SystemUIQ-启动流程

SystemUI的启动流程

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hi,大家好，我是爱吃香蕉的猴子，趁元旦假期在家把之前本地记录的关于SystmeUI启动流程的内容，整理一下.

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熟悉android 开发的都应该熟悉SystemUI, 和名字一样 系统的界面，当系统启动时，最先启动的Ui的则是SystemUI，现在我们从Code上来走一遍流程；

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系统服务的启动，自然从SystemServer开始：
path: com\android\server\SystemServer.java

   /**
     * The main entry point from zygote.
     */
    public static void main(String[] args) {//代码从Main开始看
        new SystemServer().run();//启动服务--> run中查看
    }

然后，我们看一下run方法

 private void run() {
    ...
    	   // Prepare the main looper thread (this thread).
            android.os.Process.setThreadPriority(//为服务设置线程
                android.os.Process.THREAD_PRIORITY_FOREGROUND);
            android.os.Process.setCanSelfBackground(false);
            Looper.prepareMainLooper();
            Looper.getMainLooper().setSlowLogThresholdMs(
                    SLOW_DISPATCH_THRESHOLD_MS, SLOW_DELIVERY_THRESHOLD_MS);

            // Initialize native services.
            System.loadLibrary("android_servers");
    	        // Start services.
        try {
            traceBeginAndSlog("StartServices");
            startBootstrapServices();
            startCoreServices();
            startOtherServices();//Start SystemUI
            SystemServerInitThreadPool.shutdown();
        } catch (Throwable ex) {
            Slog.e("System", "******************************************");
            Slog.e("System", "************ Failure starting system services", ex);
            throw ex;
     ...
     }

startOtherServices();启动各种服务

    /**
     * Starts a miscellaneous grab bag of stuff that has yet to be refactored
     * and organized.
     * 其中有待重构的东西
     */
    private void startOtherServices() {
     
    ....
    	    try {
     
                startSystemUi(context, windowManagerF);
            } catch (Throwable e) {
     
                reportWtf("starting System UI", e);
            }
    .....
    }

startSystemUi开始启动SystemUI

static final void startSystemUi(Context context, WindowManagerService windowManager) {
        Intent intent = new Intent();
        intent.setComponent(new ComponentName("com.android.systemui",
                    "com.android.systemui.SystemUIService"));//启动SystemUIService
        intent.addFlags(Intent.FLAG_DEBUG_TRIAGED_MISSING);
        //Slog.d(TAG, "Starting service: " + intent);
        context.startServiceAsUser(intent, UserHandle.SYSTEM);//set uid
        windowManager.onSystemUiStarted();
    }//开始启动SystemUI

针对上面的代码做两个分析：
windowManager.onSystemUiStarted()执行了什么?
path:services/core/java/com/android/server/wm/WindowManagerService.java

3274     /**
3275     ┊* Called when System UI has been started.
3276     ┊*/
3277     public void onSystemUiStarted() {                                                                                           
3278     ┊   mPolicy.onSystemUiStarted();//-->PhoneWindowManager
3279     }

path:services/core/java/com/android/server/policy/PhoneWindowManager.java

4837     @Override
4838     public void onSystemUiStarted() {                                                                       
4839     ┊   bindKeyguard();
4840     }

4827     private void bindKeyguard() {                                                                           
4828     ┊   synchronized (mLock) {
4829     ┊   ┊   if (mKeyguardBound) {
4830     ┊   ┊   ┊   return;
4831     ┊   ┊   }
4832     ┊   ┊   mKeyguardBound = true;
4833     ┊   }
4834     ┊   mKeyguardDelegate.bindService(mContext);//启动了keyguard模块，后面代码不再贴
4835     }

进入SystemUIService看看执行了什么？
path: src\main\java\com\systemui\SystemUIService.java

	@Override
    public void onCreate() {
        super.onCreate();
        ((SystemUIApplication) getApplication()).startServicesIfNeeded();
        ....
    }

path: app/src/main/java/com/systemui/SystemUIApplication.java

    public void startServicesIfNeeded() {
        String[] names = getResources().getStringArray(R.array.config_systemUIServiceComponents);
        startServicesIfNeeded(/* metricsPrefix= */ "StartServices", names);
    }

从配置文件中读取各类服务，查看一下配置文件:

   
    
        com.android.systemui.util.NotificationChannels
        com.android.systemui.statusbar.CommandQueue$CommandQueueStart
        com.android.systemui.keyguard.KeyguardViewMediator
        com.android.systemui.recents.Recents
        com.android.systemui.volume.VolumeUI
        com.android.systemui.stackdivider.Divider
        com.android.systemui.SystemBars
        com.android.systemui.usb.StorageNotification
        com.android.systemui.power.PowerUI
        com.android.systemui.media.RingtonePlayer
        com.android.systemui.keyboard.KeyboardUI
        com.android.systemui.pip.PipUI
        com.android.systemui.shortcut.ShortcutKeyDispatcher
        @string/config_systemUIVendorServiceComponent
        com.android.systemui.util.leak.GarbageMonitor$Service
        com.android.systemui.LatencyTester
        com.android.systemui.globalactions.GlobalActionsComponent
        com.android.systemui.ScreenDecorations
        com.android.systemui.biometrics.BiometricDialogImpl
        com.android.systemui.SliceBroadcastRelayHandler
        com.android.systemui.SizeCompatModeActivityController
        com.android.systemui.statusbar.notification.InstantAppNotifier
        com.android.systemui.theme.ThemeOverlayController
    

然后进入startServicesIfNeeded查看：

    private void startServicesIfNeeded(String metricsPrefix, String[] services) {
    	...
    	    String clsName = services[i];
            if (DEBUG) Log.d(TAG, "loading: " + clsName);
            log.traceBegin(metricsPrefix + clsName);
            long ti = System.currentTimeMillis();
            Class cls;
            try {
                cls = Class.forName(clsName);
                Object o = cls.newInstance();
                if (o instanceof SystemUI.Injector) {
                    o = ((SystemUI.Injector) o).apply(this);
                }
                mServices[i] = (SystemUI) o;
                ...
    }

mService就是配置文件中的各个模块。所有的模块都统一继承了SystemUI.
简单画个图，方便记忆：

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有些地方还没有完全写明白，先把代码顺一遍，后续添加，谢谢
首先感谢参考了的资料：SystemUI教程

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