在广播接收器类中未获取电池状态或电池电量

Question

我正在尝试在广播接收器类中获取电池状态和电量，然后将其显示在通知中。

public class BatteryBroadcasts extends BroadcastReceiver {

private static final int NOTIFICATION_ID = 234234;
@Override
public void onReceive(Context context, Intent intent) {

    String notiText;
    NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(context).setSmallIcon(R.drawable.ic_launcher).setContentTitle("Battery Alarm").setContentText(showBatteryStatus(intent));

    Intent resultIntent = new Intent(context, MainActivity.class);
    PendingIntent resultPendingIntent =PendingIntent.getActivity(context,0,resultIntent,PendingIntent.FLAG_UPDATE_CURRENT);
    mBuilder.setContentIntent(resultPendingIntent);
    NotificationManager mNotificationManager =(NotificationManager)context.getSystemService(Context.NOTIFICATION_SERVICE);
    mNotificationManager.notify(NOTIFICATION_ID, mBuilder.build());



}
private String showBatteryStatus(Intent batteryStatus){
    String batteryStat = new String();

    int status = batteryStatus.getIntExtra(BatteryManager.EXTRA_STATUS, -1);
    boolean isCharging = status == BatteryManager.BATTERY_STATUS_CHARGING || status == BatteryManager.BATTERY_STATUS_FULL;


    int chargePlug = batteryStatus.getIntExtra(BatteryManager.EXTRA_PLUGGED, -1);
    boolean usbCharge = chargePlug == BatteryManager.BATTERY_PLUGGED_USB;
    boolean acCharge = chargePlug == BatteryManager.BATTERY_PLUGGED_AC;



    int level = batteryStatus.getIntExtra(BatteryManager.EXTRA_LEVEL, -1);
    int scale = batteryStatus.getIntExtra(BatteryManager.EXTRA_SCALE, -1);


    float batteryPct = ((float)level / (float)scale)*100;
    Log.d("in notification","battery stat "+level+"scale"+scale+" "+batteryPct);

    int voltage = batteryStatus.getIntExtra(BatteryManager.EXTRA_VOLTAGE,-1);



    if(isCharging && usbCharge )
        batteryStat="Charging on USB\n";
    if(isCharging && acCharge )
        batteryStat="Charging on AC\n";
    if(!isCharging)
        batteryStat="Discharging\n ";

    return batteryStat+batteryPct+"% battery left.";
}

}

清单文件

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.r3h.batteryalarm">

<!-- Include required permissions for Google Mobile Ads to run. -->
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.READ_PHONE_STATE"/>
<uses-permission android:name="android.permission.BATTERY_STATS"/>
<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">

    <!-- This meta-data tag is required to use Google Play Services. -->
    <meta-data
        android:name="com.google.android.gms.version"
        android:value="@integer/google_play_services_version" />

    <receiver android:name=".BatteryBroadcasts">
        <intent-filter>
            <action android:name="android.intent.action.ACTION_POWER_CONNECTED"/>
            <action android:name="android.intent.action.ACTION_POWER_DISCONNECTED"/>
        </intent-filter>
    </receiver>

    <activity
        android:name=".MainActivity"
        android:label="@string/app_name">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity> <!-- Include the AdActivity configChanges and theme. -->
    <activity
        android:name="com.google.android.gms.ads.AdActivity"
        android:configChanges="keyboard|keyboardHidden|orientation|screenLayout|uiMode|screenSize|smallestScreenSize"
        android:theme="@android:style/Theme.Translucent" />
</application>

当充电状态发生变化时，会调用 onReceive 但变量 isCharging 始终为 false，无论手机是否连接。 level 和 scale 等变量始终为 -1。

当我在活动类中使用相同的代码时，它可以完美运行。 请帮忙 。提前致谢。

Answer 1

将动作 ACTION_BATTERY_CHANGED 添加到意图过滤器。

<receiver android:name=".BatteryBroadcasts">
    <intent-filter>
        <action android:name="android.intent.action.ACTION_BATTERY_CHANGED"/>

...

Answer 2

我是这样做的：

<receiver android:name="CheckBatteryStatusReceiver" ></receiver>

然后我有这样的接收器：

public class CheckBatteryStatusReceiver extends BroadcastReceiver{
    @Override
    public void onReceive(Context context, Intent intent) {
        if (intent != null){
            int level = intent.getIntExtra(BatteryManager.EXTRA_LEVEL, 0);
            if (level <= 15){
                Toast.makeText(context, "Batter level " + level + "% is very low. Please connect to a charger.", Toast.LENGTH_SHORT).show();
            }
        }
    }
}

不要忘记在您的Activity onCreate() 中注册接收器，例如：

private void setupReceiver() {
        CheckBatteryStatusReceiver batteryStatusReceiver = new CheckBatteryStatusReceiver();
        registerReceiver(batteryStatusReceiver, new IntentFilter(Intent.ACTION_BATTERY_CHANGED));
    }

然后在onPause() 中使用：

@Override
    protected void onPause() {
        super.onPause();
        try {
            if (batteryStatusReceiver != null){
                unregisterReceiver(batteryStatusReceiver);
            }
        }catch (IllegalArgumentException e){
            e.printStackTrace();
        }
    }

当它小于 15 或 15 时，将显示 toast 消息。如果您正在使用模拟器 AVD 并且想要对其进行测试，那么我建议您应该通过 Telnet 连接到模拟器，如下所示：

telnet localhost 5554(emulator port(you can see that using adb devices))

然后使用：

auth key(you will find a key for emulator in the default path of you AndroidStudioProjects)

然后你可以使用：

power capacity 15

你会看到Toast消息弹出。

希望对你有帮助！！！