public void onError(String id) {
            Toast.makeText(getActivity(), R.string.error_loading_media,
                    Toast.LENGTH_LONG).show();
        }
    };

private MediaBrowser.ConnectionCallback mConnectionCallback =
            new MediaBrowser.ConnectionCallback() {
        @Override
        public void onConnected() {
            LogHelper.d(TAG, "onConnected: session token " + mMediaBrowser.getSessionToken());

if (mMediaId == null) {
                mMediaId = mMediaBrowser.getRoot();
            }
            mMediaBrowser.subscribe(mMediaId, mSubscriptionCallback);
            if (mMediaBrowser.getSessionToken() == null) {
                throw new IllegalArgumentException("No Session token");
            }
            MediaController mediaController = new MediaController(getActivity(),
                    mMediaBrowser.getSessionToken());
            getActivity().setMediaController(mediaController);
        }

@Override
        public void onConnectionFailed() {
            LogHelper.d(TAG, "onConnectionFailed");
        }

@Override
        public void onConnectionSuspended() {
            LogHelper.d(TAG, "onConnectionSuspended");
            getActivity().setMediaController(null);
        }
    };

public static BrowseFragment newInstance(String mediaId) {
        Bundle args = new Bundle();
        args.putString(ARG_MEDIA_ID, mediaId);
        BrowseFragment fragment = new BrowseFragment();
        fragment.setArguments(args);
        return fragment;
    }

@Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_list, container, false);

mBrowserAdapter = new BrowseAdapter(getActivity());

View controls = rootView.findViewById(R.id.controls);
        controls.setVisibility(View.GONE);

ListView listView = (ListView) rootView.findViewById(R.id.list_view);
        listView.setAdapter(mBrowserAdapter);
        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                MediaBrowser.MediaItem item = mBrowserAdapter.getItem(position);
                try {
                    FragmentDataHelper listener = (FragmentDataHelper) getActivity();
                    listener.onMediaItemSelected(item);
                } catch (ClassCastException ex) {
                    Log.e(TAG, "Exception trying to cast to FragmentDataHelper", ex);
                }
            }
        });

Bundle args = getArguments();
        mMediaId = args.getString(ARG_MEDIA_ID, null);

mMediaBrowser = new MediaBrowser(getActivity(),
                new ComponentName(getActivity(), MusicService.class),
                mConnectionCallback, null);

return rootView;
    }

@Override
    public void onStart() {
        super.onStart();
        mMediaBrowser.connect();
    }

@Override
    public void onStop() {
        super.onStop();
        mMediaBrowser.disconnect();
    }

// An adapter for showing the list of browsed MediaItem's
    private static class BrowseAdapter extends ArrayAdapter<MediaBrowser.MediaItem> {

public BrowseAdapter(Context context) {
            super(context, R.layout.media_list_item, new ArrayList<MediaBrowser.MediaItem>());
        }

static class ViewHolder {
            ImageView mImageView;
            TextView mTitleView;
            TextView mDescriptionView;
        }

@Override
        public View getView(int position, View convertView, ViewGroup parent) {

ViewHolder holder;

if (convertView == null) {
                convertView = LayoutInflater.from(getContext())
                        .inflate(R.layout.media_list_item, parent, false);
                holder = new ViewHolder();
                holder.mImageView = (ImageView) convertView.findViewById(R.id.play_eq);
                holder.mImageView.setVisibility(View.GONE);
                holder.mTitleView = (TextView) convertView.findViewById(R.id.title);
                holder.mDescriptionView = (TextView) convertView.findViewById(R.id.description);
                convertView.setTag(holder);
            } else {
                holder = (ViewHolder) convertView.getTag();
            }

MediaBrowser.MediaItem item = getItem(position);
            holder.mTitleView.setText(item.getDescription().getTitle());
            holder.mDescriptionView.setText(item.getDescription().getDescription());
            if (item.isPlayable()) {
                holder.mImageView.setImageDrawable(
                        getContext().getDrawable(R.drawable.ic_play_arrow_white_24dp));
                holder.mImageView.setVisibility(View.VISIBLE);
            }
            return convertView;
        }
    }
}