Android自带Widget中Music播放器实例是本文要介绍的内容,主要是来了解并学习Android Widget中播放器的应用,具体内容的实现来看本文详细代码。
昨天的带指针时钟比较简单,今天我们继续android自带widget剖析,相对于alarmclock而言music程序稍微复杂些,主要是涉及到众多事件的处理,不过可以看出如何是和服务进行交互的。继续按照昨天的分析步骤和过程,首先我们看下music程序中 AndroidManifest.xml中有关widgets的定义。
- <receiver android:name="MediaAppWidgetProvider">
- <intent-filter>
- <action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
- </intent-filter>
- <meta-data android:name="android.appwidget.provider" android:resource="@xml/appwidget_info" />
- </receiver>
下面是xml/appwidget_info的内容,里面包含了这个widget程序的基本定义。
- <appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android"
- android:minWidth="294dip" //最小宽度
- android:minHeight="72dip" //最小高度
- android:updatePeriodMillis="0" //更新频率
- android:initialLayout="@layout/album_appwidget"> //widget界面布局文件
- </appwidget-provider>
整个播放器的设计还是十分清晰,这里我们就不再做过多的赘述。
- public class MediaAppWidgetProvider extends AppWidgetProvider {
- public static final String CMDAPPWIDGETUPDATE = "appwidgetupdate";
- static final ComponentName THIS_APPWIDGET =
- new ComponentName("com.android.music", "com.android.music.MediaAppWidgetProvider");
- private static MediaAppWidgetProvider sInstance;
- static synchronized MediaAppWidgetProvider getInstance() {
- if (sInstance == null) {
- sInstance = new MediaAppWidgetProvider();
- }
- return sInstance;
- }
- @Override
- public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
- defaultAppWidget(context, appWidgetIds);
- // 发送一个Intent广播给MediaPlaybackService以便立即更新
- Intent updateIntent = new Intent(MediaPlaybackService.SERVICECMD);
- updateIntent.putExtra(MediaPlaybackService.CMDNAME,MediaAppWidgetProvider.CMDAPPWIDGETUPDATE);
- updateIntent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_IDS, appWidgetIds);
- updateIntent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);
- context.sendBroadcast(updateIntent);
- }
- /*
- * 初始化widget默认状态,如果服务没有运行,我们启动music的时候默认单击隐藏
- */
- private void defaultAppWidget(Context context, int[] appWidgetIds) {
- final Resources res = context.getResources();
- final RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.album_appwidget);
- views.setViewVisibility(R.id.title, View.GONE);
- views.setTextViewText(R.id.artist, res.getText(R.string.emptyplaylist));
- linkButtons(context, views, false /* 没有播放*/);
- pushUpdate(context, appWidgetIds, views);
- }
- private void pushUpdate(Context context, int[] appWidgetIds, RemoteViews views) {
- // 更新指定的列表
- final AppWidgetManager gm = AppWidgetManager.getInstance(context);
- if (appWidgetIds != null) {
- gm.updateAppWidget(appWidgetIds, views);
- } else {
- gm.updateAppWidget(THIS_APPWIDGET, views);
- }
- }
- /**
- * Check against {@link AppWidgetManager} if there are any instances of this widget.
- */
- private boolean hasInstances(Context context) {
- AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(context);
- int[] appWidgetIds = appWidgetManager.getAppWidgetIds(THIS_APPWIDGET);
- return (appWidgetIds.length > 0);
- }
- /**
- * Handle a change notification coming over from {@link MediaPlaybackService}
- */
- void notifyChange(MediaPlaybackService service, String what) {
- if (hasInstances(service)) {
- if (MediaPlaybackService.PLAYBACK_COMPLETE.equals(what) ||
- MediaPlaybackService.META_CHANGED.equals(what) ||
- MediaPlaybackService.PLAYSTATE_CHANGED.equals(what)) {
- performUpdate(service, null);
- }
- }
- }
- /**
- * Update all active widget instances by pushing changes
- */
- void performUpdate(MediaPlaybackService service, int[] appWidgetIds) {
- final Resources res = service.getResources();
- final RemoteViews views = new RemoteViews(service.getPackageName(), R.layout.album_appwidget);
- final int track = service.getQueuePosition() + 1;
- CharSequence titleName = service.getTrackName();
- CharSequence artistName = service.getArtistName();
- CharSequence errorState = null;
- // Format title string with track number, or show SD card message
- String status = Environment.getExternalStorageState();
- if (status.equals(Environment.MEDIA_SHARED) ||
- status.equals(Environment.MEDIA_UNMOUNTED)) {
- errorState = res.getText(R.string.sdcard_busy_title);
- } else if (status.equals(Environment.MEDIA_REMOVED)) {
- errorState = res.getText(R.string.sdcard_missing_title);
- } else if (titleName == null) {
- errorState = res.getText(R.string.emptyplaylist);
- }
- if (errorState != null) {
- // Show error state to user
- views.setViewVisibility(R.id.title, View.GONE);
- views.setTextViewText(R.id.artist, errorState);
- } else {
- // No error, so show normal titles
- views.setViewVisibility(R.id.title, View.VISIBLE);
- views.setTextViewText(R.id.title, titleName);
- views.setTextViewText(R.id.artist, artistName);
- }
- // Set correct drawable for pause state
- final boolean playing = service.isPlaying();
- if (playing) {
- views.setImageViewResource(R.id.control_play, R.drawable.appwidget_pause);
- } else {
- views.setImageViewResource(R.id.control_play, R.drawable.appwidget_play);
- }
- // Link actions buttons to intents
- linkButtons(service, views, playing);
- pushUpdate(service, appWidgetIds, views);
- }
- /**
- * Link up various button actions using {@link PendingIntents}.
- *
- * @param playerActive True if player is active in background, which means
- * widget click will launch {@link MediaPlaybackActivity},
- * otherwise we launch {@link MusicBrowserActivity}.
- */
- private void linkButtons(Context context, RemoteViews views, boolean playerActive) {
- // Connect up various buttons and touch events
- Intent intent;
- PendingIntent pendingIntent;
- final ComponentName serviceName = new ComponentName(context, MediaPlaybackService.class);
- if (playerActive) {
- intent = new Intent(context, MediaPlaybackActivity.class);
- pendingIntent = PendingIntent.getActivity(context,
- 0 /* no requestCode */, intent, 0 /* no flags */);
- views.setOnClickPendingIntent(R.id.album_appwidget, pendingIntent);
- } else {
- intent = new Intent(context, MusicBrowserActivity.class);
- pendingIntent = PendingIntent.getActivity(context,
- 0 /* no requestCode */, intent, 0 /* no flags */);
- views.setOnClickPendingIntent(R.id.album_appwidget, pendingIntent);
- }
- intent = new Intent(MediaPlaybackService.TOGGLEPAUSE_ACTION);
- intent.setComponent(serviceName);
- pendingIntent = PendingIntent.getService(context,
- 0 /* no requestCode */, intent, 0 /* no flags */);
- views.setOnClickPendingIntent(R.id.control_play, pendingIntent);
- intent = new Intent(MediaPlaybackService.NEXT_ACTION);
- intent.setComponent(serviceName);
- pendingIntent = PendingIntent.getService(context,
- 0 /* no requestCode */, intent, 0 /* no flags */);
- views.setOnClickPendingIntent(R.id.control_next, pendingIntent);
- }
- }
小结:Android自带Widget中Music播放器实例的内容介绍完了,希望通过Android Widget内容的学习能对你有所帮助!