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流程图

代码流程

1、先看UI显示，StatuBar加载 CollapsedStatusBarFragment 替换 status_bar_container(状态栏通知显示区域)

SystemUI\src\com\android\systemui\statusbar\phone\StatusBar.java

FragmentHostManager.get(mStatusBarWindow)            .addTagListener(CollapsedStatusBarFragment.TAG, (tag, fragment) -> {                CollapsedStatusBarFragment statusBarFragment =                        (CollapsedStatusBarFragment) fragment;                statusBarFragment.initNotificationIconArea(mNotificationIconAreaController);                mStatusBarView = (PhoneStatusBarView) fragment.getView();                mStatusBarView.setBar(this);                mStatusBarView.setPanel(mNotificationPanel);                mStatusBarView.setScrimController(mScrimController);                mStatusBarView.setBouncerShowing(mBouncerShowing);                setAreThereNotifications();                checkBarModes();                /// M: add for plmn display feature @{                attachPlmnPlugin();                ///@}            }).getFragmentManager()            .beginTransaction()            .replace(R.id.status_bar_container, new CollapsedStatusBarFragment(),                    CollapsedStatusBarFragment.TAG)            .commit();

statusBarFragment.initNotificationIconArea(mNotificationIconAreaController) 初始化通知栏区域，这是我们关心的

mStatusBarView.setBar(this) 传递statusBar处理下拉事件

mStatusBarView.setPanel(mNotificationPanel) 传递 NotificationPanelView 显示下拉UI控制

2、跟进 CollapsedStatusBarFragment 中，先看布局文件 status_bar.xml

1、notification_lights_out---ImageView默认gone2、status_bar_contents--LinearLayout	notification_icon_area--FrameLayout	system_icon_area--LinearLayout			system_icons.xml(蓝牙、wifi、VPN、网卡、SIM卡信号、飞行模式等) 电池			clock--Clock.java 3、emergency_cryptkeeper_text--ViewStub（延迟加载 紧急电话文字）

这就是我们看到的statusBar的布局，本篇只关心 notification_icon_area，其它的以后再进行分析。继续看到之前的 initNotificationIconArea()

SystemUI\src\com\android\systemui\statusbar\phone\CollapsedStatusBarFragment.java

public void initNotificationIconArea(NotificationIconAreaController        notificationIconAreaController) {    ViewGroup notificationIconArea = mStatusBar.findViewById(R.id.notification_icon_area);    mNotificationIconAreaInner =            notificationIconAreaController.getNotificationInnerAreaView();    if (mNotificationIconAreaInner.getParent() != null) {        ((ViewGroup) mNotificationIconAreaInner.getParent())                .removeView(mNotificationIconAreaInner);    }    notificationIconArea.addView(mNotificationIconAreaInner);    // Default to showing until we know otherwise.    showNotificationIconArea(false);}

获取到 notification_icon_area，FrameLayout转为ViewGroup，调用 notificationIconAreaController 获取通知要显示的view(LinearLayout)，

如果已经有显示的view，通过 view 父布局将其自身remove，然后再重新addView。最后将 mNotificationIconAreaInner 显示出来(设置透明度为1，visibility为VISIBLE)

可以看到 CollapsedStatusBarFragment 中定义了几个如下的方法。

public void hideSystemIconArea(boolean animate) {    animateHide(mSystemIconArea, animate);}public void showSystemIconArea(boolean animate) {    animateShow(mSystemIconArea, animate);}public void hideNotificationIconArea(boolean animate) {    animateHide(mNotificationIconAreaInner, animate);}public void showNotificationIconArea(boolean animate) {    animateShow(mNotificationIconAreaInner, animate);}

当状态栏下拉时，状态栏中的图标icon会慢慢的变成透明和不可见，就是通过hideSystemIconArea(true), hideNotificationIconArea(true）

3、接下来，我们需要跟进 getNotificationInnerAreaView()方法中看看通知栏icon对应的容器

SystemUI\src\com\android\systemui\statusbar\phone\NotificationIconAreaController.java

public View getNotificationInnerAreaView() {    return mNotificationIconArea;}protected void initializeNotificationAreaViews(Context context) {    reloadDimens(context);    LayoutInflater layoutInflater = LayoutInflater.from(context);    mNotificationIconArea = inflateIconArea(layoutInflater);    mNotificationIcons = (NotificationIconContainer) mNotificationIconArea.findViewById(            R.id.notificationIcons);    mNotificationScrollLayout = mStatusBar.getNotificationScrollLayout();}protected View inflateIconArea(LayoutInflater inflater) {    return inflater.inflate(R.layout.notification_icon_area, null);}//notification_icon_area.xml
   
    
   

好了，观察上面的代码，现在基本上已经理清 notification_icon_area 的布局结构了

notification_icon_area(FrameLayout) 中添加 notification_icon_area_inner(LinearLayout),

每一个通知对应的bean为 NotificationData，创建 Notification 添加到 NotificationIconContainer(FrameLayout)中

4、紧接着我们就来看下 Notification 的监听加载流程，回到 statusBar 的start()中注册 NotificationListenerWithPlugins 作为系统service监听通知消息

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);    }	private final NotificationListenerWithPlugins mNotificationListener =        new NotificationListenerWithPlugins() {    @Override    public void onListenerConnected() {        ......  services成功启动，获取当前处于活动状态的通知(没被移除的通知)，添加到通知栏，此处应该是重启后重新加载    }    @Override    public void onNotificationPosted(final StatusBarNotification sbn,            final RankingMap rankingMap) {        ...... 收到通知消息，添加或者修改		if (isUpdate) {            updateNotification(sbn, rankingMap);        } else {            addNotification(sbn, rankingMap);        }    }    @Override    public void onNotificationRemoved(StatusBarNotification sbn,            final RankingMap rankingMap) {        ...... 移除通知消息		if (sbn != null && !onPluginNotificationRemoved(sbn, rankingMap)) {            final String key = sbn.getKey();            mHandler.post(() -> removeNotification(key, rankingMap));        }    }    @Override    public void onNotificationRankingUpdate(final RankingMap rankingMap) {        ..... 通知的排序优先级改变，修改通知位置		if (rankingMap != null) {            RankingMap r = onPluginRankingUpdate(rankingMap);            mHandler.post(() -> updateNotificationRanking(r));        }    }};

继续来看下 addNotification()方法

public void addNotification(StatusBarNotification notification, RankingMap ranking)        throws InflationException {    String key = notification.getKey();    if (true/**DEBUG*/) Log.d(TAG, "addNotification key=" + key);    mNotificationData.updateRanking(ranking);    Entry shadeEntry = createNotificationViews(notification);    ......}

可以看到是通过 createNotificationViews()来创建通知 View对象，内部继续调用 inflateViews()

protected NotificationData.Entry createNotificationViews(StatusBarNotification sbn)        throws InflationException {    if (DEBUG) {        Log.d(TAG, "createNotificationViews(notification=" + sbn);    }    NotificationData.Entry entry = new NotificationData.Entry(sbn);    Dependency.get(LeakDetector.class).trackInstance(entry);    entry.createIcons(mContext, sbn);    // Construct the expanded view.    inflateViews(entry, mStackScroller);    return entry;}protected void inflateViews(Entry entry, ViewGroup parent) {    PackageManager pmUser = getPackageManagerForUser(mContext,            entry.notification.getUser().getIdentifier());    final StatusBarNotification sbn = entry.notification;    if (entry.row != null) {        entry.reset();        updateNotification(entry, pmUser, sbn, entry.row);    } else {        new RowInflaterTask().inflate(mContext, parent, entry,                row -> {                    bindRow(entry, pmUser, sbn, row);                    updateNotification(entry, pmUser, sbn, row);                });    }}

看到上面的方法中，entry在 createNotificationViews 中创建，只赋值了icons， entry.row 为null，进入 RowInflaterTask 中

SystemUI\src\com\android\systemui\statusbar\notification\RowInflaterTask.java

public void inflate(Context context, ViewGroup parent, NotificationData.Entry entry,        RowInflationFinishedListener listener) {    mListener = listener;    AsyncLayoutInflater inflater = new AsyncLayoutInflater(context);    mEntry = entry;    entry.setInflationTask(this);    inflater.inflate(R.layout.status_bar_notification_row, parent, this);}

这里我们得到了 Notification 对应的layout为 status_bar_notification_row.xml，

回调方法中将 row 和 entry 绑定，继续再调用 updateNotification()，注意这个方法是四个参数的，该类中还有重载方法是两个参数的。

private void updateNotification(Entry entry, PackageManager pmUser,        StatusBarNotification sbn, ExpandableNotificationRow row) {   	.....    entry.row = row;    entry.row.setOnActivatedListener(this);    boolean useIncreasedCollapsedHeight = mMessagingUtil.isImportantMessaging(sbn,            mNotificationData.getImportance(sbn.getKey()));    boolean useIncreasedHeadsUp = useIncreasedCollapsedHeight && mPanelExpanded;    row.setUseIncreasedCollapsedHeight(useIncreasedCollapsedHeight);    row.setUseIncreasedHeadsUpHeight(useIncreasedHeadsUp);    row.updateNotification(entry);}

紧接着调用了 ExpandableNotificationRow的 updateNotification()，内部继续调用 NotificationInflater.inflateNotificationViews()

SystemUI\src\com\android\systemui\statusbar\notification\NotificationInflater.java

@VisibleForTestingvoid inflateNotificationViews(int reInflateFlags) {    if (mRow.isRemoved()) {        // We don't want to reinflate anything for removed notifications. Otherwise views might        // be readded to the stack, leading to leaks. This may happen with low-priority groups        // where the removal of already removed children can lead to a reinflation.        return;    }    StatusBarNotification sbn = mRow.getEntry().notification;    new AsyncInflationTask(sbn, reInflateFlags, mRow, mIsLowPriority,            mIsChildInGroup, mUsesIncreasedHeight, mUsesIncreasedHeadsUpHeight, mRedactAmbient,            mCallback, mRemoteViewClickHandler).execute();}

new AsyncInflationTask().execute();

@Overrideprotected InflationProgress doInBackground(Void... params) {    try {        final Notification.Builder recoveredBuilder                = Notification.Builder.recoverBuilder(mContext,                mSbn.getNotification());        Context packageContext = mSbn.getPackageContext(mContext);        Notification notification = mSbn.getNotification();        if (mIsLowPriority) {            int backgroundColor = mContext.getColor(                    R.color.notification_material_background_low_priority_color);            recoveredBuilder.setBackgroundColorHint(backgroundColor);        }        if (notification.isMediaNotification()) {            MediaNotificationProcessor processor = new MediaNotificationProcessor(mContext,                    packageContext);            processor.setIsLowPriority(mIsLowPriority);            processor.processNotification(notification, recoveredBuilder);        }        return createRemoteViews(mReInflateFlags,                recoveredBuilder, mIsLowPriority, mIsChildInGroup,                mUsesIncreasedHeight, mUsesIncreasedHeadsUpHeight, mRedactAmbient,                packageContext);    } catch (Exception e) {        mError = e;        return null;    }}@Overrideprotected void onPostExecute(InflationProgress result) {    if (mError == null) {        mCancellationSignal = apply(result, mReInflateFlags, mRow, mRedactAmbient,                mRemoteViewClickHandler, this);    } else {        handleError(mError);    }}

从msbn中获取 notifaction，判断是否是媒体类型的通知，进行对应的主题背景色修改，通过传递的优先级设置通知背景色，继续看核心方法 createRemoteViews()

private static InflationProgress createRemoteViews(int reInflateFlags,        Notification.Builder builder, boolean isLowPriority, boolean isChildInGroup,        boolean usesIncreasedHeight, boolean usesIncreasedHeadsUpHeight, boolean redactAmbient,        Context packageContext) {    InflationProgress result = new InflationProgress();    isLowPriority = isLowPriority && !isChildInGroup;    if ((reInflateFlags & FLAG_REINFLATE_CONTENT_VIEW) != 0) {        result.newContentView = createContentView(builder, isLowPriority, usesIncreasedHeight);    }    if ((reInflateFlags & FLAG_REINFLATE_EXPANDED_VIEW) != 0) {        result.newExpandedView = createExpandedView(builder, isLowPriority);    }    if ((reInflateFlags & FLAG_REINFLATE_HEADS_UP_VIEW) != 0) {        result.newHeadsUpView = builder.createHeadsUpContentView(usesIncreasedHeadsUpHeight);    }    if ((reInflateFlags & FLAG_REINFLATE_PUBLIC_VIEW) != 0) {        result.newPublicView = builder.makePublicContentView();    }    if ((reInflateFlags & FLAG_REINFLATE_AMBIENT_VIEW) != 0) {        result.newAmbientView = redactAmbient ? builder.makePublicAmbientNotification()                : builder.makeAmbientNotification();    }    result.packageContext = packageContext;    return result;}

这里就是创建各种布局 CONTENT_VIEW、EXPANDED_VIEW、HEADS_UP_VIEW、PUBLIC_VIEW、AMBIENT_VIEW，

然后回到 AsyncInflationTask 的 onPostExecute()中执行 apply(),代码太多就不贴了, SystemUI部分的通知流程分析技术，欢迎留言讨论。

statusBar左边区域(notification_icon_area)看完了，接下来看下右边的系统图标区域(system_icon_area)

从根源上屏蔽Notification

frameworks/base/services/core/java/com/android/server/notification/NotificationManagerService.java

注释如下代码

mHandler.post(new EnqueueNotificationRunnable(userId, r))

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