BroadcastReceiver 在我的服务中不时停止工作，为什么？

Question

我现在正在为 Android 编写电池小部件。但问题来了，我在服务中注册了两个 BroadcastReceiver。我在 AppWidgetProvider 的 onEnable() 方法上启动我的服务，然后在 onDisable() 中停止它。该服务旨在侦听电池状态更新和方向更改，并通过将我的自定义 Intent 发送到我的 AppWidgetProvider 来通知小部件进行自我更新。因为普通的 AppWidgetProvider 都无法接收到广播（battery_state_changed 和 configuration_changed），而 AppWidgetProvider 本身也无法注册 BroadcastReceivers。

在一两天内一切正常。但有时，当电池状态发生变化时，小部件没有自行更新，似乎我的服务中的接收器没有工作，或者自定义 Intent 突然停止成功到达我的 AppWidgetProvider。

知道为什么会这样吗？

package com.carllee.widgets.kittenbatterywidget;

import android.app.Service;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.IBinder;

public class BatteryStateMoniterService extends Service {
    private static final String TAG = "BatteryStateMoniterService";
    private BatteryStateReceiver batteryStateReceiver;
    private OrientationChangeReceiver orientationChangeReceiver;

    @Override
    public void onCreate() {
        super.onCreate();
        Logger.log(TAG, "onCreate");
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        if (batteryStateReceiver == null) {
            this.unregisterReceiver(batteryStateReceiver);
        }
        if (orientationChangeReceiver == null) {
            this.unregisterReceiver(orientationChangeReceiver);
        }
        Logger.log(TAG, "onDestroy");
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        if (batteryStateReceiver == null) {
            registerBatteryStateReceiver();
        }

        if (orientationChangeReceiver == null) {
            registerOrientationChangeReceiver();
        }
        Logger.log(TAG, "onStartCommand");
        return START_STICKY;
    }

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    private void registerBatteryStateReceiver() {
        IntentFilter filter = new IntentFilter();
        filter.addAction(Intent.ACTION_BATTERY_CHANGED);
        filter.addAction(Intent.ACTION_BATTERY_LOW);
        filter.addAction(Intent.ACTION_BATTERY_OKAY);
        batteryStateReceiver = new BatteryStateReceiver();
        this.registerReceiver(batteryStateReceiver, filter);
    }

    private void registerOrientationChangeReceiver() {
        IntentFilter filter = new IntentFilter();
        filter.addAction(Intent.ACTION_CONFIGURATION_CHANGED);
        orientationChangeReceiver = new OrientationChangeReceiver();
        this.registerReceiver(orientationChangeReceiver, filter);
    }

}

Answer 1

好吧，首先，声明：

    if (batteryStateReceiver == null) {
        this.unregisterReceiver(batteryStateReceiver);
    }
    if (orientationChangeReceiver == null) {
        this.unregisterReceiver(orientationChangeReceiver);
    }

没有任何意义。您每次都会收到NullPointerException。将== 更改为!= ;)

另外，请参阅my post about keeping background services alive.

在后台长时间运行（非必要）调用startForeground() 的复杂服务示例。但是，它仍然可以被系统或用户杀死。