Android時(shí)鐘應(yīng)用的定時(shí)框架分析
來(lái)源：程序員人生 發(fā)布時(shí)間：2014-10-10 08:00:00 閱讀次數(shù)：3369次
Android系統(tǒng)鬧鐘定時(shí)功能框架，總體來(lái)說(shuō)就是用數(shù)據(jù)庫(kù)存儲(chǔ)定時(shí)數(shù)據(jù)，有一個(gè)狀態(tài)管理器來(lái)統(tǒng)一管理這些定時(shí)狀態(tài)的觸發(fā)和更新。在Andriod系統(tǒng)中實(shí)現(xiàn)定時(shí)功能，最終還是要用到系統(tǒng)提供的AlarmManager，只是當(dāng)一個(gè)定時(shí)完成后怎么繼續(xù)處理，或者中間怎么更新定時(shí)的時(shí)間或者狀態(tài)，像鬧鐘這種應(yīng)用程序，每天重復(fù)定時(shí)，或者一周選擇其中的幾天，鬧鐘響了延遲5分鐘再次響鈴，這時(shí)候就需要想一種好的辦法來(lái)讓管理這些數(shù)據(jù)和狀態(tài)，下面就分析一下Android系統(tǒng)鬧鐘的實(shí)現(xiàn)。
1、基本結(jié)構(gòu)
Alarm
代表一條定時(shí)數(shù)據(jù)
AlarmInstance
代表一個(gè)定時(shí)項(xiàng)目的實(shí)例，一個(gè)AlarmInstance對(duì)應(yīng)到一個(gè)Alarm，相比Alarm多存儲(chǔ)了一些狀態(tài)信息
AlarmStateManager
狀態(tài)管理器，對(duì)定時(shí)項(xiàng)目進(jìn)行調(diào)度，添加、刪除、更改狀態(tài)，是一個(gè)BroadcastReciever，定時(shí)到點(diǎn)后發(fā)廣播到這里進(jìn)行下一步處理
AlarmService
響應(yīng)結(jié)果，也就是定時(shí)到達(dá)后要做的事，響鈴，停止響鈴
ClockDataHelper
里面創(chuàng)建了三個(gè)表，ALARMS_TABLE，INSTANCE_TABLE，CITIES_TABLE，前兩個(gè)分別對(duì)應(yīng)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");
}
這里說(shuō)一下幾個(gè)特殊的字段，對(duì)于Alarm表，DAYS_OF_WEEK表示一周內(nèi)需要定時(shí)的天（鬧鐘有個(gè)功能是選擇一周中的幾天），這里是個(gè)int值，用位來(lái)表示設(shè)置的天數(shù)，源碼中有個(gè)專(zhuān)門(mén)的類(lèi)DaysOfWeek來(lái)存儲(chǔ)和處理。
AlarmInstance表中有一個(gè)ALARM_ID，關(guān)聯(lián)到一個(gè)Alarm，可以看到在AlarmInstance表里也有時(shí)間，為什么不和Alarm表合成一個(gè)表？應(yīng)該是這樣的，Alarm表示原始的定時(shí)項(xiàng)，是一個(gè)基礎(chǔ)數(shù)據(jù)，而AlarmInstance則代表了一個(gè)使用中的定時(shí)項(xiàng)目，或者是一個(gè)已經(jīng)激活的定時(shí)項(xiàng)目，它的時(shí)間是可以變化的，比如鬧鐘響了以后延時(shí)5分鐘再響，就需要改變這里的時(shí)間，而基礎(chǔ)數(shù)據(jù)不能變，還需要顯示在那里。ALARM_STATE代表了當(dāng)前定時(shí)項(xiàng)目的狀態(tài)，具體調(diào)度都在AlarmStateManager中管理。
忘了在哪里看到的，“編程最重要的是設(shè)計(jì)數(shù)據(jù)結(jié)構(gòu)，接下來(lái)是分解各種代碼塊”。數(shù)據(jù)結(jié)構(gòu)是基礎(chǔ)，就像建筑里的鋼筋水泥磚瓦，有了基礎(chǔ)的材料后，剩下的工作就是對(duì)這些材料處理，也就是設(shè)計(jì)具體的處理邏輯。
2、具體的類(lèi)分析
Alarm
從上面也可以看出，Alarm類(lèi)作為定時(shí)的基礎(chǔ)數(shù)據(jù)結(jié)構(gòu)，主要是封裝了一些數(shù)據(jù)庫(kù)操作，完成增刪改查功能。額外有一個(gè)方法createInstanceAfter，根據(jù)自身來(lái)創(chuàng)建一個(gè)AlarmInstance實(shí)例。代碼如下
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與Alarm很相似，像Alarm中的增刪改查操作在AlarmInstance中都有相似的方法。那有什么不同呢，就是上面說(shuō)的AlarmInstance的時(shí)間是可以根據(jù)當(dāng)前狀態(tài)改變的，也就多了時(shí)間的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
鬧鐘定時(shí)的核心邏輯就在這里，AlarmStateManager就是管理所有定時(shí)項(xiàng)目狀態(tài)的調(diào)度器。
可以看到上面大多是static類(lèi)型的方法，用于設(shè)置各種狀態(tài)值。
先看一下定時(shí)的幾種狀態(tài)：
SILENT_STATE，alarm被激活，但是不需要顯示任何東西，下一個(gè)狀態(tài)是LOW_NOTIFICATION_STATE；
LOW_NOTIFICATION_STATE，這個(gè)狀態(tài)表示alarm離觸發(fā)的時(shí)間不遠(yuǎn)了，時(shí)間差是AlarmInstance.LOW_NOTIFICATION_HOUR_OFFSET=-2，也就是2個(gè)小時(shí)。下一個(gè)狀態(tài)會(huì)進(jìn)入HIGH_NOTIFICATION_STATE，HIDE_NOTIFICATION_STATE，DISMISS_STATE；
HIDE_NOTIFICATION_STATE，這是一個(gè)暫時(shí)態(tài)，表示用戶(hù)想隱藏掉通知，這個(gè)狀態(tài)會(huì)一直持續(xù)到HIGH_NOTIFICATION_STATE；
HIGH_NOTIFICATION_STATE，這個(gè)狀態(tài)和LOW_NOTIFICATION_STATE相似，但不允許用戶(hù)隱藏通知，負(fù)責(zé)觸發(fā)FIRED_STATE或者DISMISS_STATE；
SNOOZED_STATE，像HIGH_NOTIFICATION_STATE，但是會(huì)增加一點(diǎn)定時(shí)的時(shí)間來(lái)完成延遲功能；
FIRED_STATE，表示響鈴狀態(tài)，會(huì)啟動(dòng)AlarmService直到用戶(hù)將其變?yōu)镾NOOZED_STATE或者DISMISS_STATE，如果用戶(hù)放任不管，會(huì)之后進(jìn)入MISSED_STATE；
MISSED_STATE，這個(gè)狀態(tài)在FIRED_STATE之后，會(huì)在通知欄給出一個(gè)提醒剛才響鈴了；
DISMISS_STATE，這個(gè)狀態(tài)表示定時(shí)結(jié)束了，會(huì)根據(jù)定時(shí)項(xiàng)目的設(shè)置判斷是否需要重復(fù)，從而決定要?jiǎng)h除這個(gè)項(xiàng)目還是繼續(xù)設(shè)定一個(gè)新的定時(shí)。
上面的 setXXXState 方法就是對(duì)這些狀態(tài)的處理，同時(shí)會(huì)規(guī)劃一個(gè)定時(shí)轉(zhuǎn)換到下一個(gè)狀態(tài)。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，同時(shí)通過(guò)scheduleInstanceStateChange（）規(guī)劃下一個(gè)狀態(tài)：
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);
}
}
通過(guò)AlarmManager發(fā)起一個(gè)定時(shí)，定時(shí)的時(shí)間從調(diào)用處可以看到是有AlarmInstance得到的，比如在setSilentState()中的定時(shí)時(shí)間是instance.getLowNotificationTime()：
public Calendar getLowNotificationTime() {
Calendar calendar = getAlarmTime();
calendar.add(Calendar.HOUR_OF_DAY, LOW_NOTIFICATION_HOUR_OFFSET);
return calendar;
}
LOW_NOTIFICATION_HOUR_OFFSET值為-2，也就是在鬧鈴響之前的兩小時(shí)那一刻會(huì)發(fā)這個(gè)LOW_NOTIFICATION_STATE的廣播出來(lái)，AlarmStateManager接收到這個(gè)廣播處理再轉(zhuǎn)移到下一個(gè)。廣播的接收在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方法中統(tǒng)一處理，狀態(tài)的分發(fā)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);
}
}
對(duì)沒(méi)一個(gè)state又轉(zhuǎn)移相應(yīng)的setXXXState方法中，完成下一次狀態(tài)的轉(zhuǎn)換，形成一個(gè)定時(shí)的循環(huán)，直到在DISMISSED_STATE里停用或者刪除定時(shí)項(xiàng)目，如果需要重復(fù)則獲取下一次定時(shí)的時(shí)間。
整體的框架就是這樣，在AlarmStateManager里使用AlarmManager形成了一個(gè)定時(shí)的狀態(tài)機(jī)，不斷轉(zhuǎn)移到下一個(gè)狀態(tài)處理。
源碼在這里https://android.googlesource.com/platform/packages/apps/DeskClock/+/android-4.4.4_r2.0.1
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