Android 7.0 SystemUI 之启动和状态栏和导航栏简介

一、SystemUI 是什么

首先SystemUI 是一个系统应用,apk路径位于/system/priv-app

源码路径位于:/framework/base/packages/SystemUI

它负责的功能如下:

状态栏信息的展示:比如电量信息，时间，wifi状态等
通知栏消息
壁纸管理
截图功能
近期任务栏显示,比如长按home键显示最近使用的app
录制屏幕功能
截图服务

以下是7.0 SystemUI 的代码截图

二、SystemUI 的启动

SystemUI 是在SystemServer里的AMS实例的systemReady方法里调用startSystemUi方法启动

SystemServer路径:/base/services/java/com/android/server/SystemServer.java

mActivityManagerService.systemReady(new Runnable() {......static final void startSystemUi(Context context) {Intent intent = new Intent();intent.setComponent(new ComponentName("com.android.systemui","com.android.systemui.SystemUIService"));intent.addFlags(Intent.FLAG_DEBUG_TRIAGED_MISSING);//Slog.d(TAG, "Starting service: " + intent);context.startServiceAsUser(intent, UserHandle.SYSTEM);}......

在这个方法里启动一个SystemUIService服务.

public class SystemUIService extends Service {@Overridepublic void onCreate() {super.onCreate();((SystemUIApplication) getApplication()).startServicesIfNeeded();}......

在onCreate方法中会调用SystemUIApplication的startServicesIfNeeded方法，这个方法会调用 startServicesIfNeeded(SERVICES)方法启动一系列服务(并不是真正的服务,都继承自SystemUI),可以这么说SystemUI就是一个容器,里面装有负责不同功能的模块。

public class SystemUIApplication extends Application {......private final Class<?>[] SERVICES = new Class[] {com.android.systemui.tuner.TunerService.class,com.android.systemui.keyguard.KeyguardViewMediator.class,com.android.systemui.recents.Recents.class,com.android.systemui.volume.VolumeUI.class,Divider.class,com.android.systemui.statusbar.SystemBars.class,com.android.systemui.usb.StorageNotification.class,com.android.systemui.power.PowerUI.class,com.android.systemui.media.RingtonePlayer.class,com.android.systemui.keyboard.KeyboardUI.class,com.android.systemui.tv.pip.PipUI.class,com.android.systemui.shortcut.ShortcutKeyDispatcher.class};public void startServicesIfNeeded() {startServicesIfNeeded(SERVICES);}......

startServicesIfNeeded方法会遍历services这个数组,依次调用service的start方法启动服务

private void startServicesIfNeeded(Class<?>[] services) {//如果已经启动了就返回if (mServicesStarted) {return;}//如果没启动完成完成if (!mBootCompleted) {if ("1".equals(SystemProperties.get("sys.boot_completed"))) {mBootCompleted = true;if (DEBUG) Log.v(TAG, "BOOT_COMPLETED was already sent");}}final int N = services.length;for (int i=0; i<N; i++) {Class<?> cl = services[i];if (DEBUG) Log.d(TAG, "loading: " + cl);try {Object newService = SystemUIFactory.getInstance().createInstance(cl);mServices[i] = (SystemUI) ((newService == null) ? cl.newInstance() : newService);} catch (IllegalAccessException ex) {throw new RuntimeException(ex);} catch (InstantiationException ex) {throw new RuntimeException(ex);}//启动服务      mServices[i].start();//如果启动完成了if (mBootCompleted) {mServices[i].onBootCompleted();}}mServicesStarted = true;}

这里以com.android.systemui.statusbar.SystemBars.class为例,讲解一下

三、状态栏和导航栏的启动

SystemBars的start方法会创建一个ServiceMonitor(服务监听者),会进入到ServiceMonitor的start方法

 public class SystemBars extends SystemUI implements ServiceMonitor.Callbacks {......public void start() {//  ServiceMonitor是服务监听者mServiceMonitor = new ServiceMonitor(TAG, DEBUG, mContext, Settings.Secure.BAR_SERVICE_COMPONENT, this);mServiceMonitor.start();  // will call onNoService if no remote service is found}......   }

在ServiceMonitor的start方法启动

  public class ServiceMonitor {......    public void start() {......mHandler.sendEmptyMessage(MSG_START_SERVICE);}......    }

在Handler里处理这个MSG_START_SERVICE

  public class ServiceMonitor {......    private final Handler mHandler = new Handler() {public void handleMessage(Message msg) {switch(msg.what) {case MSG_START_SERVICE://启动服务startService();break;case MSG_CONTINUE_START_SERVICE:continueStartService();break;case MSG_STOP_SERVICE:stopService();break;case MSG_PACKAGE_INTENT:packageIntent((Intent)msg.obj);break;case MSG_CHECK_BOUND:checkBound();break;case MSG_SERVICE_DISCONNECTED:serviceDisconnected((ComponentName)msg.obj);break;}}};......}

startService方法如下

 public class ServiceMonitor {......    private void startService() {//获取服务组件名称mServiceName = getComponentNameFromSetting();//如果为空，回调服务的onNoService方法if (mServiceName == null) {mBound = false;mCallbacks.onNoService();} else {//不为空,回调服务的的onServiceStartAttempt方法long delay = mCallbacks.onServiceStartAttempt();mHandler.sendEmptyMessageDelayed(MSG_CONTINUE_START_SERVICE, delay);}}......}

这里对mServiceName是否为空进行判断，总之无论如何它最终都会启动这个服务。

回调SystemBars的onNoService里创建StatusBar

   public class SystemBars extends SystemUI implements ServiceMonitor.Callbacks {......@Overridepublic void onNoService() {if (DEBUG) Log.d(TAG, "onNoService");//创建StatusBarcreateStatusBarFromConfig();  // fallback to using an in-process implementation}......

  private void createStatusBarFromConfig() {//config_statusBarComponent就是PhoneStatusBarfinal String clsName = mContext.getString(R.string.config_statusBarComponent);Class<?> cls = null;try {cls = mContext.getClassLoader().loadClass(clsName);} catch (Throwable t) {throw andLog("Error loading status bar component: " + clsName, t);}try {//创建BaseStatusBar实例mStatusBar = (BaseStatusBar) cls.newInstance();} catch (Throwable t) {throw andLog("Error creating status bar component: " + clsName, t);}mStatusBar.mContext = mContext;mStatusBar.mComponents = mComponents;//启动mStatusBar.start();}

在createStatusBarFromConfig方法里会获取一个config_statusBarComponent的字符串值，这个值就是PhoneStatusBar的clasName

所以这里的mStatusBar是PhoneStatusBar实例,启动了PhoneStatusBar

PhoneStatusBar的start方法

public class PhoneStatusBar extends BaseStatusBar implements DemoMode, DragDownHelper.DragDownCallback, ActivityStarter, OnUnlockMethodChangedListener,HeadsUpManager.OnHeadsUpChangedListener {......public void start() {......//调用父类的start方法,在父类BaseStatusBar里调用createAndAddWindows方法// 3.1super.start(); // calls createAndAddWindows()......//添加导航栏// 3.2addNavigationBar();......}

它会回调父类BaseStatusBar 的start方法

3.1、 super.start()

public abstract class BaseStatusBar extends SystemUI implementsCommandQueue.Callbacks, ActivatableNotificationView.OnActivatedListener,ExpandableNotificationRow.ExpansionLogger, NotificationData.Environment,ExpandableNotificationRow.OnExpandClickListener,OnGutsClosedListener {  ......public void start() {....../*实例化IStatusBarService,随后BaseStatusBar将自己注册到IStatusBarService之中。以此声明本实例才是状态栏的真正实现者，IStatusBarService会将其所接受到的请求转发给本实例。IStatusBarService会保存SystemUi的状态信息,避免SystemUi崩溃而造成信息的丢失*/mBarService = IStatusBarService.Stub.asInterface(ServiceManager.getService(Context.STATUS_BAR_SERVICE));......//IStatusBarService与BaseStatusBar进行通信的桥梁。mCommandQueue = new CommandQueue(this);/*switches则存储了一些杂项：禁用功能列表，SystemUIVisiblity，是否在导航栏中显示虚拟的菜单键，输入法窗口是否可见、输入法窗口是否消费BACK键、是否接入了实体键盘、实体键盘是否被启用。*/int[] switches = new int[9];ArrayList<IBinder> binders = new ArrayList<IBinder>();/*它保存了用于显示在状态栏的系统状态区中的状态图标列表。在完成注册之后，IStatusBarService将会在其中填充两个数组，一个字符串数组用于表示状态的名称，一个StatusBarIcon类型的数组用于存储需要显示的图标资源。*/ArrayList<String> iconSlots = new ArrayList<>();ArrayList<StatusBarIcon> icons = new ArrayList<>();Rect fullscreenStackBounds = new Rect();Rect dockedStackBounds = new Rect();//IStatusBarService注册一些信息try {mBarService.registerStatusBar(mCommandQueue, iconSlots, icons, switches, binders,fullscreenStackBounds, dockedStackBounds);} catch (RemoteException ex) {}//创建状态栏窗口createAndAddWindows();......}......}

BaseStatusBar进行一些设置,获取了IStatusBarService实例并注册一些信息到IStatusBarService中,IStatusBarService是一个系统服务,BaseStatusBar将自己注册到IStatusBarService之中,IStatusBarService会把操作状态栏和导航栏的请求转发给BaseStatusBar

为了保证SystemUI意外退出后不会发生信息丢失，IStatusBarService保存了所有需要状态栏与导航栏进行显示或处理的信息副本。在注册时将一个继承自IStatusBar.Stub的CommandQueue的实例注册到IStatusBarService以建立通信，并将信息副本取回。

 public class CommandQueue extends IStatusBar.Stub {

IStatusBarService的真身是StatusBarManagerService

路径:./services/core/java/com/android/server/statusbar/StatusBarManagerService.java

它的注册方法做一些数据的初始化

public class StatusBarManagerService extends IStatusBarService.Stub {......public void registerStatusBar(IStatusBar bar, List<String> iconSlots,List<StatusBarIcon> iconList, int switches[], List<IBinder> binders,Rect fullscreenStackBounds, Rect dockedStackBounds) {//检查权限   enforceStatusBarService();mBar = bar;synchronized (mIcons) {for (String slot : mIcons.keySet()) {iconSlots.add(slot);iconList.add(mIcons.get(slot));}}synchronized (mLock) {switches[0] = gatherDisableActionsLocked(mCurrentUserId, 1);switches[1] = mSystemUiVisibility;switches[2] = mMenuVisible ? 1 : 0;switches[3] = mImeWindowVis;switches[4] = mImeBackDisposition;switches[5] = mShowImeSwitcher ? 1 : 0;switches[6] = gatherDisableActionsLocked(mCurrentUserId, 2);switches[7] = mFullscreenStackSysUiVisibility;switches[8] = mDockedStackSysUiVisibility;binders.add(mImeToken);fullscreenStackBounds.set(mFullscreenStackBounds);dockedStackBounds.set(mDockedStackBounds);}}......}

这几者的关系如下

回到PhoneStatusBar中, 父类BaseStatusBar中的createAndAddWindows为抽象方法,由子类实现,看下PhoneStatusBar的
createAndAddWindows

  @Overridepublic void createAndAddWindows() {//添加状态栏窗口addStatusBarWindow();}

方法实现如下

  private void addStatusBarWindow() {//创建控件  makeStatusBarView();//创建StatusBarWindowManager实例    mStatusBarWindowManager = new StatusBarWindowManager(mContext);//创建远程输入控制实例    mRemoteInputController = new RemoteInputController(mStatusBarWindowManager,mHeadsUpManager);//添加状态栏窗口   mStatusBarWindowManager.add(mStatusBarWindow, getStatusBarHeight());}

看下makeStatusBarView方法

makeStatusBarView的方法里调用 inflateStatusBarWindow(context)加载布局

 protected void inflateStatusBarWindow(Context context) {mStatusBarWindow = (StatusBarWindowView) View.inflate(context, R.layout.super_status_bar, null);}

这里介绍下布局

状态栏布局介绍

整个状态栏的父布局是R.layout.super_status_bar,对应的是StatusBarWindowView这个自定义布局.


<com.android.systemui.statusbar.phone.StatusBarWindowView
    xmlns:android="http://schemas.android.com/apk/res/android"xmlns:sysui="http://schemas.android.com/apk/res-auto"android:layout_width="match_parent"android:layout_height="match_parent"android:fitsSystemWindows="true">......<!--正常状态栏下的布局 --><include layout="@layout/status_bar"android:layout_width="match_parent"android:layout_height="@dimen/status_bar_height" /><!--状态栏图标下的SeekBar布局 --><include layout="@layout/brightness_mirror" /><!--车载模式的布局  --><ViewStub android:id="@+id/fullscreen_user_switcher_stub"android:layout="@layout/car_fullscreen_user_switcher"android:layout_width="match_parent"android:layout_height="match_parent"/><!--状态栏下拉的布局  --><include layout="@layout/status_bar_expanded"android:layout_width="match_parent"android:layout_height="match_parent"android:visibility="gone" /></com.android.systemui.statusbar.phone.StatusBarWindowView>

我这里以主要的布局层次做介绍,结合图片分析会更加清楚

StatusBarWindowView里有几个主要的布局

layout/status_bar
layout/brightness_mirror
layout/status_bar_expanded

如下图

1.layout/status_bar

这个是正常状态下(未下拉的状态栏图标区域)

这个布局对应的是PhoneStatusBarView

<com.android.systemui.statusbar.phone.PhoneStatusBarView
    xmlns:android="http://schemas.android.com/apk/res/android"xmlns:systemui="http://schemas.android.com/apk/res/com.android.systemui"android:id="@+id/status_bar"android:background="@drawable/system_bar_background"android:orientation="vertical"android:focusable="false"android:descendantFocusability="afterDescendants">......<!--状态栏  --><LinearLayout android:id="@+id/status_bar_contents"android:layout_width="match_parent"android:layout_height="match_parent"android:paddingStart="6dp"android:paddingEnd="8dp"android:orientation="horizontal"><!-- The alpha of this area is controlled from both PhoneStatusBarTransitions andPhoneStatusBar (DISABLE_NOTIFICATION_ICONS). --><!-- 通知图标区域--><com.android.systemui.statusbar.AlphaOptimizedFrameLayout
            android:id="@+id/notification_icon_area"android:layout_width="0dip"android:layout_height="match_parent"android:layout_weight="1"android:orientation="horizontal" /><!-- 系统图标区域 --><com.android.keyguard.AlphaOptimizedLinearLayout android:id="@+id/system_icon_area"android:layout_width="wrap_content"android:layout_height="match_parent"android:orientation="horizontal"><!-- 系统图标 --><include layout="@layout/system_icons" /><!-- 时钟信息 --><com.android.systemui.statusbar.policy.Clock
                android:id="@+id/clock"android:textAppearance="@style/TextAppearance.StatusBar.Clock"android:layout_width="wrap_content"android:layout_height="match_parent"android:singleLine="true"android:paddingStart="@dimen/status_bar_clock_starting_padding"android:paddingEnd="@dimen/status_bar_clock_end_padding"android:gravity="center_vertical|start"/></com.android.keyguard.AlphaOptimizedLinearLayout></LinearLayout></com.android.systemui.statusbar.phone.PhoneStatusBarView>

以下是细节图,连线表示层次结构

其中,状态栏的区域分为以下几种

通知栏图标,在状态栏的最左侧显示通知信息,比如来了一个短信,那么就会弹出一个短信图标
时间信息,显示一个时间,比如上午9:58
信号图标,显示手机信号,wifi信号等
电量图标,显示当前电量状态
状态图标,wifi,蓝牙等开关状态

2.@layout/brightness_mirror

这个布局就是中间那个调整亮度的seekBar.没啥好介绍的.

3.@layout/status_bar_expanded

这个布局是下拉时的状态栏的布局

<com.android.systemui.statusbar.phone.NotificationPanelView xmlns:android="http://schemas.android.com/apk/res/android"xmlns:systemui="http://schemas.android.com/apk/res/com.android.systemui"android:id="@+id/notification_panel"android:layout_width="match_parent"android:layout_height="match_parent"android:background="@android:color/transparent"><!--锁屏时的时钟布局  --><include
        layout="@layout/keyguard_status_view"android:layout_height="wrap_content"android:visibility="gone" /><com.android.systemui.statusbar.phone.NotificationsQuickSettingsContainer
        android:layout_width="match_parent"android:layout_height="match_parent"android:layout_gravity="@integer/notification_panel_layout_gravity"android:id="@+id/notification_container_parent"android:clipToPadding="false"android:clipChildren="false"><!--quciksetting区域  --><com.android.systemui.AutoReinflateContainer
            android:id="@+id/qs_auto_reinflate_container"android:layout="@layout/qs_panel"android:layout_width="@dimen/notification_panel_width"android:layout_height="match_parent"android:layout_gravity="@integer/notification_panel_layout_gravity"android:clipToPadding="false"android:clipChildren="false" /><!-- 通知栏区域 --><com.android.systemui.statusbar.stack.NotificationStackScrollLayout
            android:id="@+id/notification_stack_scroller"android:layout_width="@dimen/notification_panel_width"android:layout_height="match_parent"android:layout_gravity="@integer/notification_panel_layout_gravity"android:layout_marginBottom="@dimen/close_handle_underlap" /><!--锁屏切换 --><ViewStub
            android:id="@+id/keyguard_user_switcher"android:layout="@layout/keyguard_user_switcher"android:layout_height="match_parent"android:layout_width="match_parent" /><!--锁屏下的状态栏 --><include
            layout="@layout/keyguard_status_bar"android:visibility="invisible" /></com.android.systemui.statusbar.phone.NotificationsQuickSettingsContainer><!--锁屏界面底部的图标 --><include
            layout="@layout/keyguard_bottom_area"android:visibility="gone" /></com.android.systemui.statusbar.phone.NotificationPanelView><!-- end of sliding panel -->

细节图

创建完布局后，就会添加窗口到WindowManager里,这样状态栏就创建完成了.接下来会回到3.2 addNavigationBar()的步骤中.

3.2、addNavigationBar

这个方法是添加底部的导航栏的,就是那些home键,back键所在的区域.


public class PhoneStatusBar extends BaseStatusBar implements DemoMode, DragDownHelper.DragDownCallback, ActivityStarter, OnUnlockMethodChangedListener,HeadsUpManager.OnHeadsUpChangedListener {......protected void addNavigationBar() {if (mNavigationBarView == null) return;//初始化导航栏prepareNavigationBarView();//添加到WindowManager中mWindowManager.addView(mNavigationBarView, getNavigationBarLayoutParams());}......}

在这个方法里先初始化导航栏,然后把导航栏添加到窗口中.

prepareNavigationBarView()

public class PhoneStatusBar extends BaseStatusBar implements DemoMode, DragDownHelper.DragDownCallback, ActivityStarter, OnUnlockMethodChangedListener,HeadsUpManager.OnHeadsUpChangedListener {......private void prepareNavigationBarView() {//重新初始化 mNavigationBarView.reorient();//最近应用键ButtonDispatcher recentsButton = mNavigationBarView.getRecentsButton();recentsButton.setOnClickListener(mRecentsClickListener);recentsButton.setOnTouchListener(mRecentsPreloadOnTouchListener);recentsButton.setLongClickable(true);recentsButton.setOnLongClickListener(mRecentsLongClickListener);//后退键ButtonDispatcher backButton = mNavigationBarView.getBackButton();backButton.setLongClickable(true);backButton.setOnLongClickListener(mLongPressBackListener);//home键ButtonDispatcher homeButton = mNavigationBarView.getHomeButton();homeButton.setOnTouchListener(mHomeActionListener);homeButton.setOnLongClickListener(mLongPressHomeListener);//监听配置改变mAssistManager.onConfigurationChanged();}......}

四、结束

关于SystemUI的状态栏和导航栏就介绍完了，讲的很浅显，只是从整体上梳理了下流程.

原文地址：　http://blog.csdn.net/qq_31530015/article/details/53507968