SystemUI源码分析三(StatusBar的加载流程)

SystemServer中调用startsystemui函数启动SystemUIService,在SystemUIService的onCreate()函数中执行一下这个语句

((SystemUIApplication) getApplication()).startServicesIfNeeded();

SystemBar继承SystemUI,因此被启动了。

那接下来就进入SystemBar这个类中看onStart()函数

public void start(){
    if(DEBUG)Log.d(TAG,"start");
    //创建监听器对象
    mServiceMonitor = new ServiceMonitor(TAG,DEBUG,mContext,Settings.Secure.BAR_SERVICE_COMPONENT,this);
    //开始监听
    mServiceMonitor.start();
}

ServiceMonitor.java

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
    //监听应用的安装卸载变化
    IntentFilter filter = new IntentFilter();
    filter.addAction(Intent.ACTION_PACKAGE_addED);
    filter.addAction(Intent.ACTION_PACKAGE_CHANGED);
    filter.addAction(Intent.ACTION_PACKAGE_REMOVED);
    filter.addDataScheme("package");
    mContext.registerReceiver(mBroadcastReceiver, filter);

    //发送消息给主线程，启动Service
    mHandler.sendEmptyMessage(MSG_START_SERVICE);
}
/*处理接收到的消息*/
private final Handler mHandler = new Handler() {
    public void handleMessage(Message msg) {
        switch(msg.what) {
            case MSG_START_SERVICE:
                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;
        }
    }
};

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);
    }
}

先获取Service的componentName,如果为null则回调onNoService方法。如果不为null,则通过mHandler发送消息给主线程。

private void continueStartService() {
    if (mDebug) Log.d(mTag, "continueStartService");
    Intent intent = new Intent().setComponent(mServiceName);
    try {
        mServiceConnection = new SC();
        mBound = mContext.bindService(intent, mServiceConnection, Context.BIND_AUTO_CREATE);
        if (mDebug) Log.d(mTag, "mBound: " + mBound);
    } catch (Throwable t) {
        Log.w(mTag, "Error binding to service: " + mServiceName, t);
    }
    if (!mBound) {
        mCallbacks.onNoService();
    }
}

获取的componentName不管是不是空，最终都会回调onNoService()。

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");
    //取出className
    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 {
        //动态加载class文件
        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BaseStatusBar
    mStatusBar.start();
    if (DEBUG) Log.d(TAG, "started " + mStatusBar.getClass().getSimpleName());
}

frameworksbasepackagesSystemUIresvaluesconfig.xml
R.string.config_statusBarComponent的值是:

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

PhoneStatusBar继承自BaseStatusBar

启动BaseStatusBar,那就接着来看BaseStatusBar.java,这个类继承自SystemUI

public void start(){
    createAndAddWindows();
}

/**
 * Create all windows necessary for the status bar (including navigation, overlay panels, etc)
 * and add them to the window manager.
 */
protected abstract void createAndAddWindows();

是个抽象函数，PhoneStatusBar继承自BaseStatusBar,那我们来看下PhoneStatusBar

 public void start() {
    ……
    super.start(); // calls createAndAddWindows()
}

果然是PhoneStatusBar启动时调用了父类(BaseStatusBar)的createAndAddWindows(),这里PhoneStatusBar实现了父类的抽象方法。主要是添加状态栏、添加导航栏、更新图标

一、添加状态栏

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

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

这个函数做了两件事

(1)创建PhoneStatusBarView并初始化PhoneStatusBarView中的控件。

(2)创建StatusBarWindowManager对象，调用它的add()函数为PhoneStatusBarView创建窗口，包括窗口的大小、位置、是否透明等属性。

先来分析makeStatusBarView()函数。

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

    Resources res = context.getResources();

    //获取屏幕参数
    updateDisplaySize(); // populates mDisplayMetrics
    //更新Panels资源数据，statusbar包含很多panel,在创建PhoneStatusBarView时需要更新panel数据
    updateResources();

    //引入StatusBarWindowView布局
    mStatusBarWindow = (StatusBarWindowView) View.inflate(context,
            R.layout.super_status_bar, null);
    //statusbarwindow
    mStatusBarWindow.setService(this);
    //设置触摸事件监听器
    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);
        }
    });

    //初始化statusbarview
    mStatusBarView = (PhoneStatusBarView) mStatusBarWindow.findViewById(R.id.status_bar);
    mStatusBarView.setBar(this);

    //初始化panelholder
    PanelHolder holder = (PanelHolder) mStatusBarWindow.findViewById(R.id.panel_holder);
    mStatusBarView.setPanelHolder(holder);

    //初始化通知panel
    mNotificationPanel = (NotificationPanelView) mStatusBarWindow.findViewById(
            R.id.notification_panel);
    mNotificationPanel.setStatusBar(this);


    if (!mHighEnd) {
        mStatusBarWindow.setBackground(null);
        //设置notificationpanel背景
        mNotificationPanel.setBackground(new FastColorDrawable(context.getColor(
                R.color.notification_panel_solid_background)));
    }

    //通知样式
    mHeadsUpManager = new HeadsUpManager(context, mStatusBarWindow);
    mHeadsUpManager.setBar(this);
    mHeadsUpManager.addListener(this);
    mHeadsUpManager.addListener(mNotificationPanel);
    mNotificationPanel.setHeadsUpManager(mHeadsUpManager);
    mNotificationData.setHeadsUpManager(mHeadsUpManager);

    if (MULTIUSER_DEBUG) {
        mNotificationPanelDebugText = (TextView) mNotificationPanel.findViewById(
            

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