第二节 Framework UEvent -> SystemUI
逻辑主要在Framework里面的NotificationManagerService.java
UsbDeviceManager.java 到framework的NotificationManagerService.java，这里面涉及到通知的分类和排序，通知的显示风格等等，然后通过NotificationListenerService来通知SystemUI.
在SystemUI注册服务，然后在framework层回调，贯通SystemUI以及Framework。
UsbDeviceManager.java中——》
mNotificationManager.notifyAsUser(null, id, notification,UserHandle.ALL);
调用NotificationManager的notifyAsUser（）往上上传notification，跟到方法里面看下，
路径：framework/base/core/java/android/app/NotificationManager.java
INotificationManager service = getService();//获取IBinder对象
我们看下Notification的addFieldsFromContext方法做了哪些事情：路径：frameworks/base/core/java/android/app/Notification.javapublic 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"
} 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。[java] view plain copy
在CODE上查看代码片派生到我的代码片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<N; i++) { final NotificationRecord r = mNotificationList.get(i); if (r.sbn.getPackageName().equals(pkg) && r.sbn.getUserId() == userId) { if (r.sbn.getId() == id && TextUtils.equals(r.sbn.getTag(), tag)) { break; // Allow updating existing notification } count++; if (count >= 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); } } } 到这里，就开始进入SystemUI了。
// 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()); }
其中，mListeners为NotificationListeners，为内部类。查看方法notifyPostedLocked（）
/*** asynchronously notify all listeners about a new notification** <p>* Also takes care of removing a notification that has been visible to a listener before,* but isn't anymore.*/public void notifyPostedLocked(StatusBarNotification sbn, StatusBarNotification oldSbn) {// Lazily initialized snapshots of the notification.TrimCache trimCache = new TrimCache(sbn);通知所有的监听者关于这个新通知，for (final ManagedServiceInfo info : mServices) {boolean sbnVisible = isVisibleToListener(sbn, info);boolean oldSbnVisible = oldSbn != null ? isVisibleToListener(oldSbn, info) : false;// This notification hasn't been and still isn't visible -> ignore.if (!oldSbnVisible && !sbnVisible) {continue;}final NotificationRankingUpdate update = makeRankingUpdateLocked(info);// This notification became invisible -> remove the old one.if (oldSbnVisible && !sbnVisible) {final StatusBarNotification oldSbnLightClone = oldSbn.cloneLight();mHandler.post(new Runnable() {@Overridepublic void run() {notifyRemoved(info, oldSbnLightClone, update);}});continue;}final StatusBarNotification sbnToPost = trimCache.ForListener(info);mHandler.post(new Runnable() {@Overridepublic void run() {notifyPosted(info, sbnToPost, update);}});}}
然后在notifyPosted()方法里面推送通知，我们来看下这个方法：
private void notifyPosted(final ManagedServiceInfo info,final StatusBarNotification sbn, NotificationRankingUpdate rankingUpdate) {final INotificationListener listener = (INotificationListener)info.service;StatusBarNotificationHolder sbnHolder = new StatusBarNotificationHolder(sbn);try {listener.onNotificationPosted(sbnHolder, rankingUpdate);} catch (RemoteException ex) {Log.e(TAG, "unable to notify listener (posted): " + listener, ex);}}
然后监听者调用onNotificationPosted（）继续往上推送
路径：frameworks/base/core/java/android/service/notification/INotificationListener.aidl
INotificationManager.aidl BaseStatusBar.java
目录：frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/BaseStatusBar.java
在BaseStatusBar.java 里面注册NotificationListenerService。
try {mNotificationListener.registerAsSystemService(mContext,new ComponentName(mContext.getPackageName(), getClass().getCanonicalName()),UserHandle.USER_ALL);} catch (RemoteException e) {Log.e(TAG, "Unable to register notification listener", e);}！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！
在registerAsSystemService中调用registerListener方法。这个方法在INotificationManager.stub中声明了，而INotificationManager.stub 跟NotificationManagerService进行了绑定。so 跟进了NotificationManagerService.java
frameworks/base/core/java/android/app/INotificationManager.aidl
framework/base/services/core/java/com/android/server/notification/NotificationManagerService.java
在NotificationManagerService.java里面
private final IBinder mService = new INotificationManager.Stub()
----> NotificationManagerService.java在实例化INotificationManager.stub 对象的时候，对registerListener 进行了override。在这个方法中，它首先去调用enforceSystemOrSystemUI，接着才去registerService。很显然，想要的答案就在enforceSystemOrSystemUI 中。so 跟进enforceSystemOrSystemUI。这个方法呢，也是在实例化INotificationManager.stub 对象mService的时候，对其 进行了override。
这样NotificationManagerService和NotificationListenerService连接上，可以吧消息传到systemUI进去。