定时任务_AlertManger

参考:Schedule exact alarms are denied by default | Android Developers

permission: 

Calendar and alarm clock apps should declare USE_EXACT_ALARM

判断是否有权限:canScheduleExactAlarms()

如果没有权限, 请求用户打开权限: action: Settings.ACTION_REQUEST_SCHEDULE_EXACT_ALARM

通过接受广播判断用户是否授予该权限:

AlarmManager.ACTION_SCHEDULE_EXACT_ALARM_PERMISSION_STATE_CHANGED

AlarmManager manager = ContextCompat.getSystemService(context, AlarmManager.class);
        if (!manager.canScheduleExactAlarms()) {
            IntentFilter filter = new IntentFilter(AlarmManager.ACTION_SCHEDULE_EXACT_ALARM_PERMISSION_STATE_CHANGED);
            context.registerReceiver(receiver, filter, Context.RECEIVER_EXPORTED);
            context.startActivity(new Intent(ACTION_REQUEST_SCHEDULE_EXACT_ALARM));
        } else {
            showAlarm(context, manager);
        }



 private BroadcastReceiver receiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            AlarmManager manager = ContextCompat.getSystemService(context, AlarmManager.class);
            if (intent.getAction().equals(AlarmManager.ACTION_SCHEDULE_EXACT_ALARM_PERMISSION_STATE_CHANGED)) {
                context.unregisterReceiver(receiver);
                if (manager.canScheduleExactAlarms()) {
                    showAlarm(context, manager);
                }
            }
        }
    };

如果有权限, 则可以开启定时服务

        Intent intent = new Intent();
        intent.setAction("Alarm time");
        PendingIntent pending = PendingIntent.getBroadcast(context, 1, intent, PendingIntent.FLAG_IMMUTABLE);
        manager.setExact(AlarmManager.RTC, System.currentTimeMillis() + 10 * 1000, pending);



 /**
     * RTC
     * Alarm time in System.currentTimeMillis() (wall clock time in UTC). This alarm does not wake the device up; if it goes off while the device is asleep, it will not be delivered until the next time the device wakes up.
     *
     *
     * RTC_WAKEUP
     * Alarm time in System.currentTimeMillis() (wall clock time in UTC), which will wake up the device when it goes off.
     *
     *
     * ELAPSED_REALTIME :从启动到现在的时间
     * Alarm time in SystemClock.elapsedRealtime() (time since boot, including sleep). This alarm does not wake the device up; if it goes off while the device is asleep, it will not be delivered until the next time the device wakes up.
     *
     *
     * ELAPSED_REALTIME_WAKEUP
     * Alarm time in SystemClock.elapsedRealtime() (time since boot, including sleep), which will wake up the device when it goes off.
     **/



 /**
     * this alarm will be allowed to execute even when the system is in low-power idle modes.
     *
     * When the alarm is dispatched, the app will also be added to the system's temporary power exemption list
     * for approximately 10 seconds to allow that application to acquire further wake locks in which to complete its work.
     * there are restrictions on how frequently these alarms will go off for a particular application.
     * Under normal system operation, it will not dispatch these alarms more than about every minute.
     * @param context
     * @param manager
     */
    private void setExactAndAllowWhileIdle(Context context, AlarmManager manager) {

        Intent intent = new Intent();
        intent.setAction("Alarm time");
        PendingIntent pending = PendingIntent.getBroadcast(context, 1, intent, PendingIntent.FLAG_IMMUTABLE);
        manager.setExactAndAllowWhileIdle(AlarmManager.RTC, System.currentTimeMillis() + 10 * 1000, pending);
    }

    /**
     * 在指定时间窗口内执行
     *
     * @param context
     * @param manager
     */
    private void setWindow(Context context, AlarmManager manager) {

        Intent intent = new Intent();
        intent.setAction("Alarm time");
        PendingIntent pending = PendingIntent.getBroadcast(context, 1, intent, PendingIntent.FLAG_IMMUTABLE);
        manager.setWindow(AlarmManager.RTC, System.currentTimeMillis() + 10 * 1000, System.currentTimeMillis() + 10 * 60 * 1000, pending);
    }

    private void set(Context context, AlarmManager manager) {

        Intent intent = new Intent();
        intent.setAction("Alarm time");
        PendingIntent pending = PendingIntent.getBroadcast(context, 1, intent, PendingIntent.FLAG_IMMUTABLE);
        manager.set(AlarmManager.RTC, System.currentTimeMillis() + 10 * 1000, pending);
    }