Android8.1 SystemUI源碼分析之 Notification流程

代碼流程

1、先看UI顯示，StatuBar加載 CollapsedStatusBarFragment 替換 status_bar_container(狀態欄通知顯示區域)

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) 初始化通知欄區域，這是我們關心的

mStatusBarView.setBar(this) 傳遞statusBar處理下拉事件

mStatusBarView.setPanel(mNotificationPanel) 傳遞 NotificationPanelView 顯示下拉UI控制

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

1、notification_lights_out---ImageView默認gone

2、status_bar_contents--LinearLayout

	notification_icon_area--FrameLayout

	system_icon_area--LinearLayout

			system_icons.xml(藍牙、wifi、VPN、網卡、SIM卡信號、飛行模式等) 電池

			clock--Clock.java 

3、emergency_cryptkeeper_text--ViewStub（延遲加載 緊急電話文字）

這就是我們看到的statusBar的布局，本篇只關心 notification_icon_area，其它的以后再進行分析。繼續看到之前的 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);
}

獲取到 notification_icon_area，FrameLayout轉為ViewGroup，調用 notificationIconAreaController 獲取通知要顯示的view(LinearLayout)，

如果已經有顯示的view，通過 view 父布局將其自身remove，然后再重新addView。最后將 mNotificationIconAreaInner 顯示出來(設置透明度為1，visibility為VISIBLE)

可以看到 CollapsedStatusBarFragment 中定義了幾個如下的方法。

 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);
}

當狀態欄下拉時，狀態欄中的圖標icon會慢慢的變成透明和不可見，就是通過hideSystemIconArea(true), hideNotificationIconArea(true）

3、接下來，我們需要跟進 getNotificationInnerAreaView()方法中看看通知欄icon對應的容器

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
<com.android.keyguard.AlphaOptimizedLinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/notification_icon_area_inner"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<com.android.systemui.statusbar.phone.NotificationIconContainer
    android:id="@+id/notificationIcons"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_alignParentStart="true"
    android:gravity="center_vertical"
    android:orientation="horizontal"/>
</com.android.keyguard.AlphaOptimizedLinearLayout>

好了，觀察上面的代碼，現在基本上已經理清 notification_icon_area 的布局結構了

notification_icon_area(FrameLayout) 中添加 notification_icon_area_inner(LinearLayout),

每一個通知對應的bean為 NotificationData，創建 Notification 添加到 NotificationIconContainer(FrameLayout)中

4、緊接着我們就來看下 Notification 的監聽加載流程，回到 statusBar 的start()中注冊 NotificationListenerWithPlugins 作為系統service監聽通知消息

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成功啟動，獲取當前處於活動狀態的通知(沒被移除的通知)，添加到通知欄，此處應該是重啟后重新加載
    }

    @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) {
        ..... 通知的排序優先級改變，修改通知位置
		if (rankingMap != null) {
            RankingMap r = onPluginRankingUpdate(rankingMap);
            mHandler.post(() -> updateNotificationRanking(r));
        }
    }

};

繼續來看下 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);
    ......
}

可以看到是通過 createNotificationViews()來創建通知 View對象，內部繼續調用 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 中創建，只賦值了icons， entry.row 為null，進入 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);
}

這里我們得到了 Notification 對應的layout為 status_bar_notification_row.xml，

回調方法中將 row 和 entry 綁定，繼續再調用 updateNotification()，注意這個方法是四個參數的，該類中還有重載方法是兩個參數的。

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);
}

緊接着調用了 ExpandableNotificationRow的 updateNotification()，內部繼續調用 NotificationInflater.inflateNotificationViews()

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

@VisibleForTesting
void 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();

@Override
protected 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;
    }
}

@Override
protected void onPostExecute(InflationProgress result) {
    if (mError == null) {
        mCancellationSignal = apply(result, mReInflateFlags, mRow, mRedactAmbient,
                mRemoteViewClickHandler, this);
    } else {
        handleError(mError);
    }
}

從msbn中獲取 notifaction，判斷是否是媒體類型的通知，進行對應的主題背景色修改，通過傳遞的優先級設置通知背景色，繼續看核心方法 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;
}

這里就是創建各種布局 CONTENT_VIEW、EXPANDED_VIEW、HEADS_UP_VIEW、PUBLIC_VIEW、AMBIENT_VIEW，

然后回到 AsyncInflationTask 的 onPostExecute()中執行 apply(),代碼太多就不貼了, SystemUI部分的通知流程分析技術，歡迎留言討論。

statusBar左邊區域(notification_icon_area)看完了，接下來看下右邊的系統圖標區域(system_icon_area)

Android8.1 SystemUI源碼分析之 電池時鍾刷新

從根源上屏蔽Notification

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

注釋如下代碼

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