Android NotificationManager简读

今天发觉系统状态栏不能够显示通知条了,但是通知还是有声音之类的,只是不能够显示了,是突然不可以显示了.所以突然看了一下源代码.

应用程序中发送通知Notification都需要获取通知服务:

NotificationManager nm = (NotificationManager)getSystemService(Context.NOTIFICATION_SERVICE);

看来是通过NotificationManager管理器获取的,根据Android的代理模式,就会对应NotificationManagerService,所以大致梳理一下.

源代码路径都在:

~\base\services\core\java\com\android\server\notification

思路差不多如下:

一般从NotificationManager开始:为什么从notify开始呢?因为每次要发送通知都是通过最后notify方法的.

public void notify(int id, Notification notification)    {        notify(null, id, notification);    }

然后进一步:

public void notify(String tag, int id, Notification notification)    {        int[] idOut = new int[1];        INotificationManager service = getService();        String pkg = mContext.getPackageName();        if (notification.sound != null) {            notification.sound = notification.sound.getCanonicalUri();        }        if (localLOGV) Log.v(TAG, pkg + ": notify(" + id + ", " + notification + ")");        try {            service.enqueueNotificationWithTag(pkg, tag, id, notification, idOut,                    UserHandle.myUserId());            if (id != idOut[0]) {                Log.w(TAG, "notify: id corrupted: sent " + id + ", got back " + idOut[0]);            }        } catch (RemoteException e) {        }    }

其中程序中的service即NofiticationManagerService,然后再看看:这个服务都是系统SystemServer中的run启动的.

service.enqueueNotificationWithTag(pkg, tag, id, notification, idOut,                    UserHandle.myUserId());

...

// Notifications    // ============================================================================    public void enqueueNotificationWithTag(String pkg, String tag, int id, Notification notification,            int[] idOut, int userId)    {        enqueueNotificationInternal(pkg, Binder.getCallingUid(), Binder.getCallingPid(),                tag, id, notification, idOut, userId);    }

...

// Not exposed via Binder; for system use only (otherwise malicious apps could spoof the    // uid/pid of another application)    public void enqueueNotificationInternal(String pkg, int callingUid, int callingPid,            String tag, int id, Notification notification, int[] idOut, int userId)    {        if (DBG) {            Slog.v(TAG, "enqueueNotificationInternal: pkg=" + pkg + " id=" + id + " notification=" + notification);        }        checkCallerIsSystemOrSameApp(pkg);        final boolean isSystemNotification = ("android".equals(pkg));        userId = ActivityManager.handleIncomingUser(callingPid,                callingUid, userId, true, false, "enqueueNotification", pkg);        final UserHandle user = new UserHandle(userId);        // Limit the number of notifications that any given package except the android        // package can enqueue.  Prevents DOS attacks and deals with leaks.        if (!isSystemNotification) {            synchronized (mNotificationList) {                int count = 0;                final int N = mNotificationList.size();                for (int i=0; i<N; i++) {                    final NotificationRecord r = mNotificationList.get(i);                    if (r.pkg.equals(pkg) && r.userId == userId) {                        count++;                        if (count >= MAX_PACKAGE_NOTIFICATIONS) {                            Slog.e(TAG, "Package has already posted " + count                                    + " notifications.  Not showing more.  package=" + pkg);                            return;                        }                    }                }            }        }        // This conditional is a dirty hack to limit the logging done on        //     behalf of the download manager without affecting other apps.        if (!pkg.equals("com.android.providers.downloads")                || Log.isLoggable("DownloadManager", Log.VERBOSE)) {            EventLog.writeEvent(EventLogTags.NOTIFICATION_ENQUEUE, pkg, id, tag, userId,                    notification.toString());        }        if (pkg == null || notification == null) {            throw new IllegalArgumentException("null not allowed: pkg=" + pkg                    + " id=" + id + " notification=" + notification);        }        if (notification.icon != 0) {            if (notification.contentView == null) {                throw new IllegalArgumentException("contentView required: pkg=" + pkg                        + " id=" + id + " notification=" + notification);            }        }        // === Scoring ===        // 0. Sanitize inputs        notification.priority = clamp(notification.priority, Notification.PRIORITY_MIN, Notification.PRIORITY_MAX);        // Migrate notification flags to scores        if (0 != (notification.flags & Notification.FLAG_HIGH_PRIORITY)) {            if (notification.priority < Notification.PRIORITY_MAX) notification.priority = Notification.PRIORITY_MAX;        } else if (SCORE_ONGOING_HIGHER && 0 != (notification.flags & Notification.FLAG_ONGOING_EVENT)) {            if (notification.priority < Notification.PRIORITY_HIGH) notification.priority = Notification.PRIORITY_HIGH;        }        // 1. initial score: buckets of 10, around the app         int score = notification.priority * NOTIFICATION_PRIORITY_MULTIPLIER; //[-20..20]        // 2. Consult external heuristics (TBD)        // 3. Apply local rules        // blocked apps        if (ENABLE_BLOCKED_NOTIFICATIONS && !isSystemNotification && !areNotificationsEnabledForPackageInt(pkg)) {            score = JUNK_SCORE;            Slog.e(TAG, "Suppressing notification from package " + pkg + " by user request.");        }        if (DBG) {            Slog.v(TAG, "Assigned score=" + score + " to " + notification);        }        if (score < SCORE_DISPLAY_THRESHOLD) {            // Notification will be blocked because the score is too low.            return;        }        // Should this notification make noise, vibe, or use the LED?        final boolean canInterrupt = (score >= SCORE_INTERRUPTION_THRESHOLD);        synchronized (mNotificationList) {            NotificationRecord r = new NotificationRecord(pkg, tag, id,                     callingUid, callingPid, userId,                    score,                    notification);            NotificationRecord old = null;            int index = indexOfNotificationLocked(pkg, tag, id, userId);            if (index < 0) {                mNotificationList.add(r);            } else {                old = mNotificationList.remove(index);                mNotificationList.add(index, r);                // Make sure we don't lose the foreground service state.                if (old != null) {                    notification.flags |=                        old.notification.flags&Notification.FLAG_FOREGROUND_SERVICE;                }            }            // Ensure if this is a foreground service that the proper additional            // flags are set.            if ((notification.flags&Notification.FLAG_FOREGROUND_SERVICE) != 0) {                notification.flags |= Notification.FLAG_ONGOING_EVENT                        | Notification.FLAG_NO_CLEAR;            }            final int currentUser;            final long token = Binder.clearCallingIdentity();            try {                currentUser = ActivityManager.getCurrentUser();            } finally {                Binder.restoreCallingIdentity(token);            }            if (notification.icon != 0) {                final StatusBarNotification n = new StatusBarNotification(                        pkg, id, tag, r.uid, r.initialPid, score, notification, user);                if (old != null && old.statusBarKey != null) {                    r.statusBarKey = old.statusBarKey;                    long identity = Binder.clearCallingIdentity();                    try {                        mStatusBar.updateNotification(r.statusBarKey, n);                    }                    finally {                        Binder.restoreCallingIdentity(identity);                    }                } else {                    long identity = Binder.clearCallingIdentity();                    try {                        r.statusBarKey = mStatusBar.addNotification(n);                        if ((n.notification.flags & Notification.FLAG_SHOW_LIGHTS) != 0                                && canInterrupt) {                            mAttentionLight.pulse();                        }                    }                    finally {                        Binder.restoreCallingIdentity(identity);                    }                }                // Send accessibility events only for the current user.                if (currentUser == userId) {                    sendAccessibilityEvent(notification, pkg);                }            } else {                Slog.e(TAG, "Ignoring notification with icon==0: " + notification);                if (old != null && old.statusBarKey != null) {                    long identity = Binder.clearCallingIdentity();                    try {                        mStatusBar.removeNotification(old.statusBarKey);                    }                    finally {                        Binder.restoreCallingIdentity(identity);                    }                }            }            // If we're not supposed to beep, vibrate, etc. then don't.            if (((mDisabledNotifications & StatusBarManager.DISABLE_NOTIFICATION_ALERTS) == 0)                    && (!(old != null                        && (notification.flags & Notification.FLAG_ONLY_ALERT_ONCE) != 0 ))                    && (r.userId == UserHandle.USER_ALL ||                        (r.userId == userId && r.userId == currentUser))                    && canInterrupt                    && mSystemReady) {                final AudioManager audioManager = (AudioManager) mContext                .getSystemService(Context.AUDIO_SERVICE);                // sound                final boolean useDefaultSound =                    (notification.defaults & Notification.DEFAULT_SOUND) != 0;                Uri soundUri = null;                boolean hasValidSound = false;                if (useDefaultSound) {                    soundUri = Settings.System.DEFAULT_NOTIFICATION_URI;                    // check to see if the default notification sound is silent                    ContentResolver resolver = mContext.getContentResolver();                    hasValidSound = Settings.System.getString(resolver,                           Settings.System.NOTIFICATION_SOUND) != null;                } else if (notification.sound != null) {                    soundUri = notification.sound;                    hasValidSound = (soundUri != null);                }                if (hasValidSound) {                    boolean looping = (notification.flags & Notification.FLAG_INSISTENT) != 0;                    int audioStreamType;                    if (notification.audioStreamType >= 0) {                        audioStreamType = notification.audioStreamType;                    } else {                        audioStreamType = DEFAULT_STREAM_TYPE;                    }                    mSoundNotification = r;                    // do not play notifications if stream volume is 0                    // (typically because ringer mode is silent) or if speech recognition is active.                    if ((audioManager.getStreamVolume(audioStreamType) != 0)                            && !audioManager.isSpeechRecognitionActive()) {                        final long identity = Binder.clearCallingIdentity();                        try {                            final IRingtonePlayer player = mAudioService.getRingtonePlayer();                            if (player != null) {                                player.playAsync(soundUri, user, looping, audioStreamType);                            }                        } catch (RemoteException e) {                        } finally {                            Binder.restoreCallingIdentity(identity);                        }                    }                }                // vibrate                // Does the notification want to specify its own vibration?                final boolean hasCustomVibrate = notification.vibrate != null;                // new in 4.2: if there was supposed to be a sound and we're in vibrate mode,                // and no other vibration is specified, we fall back to vibration                final boolean convertSoundToVibration =                           !hasCustomVibrate                        && hasValidSound                        && (audioManager.getRingerMode() == AudioManager.RINGER_MODE_VIBRATE);                // The DEFAULT_VIBRATE flag trumps any custom vibration AND the fallback.                final boolean useDefaultVibrate =                        (notification.defaults & Notification.DEFAULT_VIBRATE) != 0;                if ((useDefaultVibrate || convertSoundToVibration || hasCustomVibrate)                        && !(audioManager.getRingerMode() == AudioManager.RINGER_MODE_SILENT)) {                    mVibrateNotification = r;                    if (useDefaultVibrate || convertSoundToVibration) {                        // Escalate privileges so we can use the vibrator even if the notifying app                        // does not have the VIBRATE permission.                        long identity = Binder.clearCallingIdentity();                        try {                            mVibrator.vibrate(useDefaultVibrate ? mDefaultVibrationPattern                                                                : mFallbackVibrationPattern,                                ((notification.flags & Notification.FLAG_INSISTENT) != 0) ? 0: -1);                        } finally {                            Binder.restoreCallingIdentity(identity);                        }                    } else if (notification.vibrate.length > 1) {                        // If you want your own vibration pattern, you need the VIBRATE permission                        mVibrator.vibrate(notification.vibrate,                            ((notification.flags & Notification.FLAG_INSISTENT) != 0) ? 0: -1);                    }                }            }            // this option doesn't shut off the lights            // light            // the most recent thing gets the light            mLights.remove(old);            if (mLedNotification == old) {                mLedNotification = null;            }            //Slog.i(TAG, "notification.lights="            //        + ((old.notification.lights.flags & Notification.FLAG_SHOW_LIGHTS) != 0));            if ((notification.flags & Notification.FLAG_SHOW_LIGHTS) != 0                    && canInterrupt) {                mLights.add(r);                updateLightsLocked();            } else {                if (old != null                        && ((old.notification.flags & Notification.FLAG_SHOW_LIGHTS) != 0)) {                    updateLightsLocked();                }            }        }        idOut[0] = id

这一段程序就有点又臭又长,但是其实很简单.

synchronized (mNotificationList) {            NotificationRecord r = new NotificationRecord(pkg, tag, id,                     callingUid, callingPid, userId,                    score,                    notification);            NotificationRecord old = null;            int index = indexOfNotificationLocked(pkg, tag, id, userId);            if (index < 0) {                mNotificationList.add(r);            } else {                old = mNotificationList.remove(index);                mNotificationList.add(index, r);                // Make sure we don't lose the foreground service state.                if (old != null) {                    notification.flags |=                        old.notification.flags&Notification.FLAG_FOREGROUND_SERVICE;                }            }

上面的通过一个NotificationRecord结构体记录所有的通知信息并且保存,有点类似ActivityRecord等,这个***Record在Android系统里还是比较常见的.其中里面mNotificationList就是ArrayList<NotificationRecord>,这个都是老套路了.

其实看到下面的就差不多了:

 if (notification.icon != 0) {                final StatusBarNotification n = new StatusBarNotification(                        pkg, id, tag, r.uid, r.initialPid, score, notification, user);                if (old != null && old.statusBarKey != null) {                    r.statusBarKey = old.statusBarKey;                    long identity = Binder.clearCallingIdentity();                    try {                        mStatusBar.updateNotification(r.statusBarKey, n);                    }                    finally {                        Binder.restoreCallingIdentity(identity);                    }                } else {                    long identity = Binder.clearCallingIdentity();                    try {                        r.statusBarKey = mStatusBar.addNotification(n);                        if ((n.notification.flags & Notification.FLAG_SHOW_LIGHTS) != 0                                && canInterrupt) {                            mAttentionLight.pulse();                        }                    }                    finally {                        Binder.restoreCallingIdentity(identity);                    }                }

其他后面都是处理这个通知是否需要一个通知音播放,或者闪灯等一些视觉听觉方面的操作.

上面程序,其中StatusBarNotification是一个Parcel的数据结构体.

mStatusBar是StatusBarManagerService对象,

如果这个通知是第一次生成:

r.statusBarKey = mStatusBar.addNotification(n);                        if ((n.notification.flags & Notification.FLAG_SHOW_LIGHTS) != 0                                && canInterrupt) {                            mAttentionLight.pulse();                        }

如果不是第一次了,那么就更新一次:

mStatusBar.updateNotification(r.statusBarKey, n);

他就会添加,看StatusBarManagerService类中:

// ================================================================================    // Callbacks for NotificationManagerService.    // ================================================================================    public IBinder addNotification(StatusBarNotification notification) {        synchronized (mNotifications) {            IBinder key = new Binder();            mNotifications.put(key, notification);            if (mBar != null) {                try {                    mBar.addNotification(key, notification);                } catch (RemoteException ex) {                }            }            return key;        }    }

其实前面看到parcelable就需要联想到Binder这个提供储存的"代理商".

其中:

mBar.addNotification(key, notification);

这个mBar是一个IStatusBar对象,这个地方addNotification就是有CommandQueue类完成的:

    public void addNotification(IBinder key, StatusBarNotification notification) {        synchronized (mList) {            NotificationQueueEntry ne = new NotificationQueueEntry();            ne.key = key;            ne.notification = notification;            mHandler.obtainMessage(MSG_ADD_NOTIFICATION, 0, 0, ne).sendToTarget();        }    }

防止堵塞,发送一个Handler事件,处理这个MSG_ADD_NOTIFICATION事件如下:

case MSG_ADD_NOTIFICATION: {                    final NotificationQueueEntry ne = (NotificationQueueEntry)msg.obj;                    mCallbacks.addNotification(ne.key, ne.notification);                    break;                }

其中:

mCallbacks.addNotification(ne.key, ne.notification);

是一个回调.

上面的通过StatusBarManagerService这个服务进程进行添加,更新和保存管理通知信息,在SystemUI工程中使用如下BastStatusBar.java类:

mBarService = IStatusBarService.Stub.asInterface(                ServiceManager.getService(Context.STATUS_BAR_SERVICE));

// Connect in to the status bar manager service        StatusBarIconList iconList = new StatusBarIconList();        ArrayList<IBinder> notificationKeys = new ArrayList<IBinder>();        ArrayList<StatusBarNotification> notifications = new ArrayList<StatusBarNotification>();        mCommandQueue = new CommandQueue(this, iconList);        int[] switches = new int[7];        ArrayList<IBinder> binders = new ArrayList<IBinder>();        try {            mBarService.registerStatusBar(mCommandQueue, iconList, notificationKeys, notifications,                    switches, binders);        } catch (RemoteException ex) {            // If the system process isn't there we're doomed anyway.        }

首先连接上面的服务,然后从服务中获取所有的通知List信息.

后面显示到状态栏上面:

protected StatusBarIconView addNotificationViews(IBinder key,            StatusBarNotification notification)

通过它生产通知View,然后被状态面板添加进去.

下面还有几个细节需要注意:

<1> : 由何APP发出的通知,是有记录在案的,即通知同时附带了发送通知APP的所有信息,比如报名,UID之类的等,通知分为系统通知和普通应用通知.

<2> : 5.0版本以后的新版本,通知是有优先级的(当然mNotificationList这个NotificationRecord集合在手,也可以人为在老版本自己定义优先级规则,通过上面获取的APP信息判断哪些APP的通知可以在何种情况下被添加,然后同步到状态栏).

<3> : 5.0版本以后的新版本,通知需要考虑更多条件,程序里面用Conditions,以及很多手机已经在用的ZenMode,即勿扰模式,这里面约束条件还是挺多的(比如通知来了不亮屏,通知来了不播放提示音,即使设置了,等等),有兴趣的可以自行下载N版本的源代码去看一看.

至于里面涉及的SystemUI状态栏工程,在我个人看来就是APP Service+WindowManager链接各种系统Service撑起来的.