5.0systemUI启动流程

5.0SytemUI启动流程：
SystemUI是常驻到Android系统的，所以需要Service。
SystemUIService extends Service ——>在 SystemUIService的OnCreate（）方法中——–>((SystemUIApplication) getApplication()).startServicesIfNeeded();进入SystemUIApplication中看看` public void onCreate() {
super.onCreate();
//add by fanguoqing
gInst = this;
// Set the application theme that is inherited by all services. Note that setting the
// application theme in the manifest does only work for activities. Keep this in sync with
// the theme set there.
setTheme(R.style.systemui_theme);

    IntentFilter filter = new IntentFilter(Intent.ACTION_BOOT_COMPLETED);
    filter.setPriority(IntentFilter.SYSTEM_HIGH_PRIORITY);
    registerReceiver(new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            if (mBootCompleted) return;

            if (DEBUG) Log.v(TAG, "BOOT_COMPLETED received");
            unregisterReceiver(this);
            mBootCompleted = true;
            if (mServicesStarted) {
                final int N = mServices.length;
                for (int i = 0; i < N; i++) {
                    mServices[i].onBootCompleted();
                }
            }
        }
    }, filter);
}`


      在.onCreate()中注册了一个监听开机的广播当开机完成onBootCompleted()，启动SystemUI。当调用startServicesIfNeeded()时启动

    private final Class[] SERVICES = new Class[] {
            com.android.systemui.keyguard.KeyguardViewMediator.class,
            com.android.systemui.recent.Recents.class,
            com.android.systemui.volume.VolumeUI.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
    };

启动这些类。

 public void startServicesIfNeeded() {
        if (mServicesStarted) {
            return;
        }

        if (!mBootCompleted) {
            // check to see if maybe it was already completed long before we began
            // see ActivityManagerService.finishBooting()
            if ("1".equals(SystemProperties.get("sys.boot_completed"))) {
                mBootCompleted = true;
                if (DEBUG) Log.v(TAG, "BOOT_COMPLETED was already sent");
            }
        }

        Log.v(TAG, "Starting SystemUI services.");
        final int N = SERVICES.length;
        for (int i=0; i cl = SERVICES[i];
            if (DEBUG) Log.d(TAG, "loading: " + cl);
            try {
                mServices[i] = (SystemUI)cl.newInstance();
            } catch (IllegalAccessException ex) {
                throw new RuntimeException(ex);
            } catch (InstantiationException ex) {
                throw new RuntimeException(ex);
            }
            mServices[i].mContext = this;
            mServices[i].mComponents = mComponents;
            if (DEBUG) Log.d(TAG, "running: " + mServices[i]);
            mServices[i].start();

            if (mBootCompleted) {
                mServices[i].onBootCompleted();
            }
        }
        mServicesStarted = true;
    }

mServices[i].start();调用了这些类的start（）方法。这些类都是继承自SystemUI.class SystemUI是一个抽象类

public abstract class SystemUI {
    public Context mContext;
    public Map, Object> mComponents;

    public abstract void start();

    protected void onConfigurationChanged(Configuration newConfig) {
    }

    public void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
    }

    protected void onBootCompleted() {
    }

    @SuppressWarnings("unchecked")
    public  T getComponent(Class interfaceType) {
        return (T) (mComponents != null ? mComponents.get(interfaceType) : null);
    }

    public  void putComponent(Class interfaceType, C component) {
        if (mComponents != null) {
            mComponents.put(interfaceType, component);
        }
    }
}

SystemUI抽象了一个start（）；

PhoneStatusBar继承自BaseStatusBar。BaseStatusBar继承自SystemUI；
那就看看start（）

 @Override
    public void start() {
        mDisplay = ((WindowManager)mContext.getSystemService(Context.WINDOW_SERVICE))
                .getDefaultDisplay();
        updateDisplaySize();
        mScrimSrcModeEnabled = mContext.getResources().getBoolean(
                R.bool.config_status_bar_scrim_behind_use_src);

        /// M: [SystemUI] Support Smartbook Feature. @{
        if (SIMHelper.isMtkSmartBookSupport()) {
            /// M: [ALPS01097705] Query the plug-in state as soon as possible.
            mIsDisplayDevice = SIMHelper.isSmartBookPluggedIn(mContext);
            Log.v(TAG, "start, mIsDisplayDevice=" + mIsDisplayDevice);
        }
        /// @}

        super.start(); // calls createAndAddWindows()

        mMediaSessionManager
                = (MediaSessionManager) mContext.getSystemService(Context.MEDIA_SESSION_SERVICE);
        // TODO: use MediaSessionManager.SessionListener to hook us up to future updates
        // in session state

        addNavigationBar();

        // Lastly, call to the icon policy to install/update all the icons.
        mIconPolicy = new PhoneStatusBarPolicy(mContext, mCastController, mHotspotController);
        mSettingsObserver.onChange(false); // set up

        mHeadsUpObserver.onChange(true); // set up
        if (ENABLE_HEADS_UP) {
            mContext.getContentResolver().registerContentObserver(
                    Settings.Global.getUriFor(Settings.Global.HEADS_UP_NOTIFICATIONS_ENABLED), true,
                    mHeadsUpObserver);
            mContext.getContentResolver().registerContentObserver(
                    Settings.Global.getUriFor(SETTING_HEADS_UP_TICKER), true,
                    mHeadsUpObserver);
        }
        mUnlockMethodCache = UnlockMethodCache.getInstance(mContext);
        mUnlockMethodCache.addListener(this);
        startKeyguard();

        mDozeServiceHost = new DozeServiceHost();
        putComponent(DozeHost.class, mDozeServiceHost);
        putComponent(PhoneStatusBar.class, this);

        setControllerUsers();

        notifyUserAboutHiddenNotifications();

        mScreenPinningRequest = new ScreenPinningRequest(mContext);
    }

super.start(); // calls createAndAddWindows()代码中调用了父类的start（），看看父类中的start（）做了什么

public void start() {
        mWindowManager = (WindowManager)mContext.getSystemService(Context.WINDOW_SERVICE);
        mWindowManagerService = WindowManagerGlobal.getWindowManagerService();
        mDisplay = mWindowManager.getDefaultDisplay();
        mDevicePolicyManager = (DevicePolicyManager)mContext.getSystemService(
                Context.DEVICE_POLICY_SERVICE);

        mNotificationColorUtil = NotificationColorUtil.getInstance(mContext);

        mNotificationData = new NotificationData(this);

        mAccessibilityManager = (AccessibilityManager)
                mContext.getSystemService(Context.ACCESSIBILITY_SERVICE);

        mDreamManager = IDreamManager.Stub.asInterface(
                ServiceManager.checkService(DreamService.DREAM_SERVICE));
        mPowerManager = (PowerManager) mContext.getSystemService(Context.POWER_SERVICE);

        mSettingsObserver.onChange(false); // set up
        mContext.getContentResolver().registerContentObserver(
                Settings.Global.getUriFor(Settings.Global.DEVICE_PROVISIONED), true,
                mSettingsObserver);
        mContext.getContentResolver().registerContentObserver(
                Settings.Global.getUriFor(Settings.Global.ZEN_MODE), false,
                mSettingsObserver);
        mContext.getContentResolver().registerContentObserver(
                Settings.Secure.getUriFor(Settings.Secure.LOCK_SCREEN_SHOW_NOTIFICATIONS), false,
                mSettingsObserver,
                UserHandle.USER_ALL);

        mContext.getContentResolver().registerContentObserver(
                Settings.Secure.getUriFor(Settings.Secure.LOCK_SCREEN_ALLOW_PRIVATE_NOTIFICATIONS),
                true,
                mLockscreenSettingsObserver,
                UserHandle.USER_ALL);

        mBarService = IStatusBarService.Stub.asInterface(
                ServiceManager.getService(Context.STATUS_BAR_SERVICE));

        mRecents = getComponent(RecentsComponent.class);
        mRecents.setCallback(this);

        final Configuration currentConfig = mContext.getResources().getConfiguration();
        mLocale = currentConfig.locale;
        mLayoutDirection = TextUtils.getLayoutDirectionFromLocale(mLocale);
        mFontScale = currentConfig.fontScale;

        mUserManager = (UserManager) mContext.getSystemService(Context.USER_SERVICE);

        mLinearOutSlowIn = AnimationUtils.loadInterpolator(mContext,
                android.R.interpolator.linear_out_slow_in);
        mFastOutLinearIn = AnimationUtils.loadInterpolator(mContext,
                android.R.interpolator.fast_out_linear_in);

        // Connect in to the status bar manager service
        StatusBarIconList iconList = new StatusBarIconList();
        mCommandQueue = new CommandQueue(this, iconList);

        int[] switches = new int[8];
        ArrayList binders = new ArrayList();
        try {
            mBarService.registerStatusBar(mCommandQueue, iconList, switches, binders);
        } catch (RemoteException ex) {
            // If the system process isn't there we're doomed anyway.
        }

        createAndAddWindows();

        disable(switches[0], false /* animate */);
        setSystemUiVisibility(switches[1], 0xffffffff);
        topAppWindowChanged(switches[2] != 0);
        // StatusBarManagerService has a back up of IME token and it's restored here.
        setImeWindowStatus(binders.get(0), switches[3], switches[4], switches[5] != 0);

        // Set up the initial icon state
        int N = iconList.size();
        int viewIndex = 0;
        for (int i=0; iif (icon != null) {
                addIcon(iconList.getSlot(i), i, viewIndex, icon);
                viewIndex++;
            }
        }

        // Set up the initial notification state.
        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);
        }


        if (DEBUG) {
            Log.d(TAG, String.format(
                    "init: icons=%d disabled=0x%08x lights=0x%08x menu=0x%08x imeButton=0x%08x",
                   iconList.size(),
                   switches[0],
                   switches[1],
                   switches[2],
                   switches[3]
                   ));
        }

        mCurrentUserId = ActivityManager.getCurrentUser();
        setHeadsUpUser(mCurrentUserId);

        IntentFilter filter = new IntentFilter();
        filter.addAction(Intent.ACTION_USER_SWITCHED);
        filter.addAction(Intent.ACTION_USER_ADDED);
        filter.addAction(BANNER_ACTION_CANCEL);
        filter.addAction(BANNER_ACTION_SETUP);
        filter.addAction(DevicePolicyManager.ACTION_DEVICE_POLICY_MANAGER_STATE_CHANGED);
        mContext.registerReceiver(mBroadcastReceiver, filter);

        updateCurrentProfilesCache();
    }

父类中的start（）做了一些初始化操作，看createAndAddWindows();这个是一个抽象方法，那到子类中看看具体做了一些什么。看

 @Override
    public void createAndAddWindows() {
        addStatusBarWindow();
    }

    private void addStatusBarWindow() {
        makeStatusBarView();
        mStatusBarWindowManager = new StatusBarWindowManager(mContext);
        mStatusBarWindowManager.add(mStatusBarWindow, getStatusBarHeight());
    }

加载StatusBar，—->初始化布局控件并加入到view中，还有注册了一些广播，最终会返回PhoneStatusBarView。PhoneStatusBarView是一个FrameLayout。

  mStatusBarWindowManager = new StatusBarWindowManager(mContext);
        mStatusBarWindowManager.add(mStatusBarWindow, getStatusBarHeight());

这里将会把Statusbar交给mStatusBarWindowManager去管理，StatusBarWindowManager是一个系统服务。

回到父类BaseStatusBar的start（）往下，就会看到注册了通知的系统管理。继续往下，就会进入到子类的start（）；
addNavigationBar();加入导航栏，初始化了导航栏一些监听事件
并通过 mWindowManager.addView(mNavigationBarView, getNavigationBarLayoutParams());交给WindowManager去处理
。
看看启动时序图