Android AlarmManager RTC_WAKEUP 不准确？

Question

我正在尝试找到一种在特定时间执行某些代码的方法。为此，我目前正在尝试仅使用 Android 提供的内容：AlarmManger。当设置它被执行的时间时，但不完全是我设置时间的时间 -> 总是有一个延迟，当时间离当前更远时，延迟似乎更长。我该如何解决？当用户不在应用程序中但没有使用任务管理器关闭它时，代码运行很重要。

（抱歉格式化）

MainActivity:
public class MainActivity extends AppCompatActivity implements View.OnClickListener {

        private final String tag = "MainActivity";

        private TimePicker timePicker;
        private Button button;

        private boolean isRunning;
        private PendingIntent servicePI;
        private AlarmManager alarmManager;

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            init();
        }

        @Override
        public void onClick(View v) {
            if (isRunning) {
                Log.d(tag, "Stop service");

                alarmManager.cancel(servicePI);
                setState(false);
            }else {
                Log.d(tag, "Start service");

                int[] alarmTime = new int[2];
                if (Build.VERSION.SDK_INT < 23) {
                    alarmTime[0] = timePicker.getCurrentHour();
                    alarmTime[1] = timePicker.getCurrentMinute();
                }else {
                    alarmTime[0] = timePicker.getHour();
                    alarmTime[1] = timePicker.getMinute();
                }

                Calendar c = Calendar.getInstance();
                c.set(Calendar.HOUR_OF_DAY, alarmTime[0]);
                c.set(Calendar.MINUTE, alarmTime[1]);
                c.set(Calendar.SECOND, 0);

                alarmManager.set(AlarmManager.RTC_WAKEUP, c.getTimeInMillis(), servicePI);
                setState(true);
            }
        }

        private void setState(boolean state) {
            isRunning = state;
            if (state)
                button.setText("Stop");
            else
                button.setText("Start");
        }

        private void init() {
            timePicker = findViewById(R.id.timePicker);
            button = findViewById(R.id.button_power);
            button.setOnClickListener(this);

            setState(false);

            Intent service = new Intent(getApplicationContext(), MyService.class);
            servicePI = PendingIntent.getService(getApplication(), 0, service,0);
            alarmManager = (AlarmManager) getApplicationContext().getSystemService(Context.ALARM_SERVICE);
        }
    }


MyService:
public class MyService extends Service {

            private final String tag = "MyService";

            @Override
            public int onStartCommand(Intent intent, int flags, int startId) {
                Log.d(tag, "Start");
                return super.onStartCommand(intent, flags, startId);
            }

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

Answer 1

对 AlarmManager.set() 的调用不准确。这允许 Android 优化设备的电源使用。如果您需要准确交付，您需要使用 setExact() 或 setExactAndAllowWhileIdle()。请参阅 documentation.

中的注释

Android AlarmManager RTC_WAKEUP 不准确？

Android AlarmManager RTC_WAKEUP inprecise?

java

android

alarmmanager

android-pendingintent