一、SystemUI 整体启动入口

1. SystemUIService.onCreate

程序进程创建 SystemUIService 后会调用 SystemUIApplication.startServicesIfNeeded 启动所有 SystemUI 子服务。

// frameworks/base/packages/SystemUI/src/com/android/systemui/SystemUIService.java
@Override
public void onCreate {
super.onCreate;// Start all of SystemUI
getApplication).startServicesIfNeeded;}

2. 读取 config.xml 中声明的 Service 列表

SystemUIApplication.startServicesIfNeeded 会通过 SystemUIFactory.getInstance.getSystemUIServiceComponents 读取资源数组 @array/config_systemUIServiceComponents。

// frameworks/base/packages/SystemUI/src/com/android/systemui/SystemUIApplication.java
public void startServicesIfNeeded {
String names = SystemUIFactory.getInstance
.getSystemUIServiceComponents);startServicesIfNeeded;}

config.xml 示例

// frameworks/base/packages/SystemUI/res/values/config.xml

com.android.systemui.util.NotificationChannels
com.android.systemui.keyguard.KeyguardViewMediator
com.android.systemui.recents.Recents
...
com.android.systemui.statusbar.phone.StatusBar
...

3. 动态实例化并调用 start

SystemUIApplication.startServicesIfNeeded 会遍历上述类名。用反射创建实例（实现了 SYSTEM_UI)，随后调用它们的 .start 方法。

// frameworks/base/packages/SystemUI/src/com/android/systemui/SystemUIApplication.java
private void startServicesIfNeeded {
if return;mServices = new SystemUI;for {
try {
String clsName = services;怎么说呢，SystemUI obj = mComponentHelper.resolveSystemUI;if {
Constructor ctor = Class.forName
.getConstructor;obj = ctor.newInstance;}
mServices = obj;} catch {
throw new RuntimeException;怎么说呢，}
// 真正启动 Service
mServices.start;if ) {
mServices.onBootCompleted;按理说，}
}
mServicesStarted = true;其实，}

二、StatusBar 的具体启动过程

1. StatusBar.start

StatusBar 继承自 SystemUI。是负责管理状态栏、通知栏、导航栏的“大总管”。

// frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/StatusBar.java
@Override
public void start {
// ① 获取程序服务 IStatusBarService
mBarService = IStatusBarService.Stub.asInterface(
ServiceManager.getService);// ② 获取 KeyguardManager
mKeyguardManager =
mContext.getSystemService;// ③ 注册 CommandQueue 到远程服务，获取初始化图标列表等信息
mCommandQueue.addCallback;RegisterStatusBarResult result = null;try {
result = mBarService.registerStatusBar;} catch {
ex.rethrowFromSystemServer;}
// ④ 创建状态栏、通知栏、导航栏窗口还有对应 View 层级结构
createAndAddWindows;setUpPresenter;// ⑤ 初始化图标状态
for;i++) {
mCommandQueue.setIcon,result.mIcons.valueAt);}
// ⑥ 启动图标策略对象，真正把图标放进 UI 中
mIconPolicy.init;// ⑦ 注册 Keyguard 状态回调并启动锁屏流程等...
}

2. 向 StatusBarManagerService 注册 CommandQueue 并获取初始数据

StatusBarManagerService.registerStatusBar 把客户端的 IStatusBar 保存到服务端，同时返回当前已存在的图标列表及各种 UI 状态。

// frameworks/base/services/core/java/com/android/server/statusbar/StatusBarManagerService.java
public RegisterStatusBarResult registerStatusBar {
enforceStatusBarService;Slog.i，// 保存客户端对象并绑定死亡监听器，以便进程挂掉时清理资源
mBar = bar;mDeathRecipient.linkToDeath;// 返回当前程序保存的所有图标还有 UI 状态信息
ArrayMap icons;synchronized { icons = new ArrayMap<>;}
synchronized {
UiState state = mDisplayUiState.get;int transientBars = new int;for {
transientBars = state.mTransientBaTypes.valueAt;}
return new RegisterStatusBarResult(
icons,garDisableActionsLocked,state.mAppearance,state.mAppearanceRegions,state.mImeWindowVis,state.mImeBackDisposition。state.mShowImeSwitcher,garDisableActionsLocked,state.mImeToken,state.mNavbarColorManagedByIme,state.mBehavior,state.mFullscreen,transientBars);}
}

三、PhoneStatusBarPolicy：程序图标初始化入口

1. 什么是 PhoneStatus BarPolicy？

User Pain Point： "我看到很多 Icon 类。却不知道到底是哪段代码把它们放进状态栏的"

PhoneStatus BarPolicy 是负责决定开机时哪些程序图标需要显示，还有后续如何监听程序变化来更新这些图标。说起来，

2. init 方法全景——注册广播、观察者并创建默认图标

// frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBarPolicy.java
public void init {
// 注册各种程序广播。如耳机插拔、SIM 状态变化等
IntentFilter filter = new IntentFilter;其实，filter.addAction;filter.addAction;说起来，...
mBroadcastDispatcher.registerReceiverWithHandler(
mIntentReceiver。filter,mHandler);不过，// 注册 RingerModeObserver。实时监听音量/免打扰状态
Observer observer =
ringer -> mHandler.post;mRingerModeTracker.getRingerMode.observeForever;mRingerModeTracker.getRingerModeInternal.observeForever;// 注册使用者切换回调
try {
mIActivityManager.registerUserSwitchObserver(
mUserSwitchListener,TAG);} catch { /* ignore */ }
// 初始化各类程序图标 —— 调用 IconController 设置默认资源与可见性
mIconController.setIcon(mSlotAlarmClock。R.drawable.stat_sys_alarm,null);mIconController.setIconVisibility;mIconController.setIcon(mSlotZen。R.drawable.stat_sys_dnd,null);不过，mIconController.setIconVisibility;// ，更多 icon 初始化省略 …// 为后续事件注册回调
mBluetooth.addCallback;
mProvisionedController.addCallback;mZenController.addCallback;...
}

四、状态栏图标控制链路：从 Policy 到 View

1. Status Bar Icon Controller 实例化

The controller reads resource array @array/config_statusBArIcons。which defines default slots.

// frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/StatusBarIconControllerImpl.java
public StatusBArIconControllerImpl(Context context,CommandQueue commandQueue,DemoModeController demoModeController) {
super
.getStringArray);Dependency.get.addCallback;commandQueue.addCallback;Dependency.get.addTunable;loadDimens，老实说，// 加载尺寸资源如 icon 大小等
demoModeCont roller.addCallback;}

2. setIcon – 把资源映射为实际 View

// frameworks/base/packages/SystemU I/src/com/android/systemui/statusbar/phone/
StatusBArIControllerImpl.java
public void setI con{
int index=getSlotIndex;Stat usBArIc onHolder holder=getIc on;if{
Stat usBArIc icon=new Stat usBArIc(UserHandle.SYSTEM。mContext.getPackageName,Icon.createWithResource,null,null,contentDescription );holder=Stat usBArIcHolder.fromIc on;setI con，说起来，}else{
holder.ge tIc on.ic on= Icon.createWithResource(
mContext。resourceId );holder.ge tIc on.co ntentDescription=contentDescrip tion;handleSet，}
}

public void setI con{ boolean isNew=getI con)==null;按理说，super.setI con;if{ addS ystemI con;} else{ handleSet;怎么说呢，} }

private void addS ystemI con(int index。Stat usBArIco nHolder holder){ String slot=getSlotNam e;int viewIndex=getVie wIndex);boolean hidden=mIc onHideList.conta ins;mIConGroups.forEach(l -> l.onI conAdded(viewIndex。slot,hidden,holder ));}

private void handleSet(int index。Stat usBArIco nHolder holder){ int viewIndex=getVie wIndex(index,holder.ge tTag);mIConGroups.forEach(l -> l.onSetI co nHolder(viewInde x,holder ));}

3. IconGroup 接口实现 – 最终把 Icon 添加到布局

• StatusBArIconControll erImpl → IconGroup list → IconM anager 实现类
• DARK ICON MANAGER 在 CollapsedS tatusB ArFragment 中被创建，用来真正向视图层添加或更新图标。
• The concrete methods finally call Add / Update status bar view objects such as StatusB ArIc onView or Status B ArWifiView.

A. 添加普通图片式图标

// Frameworks/.../Statu sBa rC ontroller.ja va
protected Statu sBa rIceView addIc on(int index。String slot,boolean blocked,Stat us BArIc on ic on ){
Statu sBa rIceView view=onCreateStatu sBa rIceVi ew(slot,blocked );view.set，mGroup.ad dView);return view，}

B. 添加 Wi‑Fi / Mobile 信号条形图标

// Framew ork s/.../Statu s Ba rC ont roller.ja v a protected Statu sBa rWifiVie w addSignal Ic ono(int index。String slot,Wifi Ic onoState sta te ){ Statu sBa rWifiVi ew view=onCreateSta tusBa rwifiV iew;view.applyWifiState;mGroup.ad dVie w);if{mDemoStatu sIi cons.ad dDemoWif iVi ew;} return view;}

五、创建窗口并将 View 注入 WindowManager

• NotificationShadeWindowView
• S ta tus Bar Window View

// framew ork/s/bas e/p ackages/Syst emU I/src/c om/a ndroid/sys temu i/st atusba r/ph o ne/St atu sb ar.j av a

public v oid cr eateA ndAd dWin dows{ // 创建 Notification Shade 窗口还有其内部视图     mak eAndA ddWi ndows;...     // 创建 State Bar 窗口     cr eateNavi gati onBat re su lt );... }

2．makeSta tusBa rView – Inflating layout 并绑定 Fragment

• inflateSta tus Ba rW indow → 加载 super_notification_shade.xml 与 status_bar.xml 两套根布局。不过，
• FragmentHostMana ger 加载 CollapsedS ta tus B arFragment。将 status_bar.xml 注入容器。

protected vo id makeStatu sb arView{ inflateStat uSBa rwindo w;// 通知面板根视窗 ...                                       // 通知面板控制器设置 …FragmentHostManag er.get .addTagListener->{ Collap sedSta tusBarrFr agme nt frag= fragment;Phon eStat usBa rView old​=​mStatus​Bal lView;​​mS tat​us​B arV​iew=frag​.g etVi ew;​，​set…，…NotificationShadeWind owVi ewCo ntroller.se­tSta tu sb arVi ew​;} ) .getFragmen tManag er.beg inTransaction .replace,Coll apse dSa t­us­b­arF rag.TAG) .commit;} )

三．inflateStat uSBa rwindo w – 构造根布局对象 “supernotificationshade” 与 “superstatusbar”

• SuperNotifi cationShadeWindowVi ew 包含 BackDrop 、多层 Scrim 、LightRevealScrim 、QS 面板等。
• SuperStatu s Ba r 包含“status_bar_launch_animation_container”“status_b ar_container” 两个占位容器。

关键 XML 示例：

• notifi cationsh ade xml —‑＞

sta tus ba rl xm l —‑＞

5．将窗口添加到 WindowManag er via LayoutParams：

• NotificationShadeWindowC ontroller.attach → TYPENOTIFICATIONSHADE 窗口类型；透明像素格式，全屏覆盖。
• Statu s Ba rWindowC ontroller.attach → TYPESTATUSBAR 窗口类型；高度为 status bar 高度；一样使用透明像素格式，

/* Notification Shade */ public vo id attac h{ lp=new LayoutPar ams;老实说，lp.gravity=Gra vity.TOP;windowM anager.a ddVie w;}

/* Status Bar */ public vo id attac h{ lp=new LayoutPar ams(ViewGr oup.LayoutPa ram.s.MATCHPA RENT,…LayoutPa rms.TYPESTATU S_BAR,…)，lp.gravity=Gra vity.TOP;windowMan ager.a ddVie w;}

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