Android系统闹钟定时功能框架,总体来说就是用数据库存储定时数据,有一个状态管理器来统一管理这些定时状态的触发和更新。在Andriod系统中实现定时功能,最终还是要用到系统提供的AlarmManager,只是当一个定时完成后怎么继续处理,或者中间怎么更新定时的时间或者状态,像闹钟这种应用程序,每天重复定时,或者一周选择其中的几天,闹钟响了延迟5分钟再次响铃,这时候就需要想一种好的办法来让管理这些数据和状态,下面就分析一下Android系统闹钟的实现。
1、基本结构
Alarm
代表一条定时数据
AlarmInstance
代表一个定时项目的实例,一个AlarmInstance对应到一个Alarm,相比Alarm多存储了一些状态信息
AlarmStateManager
状态管理器,对定时项目进行调度,添加、删除、更改状态,是一个BroadcastReciever,定时到点后发广播到这里进行下一步处理
AlarmService
响应结果,也就是定时到达后要做的事,响铃,停止响铃
ClockDataHelper
里面创建了三个表,ALARMS_TABLE,INSTANCE_TABLE,CITIES_TABLE,前两个分别对应到上面的Alarm和AlarmInstance。
- private static void createAlarmsTable(SQLiteDatabase db) {
- db.execSQL(“CREATE TABLE “ + ALARMS_TABLE_NAME + ” (“ +
- ClockContract.AlarmsColumns._ID + ” INTEGER PRIMARY KEY,” +
- ClockContract.AlarmsColumns.HOUR + ” INTEGER NOT NULL, “ +
- ClockContract.AlarmsColumns.MINUTES + ” INTEGER NOT NULL, “ +
- ClockContract.AlarmsColumns.DAYS_OF_WEEK + ” INTEGER NOT NULL, “ +
- ClockContract.AlarmsColumns.ENABLED + ” INTEGER NOT NULL, “ +
- ClockContract.AlarmsColumns.VIBRATE + ” INTEGER NOT NULL, “ +
- ClockContract.AlarmsColumns.LABEL + ” TEXT NOT NULL, “ +
- ClockContract.AlarmsColumns.RINGTONE + ” TEXT, “ +
- ClockContract.AlarmsColumns.DELETE_AFTER_USE + ” INTEGER NOT NULL DEFAULT 0);”);
- Log.i(“Alarms Table created”);
- }
- private static void createInstanceTable(SQLiteDatabase db) {
- db.execSQL(“CREATE TABLE “ + INSTANCES_TABLE_NAME + ” (“ +
- ClockContract.InstancesColumns._ID + ” INTEGER PRIMARY KEY,” +
- ClockContract.InstancesColumns.YEAR + ” INTEGER NOT NULL, “ +
- ClockContract.InstancesColumns.MONTH + ” INTEGER NOT NULL, “ +
- ClockContract.InstancesColumns.DAY + ” INTEGER NOT NULL, “ +
- ClockContract.InstancesColumns.HOUR + ” INTEGER NOT NULL, “ +
- ClockContract.InstancesColumns.MINUTES + ” INTEGER NOT NULL, “ +
- ClockContract.InstancesColumns.VIBRATE + ” INTEGER NOT NULL, “ +
- ClockContract.InstancesColumns.LABEL + ” TEXT NOT NULL, “ +
- ClockContract.InstancesColumns.RINGTONE + ” TEXT, “ +
- ClockContract.InstancesColumns.ALARM_STATE + ” INTEGER NOT NULL, “ +
- ClockContract.InstancesColumns.ALARM_ID + ” INTEGER REFERENCES “ +
- ALARMS_TABLE_NAME + “(“ + ClockContract.AlarmsColumns._ID + “) “ +
- “ON UPDATE CASCADE ON DELETE CASCADE” +
- “);”);
- Log.i(“Instance table created”);
- }
这里说一下几个特殊的字段,对于Alarm表,DAYS_OF_WEEK表示一周内需要定时的天(闹钟有个功能是选择一周中的几天),这里是个int值,用位来表示设置的天数,源码中有个专门的类DaysOfWeek来存储和处理。
AlarmInstance表中有一个ALARM_ID,关联到一个Alarm,可以看到在AlarmInstance表里也有时间,为什么不和Alarm表合成一个表?应该是这样的,Alarm表示原始的定时项,是一个基础数据,而AlarmInstance则代表了一个使用中的定时项目,或者是一个已经激活的定时项目,它的时间是可以变化的,比如闹钟响了以后延时5分钟再响,就需要改变这里的时间,而基础数据不能变,还需要显示在那里。ALARM_STATE代表了当前定时项目的状态,具体调度都在AlarmStateManager中管理。
忘了在哪里看到的,“编程最重要的是设计数据结构,接下来是分解各种代码块”。数据结构是基础,就像建筑里的钢筋水泥砖瓦,有了基础的材料后,剩下的工作就是对这些材料处理,也就是设计具体的处理逻辑。
2、具体的类分析
Alarm
从上面也可以看出,Alarm类作为定时的基础数据结构,主要是封装了一些数据库操作,完成增删改查功能。额外有一个方法createInstanceAfter,根据自身来创建一个AlarmInstance实例。代码如下
- public AlarmInstance createInstanceAfter(Calendar time) {
- Calendar nextInstanceTime = Calendar.getInstance();
- nextInstanceTime.set(Calendar.YEAR, time.get(Calendar.YEAR));
- nextInstanceTime.set(Calendar.MONTH, time.get(Calendar.MONTH));
- nextInstanceTime.set(Calendar.DAY_OF_MONTH, time.get(Calendar.DAY_OF_MONTH));
- nextInstanceTime.set(Calendar.HOUR_OF_DAY, hour);
- nextInstanceTime.set(Calendar.MINUTE, minutes);
- nextInstanceTime.set(Calendar.SECOND, 0);
- nextInstanceTime.set(Calendar.MILLISECOND, 0);
- // If we are still behind the passed in time, then add a day
- if (nextInstanceTime.getTimeInMillis() <= time.getTimeInMillis()) {
- nextInstanceTime.add(Calendar.DAY_OF_YEAR, 1);
- }
- // The day of the week might be invalid, so find next valid one
- int addDays = daysOfWeek.calculateDaysToNextAlarm(nextInstanceTime);
- if (addDays > 0) {
- nextInstanceTime.add(Calendar.DAY_OF_WEEK, addDays);
- }
- AlarmInstance result = new AlarmInstance(nextInstanceTime, id);
- result.mVibrate = vibrate;
- result.mLabel = label;
- result.mRingtone = alert;
- return result;
- }
AlarmInstance
AlarmInstance与Alarm很相似,像Alarm中的增删改查操作在AlarmInstance中都有相似的方法。那有什么不同呢,就是上面说的AlarmInstance的时间是可以根据当前状态改变的,也就多了时间的set和get方法。
- public void setAlarmTime(Calendar calendar) {
- mYear = calendar.get(Calendar.YEAR);
- mMonth = calendar.get(Calendar.MONTH);
- mDay = calendar.get(Calendar.DAY_OF_MONTH);
- mHour = calendar.get(Calendar.HOUR_OF_DAY);
- mMinute = calendar.get(Calendar.MINUTE);
- }
- /**
- * Return the time when a alarm should fire.
- *
- * @return the time
- */
- public Calendar getAlarmTime() {
- Calendar calendar = Calendar.getInstance();
- calendar.set(Calendar.YEAR, mYear);
- calendar.set(Calendar.MONTH, mMonth);
- calendar.set(Calendar.DAY_OF_MONTH, mDay);
- calendar.set(Calendar.HOUR_OF_DAY, mHour);
- calendar.set(Calendar.MINUTE, mMinute);
- calendar.set(Calendar.SECOND, 0);
- calendar.set(Calendar.MILLISECOND, 0);
- return calendar;
- }
AlarmStateManager
闹钟定时的核心逻辑就在这里,AlarmStateManager就是管理所有定时项目状态的调度器。
可以看到上面大多是static类型的方法,用于设置各种状态值。
先看一下定时的几种状态:
SILENT_STATE,alarm被激活,但是不需要显示任何东西,下一个状态是LOW_NOTIFICATION_STATE;
LOW_NOTIFICATION_STATE,这个状态表示alarm离触发的时间不远了,时间差是AlarmInstance.LOW_NOTIFICATION_HOUR_OFFSET=-2,也就是2个小时。下一个状态会进入HIGH_NOTIFICATION_STATE,HIDE_NOTIFICATION_STATE,DISMISS_STATE;
HIDE_NOTIFICATION_STATE,这是一个暂时态,表示用户想隐藏掉通知,这个状态会一直持续到HIGH_NOTIFICATION_STATE;
HIGH_NOTIFICATION_STATE,这个状态和LOW_NOTIFICATION_STATE相似,但不允许用户隐藏通知,负责触发FIRED_STATE或者DISMISS_STATE;
SNOOZED_STATE,像HIGH_NOTIFICATION_STATE,但是会增加一点定时的时间来完成延迟功能;
FIRED_STATE,表示响铃状态,会启动AlarmService直到用户将其变为SNOOZED_STATE或者DISMISS_STATE,如果用户放任不管,会之后进入MISSED_STATE;
MISSED_STATE,这个状态在FIRED_STATE之后,会在通知栏给出一个提醒刚才响铃了;
DISMISS_STATE,这个状态表示定时结束了,会根据定时项目的设置判断是否需要重复,从而决定要删除这个项目还是继续设定一个新的定时。
上面的 setXXXState 方法就是对这些状态的处理,同时会规划一个定时转换到下一个状态。比如setSilentState:
- public static void setSilentState(Context context, AlarmInstance instance) {
- Log.v(“Setting silent state to instance “ + instance.mId);
- // Update alarm in db
- ContentResolver contentResolver = context.getContentResolver();
- instance.mAlarmState = AlarmInstance.SILENT_STATE;
- AlarmInstance.updateInstance(contentResolver, instance);
- // Setup instance notification and scheduling timers
- AlarmNotifications.clearNotification(context, instance);
- scheduleInstanceStateChange(context, instance.getLowNotificationTime(),
- instance, AlarmInstance.LOW_NOTIFICATION_STATE);
- }
更新AlarmInstance的信息,同时通过scheduleInstanceStateChange()规划下一个状态:
- private static void scheduleInstanceStateChange(Context context, Calendar time,
- AlarmInstance instance, int newState) {
- long timeInMillis = time.getTimeInMillis();
- Log.v(“Scheduling state change “ + newState + ” to instance “ + instance.mId +
- ” at “ + AlarmUtils.getFormattedTime(context, time) + ” (“ + timeInMillis + “)”);
- Intent stateChangeIntent = createStateChangeIntent(context, ALARM_MANAGER_TAG, instance,
- newState);
- PendingIntent pendingIntent = PendingIntent.getBroadcast(context, instance.hashCode(),
- stateChangeIntent, PendingIntent.FLAG_UPDATE_CURRENT);
- AlarmManager am = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
- if (Utils.isKitKatOrLater()) {
- am.setExact(AlarmManager.RTC_WAKEUP, timeInMillis, pendingIntent);
- } else {
- am.set(AlarmManager.RTC_WAKEUP, timeInMillis, pendingIntent);
- }
- }
通过AlarmManager发起一个定时,定时的时间从调用处可以看到是有AlarmInstance得到的,比如在setSilentState()中的定时时间是instance.getLowNotificationTime():
- public Calendar getLowNotificationTime() {
- Calendar calendar = getAlarmTime();
- calendar.add(Calendar.HOUR_OF_DAY, LOW_NOTIFICATION_HOUR_OFFSET);
- return calendar;
- }
LOW_NOTIFICATION_HOUR_OFFSET值为-2,也就是在闹铃响之前的两小时那一刻会发这个LOW_NOTIFICATION_STATE的广播出来,AlarmStateManager接收到这个广播处理再转移到下一个。广播的接收在onReciever方法中,
- @Override
- public void onReceive(final Context context, final Intent intent) {
- final PendingResult result = goAsync();
- final PowerManager.WakeLock wl = AlarmAlertWakeLock.createPartialWakeLock(context);
- wl.acquire();
- AsyncHandler.post(new Runnable() {
- @Override
- public void run() {
- handleIntent(context, intent);
- result.finish();
- wl.release();
- }
- });
- }
- private void handleIntent(Context context, Intent intent) {
- final String action = intent.getAction();
- Log.v(“AlarmStateManager received intent “ + intent);
- if (CHANGE_STATE_ACTION.equals(action)) {
- Uri uri = intent.getData();
- AlarmInstance instance = AlarmInstance.getInstance(context.getContentResolver(),
- AlarmInstance.getId(uri));
- if (instance == null) {
- // Not a big deal, but it shouldn’t happen
- Log.e(“Can not change state for unknown instance: “ + uri);
- return;
- }
- int globalId = getGlobalIntentId(context);
- int intentId = intent.getIntExtra(ALARM_GLOBAL_ID_EXTRA, –1);
- int alarmState = intent.getIntExtra(ALARM_STATE_EXTRA, –1);
- if (intentId != globalId) {
- Log.i(“Ignoring old Intent. IntentId: “ + intentId + ” GlobalId: “ + globalId +
- ” AlarmState: “ + alarmState);
- return;
- }
- if (alarmState >= 0) {
- setAlarmState(context, instance, alarmState);
- } else {
- registerInstance(context, instance, true);
- }
- } else if (SHOW_AND_DISMISS_ALARM_ACTION.equals(action)) {
- Uri uri = intent.getData();
- AlarmInstance instance = AlarmInstance.getInstance(context.getContentResolver(),
- AlarmInstance.getId(uri));
- long alarmId = instance.mAlarmId == null ? Alarm.INVALID_ID : instance.mAlarmId;
- Intent viewAlarmIntent = Alarm.createIntent(context, DeskClock.class, alarmId);
- viewAlarmIntent.putExtra(DeskClock.SELECT_TAB_INTENT_EXTRA, DeskClock.ALARM_TAB_INDEX);
- viewAlarmIntent.putExtra(AlarmClockFragment.SCROLL_TO_ALARM_INTENT_EXTRA, alarmId);
- viewAlarmIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
- context.startActivity(viewAlarmIntent);
- setDismissState(context, instance);
- }
- }
- }
在handleIntent方法中统一处理,状态的分发在setAlarmState中:
- public void setAlarmState(Context context, AlarmInstance instance, int state) {
- switch(state) {
- case AlarmInstance.SILENT_STATE:
- setSilentState(context, instance);
- break;
- case AlarmInstance.LOW_NOTIFICATION_STATE:
- setLowNotificationState(context, instance);
- break;
- case AlarmInstance.HIDE_NOTIFICATION_STATE:
- setHideNotificationState(context, instance);
- break;
- case AlarmInstance.HIGH_NOTIFICATION_STATE:
- setHighNotificationState(context, instance);
- break;
- case AlarmInstance.FIRED_STATE:
- setFiredState(context, instance);
- break;
- case AlarmInstance.SNOOZE_STATE:
- setSnoozeState(context, instance);
- break;
- case AlarmInstance.MISSED_STATE:
- setMissedState(context, instance);
- break;
- case AlarmInstance.DISMISSED_STATE:
- setDismissState(context, instance);
- break;
- default:
- Log.e(“Trying to change to unknown alarm state: “ + state);
- }
- }
对没一个state又转移相应的setXXXState方法中,完成下一次状态的转换,形成一个定时的循环,直到在DISMISSED_STATE里停用或者删除定时项目,如果需要重复则获取下一次定时的时间。
整体的框架就是这样,在AlarmStateManager里使用AlarmManager形成了一个定时的状态机,不断转移到下一个状态处理。
源码在这里https://android.googlesource.com/platform/packages/apps/DeskClock/+/android-4.4.4_r2.0.1
原创文章,作者:奋斗,如若转载,请注明出处:https://blog.ytso.com/tech/app/5578.html