Android(安卓)N NotificationManagerService源码分析

关于NotificationManagerService的使用推荐参考下面资料，写的不错：

Android4.4 NotificationManagerService使用详解与原理分析（一）、（二）：点击打开链接

这里主要分析framework层的源码。

相关文件主要有：

frameworks\base\core\java\android\app\NotificationManager.java;

frameworks\base\services\core\java\com\android\server\notification\NotificationManagerService.java;

frameworks\base\services\core\java\com\android\server\statusbar\StatusBarManagerService.java;

第三方应用发起通知时，调用的是NotificationManager的notify方法，我们就从这里入手。

notify方法表示发送一个显示在状态栏上的通知，代码如下：

    /**     * Post a notification to be shown in the status bar. If a notification with     * the same id has already been posted by your application and has not yet been canceled, it     * will be replaced by the updated information.     *     * @param id An identifier for this notification unique within your     *        application.     * @param notification A {@link Notification} object describing what to show the user. Must not     *        be null.     */    public void notify(int id, Notification notification)    {        notify(null, id, notification);    }

如果你的第三方应用发送了一个相同id的通知，并且没有被取消，它将被更新的信息所取代。

    /**     * Post a notification to be shown in the status bar. If a notification with     * the same tag and id has already been posted by your application and has not yet been     * canceled, it will be replaced by the updated information.     *     * @param tag A string identifier for this notification.  May be {@code null}.     * @param id An identifier for this notification.  The pair (tag, id) must be unique     *        within your application.     * @param notification A {@link Notification} object describing what to     *        show the user. Must not be null.     */    public void notify(String tag, int id, Notification notification)    {        notifyAsUser(tag, id, notification, new UserHandle(UserHandle.myUserId()));    }

如果你的第三方应用发送了一个相同tag和id的通知，并且没有被取消，它将被更新的信息所取代。

    /**     * @hide     */    public void notifyAsUser(String tag, int id, Notification notification, UserHandle user)    {        int[] idOut = new int[1];        INotificationManager service = getService();//获取IBinder对象（NotificationManagerService）        String pkg = mContext.getPackageName();        // Fix the notification as best we can.        Notification.addFieldsFromContext(mContext, notification);//"android.appinfo"、"android.originatingUserId"        if (notification.sound != null) {            notification.sound = notification.sound.getCanonicalUri();            if (StrictMode.vmFileUriExposureEnabled()) {                notification.sound.checkFileUriExposed("Notification.sound");            }        }        fixLegacySmallIcon(notification, pkg);        if (mContext.getApplicationInfo().targetSdkVersion > Build.VERSION_CODES.LOLLIPOP_MR1) {            if (notification.getSmallIcon() == null) {                throw new IllegalArgumentException("Invalid notification (no valid small icon): "                        + notification);            }        }        if (localLOGV) Log.v(TAG, pkg + ": notify(" + id + ", " + notification + ")");        final Notification copy = Builder.maybeCloneStrippedForDelivery(notification);        try {            service.enqueueNotificationWithTag(pkg, mContext.getOpPackageName(), tag, id,                    copy, idOut, user.getIdentifier());            if (id != idOut[0]) {                Log.w(TAG, "notify: id corrupted: sent " + id + ", got back " + idOut[0]);            }        } catch (RemoteException e) {            throw e.rethrowFromSystemServer();        }    }

我们看下Notification的addFieldsFromContext方法做了哪些事情：

    /**     * @hide     */    public static void addFieldsFromContext(Context context, Notification notification) {        addFieldsFromContext(context.getApplicationInfo(), context.getUserId(), notification);    }    /**     * @hide     */    public static void addFieldsFromContext(ApplicationInfo ai, int userId,            Notification notification) {        notification.extras.putParcelable(EXTRA_BUILDER_APPLICATION_INFO, ai);//"android.appinfo"        notification.extras.putInt(EXTRA_ORIGINATING_USERID, userId);//"android.originatingUserId"    }

主要是保存了当前应用对应的ApplicationInfo对象和对应的userId。在Android4.4中Notification新增了extras字段，用来保存系统通知的一些具体信息，定义如下：

    /**     * Additional semantic data to be carried around with this Notification.     *      * The extras keys defined here are intended to capture the original inputs to {@link Builder}     * APIs, and are intended to be used by     * {@link android.service.notification.NotificationListenerService} implementations to extract     * detailed information from notification objects.     */    public Bundle extras = new Bundle();

addFieldsFromContext方法主要实现将当前应用的ApplicationInfo对象保存到“android.appinfo”字段，将当前的userId保存到“android.originatingUserId”字段中。

fixLegacySmalIcon，notify函数会判断notification是否有small icon，如果没有设icon或small icon，用notify方法时会抛出异常。fixLegacySmallIcon方法如下：

    private void fixLegacySmallIcon(Notification n, String pkg) {        if (n.getSmallIcon() == null && n.icon != 0) {            n.setSmallIcon(Icon.createWithResource(pkg, n.icon));        }    }

完成上面的操作后，调用通知管理类NotificationManagerService的enqueueNotificationWithTag方法，

        @Override        public void enqueueNotificationWithTag(String pkg, String opPkg, String tag, int id,                Notification notification, int[] idOut, int userId) throws RemoteException {            enqueueNotificationInternal(pkg, opPkg, Binder.getCallingUid(),                    Binder.getCallingPid(), tag, id, notification, idOut, userId);        }

我们看到在enqueueNotificationWithTag方法中调用了enqueueNotificationInternal方法，这里就是通知处理的核心了。

    void enqueueNotificationInternal(final String pkg, final String opPkg, final int callingUid,            final int callingPid, final String tag, final int id, final Notification notification,            int[] idOut, int incomingUserId) {        if (DBG) {            Slog.v(TAG, "enqueueNotificationInternal: pkg=" + pkg + " id=" + id                    + " notification=" + notification);        }        checkCallerIsSystemOrSameApp(pkg);        // 校验UID        final boolean isSystemNotification = isUidSystem(callingUid) || ("android".equals(pkg));        final boolean isNotificationFromListener = mListeners.isListenerPackage(pkg);        final int userId = ActivityManager.handleIncomingUser(callingPid,                callingUid, incomingUserId, true, false, "enqueueNotification", pkg);        final UserHandle user = new UserHandle(userId);        // Fix the notification as best we can.        try {            final ApplicationInfo ai = getContext().getPackageManager().getApplicationInfoAsUser(                    pkg, PackageManager.MATCH_DEBUG_TRIAGED_MISSING,                    (userId == UserHandle.USER_ALL) ? UserHandle.USER_SYSTEM : userId);            Notification.addFieldsFromContext(ai, userId, notification);        } catch (NameNotFoundException e) {            Slog.e(TAG, "Cannot create a context for sending app", e);            return;        }        mUsageStats.registerEnqueuedByApp(pkg);        // Limit the number of notifications that any given package except the android        // package or a registered listener can enqueue.  Prevents DOS attacks and deals with leaks.        // 这里会做一个限制，除了系统级别的应用之外，其他应用的notification数量会做限制,用来防止DOS攻击导致的泄露        if (!isSystemNotification && !isNotificationFromListener) {            synchronized (mNotificationList) {                final float appEnqueueRate = mUsageStats.getAppEnqueueRate(pkg);                if (appEnqueueRate > mMaxPackageEnqueueRate) {                    mUsageStats.registerOverRateQuota(pkg);                    final long now = SystemClock.elapsedRealtime();                    if ((now - mLastOverRateLogTime) > MIN_PACKAGE_OVERRATE_LOG_INTERVAL) {                        Slog.e(TAG, "Package enqueue rate is " + appEnqueueRate                                + ". Shedding events. package=" + pkg);                        mLastOverRateLogTime = now;                    }                    return;                }                int count = 0;                final int N = mNotificationList.size();                for (int i=0; i= MAX_PACKAGE_NOTIFICATIONS) {// 同一个应用发送notification数量不能超过50                            mUsageStats.registerOverCountQuota(pkg);                            Slog.e(TAG, "Package has already posted " + count                                    + " notifications.  Not showing more.  package=" + pkg);                            return;                        }                    }                }            }        }        if (pkg == null || notification == null) {//通知不能为空            throw new IllegalArgumentException("null not allowed: pkg=" + pkg                    + " id=" + id + " notification=" + notification);        }        // Whitelist pending intents.        if (notification.allPendingIntents != null) {            final int intentCount = notification.allPendingIntents.size();            if (intentCount > 0) {                final ActivityManagerInternal am = LocalServices                        .getService(ActivityManagerInternal.class);                final long duration = LocalServices.getService(                        DeviceIdleController.LocalService.class).getNotificationWhitelistDuration();                for (int i = 0; i < intentCount; i++) {                    PendingIntent pendingIntent = notification.allPendingIntents.valueAt(i);                    if (pendingIntent != null) {                        am.setPendingIntentWhitelistDuration(pendingIntent.getTarget(), duration);                    }                }            }        }        // Sanitize inputs        notification.priority = clamp(notification.priority, Notification.PRIORITY_MIN,                Notification.PRIORITY_MAX);        // setup local book-keeping        // 验证完条件后，将前面传递进来的Notification封装成一个StatusBarNotification对象,        final StatusBarNotification n = new StatusBarNotification(                pkg, opPkg, id, tag, callingUid, callingPid, 0, notification,                user);        // 封装NotificationRecord对象        final NotificationRecord r = new NotificationRecord(getContext(), n);        mHandler.post(new EnqueueNotificationRunnable(userId, r));        idOut[0] = id;    }

开启线程，异步处理。

    private class EnqueueNotificationRunnable implements Runnable {        private final NotificationRecord r;        private final int userId;        EnqueueNotificationRunnable(int userId, NotificationRecord r) {            this.userId = userId;            this.r = r;        };        @Override        public void run() {            synchronized (mNotificationList) {                final StatusBarNotification n = r.sbn;                if (DBG) Slog.d(TAG, "EnqueueNotificationRunnable.run for: " + n.getKey());                NotificationRecord old = mNotificationsByKey.get(n.getKey());                if (old != null) {                    // Retain ranking information from previous record                    r.copyRankingInformation(old);                }                final int callingUid = n.getUid();                final int callingPid = n.getInitialPid();                final Notification notification = n.getNotification();                final String pkg = n.getPackageName();                final int id = n.getId();                final String tag = n.getTag();                final boolean isSystemNotification = isUidSystem(callingUid) ||                        ("android".equals(pkg));                // Handle grouped notifications and bail out early if we                // can to avoid extracting signals.                handleGroupedNotificationLocked(r, old, callingUid, callingPid);                // 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)) {                    int enqueueStatus = EVENTLOG_ENQUEUE_STATUS_NEW;                    if (old != null) {                        enqueueStatus = EVENTLOG_ENQUEUE_STATUS_UPDATE;                    }                    EventLogTags.writeNotificationEnqueue(callingUid, callingPid,                            pkg, id, tag, userId, notification.toString(),                            enqueueStatus);                }                mRankingHelper.extractSignals(r);                final boolean isPackageSuspended = isPackageSuspendedForUser(pkg, callingUid);                // blocked apps 判断pkg是否可以显示通知                if (r.getImportance() == NotificationListenerService.Ranking.IMPORTANCE_NONE                        || !noteNotificationOp(pkg, callingUid) || isPackageSuspended) {                    if (!isSystemNotification) {//不拦截系统通知                        if (isPackageSuspended) {                            Slog.e(TAG, "Suppressing notification from package due to package "                                    + "suspended by administrator.");                            mUsageStats.registerSuspendedByAdmin(r);                        } else {                            Slog.e(TAG, "Suppressing notification from package by user request.");                            mUsageStats.registerBlocked(r);                        }                        return;                    }                }                // tell the ranker service about the notification                if (mRankerServices.isEnabled()) {                    mRankerServices.onNotificationEnqueued(r);                    // TODO delay the code below here for 100ms or until there is an answer                }                // 获取是否已经发送过此notification                int index = indexOfNotificationLocked(n.getKey());                if (index < 0) {                    // 如果是新发送的notification,就走新增流程.                    mNotificationList.add(r);                    mUsageStats.registerPostedByApp(r);                } else {                    //如果有发送过，就获取oldNtificationRecord，后面走更新流程 mStatusBar.updateNotification(r.statusBarKey, n)                    old = mNotificationList.get(index);                    mNotificationList.set(index, r);                    mUsageStats.registerUpdatedByApp(r, old);                    // Make sure we don't lose the foreground service state.                    notification.flags |=                            old.getNotification().flags & Notification.FLAG_FOREGROUND_SERVICE;                    r.isUpdate = true;                }                Slog.d(TAG, "NotificationRecord, r = "+r);                mNotificationsByKey.put(n.getKey(), r);                // 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;                }                applyZenModeLocked(r);                mRankingHelper.sort(mNotificationList);//将mNotificationList排序                // 如果notification设置了smallIcon，调用所有NotificationListeners的notifyPostedLocked方法，                // 通知有新的notification，传入的参数为上面封装成的StatusBarNotification对象.                if (notification.getSmallIcon() != null) {                    StatusBarNotification oldSbn = (old != null) ? old.sbn : null;                    mListeners.notifyPostedLocked(n, oldSbn);                } else {                    Slog.e(TAG, "Not posting notification without small icon: " + notification);                    if (old != null && !old.isCanceled) {                        mListeners.notifyRemovedLocked(n);                    }                    // ATTENTION: in a future release we will bail out here                    // so that we do not play sounds, show lights, etc. for invalid                    // notifications                    Slog.e(TAG, "WARNING: In a future release this will crash the app: "                            + n.getPackageName());                }                // buzzBeepBlinkLocked方法负责对消息进行处理。                // 通知status bar显示该notification,确认是否需要声音，震动和闪光，如果需要，那么就发出声音，震动和闪光                buzzBeepBlinkLocked(r);            }        }    }

最后调用buzzBeepBlinkLocked方法对消息进行处理。

    void buzzBeepBlinkLocked(NotificationRecord record) {        boolean buzz = false;        boolean beep = false;        boolean blink = false;        final Notification notification = record.sbn.getNotification();        final String key = record.getKey();        // Should this notification make noise, vibe, or use the LED?是否需要声音、震动、led        final boolean aboveThreshold = record.getImportance() >= IMPORTANCE_DEFAULT;        final boolean canInterrupt = aboveThreshold && !record.isIntercepted();        if (DBG || record.isIntercepted())            Slog.v(TAG,                    "pkg=" + record.sbn.getPackageName() + " canInterrupt=" + canInterrupt +                            " intercept=" + record.isIntercepted()            );        final int currentUser;        final long token = Binder.clearCallingIdentity();        try {            currentUser = ActivityManager.getCurrentUser();        } finally {            Binder.restoreCallingIdentity(token);        }        // If we're not supposed to beep, vibrate, etc. then don't.        final String disableEffects = disableNotificationEffects(record);        if (disableEffects != null) {            ZenLog.traceDisableEffects(record, disableEffects);        }        // Remember if this notification already owns the notification channels.        boolean wasBeep = key != null && key.equals(mSoundNotificationKey);        boolean wasBuzz = key != null && key.equals(mVibrateNotificationKey);        // These are set inside the conditional if the notification is allowed to make noise.        boolean hasValidVibrate = false;        boolean hasValidSound = false;        boolean smsRingtone =  false;        if (mCarrierConfig == null) {            mCarrierConfig = mConfigManager.getConfig();        } else {            smsRingtone = mCarrierConfig.getBoolean(                CarrierConfigManager.KEY_CONFIG_SMS_RINGTONE_INCALL);        }        if ((disableEffects == null || (smsRingtone && mInCall))                && (record.getUserId() == UserHandle.USER_ALL ||                    record.getUserId() == currentUser ||                    mUserProfiles.isCurrentProfile(record.getUserId()))                && canInterrupt                && mSystemReady                && mAudioManager != null) {            if (DBG) Slog.v(TAG, "Interrupting!");            // should we use the default notification sound? (indicated either by            // DEFAULT_SOUND or because notification.sound is pointing at            // Settings.System.NOTIFICATION_SOUND)            final boolean useDefaultSound =                   (notification.defaults & Notification.DEFAULT_SOUND) != 0 ||                           Settings.System.DEFAULT_NOTIFICATION_URI                                   .equals(notification.sound);            Uri soundUri = null;            if (useDefaultSound) {                soundUri = Settings.System.DEFAULT_NOTIFICATION_URI;                // check to see if the default notification sound is silent                ContentResolver resolver = getContext().getContentResolver();                hasValidSound = Settings.System.getString(resolver,                       Settings.System.NOTIFICATION_SOUND) != null;            } else if (notification.sound != null) {                soundUri = notification.sound;                hasValidSound = (soundUri != null);            }            // 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                            && (mAudioManager.getRingerModeInternal() == AudioManager.RINGER_MODE_VIBRATE);            // The DEFAULT_VIBRATE flag trumps any custom vibration AND the fallback.            final boolean useDefaultVibrate =                    (notification.defaults & Notification.DEFAULT_VIBRATE) != 0;            hasValidVibrate = useDefaultVibrate || convertSoundToVibration ||                    hasCustomVibrate;            // We can alert, and we're allowed to alert, but if the developer asked us to only do            // it once, and we already have, then don't.            if (!(record.isUpdate                    && (notification.flags & Notification.FLAG_ONLY_ALERT_ONCE) != 0)) {                sendAccessibilityEvent(notification, record.sbn.getPackageName());                if (hasValidSound) {                    boolean looping =                            (notification.flags & Notification.FLAG_INSISTENT) != 0;                    AudioAttributes audioAttributes = audioAttributesForNotification(notification);                    mSoundNotificationKey = key;                    // do not play notifications if stream volume is 0 (typically because                    // ringer mode is silent) or if there is a user of exclusive audio focus                    if ((mAudioManager.getStreamVolume(                            AudioAttributes.toLegacyStreamType(audioAttributes)) != 0)                            && !mAudioManager.isAudioFocusExclusive()) {                        final long identity = Binder.clearCallingIdentity();                        try {                            final IRingtonePlayer player =                                    mAudioManager.getRingtonePlayer();                            if (player != null) {                                if (DBG) Slog.v(TAG, "Playing sound " + soundUri                                        + " with attributes " + audioAttributes);                                player.playAsync(soundUri, record.sbn.getUser(), looping,                                        audioAttributes);                                beep = true;                            }                        } catch (RemoteException e) {                        } finally {                            Binder.restoreCallingIdentity(identity);                        }                    }                }                if (hasValidVibrate && !(mAudioManager.getRingerModeInternal()                        == AudioManager.RINGER_MODE_SILENT)) {                    mVibrateNotificationKey = key;                    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(record.sbn.getUid(), record.sbn.getOpPkg(),                                useDefaultVibrate ? mDefaultVibrationPattern                                    : mFallbackVibrationPattern,                                ((notification.flags & Notification.FLAG_INSISTENT) != 0)                                    ? 0: -1, audioAttributesForNotification(notification));                            buzz = true;                        } finally {                            Binder.restoreCallingIdentity(identity);                        }                    } else if (notification.vibrate.length > 1) {                        // If you want your own vibration pattern, you need the VIBRATE                        // permission                                                    mVibrator.vibrate(record.sbn.getUid(), record.sbn.getOpPkg(),                                    notification.vibrate,                                ((notification.flags & Notification.FLAG_INSISTENT) != 0)                                        ? 0: -1, audioAttributesForNotification(notification));                            buzz = true;                    }                }            }        }        // If a notification is updated to remove the actively playing sound or vibrate,        // cancel that feedback now        if (wasBeep && !hasValidSound) {            clearSoundLocked();        }        if (wasBuzz && !hasValidVibrate) {            clearVibrateLocked();        }        // light        // release the light        boolean wasShowLights = mLights.remove(key);        if ((notification.flags & Notification.FLAG_SHOW_LIGHTS) != 0 && aboveThreshold                && ((record.getSuppressedVisualEffects()                & NotificationListenerService.SUPPRESSED_EFFECT_SCREEN_OFF) == 0)) {            mLights.add(key);            updateLightsLocked();            if (mUseAttentionLight) {                mAttentionLight.pulse();            }            blink = true;        } else if (wasShowLights) {            updateLightsLocked();        }        if (buzz || beep || blink) {            if (((record.getSuppressedVisualEffects()                    & NotificationListenerService.SUPPRESSED_EFFECT_SCREEN_OFF) != 0)) {                if (DBG) Slog.v(TAG, "Suppressed SystemUI from triggering screen on");            } else {                EventLogTags.writeNotificationAlert(key,                        buzz ? 1 : 0, beep ? 1 : 0, blink ? 1 : 0);                // 后将mBuzzBeepBlinked post到工作handler，最后会调用到mStatusBar.buzzBeepBlinked()                mHandler.post(mBuzzBeepBlinked);            }        }    }

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