java - AlarmManager 未添加新警报，或未触发接收器

Question

我目前正在开发一个使用 Android 的 AlarmManager 的应用程序。我正在尝试向 AlarmManager 添加一个新警报，但是经过几个小时的尝试各种事情并检查 SO 上的各种线程后，我仍然处于砖墙之中。我的代码有问题吗？

<小时/>

主要 Activity - saveAlarm() 函数

/**
 * Saves the current alarm. Adds to the database if it doesn't already exist, or updates if it does.
 * Also sets alert with AlarmManager.
 */
public void saveAlarm() {
    // Create Database instance
    DbHandler db = new DbHandler(getApplicationContext());

    if(alarm.getId() == -1) {
        // Saving a new alarm
        db.open();
        alarm.setId(db.addAlarm(alarm));
        db.close();
    }
    else {
        db.open();
        db.updateAlarm(alarm);
        db.close();
    }

    // Create the wakeup intent
    Intent intent = new Intent(this, AlarmReceiver.class);
    intent.putExtra("alarm_id", alarm.getId());

    // Create the Pending Intent
    PendingIntent sender = PendingIntent.getBroadcast(this, AlarmPlayer.REQUEST_ALARM + alarm.getId(), intent, PendingIntent.FLAG_UPDATE_CURRENT);

    // Debug
    Calendar now = Calendar.getInstance();
    long dTime  = alarm.getNextAlarmTime().getTimeInMillis() - now.getTimeInMillis();
    Log.d(TAG, "Setting alarm for " + (dTime / 1000) + " seconds time");

    // Add to Android Alarm Manager
    AlarmManager am = (AlarmManager) getSystemService(ALARM_SERVICE);
    am.set(AlarmManager.RTC_WAKEUP, alarm.getNextAlarmTime().getTimeInMillis(), sender);    
}

我已验证是否将正确的时间传递到 am.set(请参阅上面的调试部分)。

<小时/>

AlarmReceiver.class

/**
* This class listens out for broadcasts from AlarmManager
* and launches the AlarmPlayer activity accordingly.
* @author Michael
*
*/
public class AlarmReceiver extends BroadcastReceiver {

     @Override
    public void onReceive(Context c, Intent intent) {
        Log.d("RSS Alarm", "Waking up alarm");
            // Launch the AlarmPlayer activity
        Intent i = new Intent(c, AlarmPlayer.class);
        i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        c.startActivity(i);
    }

}

<小时/>

我还有<receiver android:process=":remote" android:name="AlarmReceiver" />在 AndroidManifest.xml 中设置。我不知道是什么导致了这个问题，但它仍然发生了。任何帮助将不胜感激，非常感谢。

<小时/>

编辑 1 将时区更改为 UTC 似乎并不能解决任何问题，无论如何，我的日历似乎默认为 UTC。当前代码:

// Debug
Calendar now = Calendar.getInstance(TimeZone.getTimeZone("UTC"));
long dTime  = alarm.getNextAlarmTime().getTimeInMillis() - now.getTimeInMillis();
Log.d(TAG, "Setting alarm for " + (dTime / 1000) + " seconds time");

// Add to Android Alarm Manager
AlarmManager am = (AlarmManager) getSystemService(ALARM_SERVICE);
Log.d(TAG, "Timezone offset is " + TimeZone.getDefault().getRawOffset());
Log.d(TAG, "UTC time is currently " + Calendar.getInstance(TimeZone.getTimeZone("UTC")).getTimeInMillis() / 1000);
am.set(AlarmManager.RTC_WAKEUP, (alarm.getNextAlarmTime().getTimeInMillis() - TimeZone.getDefault().getRawOffset()), sender);

Answer 1

这是否可能是 AlarmManager.set(AlarmManager.RTC_WAKEUP, ...) 需要 UTC 时间的情况？如果您设置“本地时间”并且不调整为 UTC，这会导致问题。简而言之，警报可能已正确添加，但它不会在您期望的时候触发，除非您的时区是 UTC。

来自文档...

public static final int RTC_WAKEUP Since: API Level 1

Alarm time in System.currentTimeMillis() (wall clock time in UTC), which will wake up the device when it goes off.