SystemUI-StatusBar启动过程简单分析
SystemUI的启动
SystemUI本质上是一个app，在系统中对应的源码路径为：
frameworks/base/packages/SystemUI
在源码中编译后会生成
out/target/product/product_name/system/priv-app/SystemUI/SystemUI.apk。
在system/priv-app下意味着SystemUI开机就会被安装，SystemUI并不是自己启动的，它是在SystemServer进程创建过程中被开启的，SystemServer进程启动时会启动各种系统服务（如AMS、PMS等）SystemUI的启动就在这一流程中，下面以源码中流程代码来分析这一启动过程：
以下源码基于MT2712 MR2004 Android9.0版本源码，流程代码中省略了一些内容
platform/frameworks/base/services/java/com/android/server/SystemServer.java
public final class SystemServer {
....
// SystemServer进程启动入口
public static void main(String[] args) {
new SystemServer().run();
}
private void run() {
....
// 启动各种系统服务
try {
startBootstrapServices();
startCoreServices();
// SystemUI的启动在其他服务的启动过程中
startOtherServices();
SystemServerInitThreadPool.shutdown();
} catch (Throwable ex) {
....
} finally {
traceEnd();
}
....
// Loop forever.
Looper.loop();
}
....
private void startOtherServices() {
....
final WindowManagerService windowManagerF1 = wm;
traceBeginAndSlog("StartSystemUI");
try {
// 启动SystemUI入口
startSystemUi(context, windowManagerF1);
} catch (Throwable e) {
reportWtf("starting System UI", e);
}
....
}
static final void startSystemUi(Context context, WindowManagerService windowManager) {
Intent intent = new Intent();
intent.setComponent(new ComponentName("com.android.systemui",
"com.android.systemui.SystemUIService"));
intent.addFlags(Intent.FLAG_DEBUG_TRIAGED_MISSING);
context.startServiceAsUser(intent, UserHandle.SYSTEM);
windowManager.onSystemUiStarted();
}
}
通过最后调用到的startSystemUi可以看出，最后通过创建Intent，启动SystemUIService。
SystemUI的加载
这里进入frameworks/basepackages/SystemUI/src/com/android/systemui/SystemUIService.java源码中查看启动后执行了什么
public class SystemUIService extends Service {
@Override
public void onCreate() {
super.onCreate();
((SystemUIApplication) getApplication()).startServicesIfNeeded();
....
}
}
在onCreate中获取了SystemUIApplication并调用了其startServicesIfNeeded方法
platform/frameworks/base/packages/SystemUI/src/com/android/systemui/SystemUIApplication.java
public class SystemUIApplication extends Application implements SysUiServiceProvider {
....
public void startServicesIfNeeded() {
String[] names = getResources().getStringArray(R.array.config_systemUIServiceComponents);
startServicesIfNeeded(names);
}
private void startServicesIfNeeded(String[] services) {
if (mServicesStarted) {
return;
}
mServices = new SystemUI[services.length];
....
final int N = services.length;
for (int i = 0; i < N; i++) {
String clsName = services[i];
....
Class cls;
try {
// 通过反射调组件类启动
cls = Class.forName(clsName);
mServices[i] = (SystemUI) cls.newInstance();
} catch(ClassNotFoundException ex){
throw new RuntimeException(ex);
} catch (IllegalAccessException ex) {
throw new RuntimeException(ex);
} catch (InstantiationException ex) {
throw new RuntimeException(ex);
}
mServices[i].mContext = this;
mServices[i].mComponents = mComponents;
mServices[i].start();
....
if (mBootCompleted) {
mServices[i].onBootCompleted();
}
}
....
mServicesStarted = true;
}
}
在方法内创建了一个字符数组names，读取res/values/config.xml文件中定义的数组config_systemUIServiceComponents里面包含了各种SystemUI的各个组件和服务类的完整路径，之后通过循环和反射调用各个组件的start方法，并将它们放入一个SystemUI数组管理；
- com.android.systemui.Dependency
- com.android.systemui.Dependency
- com.android.systemui.util.NotificationChannels
- com.android.systemui.statusbar.CommandQueue$CommandQueueStart
- com.android.systemui.keyguard.KeyguardViewMediator
- com.android.systemui.SystemBars
- com.android.systemui.volume.VolumeUI
- com.android.systemui.usb.StorageNotification
- com.android.systemui.power.PowerUI
- com.android.systemui.media.RingtonePlayer
- com.android.systemui.keyboard.KeyboardUI
- com.android.systemui.pip.PipUI
- com.android.systemui.shortcut.ShortcutKeyDispatcher
- @string/config_systemUIVendorServiceComponent
- com.android.systemui.util.leak.GarbageMonitor$Service
- com.android.systemui.LatencyTester
- com.android.systemui.globalactions.GlobalActionsComponent
- com.android.systemui.ScreenDecorations
- com.android.systemui.fingerprint.FingerprintDialogImpl
- com.android.systemui.SliceBroadcastRelayHandler
这里分析以com.android.systemui.SystemBars为主。
StatusBars的加载
platform/frameworks/base/packages/SystemUI/src/com/android/systemui/SystemBars.java
public class SystemBars extends SystemUI {
....
@Override
public void start() {
createStatusBarFromConfig();
}
....
private void createStatusBarFromConfig() {
// 读取res/values/config.xml获取config_statusBarComponent属性
// 这里读到的时com.android.systemui.statusbar.phone.StatusBar
final String clsName = mContext.getString(R.string.config_statusBarComponent);
....
Class cls = null;
try {
cls = mContext.getClassLoader().loadClass(clsName);
} catch (Throwable t) {
throw andLog("Error loading status bar component: " + clsName, t);
}
try {
mStatusBar = (SystemUI) cls.newInstance();
} catch (Throwable t) {
throw andLog("Error creating status bar component: " + clsName, t);
}
mStatusBar.mContext = mContext;
mStatusBar.mComponents = mComponents;
mStatusBar.start();
}
}
这里与上衣过程类似，也是从config.xml文件中读取一个完整路径，然后通过反射调用其start方法，这里调用到StatusBar.java类的start方法。
platform/frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/StatusBar.java
public class StatusBar extends SystemUI implements DemoMode,
DragDownHelper.DragDownCallback, ActivityStarter, OnUnlockMethodChangedListener,
OnHeadsUpChangedListener, CommandQueue.Callbacks, ZenModeController.Callback,
ColorExtractor.OnColorsChangedListener, ConfigurationListener, NotificationPresenter {
....
protected StatusBarWindowView mStatusBarWindow;
protected StatusBarWindowManager mStatusBarWindowManager;
@Override
public void start() {
....
mWindowManager = (WindowManager) mContext.getSystemService(Context.WINDOW_SERVICE);
mDisplay = mWindowManager.getDefaultDisplay();
updateDisplaySize();
....
// 1.这里开始加载StatusBar布局并添加到界面上
createAndAddWindows();
....
}
public void createAndAddWindows() {
// 2
addStatusBarWindow();
}
private void addStatusBarWindow() {
// 3.构造SatusBarView
makeStatusBarView();
....
// 6.将mStatusBarWindow加载到系统界面上
// getStatusBarHeight()对应的高度值在下方的updateResources()内进行加载
mStatusBarWindowManager.add(mStatusBarWindow, getStatusBarHeight());
}
protected void makeStatusBarView() {
....
updateResources();//包含一些状态栏高度等资源的加载
....
// 4.通过inflate将布局加载给mStatusBarWindow
inflateStatusBarWindow();
// 5.将CollapsedStatusBarFragment加载进mStatusBarWindow，对应的就是显示在顶部的状态栏
FragmentHostManager.get(mStatusBarWindow)
.addTagListener(CollapsedStatusBarFragment.TAG, (tag, fragment) -> {
CollapsedStatusBarFragment statusBarFragment =
(CollapsedStatusBarFragment) fragment;
statusBarFragment.initNotificationIconArea(mNotificationIconAreaController);
mStatusBarView = (PhoneStatusBarView) fragment.getView();
// mStatusBarView的一些设置
....
setAreThereNotifications();
checkBarModes();
}).getFragmentManager()
.beginTransaction()
.replace(R.id.status_bar_container, new CollapsedStatusBarFragment(),
CollapsedStatusBarFragment.TAG)
.commit();
....
}
protected void inflateStatusBarWindow(Context context) {
mStatusBarWindow = (StatusBarWindowView) View.inflate(context,
R.layout.super_status_bar, null);
}
}
针对StatusBar，当我们调用StatusBar的start方法后，我们会加载状态栏的一些资源（如高度），之后通过inflate将super_status_bar.xml对应的布局加载给mStatusBarWindow对象；
在super_status_bar.xml布局文件中有一个status_bar_container的FrameLayout，之后会被用来放置CollapsedStatusBarFragment,这里存放了众多的状态栏View。这一步完成后就会将将mStatusBarWindow加载到系统界面上
StatusBar加载到系统界面
StatusBar通过StatusBarWindowManager.add加载到系统界面上，具体的源码如下：
platform/frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/StatusBarWindowManager.java
/**
* 将状态栏视图添加到WindowMangager。
*
* @param statusBarView
* @param barHeight 折叠状态下状态栏高度
*/
public void add(View statusBarView, int barHeight) {
mWindowManager.getDefaultDisplay().getSize(mPoint);
int navigationbarWidth = getNavigationBarWidth();
mLp = new WindowManager.LayoutParams(
mPoint.x - navigationbarWidth,
barHeight,
navigationbarWidth,
0,
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
| WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS,
PixelFormat.TRANSLUCENT);
mLp.token = new Binder();
mLp.gravity = Gravity.TOP;
mLp.softInputMode = WindowManager.LayoutParams.SOFT_INPUT_ADJUST_RESIZE;
mLp.setTitle("StatusBar");
mLp.packageName = mContext.getPackageName();
mLp.layoutInDisplayCutoutMode = LAYOUT_IN_DISPLAY_CUTOUT_MODE_ALWAYS;
mStatusBarView = statusBarView;
mBarHeight = barHeight;
mWindowManager.addView(mStatusBarView, mLp);
mLpChanged = new WindowManager.LayoutParams();
mLpChanged.copyFrom(mLp);
}
这里传入的mStatusBarWindow就通过WindowManager加载到相应的位置上了。
CollapsedStatusBarFragment扩展学习记录
这里展示CollapsedStatusBarFragment的两个生命周期。这里包含了布局和显示内容的加载
frameworks/base、packages/SystemUI/src/com/android/systemui/statusbar/phone/CollapsedStatusBarFragment.java
public class CollapsedStatusBarFragment extends Fragment implements CommandQueue.Callbacks {
....
private PhoneStatusBarView mStatusBar;
private KeyguardMonitor mKeyguardMonitor;
private NetworkController mNetworkController;
private StatusBar mStatusBarComponent;
....
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container,
Bundle savedInstanceState) {
// 加载布局status_bar.xml
return inflater.inflate(R.layout.status_bar, container, false);
}
@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
mStatusBar = (PhoneStatusBarView) view;
if (savedInstanceState != null && savedInstanceState.containsKey(EXTRA_PANEL_STATE)) {
mStatusBar.go(savedInstanceState.getInt(EXTRA_PANEL_STATE));
}
mDarkIconManager = new DarkIconManager(view.findViewById(R.id.statusIcons));
mDarkIconManager.setShouldLog(true);
Dependency.get(StatusBarIconController.class).addIconGroup(mDarkIconManager);
// 用来显示状态栏图标的区域（(蓝牙、wifi、VPN、网卡、SIM卡信号、飞行模式等) 电池）
mSystemIconArea = mStatusBar.findViewById(R.id.system_icon_area);
mClockView = mStatusBar.findViewById(R.id.clock);
showSystemIconArea(false);
showClock(false);
initEmergencyCryptkeeperText();
initOperatorName();
}
}
CollapsedStatusBarFragment内还有一些Notification相关的内容，之后有时间再
graph LR
A-->B
继续分析。