WALLPAPER_CHANGED的BroadcastReceiver在Android中调用onReceive()多次的问题

Question

我有一个 BroadcastReceiver 并且声明它像这样:

<receiver
    android:name="com.services.Receiver"
    android:enabled="true"
    android:exported="true" >
    <intent-filter android:priority="999" >
        <action android:name="android.intent.action.WALLPAPER_CHANGED" />
    </intent-filter>
</receiver>

接收者是：

@Override
public void onReceive(final Context context, final Intent intent)
{
    change_wallpepar.myPrefs = context.getSharedPreferences("myPrefs", Context.MODE_PRIVATE);
    new Handler().postDelayed(new Runnable()
    {
        @Override
        public void run()
        {
            Log.d("MAYUR", "<< wallpepar changed >>");
            if (change_wallpepar.myPrefs.getLong("temp_for_change", 1) == 0)
            {
                context.stopService(new Intent(context, change_wallpepar.class));
            }
            else
            {
                SharedPreferences.Editor e = change_wallpepar.myPrefs.edit();
                e.putLong("temp_for_change", 0);
                e.commit();
            }
        }
    }, 4000);
}

更改壁纸时应该只被调用一次。它最初按照我的期望正常工作，但过了一段时间后，即使只更改壁纸一次，它也会多次（10-18次）调用 onreceive()。更奇怪的是，在 Samsung Galaxy 平板电脑版本 4.4.2 上可以正常工作，但在摩托罗拉（Moto E 4.4.4）上无法正常工作。

我的服务：

public class change_wallpepar extends Service {

    @Override
    public void onCreate()
    {
        // TODO Auto-generated method stub
        super.onCreate();
        mytimer = new Timer();
        wpm = WallpaperManager.getInstance(change_wallpepar.this);
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId)
    {
        // TODO Auto-generated method stub
        myPrefs = getSharedPreferences("myPrefs", MODE_PRIVATE);
        intervall = myPrefs.getLong("someValue", 60000);

        path_of_wallpepar.clear();
        path_of_wallpepar.add("" + "/storage/emulated/0/Android/data/WallpeparAppHistoryPhotos/514.jpg");
        path_of_wallpepar.add("" + "/storage/emulated/0/Android/data/WallpeparAppHistoryPhotos/513.jpg");

        DisplayImageOptions defaultOption = new DisplayImageOptions.Builder().cacheInMemory(true).cacheOnDisk(true).bitmapConfig(Bitmap.Config.RGB_565).build();
        ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(change_wallpepar.this).defaultDisplayImageOptions(defaultOption).build();
        ImageLoader.getInstance().init(config);

        mytimer.schedule(new TimerTask()
        {
            @Override
            public void run()
            {

                try
                {
                    wpm.setBitmap(ImageLoader.getInstance().loadImageSync("file://" + path_of_wallpepar.get(temper)));

                }
                catch (IOException e)
                {
                    e.printStackTrace();
                }

                temper++;

                if (temper == path_of_wallpepar.size())
                    temper = 0;

                SharedPreferences.Editor e = change_wallpepar.myPrefs.edit();
                e.putLong("temp_for_change", 1);
                e.commit();

                Log.e("MAYUR", "wallpepar seted");

            }
        }, 0, intervall);

        return super.onStartCommand(intent, flags, startId);

    }

    @Override
    public IBinder onBind(Intent intent)
    {
        // TODO Auto-generated method stub

        return null;
    }

    public void onDestroy()
    {
        Toast.makeText(this, "Service Destroyed", Toast.LENGTH_SHORT).show();
        Vibrator v = (Vibrator) getSystemService(Context.VIBRATOR_SERVICE);
        v.vibrate(1000);
        mytimer.cancel();
        super.onDestroy();
    }

}

我的 Logcat 输出如下：

## Logcat ##
04-16 11:06:30.654: E/MAYUR(3405): wallpepar seted
04-16 11:06:34.636: D/MAYUR(3405): << wallpepar changed >>
04-16 11:06:59.584: E/MAYUR(3405): wallpepar seted
04-16 11:07:03.551: D/MAYUR(3405): << wallpepar changed >>
04-16 11:07:30.078: E/MAYUR(3405): wallpepar seted
04-16 11:07:33.979: D/MAYUR(3405): << wallpepar changed >>
04-16 11:07:59.433: E/MAYUR(3405): wallpepar seted
04-16 11:08:03.340: D/MAYUR(3405): << wallpepar changed >>
04-16 11:08:30.029: E/MAYUR(3405): wallpepar seted
04-16 11:08:33.933: D/MAYUR(3405): << wallpepar changed >>
04-16 11:08:59.481: E/MAYUR(3405): wallpepar seted
04-16 11:09:03.383: D/MAYUR(3405): << wallpepar changed >>
04-16 11:09:30.066: E/MAYUR(3405): wallpepar seted
04-16 11:09:33.966: D/MAYUR(3405): << wallpepar changed >>
04-16 11:09:59.448: E/MAYUR(3405): wallpepar seted
04-16 11:10:03.353: D/MAYUR(3405): << wallpepar changed >>
04-16 11:10:30.049: E/MAYUR(3405): wallpepar seted
04-16 11:10:33.955: D/MAYUR(3405): << wallpepar changed >>
04-16 11:10:59.455: E/MAYUR(3405): wallpepar seted
04-16 11:11:03.350: D/MAYUR(3405): << wallpepar changed >>
04-16 11:11:30.182: E/MAYUR(3405): wallpepar seted
04-16 11:11:34.177: D/MAYUR(3405): << wallpepar changed >>
04-16 11:11:59.406: E/MAYUR(3405): wallpepar seted
04-16 11:12:03.315: D/MAYUR(3405): << wallpepar changed >>
04-16 11:12:30.025: E/MAYUR(3405): wallpepar seted
04-16 11:12:33.929: D/MAYUR(3405): << wallpepar changed >>
04-16 11:12:34.103: D/MAYUR(3405): << wallpepar changed >>
04-16 11:12:34.298: D/MAYUR(3405): << wallpepar changed >>
04-16 11:12:34.497: D/MAYUR(3405): << wallpepar changed >>
04-16 11:12:34.676: D/MAYUR(3405): << wallpepar changed >>
04-16 11:12:34.854: D/MAYUR(3405): << wallpepar changed >>
04-16 11:12:35.022: D/MAYUR(3405): << wallpepar changed >>
04-16 11:12:35.190: D/MAYUR(3405): << wallpepar changed >>
04-16 11:12:35.355: D/MAYUR(3405): << wallpepar changed >>
04-16 11:12:35.522: D/MAYUR(3405): << wallpepar changed >>
04-16 11:12:35.683: D/MAYUR(3405): << wallpepar changed >>
04-16 11:12:35.852: D/MAYUR(3405): << wallpepar changed >>
04-16 11:12:36.023: D/MAYUR(3405): << wallpepar changed >>
04-16 11:12:36.187: D/MAYUR(3405): << wallpepar changed >>
04-16 11:12:36.350: D/MAYUR(3405): << wallpepar changed >>
04-16 11:12:36.513: D/MAYUR(3405): << wallpepar changed >>

- Mayur R. Amipara

---

请注意，如果您的目标是API 26及以上版本，则无法在清单文件中使用此功能。需要进行注册。证明：https://developer.android.com/guide/components/broadcast-exceptions - android developer

Answer 1

重复的WALLPAPER_CHANGED调用是由较小的Android设备对图像进行裁剪缩放以适应屏幕而引起的。这在AOSP代码中观察到。当屏幕比例适合或大于图像时，您不太可能看到此行为，因此平板电脑不会表现出此行为。

您可以通过仔细检查不需要的行为的迹象来解决此问题：

long lastExec = System.currentTimeMillis();

@Override
public void onReceive(final Context context, final Intent intent)
{
    change_wallpepar.myPrefs = context.getSharedPreferences("myPrefs", Context.MODE_PRIVATE);
    new Handler().postDelayed(new Runnable()
    {
        @Override
        public void run()
        {
          if(System.currentTimeMillis()-lastExec>1000)
          {
            Log.d("MAYUR", "<< wallpepar changed >>");
            if (change_wallpepar.myPrefs.getLong("temp_for_change", 1) == 0)
            {
                context.stopService(new Intent(context, change_wallpepar.class));
            }
            else
            {
                SharedPreferences.Editor e = change_wallpepar.myPrefs.edit();
                e.putLong("temp_for_change", 0);
                e.commit();
            }
          }
          lastExec = System.currentTimeMillis();
        }
    }, 4000);
}

- Aaron Gillion

Answer 2

我不确定为什么在某些设备上会出现这种情况，但最有可能的问题是特定设备的问题。虽然我无法解决该问题，但您可以保留一个变量，一旦触发监听器就切换它，并在一段时间后重置。这将导致您的监听器在短时间内忽略未来的调用... 就像防洪保护一样。

我知道这并不能解决您实际的问题，但我希望它能提供一个合适的解决方法。

- greysqrl

Answer 3

很可能是设备特定的问题。

一般来说，我猜使用标志是推荐的解决方案。

@Override
public void onReceive(final Context context, final Intent intent)
{
     private static boolean firstReceive = true;
    change_wallpepar.myPrefs = context.getSharedPreferences("myPrefs", Context.MODE_PRIVATE);
    new Handler().postDelayed(new Runnable()
    {
        @Override
        public void run()
        {
           if(firstReceive){
            Log.d("MAYUR", "<< wallpepar changed >>");
            if (change_wallpepar.myPrefs.getLong("temp_for_change", 1) == 0)
            {
                context.stopService(new Intent(context, change_wallpepar.class));
            }
            else
            {
                SharedPreferences.Editor e = change_wallpepar.myPrefs.edit();
                e.putLong("temp_for_change", 0);
                e.commit();
            }
        }
   ///CHANGE firstReceive BASED ON EITHER TIME SINCE LAST WALLPAPER CHANGE
   ///OR ANY OTHER PARAMETER THAT SUITS YOUR REQUIREMENT
    }, 4000);
  }
}

请注意，在循环中我没有再次重置标志，您可能应该在自上次更改以来一定时间后或者将当前壁纸标识符保存在共享首选项中并与之匹配并设置标志等，根据您的要求进行操作。

这个想法是为了解决问题，让您克服虚假阳性并实际更改wallpaper_change调用。这是一个解决方法，而不是解决问题存在的实际解决方案。

- Vrashabh Irde

---

firstReceive = false; 这段代码在我的队列中没有任何用处，我认为可以不用。 - Mayur R. Amipara

是的，这就是我在答案中提到的。由你来正确地重置它，以便既不允许错误的正面结果，也不要屏蔽实际的壁纸更改。 - Vrashabh Irde