Android SystemUI 启动流程和状态栏视图

SystemServer会启动SystemUiService
系统启动入口：frameworks/base/services/java/com/android/server/SystemServer.java
ActivitManagerService准备好之后，启动SystemUI

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


SystemUIService 通过反射机制启动各个SystemUI组件

    /**
     * The classes of the stuff to start.
     */
    private final Class<?>[] SERVICES = new Class[] {
            com.android.systemui.recent.Recents.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.settings.SettingsUI.class,
        };

    /**
     * Hold a reference on the stuff we start.
     */
    private final SystemUI[] mServices = new SystemUI[SERVICES.length];



  @Override
    public void onCreate() {
        HashMap<Class<?>, Object> components = new HashMap<Class<?>, Object>();
        final int N = SERVICES.length;
        for (int i=0; i<N; i++) {
            Class<?> cl = SERVICES[i];
            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 = components;
            Log.d(TAG, "running: " + mServices[i]);
            mServices[i].start();
        }
    }


StatusBar 会启动ServiceMonitor
   public void start() {
        if (DEBUG) Log.d(TAG, "start");
        mServiceMonitor = new ServiceMonitor(TAG, DEBUG,
                mContext, Settings.Secure.BAR_SERVICE_COMPONENT, this);
        mServiceMonitor.start();  // will call onNoService if no remote service is found
    }

ServiceMonitor会启动Service，调用onNoService
  public void start() {
        // listen for setting changes
        ContentResolver cr = mContext.getContentResolver();
        cr.registerContentObserver(Settings.Secure.getUriFor(mSettingKey),
                false /*notifyForDescendents*/, mSettingObserver, UserHandle.USER_ALL);

        // listen for package/component changes
        IntentFilter filter = new IntentFilter();
        filter.addAction(Intent.ACTION_PACKAGE_ADDED);
        filter.addAction(Intent.ACTION_PACKAGE_CHANGED);
        filter.addDataScheme("package");
        mContext.registerReceiver(mBroadcastReceiver, filter);

        mHandler.sendEmptyMessage(MSG_START_SERVICE);
    }

   private void startService() {
        mServiceName = getComponentNameFromSetting();
        if (mDebug) Log.d(mTag, "startService mServiceName=" + mServiceName);
        if (mServiceName == null) {
            mBound = false;
            mCallbacks.onNoService();
        } else {
            long delay = mCallbacks.onServiceStartAttempt();
            mHandler.sendEmptyMessageDelayed(MSG_CONTINUE_START_SERVICE, delay);
        }
    }

noService中 会去从配置文件中启动相应的statusrBar


    @Override
    public void onNoService() {
        if (DEBUG) Log.d(TAG, "onNoService");
        createStatusBarFromConfig();  // fallback to using an in-process implementation
    }

   private void createStatusBarFromConfig() {
        if (DEBUG) Log.d(TAG, "createStatusBarFromConfig");
        final String clsName = mContext.getString(R.string.config_statusBarComponent);
        if (clsName == null || clsName.length() == 0) {
            throw andLog("No status bar component configured", null);
        }
        Class<?> cls = null;
        try {
            cls = mContext.getClassLoader().loadClass(clsName);
        } catch (Throwable t) {
            throw andLog("Error loading status bar component: " + clsName, t);
        }
        try {
            mStatusBar = (BaseStatusBar) cls.newInstance();
        } catch (Throwable t) {
            throw andLog("Error creating status bar component: " + clsName, t);
        }
        mStatusBar.mContext = mContext;
        mStatusBar.mComponents = mComponents;
        mStatusBar.start();
        if (DEBUG) Log.d(TAG, "started " + mStatusBar.getClass().getSimpleName());
    }

    <string name="config_statusBarComponent" translatable="false">com.android.systemui.statusbar.phone.PhoneStatusBar</string>

最终启动PhoneStatusBar

PhoneStatusBar 启动时调用父类BaseStatusBar start,创建window

createAndAddWindows();紧接着调用子类addStatusBarWindow


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


之后继续调用makeStatusBarView创建Bar的视图
    private void addStatusBarWindow() {
        // Put up the view
        final int height = getStatusBarHeight();

        // Now that the status bar window encompasses the sliding panel and its
        // translucent backdrop, the entire thing is made TRANSLUCENT and is
        // hardware-accelerated.
        final WindowManager.LayoutParams lp = new WindowManager.LayoutParams(
                ViewGroup.LayoutParams.MATCH_PARENT, height,
                WindowManager.LayoutParams.TYPE_STATUS_BAR,
                WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
                        | WindowManager.LayoutParams.FLAG_TOUCHABLE_WHEN_WAKING
                        | WindowManager.LayoutParams.FLAG_SPLIT_TOUCH
                        | WindowManager.LayoutParams.FLAG_WATCH_OUTSIDE_TOUCH,
                PixelFormat.TRANSLUCENT);

        lp.flags |= WindowManager.LayoutParams.FLAG_HARDWARE_ACCELERATED;

        lp.gravity = getStatusBarGravity();
        lp.setTitle("StatusBar");
        lp.packageName = mContext.getPackageName();

        makeStatusBarView();
        mWindowManager.addView(mStatusBarWindow, lp);
    }


makeStatusBarView 会加载布局xml

    protected PhoneStatusBarView makeStatusBarView() {
        final Context context = mContext;

        Resources res = context.getResources();

        updateDisplaySize(); // populates mDisplayMetrics
        loadDimens();

        mIconSize = res
                .getDimensionPixelSize(com.android.internal.R.dimen.status_bar_icon_size);

        mStatusBarWindow = (StatusBarWindowView) View.inflate(context,
                R.layout.super_status_bar, null);
        mStatusBarWindow.mService = this;
        mStatusBarWindow.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                checkUserAutohide(v, event);
                if (event.getAction() == MotionEvent.ACTION_DOWN) {
                    if (mExpandedVisible) {
                        animateCollapsePanels();
                    }
                }
                return mStatusBarWindow.onTouchEvent(event);
            }
        });

        mStatusBarView = (PhoneStatusBarView) mStatusBarWindow
                .findViewById(R.id.status_bar);
        mStatusBarView.setBar(this);

        // volButton = (KeyButtonView) mStatusBarView.findViewById(R.id.volum);

        PanelHolder holder = (PanelHolder) mStatusBarWindow
                .findViewById(R.id.panel_holder);
        mStatusBarView.setPanelHolder(holder);

        mNotificationPanel = (NotificationPanelView) mStatusBarWindow
                .findViewById(R.id.notification_panel);
        mNotificationPanel.setStatusBar(this);
        mNotificationPanelIsFullScreenWidth = (mNotificationPanel
                .getLayoutParams().width == ViewGroup.LayoutParams.MATCH_PARENT);

        // make the header non-responsive to clicks
        mNotificationPanel.findViewById(R.id.header).setOnTouchListener(
                new View.OnTouchListener() {
                    @Override
                    public boolean onTouch(View v, MotionEvent event) {
                        return true; // e eats everything
                    }
                });

        if (!ActivityManager.isHighEndGfx()) {
            mStatusBarWindow.setBackground(null);
            mNotificationPanel.setBackground(new FastColorDrawable(context
                    .getResources().getColor(
                            R.color.notification_panel_solid_background)));
        }
        if (ENABLE_HEADS_UP) {
            mHeadsUpNotificationView = (HeadsUpNotificationView) View.inflate(
                    context, R.layout.heads_up, null);
            mHeadsUpNotificationView.setVisibility(View.GONE);
            mHeadsUpNotificationView.setBar(this);
        }
        if (MULTIUSER_DEBUG) {
            mNotificationPanelDebugText = (TextView) mNotificationPanel
                    .findViewById(R.id.header_debug_info);
            mNotificationPanelDebugText.setVisibility(View.VISIBLE);
        }

        updateShowSearchHoldoff();
}

顶层View：super_status_bar.xml： 内含 status_bar.xml 和 PanelHolder

所以如果只是一般修改顶层状态栏的视图，修改status_bar.xml和PhoneStatusBar这两个类即可。