java - Android BroadcastReceiver 不更新小部件

Question

首先，我尝试了在 stackoverflow 上找到的所有方法，但没有一个有效。

我正在开发一个电池监控应用程序，它包含一些显示信息的小部件。我使用一个名为 BatteryUpdateReceiver 的通用接收器来监听 ACTION_BATTERY_CHANGED 事件。我使用此接收器更新显示当前电池电量的小部件。但由于某些原因，它不会更新小部件。我尝试了很多方法，但无法弄清楚出了什么问题。我的代码如下。

BatteryUpdateReceiver.java

public void onReceive(Context context, Intent intent) {
        if (intent.getAction().equals(Intent.ACTION_BATTERY_CHANGED)) {
            Log.i(TAG, "Receiver ACTION_BATTERY_CHANGED fired");

            RemoteViews remoteViews = new RemoteViews(context.getPackageName(),
                    R.layout.widget);

            AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(context.getApplicationContext());
            ComponentName thisWidget = new ComponentName(context.getApplicationContext(), BatteryWidget.class);
            int[] allWidgetIds = appWidgetManager.getAppWidgetIds(thisWidget);
            for (int i=0; i < allWidgetIds.length; i++) {
                Log.i(TAG, "WID ID: " + allWidgetIds[i]);
                appWidgetManager.updateAppWidget(allWidgetIds[i], remoteViews);
            }
        }
    }

BatteryWidget.java

public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
        super.onUpdate(context, appWidgetManager, appWidgetIds);

        Log.i(TAG, "onUpdate: ");

        int currentLevel = calculateBatteryLevel(context);
        if (batteryChanged(currentLevel)) {
            batteryLevel = currentLevel;
            Log.i(TAG, "onUpdate: Battery level changed");
        }
        updateViews(context);
    }

    private boolean batteryChanged(int currentLevelLeft) {
        return (batteryLevel != currentLevelLeft);
    }

    private int calculateBatteryLevel(Context context) {
        Log.i(TAG, "calculateBatteryLevel: ");

        Intent batteryIntent = context.getApplicationContext().registerReceiver(null, new IntentFilter(Intent.ACTION_BATTERY_CHANGED));

        int level = batteryIntent.getIntExtra(BatteryManager.EXTRA_LEVEL, 0);
        int scale = batteryIntent.getIntExtra(BatteryManager.EXTRA_SCALE, 100);
        return level * 100 / scale;
    }

    private void updateViews(Context context) {
        Log.i(TAG, "updateViews: ");

        RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.widget);
        views.setTextViewText(R.id.batteryText, batteryLevel + "%");

        ComponentName componentName = new ComponentName(context, BatteryWidget.class);
        AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(context);
        appWidgetManager.updateAppWidget(componentName, views);
    }

AndroidManifest.xml

    <receiver android:name=".lib.receivers.BatteryUpdateReceiver" android:enabled="true" />

    <receiver android:name=".widget.BatteryWidget" android:label="@string/app_name" >
         <intent-filter>
              <action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
         </intent-filter>
         <meta-data
                    android:name="android.appwidget.provider" android:resource="@xml/batterywidgetinfo" />
   </receiver>

我在设备启动时使用服务注册 BatteryUpdateReceiver。

IntentFilter filterBattery = new IntentFilter();
filterBattery.addAction(Intent.ACTION_BATTERY_CHANGED);
this.mBatteryStatusReceiver = new BatteryUpdateReceiver();
getApplicationContext().registerReceiver(this.mBatteryStatusReceiver, filterBattery);
Log.i(TAG, "Receiver ACTION_BATTERY_CHANGED registered by Service");

我可以确认 BatteryUpdateReceiver 有效，因为它记录了小部件 ID。此外，如果我将接收器放在 BatteryWidget 中，那么小部件就会更新。有人能告诉我我在这里想念什么吗？我知道我可以覆盖 BatteryWidget 类中的 onReceive() 方法。但是我怎样才能以这种方式存档呢？

谢谢!

Answer 1

您应该从接收器发送一个 ACTION_APPWIDGET_UPDATE 广播，而不是直接调用 updateAppWidget()。

像这样:

@Override
public void onReceive(Context context, Intent intent) {
    AppWidgetManager widgetManager = AppWidgetManager.getInstance(getApplicationContext());
    int[] appWidgetIds = widgetManager.getAppWidgetIds(new ComponentName(context, BatteryWidget.class));

    Intent updateIntent = new Intent(AppWidgetManager.ACTION_APPWIDGET_UPDATE, null, getApplicationContext(), BatteryWidget.class);
    updateIntent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_IDS, appWidgetIds);

    sendBroadcast(updateIntent);
}