//frameworks/base/services/java/corri/android/server/SystemServer.java

//該方法主要啟動服務(wù) ActivityManagerService，PowerManagerService，LightsService，DisplayManagerService，PackageManagerService，UserManagerService。
//設(shè)置 ActivityManagerService，啟動傳感器服務(wù)。
startBootstrapServices(); // 啟動引導(dǎo)服務(wù)

//該方法主要
//啟動服務(wù) BatteryService 用于統(tǒng)計電池電量，需要 LightService。
//啟動服務(wù) UsageStatsService，用于統(tǒng)計應(yīng)用使用情況。
//啟動服務(wù) WebViewUpdateService。
startCoreServices(); // 啟動核心服務(wù)

//該方法主要啟動服務(wù) InputManagerService，WindowManagerService。
//等待 ServiceManager，SurfaceFlinger啟動完成，然后顯示啟動界面。
//啟動服務(wù) StatusBarManagerService，
//準(zhǔn)備好 window, power, package, display 服務(wù)：
//	- WindowManagerService.systemReady()
//	- PowerManagerService.systemReady()
//	- PackageManagerService.systemReady()
//	- DisplayManagerService.systemReady()
startOtherServices(); // 啟動其他服務(wù)

 //frameworks/base/services/java/corri/android/server/SystemServer.java
 private void startBootstrapServices() {
 	...
 //這里會將ATMS注冊到ServiceManager中，然后調(diào)用ATMS的start方法。
 ActivityTaskManagerService atm = mSystemServiceManager.startService(ActivityTaskManagerService.Lifecycle.class).getService();
 //重點方法1。 注冊AMS服務(wù)，并返回對應(yīng)的對象信息
 mActivityManagerService = ActivityManagerService.Lifecycle.startService(mSystemServiceManager, atm);
 mActivityManagerService.setSystemServiceManager(mSystemServiceManager);
 //設(shè)置app安裝器
 mActivityManagerService.setInstaller(installer);
 ...
 //重點方法2。 向ServiceManager中注冊Binder服務(wù)
 mActivityManagerService.setSystemProcess();
 }

// 
	public static ActivityManagerService startService(SystemServiceManager ssm, ActivityTaskManagerService atm) {
  sAtm = atm;
  //調(diào)用SM的startService方法。創(chuàng)建AMS實例，并啟動AMS
  return ssm.startService(ActivityManagerService.Lifecycle.class).getService();
 }

//frameworks/base/services/core/java/com/android/server/SystemServiceManager.java
		public SystemService startService(String className) {
 final Class<SystemService> serviceClass;
 serviceClass = (Class<SystemService>)Class.forName(className);
 return startService(serviceClass);
 }

 @SuppressWarnings("unchecked")
 public <T extends SystemService> T startService(Class<T> serviceClass) {
 try {
  final String name = serviceClass.getName();
  final T service;
  try {
  //反射構(gòu)造函數(shù)
  Constructor<T> constructor = serviceClass.getConstructor(Context.class);
  //創(chuàng)建服務(wù)
  service = constructor.newInstance(mContext);
  ...
  //啟動服務(wù)
  startService(service);
  return service;
 } finally {
  Trace.traceEnd(Trace.TRACE_TAG_SYSTEM_SERVER);
 }
 }

 public void startService(@NonNull final SystemService service) {
 // Register it.
 //注冊到ServiceManager列表中
 mServices.add(service);
 //調(diào)用服務(wù)對應(yīng)的onStart方法
 service.onStart();
 }

 public static final class Lifecycle extends SystemService {
 private final ActivityTaskManagerService mService;
 public Lifecycle(Context context) {
  super(context);
  //創(chuàng)建AMS對象
  mService = new ActivityManagerService(context, sAtm);
 }
 @Override
 public void onStart() {
  //調(diào)用AMS的start方法
  mService.start();
 }

 public ActivityManagerService getService() {
  //返回了AMS實例
  return mService;
 }
 }

 //構(gòu)造方法，
 public ActivityManagerService(Context systemContext, ActivityTaskManagerService atm) {
 //獲取系統(tǒng)的ActivityThread
 mSystemThread = ActivityThread.currentActivityThread();
 //創(chuàng)建一個ServiceThread用來處理AMS接收到的命令
 mHandlerThread = new ServiceThread(TAG,THREAD_PRIORITY_FOREGROUND, false /*allowIo*/);
 mHandlerThread.start();
 mHandler = new MainHandler(mHandlerThread.getLooper());
 mUiHandler = mInjector.getUiHandler(this);
 //低內(nèi)存監(jiān)控
 mLowMemDetector = new LowMemDetector(this);
 //初始化廣播隊列。這里包含了前臺廣播，后臺廣播等
 mFgBroadcastQueue = new BroadcastQueue(this, mHandler, "foreground", foreConstants, false);
 mBgBroadcastQueue = new BroadcastQueue(this, mHandler, "background", backConstants, true);
 mOffloadBroadcastQueue = new BroadcastQueue(this, mHandler, "offload", offloadConstants, true);
 mBroadcastQueues[0] = mFgBroadcastQueue;
 mBroadcastQueues[1] = mBgBroadcastQueue;
 mBroadcastQueues[2] = mOffloadBroadcastQueue;
 //用于保存注冊的Service
 mServices = new ActiveServices(this);
 //map，用于保存注冊的ContentProvider
 mProviderMap = new ProviderMap(this);
 mPackageWatchdog = PackageWatchdog.getInstance(mUiContext);
 mAppErrors = new AppErrors(mUiContext, this, mPackageWatchdog);

 //創(chuàng)建 /data/system目錄
 final File systemDir = SystemServiceManager.ensureSystemDir();
 //創(chuàng)建進(jìn)程統(tǒng)計服務(wù)，保存在/data/system/proccstats目錄中。
 mProcessStats = new ProcessStatsService(this, new File(systemDir, "procstats"));
 //賦值A(chǔ)TM，并進(jìn)行初始化
 mActivityTaskManager = atm;
 mActivityTaskManager.initialize(mIntentFirewall, mPendingIntentController, DisplayThread.get().getLooper());
 //CPU追蹤器進(jìn)程
 mProcessCpuThread = new Thread("CpuTracker") {
  @Override
  public void run() {
  ...
  }
 };

 }

 private void start() {
 	 //移除所有的進(jìn)程組
 removeAllProcessGroups();
 //啟動CpuTracker線程
 mProcessCpuThread.start();
 //啟動電池統(tǒng)計服務(wù)，能夠統(tǒng)計具體的應(yīng)用的電池消耗，從而來進(jìn)行一定的電量統(tǒng)計
 mBatteryStatsService.publish();
 //創(chuàng)建LocalService，并添加到LocalServices列表中
 LocalServices.addService(ActivityManagerInternal.class, new LocalService());
 mActivityTaskManager.onActivityManagerInternalAdded();
 mUgmInternal.onActivityManagerInternalAdded();
 mPendingIntentController.onActivityManagerInternalAdded();
 }

 public void setSystemProcess() {
 try {
 	//注冊ActivityService服務(wù)
  ServiceManager.addService(Context.ACTIVITY_SERVICE, this, /* allowIsolated= */ true,
   DUMP_FLAG_PRIORITY_CRITICAL | DUMP_FLAG_PRIORITY_NORMAL | DUMP_FLAG_PROTO);
  //注冊進(jìn)程狀態(tài)服務(wù)
  ServiceManager.addService(ProcessStats.SERVICE_NAME, mProcessStats);
  //注冊內(nèi)存Binder
  ServiceManager.addService("meminfo", new MemBinder(this), /* allowIsolated= */ false,DUMP_FLAG_PRIORITY_HIGH);
  //注冊圖像Binder
  ServiceManager.addService("gfxinfo", new GraphicsBinder(this));
  //注冊SQLite DB binder
  ServiceManager.addService("dbinfo", new DbBinder(this));
  if (MONITOR_CPU_USAGE) {
  	//注冊CPU使用情況的Binder
  ServiceManager.addService("cpuinfo", new CpuBinder(this),/* allowIsolated= */ false, DUMP_FLAG_PRIORITY_CRITICAL);
  }
  //注冊權(quán)限控制Binder
  ServiceManager.addService("permission", new PermissionController(this));
  //注冊進(jìn)程管理Binder
  ServiceManager.addService("processinfo", new ProcessInfoService(this));
  //獲取“android”應(yīng)用的ApplicationInfo，并裝載到mSystemThread
  ApplicationInfo info = mContext.getPackageManager().getApplicationInfo("android", STOCK_PM_FLAGS | MATCH_SYSTEM_ONLY);
  mSystemThread.installSystemApplicationInfo(info, getClass().getClassLoader());
  //創(chuàng)建ProcessRecord維護(hù)進(jìn)程的相關(guān)信息
  synchronized (this) {
  ProcessRecord app = mProcessList.newProcessRecordLocked(info, info.processName,...);
  app.setPersistent(true);
  app.pid = MY_PID;
  app.getWindowProcessController().setPid(MY_PID);
  app.maxAdj = ProcessList.SYSTEM_ADJ;
  app.makeActive(mSystemThread.getApplicationThread(), mProcessStats);
  mPidsSelfLocked.put(app);
  mProcessList.updateLruProcessLocked(app, false, null);
  updateOomAdjLocked(OomAdjuster.OOM_ADJ_REASON_NONE);
  }
 } catch (PackageManager.NameNotFoundException e) {
  throw new RuntimeException(
   "Unable to find android system package", e);
 }
 }

 private void startOtherServices() {
  //注冊系統(tǒng)的ContentProvider信息
  mActivityManagerService.installSystemProviders();
 
  mActivityManagerService.setWindowManager(wm);
  	mActivityManagerService.systemReady(() -> {
  ......//goingCallback
  }, BOOT_TIMINGS_TRACE_LOG);
 }

 mActivityManagerService.systemReady(() -> {
  try {
  //啟動NativeCrash的監(jiān)測
  mActivityManagerService.startObservingNativeCrashes();
  } catch (Throwable e) {
  reportWtf("observing native crashes", e);
  }
  if (!mOnlyCore && mWebViewUpdateService != null) {
  webviewPrep = SystemServerInitThreadPool.get().submit(() -> {
   //啟動WebView相關(guān)
   mWebViewUpdateService.prepareWebViewInSystemServer();
  }, WEBVIEW_PREPARATION);
  }

  try {
  //啟動systemUI
  startSystemUi(context, windowManagerF);
  } catch (Throwable e) {
  reportWtf("starting System UI", e);
  }
  ...
 }