public class TestWidget extends AppWidgetProvider {
  public void onUpdate(Context context,AppWidgetManager appWidgetManager,int[] appWidgetIds) {
        final int N = appWidgetIds.length;

        // Perform this loop procedure for each App Widget that belongs to this provider
        for (int i=0; i<N; i++) {
            int appWidgetId = appWidgetIds[i];

            // Create an Intent to launch UpdateService
            Intent intent = new Intent(context,UpdateService.class);
            PendingIntent pendingIntent = PendingIntent.getService(context,intent,0);

            // Get the layout for the App Widget and attach an on-click listener to the button
            RemoteViews views = new RemoteViews(context.getPackageName(),R.layout.appwidget_provider_layout);
            views.setOnClickPendingIntent(R.id.button,pendingIntent);

            // Tell the AppWidgetManager to perform an update on the current App Widget
            appWidgetManager.updateAppWidget(appWidgetId,views);
        }
    }

    public static class UpdateService extends Service {
        @Override
        public int onStartCommand(Intent intent,int flags,int startId) {
          //process your click here
          return START_NOT_STICKY;
        }
    }
}

您还应该在清单文件中注册新服务：

<service android:name="com.xxx.yyy.TestWidget$UpdateService">

您可以在SDK中的维基词典示例中找到UpdateService实现的另一个示例

而这里还有另一个好办法Clickable widgets in android