Java tutorial
/* * Copyright (C) 2014 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package cat.terrones.devops.radiofx.ui; import android.app.Activity; import android.app.Fragment; import android.content.BroadcastReceiver; import android.content.Context; import android.content.Intent; import android.content.IntentFilter; import android.net.ConnectivityManager; import android.os.Bundle; import android.support.annotation.NonNull; import android.support.v4.app.FragmentActivity; import android.support.v4.media.MediaBrowserCompat; import android.support.v4.media.MediaMetadataCompat; import android.support.v4.media.session.MediaControllerCompat; import android.support.v4.media.session.PlaybackStateCompat; import android.util.Log; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.AdapterView; import android.widget.ArrayAdapter; import android.widget.ListView; import android.widget.TextView; import android.widget.Toast; import cat.terrones.devops.radiofx.R; import cat.terrones.devops.radiofx.utils.MediaIDHelper; import cat.terrones.devops.radiofx.utils.Utils; import java.util.ArrayList; import java.util.List; import cat.terrones.devops.radiofx.ui.interfaces.MediaBrowserProvider; import cat.terrones.devops.radiofx.utils.Utils; /** * A Fragment that lists all the various browsable queues available * from a {@link android.service.media.MediaBrowserService}. * <p/> * It uses a {@link MediaBrowserCompat} to connect to the {@link cat.terrones.devops.radiofx.MusicService}. * Once connected, the fragment subscribes to get all the children. * All {@link MediaBrowserCompat.MediaItem}'s that can be browsed are shown in a ListView. */ public class MediaBrowserFragment extends Fragment { private static final String TAG = MediaBrowserFragment.class.getSimpleName(); private static final String ARG_MEDIA_ID = "media_id"; private BrowseAdapter mBrowserAdapter; private String mMediaId; private MediaFragmentListener mMediaFragmentListener; private View mErrorView; private TextView mErrorMessage; private final BroadcastReceiver mConnectivityChangeReceiver = new BroadcastReceiver() { private boolean oldOnline = false; @Override public void onReceive(Context context, Intent intent) { // We don't care about network changes while this fragment is not associated // with a media ID (for example, while it is being initialized) if (mMediaId != null) { boolean isOnline = Utils.isOnline(context); if (isOnline != oldOnline) { oldOnline = isOnline; checkForUserVisibleErrors(false); if (isOnline) { mBrowserAdapter.notifyDataSetChanged(); } } } } }; // Receive callbacks from the MediaController. Here we update our state such as which queue // is being shown, the current title and description and the PlaybackState. private final MediaControllerCompat.Callback mMediaControllerCallback = new MediaControllerCompat.Callback() { @Override public void onMetadataChanged(MediaMetadataCompat metadata) { super.onMetadataChanged(metadata); if (metadata == null) { return; } Log.d(TAG, "Received metadata change to media " + metadata.getDescription().getMediaId()); mBrowserAdapter.notifyDataSetChanged(); } @Override public void onPlaybackStateChanged(@NonNull PlaybackStateCompat state) { super.onPlaybackStateChanged(state); Log.d(TAG, "Received state change: " + state); checkForUserVisibleErrors(false); mBrowserAdapter.notifyDataSetChanged(); } }; private final MediaBrowserCompat.SubscriptionCallback mSubscriptionCallback = new MediaBrowserCompat.SubscriptionCallback() { @Override public void onChildrenLoaded(@NonNull String parentId, @NonNull List<MediaBrowserCompat.MediaItem> children) { try { Log.d(TAG, "fragment onChildrenLoaded, parentId=" + parentId + " count=" + children.size()); checkForUserVisibleErrors(children.isEmpty()); mBrowserAdapter.clear(); for (MediaBrowserCompat.MediaItem item : children) { mBrowserAdapter.add(item); } mBrowserAdapter.notifyDataSetChanged(); } catch (Throwable t) { Log.e(TAG, "Error on childrenloaded", t); } } @Override public void onError(@NonNull String id) { Log.e(TAG, "browse fragment subscription onError, id=" + id); Toast.makeText(getActivity(), R.string.error_loading_media, Toast.LENGTH_LONG).show(); checkForUserVisibleErrors(true); } }; @Override public void onAttach(Activity activity) { super.onAttach(activity); // If used on an activity that doesn't implement MediaFragmentListener, it // will throw an exception as expected: mMediaFragmentListener = (MediaFragmentListener) activity; } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { Log.d(TAG, "fragment.onCreateView"); View rootView = inflater.inflate(R.layout.fragment_list, container, false); mErrorView = rootView.findViewById(R.id.playback_error); mErrorMessage = (TextView) mErrorView.findViewById(R.id.error_message); mBrowserAdapter = new BrowseAdapter(getActivity()); 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) { checkForUserVisibleErrors(false); MediaBrowserCompat.MediaItem item = mBrowserAdapter.getItem(position); mMediaFragmentListener.onMediaItemSelected(item); } }); return rootView; } @Override public void onStart() { super.onStart(); // fetch browsing information to fill the listview: MediaBrowserCompat mediaBrowser = mMediaFragmentListener.getMediaBrowser(); Log.d(TAG, "fragment.onStart, mediaId=" + mMediaId + " onConnected=" + mediaBrowser.isConnected()); if (mediaBrowser.isConnected()) { onConnected(); } // Registers BroadcastReceiver to track network connection changes. this.getActivity().registerReceiver(mConnectivityChangeReceiver, new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION)); } @Override public void onStop() { super.onStop(); MediaBrowserCompat mediaBrowser = mMediaFragmentListener.getMediaBrowser(); if (mediaBrowser != null && mediaBrowser.isConnected() && mMediaId != null) { mediaBrowser.unsubscribe(mMediaId); } MediaControllerCompat controller = ((FragmentActivity) getActivity()).getSupportMediaController(); if (controller != null) { controller.unregisterCallback(mMediaControllerCallback); } this.getActivity().unregisterReceiver(mConnectivityChangeReceiver); } @Override public void onDetach() { super.onDetach(); mMediaFragmentListener = null; } public String getMediaId() { Bundle args = getArguments(); if (args != null) { return args.getString(ARG_MEDIA_ID); } return null; } public void setMediaId(String mediaId) { Bundle args = new Bundle(1); args.putString(MediaBrowserFragment.ARG_MEDIA_ID, mediaId); setArguments(args); } // Called when the MediaBrowser is connected. This method is either called by the // fragment.onStart() or explicitly by the activity in the case where the connection // completes after the onStart() public void onConnected() { if (isDetached()) { return; } mMediaId = getMediaId(); if (mMediaId == null) { mMediaId = mMediaFragmentListener.getMediaBrowser().getRoot(); } updateTitle(); // Unsubscribing before subscribing is required if this mediaId already has a subscriber // on this MediaBrowser instance. Subscribing to an already subscribed mediaId will replace // the callback, but won't trigger the initial callback.onChildrenLoaded. // // This is temporary: A bug is being fixed that will make subscribe // consistently call onChildrenLoaded initially, no matter if it is replacing an existing // subscriber or not. Currently this only happens if the mediaID has no previous // subscriber or if the media content changes on the service side, so we need to // unsubscribe first. mMediaFragmentListener.getMediaBrowser().unsubscribe(mMediaId); mMediaFragmentListener.getMediaBrowser().subscribe(mMediaId, mSubscriptionCallback); // Add MediaController callback so we can redraw the list when metadata changes: MediaControllerCompat controller = ((FragmentActivity) getActivity()).getSupportMediaController(); if (controller != null) { controller.registerCallback(mMediaControllerCallback); } } private void checkForUserVisibleErrors(boolean forceError) { boolean showError = forceError; // If offline, message is about the lack of connectivity: if (!Utils.isOnline(getActivity())) { mErrorMessage.setText(R.string.error_no_connection); showError = true; } else { // otherwise, if state is ERROR and metadata!=null, use playback state error message: MediaControllerCompat controller = ((FragmentActivity) getActivity()).getSupportMediaController(); if (controller != null && controller.getMetadata() != null && controller.getPlaybackState() != null && controller.getPlaybackState().getState() == PlaybackStateCompat.STATE_ERROR && controller.getPlaybackState().getErrorMessage() != null) { mErrorMessage.setText(controller.getPlaybackState().getErrorMessage()); showError = true; } else if (forceError) { // Finally, if the caller requested to show error, show a generic message: mErrorMessage.setText(R.string.error_loading_media); showError = true; } } mErrorView.setVisibility(showError ? View.VISIBLE : View.GONE); Log.d(TAG, "checkForUserVisibleErrors. forceError=" + forceError + " showError=" + showError + " isOnline=" + Utils.isOnline(getActivity())); } private void updateTitle() { if (MediaIDHelper.MEDIA_ID_ROOT.equals(mMediaId)) { mMediaFragmentListener.setToolbarTitle(null); return; } MediaBrowserCompat mediaBrowser = mMediaFragmentListener.getMediaBrowser(); mediaBrowser.getItem(mMediaId, new MediaBrowserCompat.ItemCallback() { @Override public void onItemLoaded(MediaBrowserCompat.MediaItem item) { mMediaFragmentListener.setToolbarTitle(item.getDescription().getTitle()); } }); } // An adapter for showing the list of browsed MediaItem's private static class BrowseAdapter extends ArrayAdapter<MediaBrowserCompat.MediaItem> { public BrowseAdapter(Activity context) { super(context, R.layout.media_list_item, new ArrayList<MediaBrowserCompat.MediaItem>()); } @Override public View getView(int position, View convertView, ViewGroup parent) { MediaBrowserCompat.MediaItem item = getItem(position); return MediaItemViewHolder.setupListView((Activity) getContext(), convertView, parent, item); } } public interface MediaFragmentListener extends MediaBrowserProvider { void onMediaItemSelected(MediaBrowserCompat.MediaItem item); void setToolbarTitle(CharSequence title); } }