以下是我的设置。 我有一个livecard服务类，它执行异步任务以从外部获取天气和天气预报数据。 它还启动了一个Pendingintent，其中两个菜单项是“ShowForecast”＆amp; “停止”
天气数据到达时会显示在主屏幕上。 但是预测数据需要更长的时间。我想隐藏ShowForecast菜单，直到异步任务成功完成。
实现此目的的最佳方法是什么？我已经阅读了有关全局变量的内容，或者通过intent.putextra或直接更新卡片菜单。 我现在想的是在我的activity类中使用一个boolean值，该值在onPrepareOptionsMenu中被检入并隐藏/显示菜单。
但是，当异步任务完成时，如何从Service类设置此布尔值？ 以下是课程片段。所有建议欢迎！ ：）
public class LiveCardMenuActivity extends Activity {
private static final String TAG = LiveCardMenuActivity.class.getSimpleName();
// default disabled menu
private boolean menu_showForecast = false;
@Override
// in this method we hide/ show forecast menu, depending if the service has gotten the data
public boolean onPrepareOptionsMenu(Menu menu) {
if(!menu_showForecast) {
menu.findItem(R.id.action_show_forecast).setVisible(false);
}
return super.onPrepareOptionsMenu(menu);
...
是具有异步任务的服务类
public class LiveCardService extends Service {
private static final String TAG = LiveCardService.class.getSimpleName();
private static final String LIVE_CARD_TAG = "LiveCardService";
private LiveCard mLiveCard;
private RemoteViews mLiveCardView;
private final Handler mHandler = new Handler();
private final UpdateLiveCardRunnable mUpdateLiveCardRunnable = new UpdateLiveCardRunnable();
private static final long DELAY_MILLIS = 1000;
// keep the weather info central, due to reuse and forecast cards
private Weather weather = new Weather();
private WeatherForecast weatherForecast = new WeatherForecast();
@Override
public IBinder onBind(Intent intent) {
return null;
}
@Override
public void onCreate() {
super.onCreate();
// and get the weather data & icon, async call
String loc = "id=2755420";
JSONWeatherTask task = new JSONWeatherTask();
task.execute(new String[]{loc});
// including the weather forecast
JSONWeatherForecastTask taskForecast = new JSONWeatherForecastTask();
taskForecast.execute(new String[]{loc});
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
if (mLiveCard == null) {
// Get an instance of a live card
mLiveCard = new LiveCard(this, LIVE_CARD_TAG);
// setup live card views
mLiveCardView = new RemoteViews(getPackageName(), R.layout.live_card);
mLiveCard.setViews(mLiveCardView);
// Display the options menu when the live card is tapped.
Intent menuIntent = new Intent(this, LiveCardMenuActivity.class);
mLiveCard.setAction(PendingIntent.getActivity(this, 0, menuIntent, 0));
mLiveCard.publish(PublishMode.REVEAL);
// Queue the update text runnable
mHandler.post(mUpdateLiveCardRunnable);
} else {
mLiveCard.navigate();
}
return START_STICKY;
}
...
private class JSONWeatherForecastTask extends AsyncTask<String, Void, WeatherForecast> {
@Override
protected WeatherForecast doInBackground(String... params) {
//
String data = ( (new WeatherHttpClient()).getWeatherForecastData(params[0]));
try {
weatherForecast = JSONWeatherForecastParser.getWeatherForecast(data);
} catch (JSONException e) {
e.printStackTrace();
}
return weatherForecast;
}
@Override
protected void onPostExecute(WeatherForecast weatherForecast) {
super.onPostExecute(weatherForecast);
// there is no showing of data yet, except voor enabling the forecast menu
Weather[] weatherForecastArray = weatherForecast.getWeatherForecastArray();
int count = weatherForecastArray.length;
if(count > 0){
//mLiveCard menu update or boolean update?
}
}
}
答案 0 :(得分：1)
Timer sample的菜单Activity有一些逻辑可根据正在运行的计时器状态动态更改其选项菜单：
MenuActivity＆＃39; onCreate回调中：绑定到TimerService。Service后，检索有关当前Timer。Activity已附加到Window，已检索到计时器信息）：打开选项菜单。以下是MenuActivity类的代码片段：
/**
* This activity manages the options menu that appears when the user taps on the timer's live
* card or says "ok glass" while the live card is settled.
*/
public class MenuActivity extends Activity {
private Timer mTimer;
private boolean mAttachedToWindow;
private boolean mIsMenuClosed;
private boolean mPreparePanelCalled;
private boolean mIsSettingTimer;
private boolean mFromLiveCardVoice;
private ServiceConnection mConnection = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
if (service instanceof TimerService.TimerBinder) {
mTimer = ((TimerService.TimerBinder) service).getTimer();
openMenu();
}
// No need to keep the service bound.
unbindService(this);
}
@Override
public void onServiceDisconnected(ComponentName name) {
// Nothing to do here.
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mFromLiveCardVoice = getIntent().getBooleanExtra(LiveCard.EXTRA_FROM_LIVECARD_VOICE, false);
if (mFromLiveCardVoice) {
// When activated by voice from a live card, enable voice commands. The menu
// will automatically "jump" ahead to the items (skipping the guard phrase
// that was already said at the live card).
getWindow().requestFeature(WindowUtils.FEATURE_VOICE_COMMANDS);
}
// Bind to the Timer service to retrive the current timer's data.
Intent serviceIntent = new Intent(this, TimerService.class);
serviceIntent.putExtra(
TimerService.EXTRA_TIMER_HASH_CODE,
getIntent().getIntExtra(TimerService.EXTRA_TIMER_HASH_CODE, 0));
serviceIntent.setData(getIntent().getData());
bindService(serviceIntent, mConnection, 0);
}
@Override
public void onAttachedToWindow() {
super.onAttachedToWindow();
mAttachedToWindow = true;
openMenu();
}
@Override
public void onDetachedFromWindow() {
super.onDetachedFromWindow();
mAttachedToWindow = false;
}
@Override
public boolean onCreatePanelMenu(int featureId, Menu menu) {
if (isMyMenu(featureId)) {
getMenuInflater().inflate(R.menu.timer, menu);
return true;
}
return super.onCreatePanelMenu(featureId, menu);
}
@Override
public boolean onPreparePanel(int featureId, View view, Menu menu) {
mPreparePanelCalled = true;
if (isMyMenu(featureId)) {
if (mTimer == null) {
// Can't prepare the menu as we're not yet bound to a timer.
return false;
} else {
// Disable or enable menu item depending on the Timer's state.
// Don't reopen menu once we are finishing. This is necessary
// since voice menus reopen themselves while in focus.
return !mIsMenuClosed;
}
}
return super.onPreparePanel(featureId, view, menu);
}
@Override
public boolean onMenuItemSelected(int featureId, MenuItem item) {
if (!isMyMenu(featureId)) {
return super.onMenuItemSelected(featureId, item);
}
// Handle item selection.
}
@Override
public void onPanelClosed(int featureId, Menu menu) {
super.onPanelClosed(featureId, menu);
if (isMyMenu(featureId)) {
mIsMenuClosed = true;
if (!mIsSettingTimer) {
// Nothing else to do, closing the Activity.
finish();
}
}
}
/**
* Opens the touch or voice menu iff all the conditions are satifisfied.
*/
private void openMenu() {
if (mAttachedToWindow && mTimer != null) {
if (mFromLiveCardVoice) {
if (mPreparePanelCalled) {
// Invalidates the previously prepared voice menu now that we can properly
// prepare it.
getWindow().invalidatePanelMenu(WindowUtils.FEATURE_VOICE_COMMANDS);
}
} else {
// Open the options menu for the touch flow.
openOptionsMenu();
}
}
}
/**
* Returns {@code true} when the {@code featureId} belongs to the options menu or voice
* menu that are controlled by this menu activity.
*/
private boolean isMyMenu(int featureId) {
return featureId == Window.FEATURE_OPTIONS_PANEL ||
featureId == WindowUtils.FEATURE_VOICE_COMMANDS;
}
}