Android系统之System Server大纲
16lz
2021-01-23
Android系统之System Server大纲
System Server content
- Android系统之System Server大纲
- 前言
- System server概要
- System server启动的入口
- System server启动的过程
- 总结
前言
System Server是android 基本服务的提供者，是android系统运行的最基本需求，所有server运行在一个叫system_process的进程中，system_process进程是android java虚拟机跑的第一个进程，从Zygote 创建而来，是andorid系统最重要的java虚拟机。可以说，整个android系统的业务都是围绕system server而展开，所以，当system_process死掉了，手机必须重启。
System server概要
System server主要包含以下服务：
- 1、 EntropyService， 熵服务，用于产生随机数；
- 2、 PowerManagerService， 电源管理服务；
- 3、 ActivityMangerService Activity，管理服务；
- 4、 TelephonyRegistry， 电话服务，电话底层通知服务；
- 5、 PackageManagerService， 程序包管理服务；
- 6、 AccountManagerService， 联系人账户管理服务；
- 7、 ContentService， 内容提供器服务，提供跨进程数据交换；
- 8、 LightService， 光感应传感器服务；
- 9、 BatteryService，电池服务；
- 10、 VibrateService，震动器服务；
- 11、 AlarmManagerService，闹钟服务；
- 12、 WindowManagerService，窗口管理服务；
- 13、 BluetoothService，蓝牙服务；
- 14、 InputMethodManagerService，输入法服务；
- 15、 AccessibilityManagerService， 辅助器管理程序服务；
- 16、 DevicePolicyManagerService，提供系统级别的设置及属性；
- 17、 StatusBarManagerService，状态栏管理服务；
- 18、 ClipboardService，粘贴板服务；
- 19、 NetworkManagerService，网络管理服务；
- 20、 TextServicesManagerService，用户管理服务；
- 21、 NetworkStatsService，手机网络状态服务；
- 22、 NetworkPolicyManagerService，low-level网络策略服务；
- 23、 WifiP2pService，Wifi点对点服务；
- 24、 WifiService，Wifi服务；
- 25、 ConnectivityService，网络连接状态服务；
- 26、 MountService，磁盘加载服务；
- 27、 NotificationManagerService，通知管理服务；
- 28、 DeviceStorageMonitorService，存储设备容量监听服务；
- 29、 LocationManagerService，位置管理服务；
- 30、 CountryDetectorService，检查用户当前所在国家服务；
- 31、 SearchManagerService，搜索管理服务；
- 32、 DropBoxManagerService，系统日志文件管理服务；
- 33、 WallpaperManagerService，壁纸管理服务；
- 34、 AudioService，AudioFlinger上层封装音频管理服务；
- 35、 UsbService，USB Host 和 device管理服务；
- 36、 UiModeManagerService，UI模式管理服务；
- 37、 BackupManagerService，备份服务；
- 38、 AppWidgetService，应用桌面部件服务；
- 39、 RecognitionManagerService，身份识别服务；
- 40、 DiskStatsService，磁盘统计服务；
- 41、 SamplingProfilerService，性能统计服务；
- 42、 NetworkTimeUpdateService，网络时间更新服务；
- 43、 InputManagerService，输入管理服务；
- 44、 FingerprintService，指纹服务；
- 45、 DreamManagerService， dreams服务；
- 46、 HdmiControlService， HDMI控制服务；
- 47、 SsvService，SIM卡状态和转换服务；
以上所列系统服务不代表最新Android系统的所有系统服务。
System server启动的入口
这些服务那么重要，它们什么时候启动？都做了些什么事情？等等这些问题是本文以及大纲下面的文章将会一一道来。
了解这些系统服务之前，先来了解一个重量级的超级类SystemServer.java， 这个类在AOSP中的路径是：frameworks/base/services/java/com/android/server/SystemServer.java，在上文中提到，从Zygote创建system_process进程时，便实例化了该类。熟悉java的开发者都知道，启动某个java程序时，最先调用的就是声明了main()方法的类。所以SystemServer.java被实例化后，便调用了main()方法。首先看看SystemServer.java的构造方法：
public SystemServer() { // Check for factory test mode. mFactoryTestMode = FactoryTest.getMode();}构造方法里面只做了从属性系统中读取了工厂测试模式，这个不在本文以及本大纲的文章中赘述的内容，这里就不在叙述了。
下面直接进入main()方法：
public static void main(String[] args) { new SystemServer().run();} 直接调用了类内的run()方法，继续跟踪：
private void run() { try { // AndroidRuntime using the same set of system properties, but only the system_server // Initialize the system context. createSystemContext(); // Create the system service manager. mSystemServiceManager = new SystemServiceManager(mSystemContext); LocalServices.addService(SystemServiceManager.class, mSystemServiceManager); } finally { Trace.traceEnd(Trace.TRACE_TAG_SYSTEM_SERVER); } // Start services. try { Trace.traceBegin(Trace.TRACE_TAG_SYSTEM_SERVER, "StartServices"); startBootstrapServices(); startCoreServices(); startOtherServices(); } catch (Throwable ex) { Slog.e("System", "******************************************"); Slog.e("System", "************ Failure starting system services", ex); throw ex; } finally { Trace.traceEnd(Trace.TRACE_TAG_SYSTEM_SERVER); } .....}上述代码中，首先创建一个system context，这个对象在整个system server中使用非常频繁。接着创建一个SystemServiceManager.java的实例，顾名思义就是SystemService的管理者，管理所有的SystemService。代码中把接着创建一个SystemServiceManager的实例通过LocalServices.addService(SystemServiceManager.class, mSystemServiceManager)语句设置到LocalService中，LocalServices的功能类似SystemServiceManager，不同点在于LocalServices专门用来管理system_process进程中的SystemService，也就没有真正的跨进程通信，也就没有Binder对象。
System server启动的过程
接着就是启动各种系统服务，在这里分三种类型的SystemService，依次启动，分别对应三个方法：
startBootstrapServices(); startCoreServices(); startOtherServices();这三个方法的顺序不能混乱，一定要按照上述顺序依次执行，先看startBootstrapServices()中启动了那些系统服务
private void startBootstrapServices() { Installer installer = mSystemServiceManager.startService(Installer.class); // Activity manager runs the show. mActivityManagerService = mSystemServiceManager.startService( ActivityManagerService.Lifecycle.class).getService(); mActivityManagerService.setSystemServiceManager(mSystemServiceManager); mActivityManagerService.setInstaller(installer); mPowerManagerService = mSystemServiceManager.startService(PowerManagerService.class); Trace.traceBegin(Trace.TRACE_TAG_SYSTEM_SERVER, "InitPowerManagement"); mActivityManagerService.initPowerManagement(); Trace.traceEnd(Trace.TRACE_TAG_SYSTEM_SERVER); // Manages LEDs and display backlight so we need it to bring up the display. mSystemServiceManager.startService(LightsService.class); // Display manager is needed to provide display metrics before package manager // starts up. mDisplayManagerService = mSystemServiceManager.startService(DisplayManagerService.class); // We need the default display before we can initialize the package manager. mSystemServiceManager.startBootPhase(SystemService.PHASE_WAIT_FOR_DEFAULT_DISPLAY); ...... // Start the package manager. ..... traceBeginAndSlog("StartUserManagerService"); mSystemServiceManager.startService(UserManagerService.LifeCycle.class); ......}上述代码可以看到，这里启动了
- Installer
- ActivityManagerService.Lifecycle
- PowerManagerService
- LightsService
- DisplayManagerService
- UserManagerService
启动这些SystemService都是通过SystemServiceManager的startService()的方式启动，启动完成后会回调SystemService的onStart()方法。
继续看第二个方法startCoreServices()启动了那些系统服务
private void startCoreServices() { // Tracks the battery level. Requires LightService. mSystemServiceManager.startService(BatteryService.class); // Tracks application usage stats. mSystemServiceManager.startService(UsageStatsService.class); mActivityManagerService.setUsageStatsManager( LocalServices.getService(UsageStatsManagerInternal.class)); // Tracks whether the updatable WebView is in a ready state and watches for update installs. mWebViewUpdateService = mSystemServiceManager.startService(WebViewUpdateService.class);}startCoreServices()中启动了
- BatteryService
- UsageStatsService
- WebViewUpdateService
上文中提到，startBootstrapServices()必须在startCoreServices()前面执行，这里就能找到一个原因，startCoreServices()中用到mActivityManagerService对象，而该对象在startBootstrapServices()中被实例化，如果先调用startCoreServices()，mActivityManagerService对象便会发生NullPointerException的RuntimeException异常。
接着就是startOtherServices()中启动的service了，先看代码
private void startOtherServices() { try { ServiceManager.addService("scheduling_policy", new SchedulingPolicyService()); mSystemServiceManager.startService(TelecomLoaderService.class); traceBeginAndSlog("StartTelephonyRegistry"); telephonyRegistry = new TelephonyRegistry(context); ServiceManager.addService("telephony.registry", telephonyRegistry); Trace.traceEnd(Trace.TRACE_TAG_SYSTEM_SERVER); mEntropyMixer = new EntropyMixer(context); mContentResolver = context.getContentResolver(); mSystemServiceManager.startService(CameraService.class); mSystemServiceManager.startService(ACCOUNT_SERVICE_CLASS); mSystemServiceManager.startService(CONTENT_SERVICE_CLASS); mActivityManagerService.installSystemProviders(); vibrator = new VibratorService(context); ServiceManager.addService("vibrator", vibrator); consumerIr = new ConsumerIrService(context); ServiceManager.addService(Context.CONSUMER_IR_SERVICE, consumerIr); mSystemServiceManager.startService(AlarmManagerService.class); final Watchdog watchdog = Watchdog.getInstance(); watchdog.init(context, mActivityManagerService); traceBeginAndSlog("StartInputManagerService"); inputManager = new InputManagerService(context); Trace.traceEnd(Trace.TRACE_TAG_SYSTEM_SERVER); wm = WindowManagerService.main(context, inputManager, mFactoryTestMode != FactoryTest.FACTORY_TEST_LOW_LEVEL, !mFirstBoot, mOnlyCore); ServiceManager.addService(Context.WINDOW_SERVICE, wm); ServiceManager.addService(Context.INPUT_SERVICE, inputManager); mSystemServiceManager.startService(VrManagerService.class); mActivityManagerService.setWindowManager(wm); inputManager.setWindowManagerCallbacks(wm.getInputMonitor()); inputManager.start(); // TODO: Use service dependencies instead. mDisplayManagerService.windowManagerAndInputReady(); ..... mSystemServiceManager.startService(BluetoothService.class); ..... mSystemServiceManager.startService(MetricsLoggerService.class); mSystemServiceManager.startService(PinnerService.class); } catch (RuntimeException e) { } // Bring up services needed for UI. if (mFactoryTestMode != FactoryTest.FACTORY_TEST_LOW_LEVEL) { mSystemServiceManager.startService(InputMethodManagerService.Lifecycle.class); traceBeginAndSlog("StartAccessibilityManagerService"); try { ServiceManager.addService(Context.ACCESSIBILITY_SERVICE, new AccessibilityManagerService(context)); } catch (Throwable e) { } } if (mFactoryTestMode != FactoryTest.FACTORY_TEST_LOW_LEVEL) { if (!disableStorage && !"0".equals(SystemProperties.get("system_init.startmountservice"))) { try { mSystemServiceManager.startService(MOUNT_SERVICE_CLASS); mountService = IMountService.Stub.asInterface( ServiceManager.getService("mount")); } catch (Throwable e) { reportWtf("starting Mount Service", e); } } } mSystemServiceManager.startService(UiModeManagerService.class); ..... if (mFactoryTestMode != FactoryTest.FACTORY_TEST_LOW_LEVEL) { if (!disableNonCoreServices) { try { mSystemServiceManager.startService(LOCK_SETTINGS_SERVICE_CLASS); lockSettings = ILockSettings.Stub.asInterface( ServiceManager.getService("lock_settings")); } catch (Throwable e) { } if (!SystemProperties.get(PERSISTENT_DATA_BLOCK_PROP).equals("")) { mSystemServiceManager.startService(PersistentDataBlockService.class); } mSystemServiceManager.startService(DeviceIdleController.class); mSystemServiceManager.startService(DevicePolicyManagerService.Lifecycle.class); } if (!disableSystemUI) { try { statusBar = new StatusBarManagerService(context, wm); ServiceManager.addService(Context.STATUS_BAR_SERVICE, statusBar); } catch (Throwable e) { } } if (!disableNonCoreServices) { try { ServiceManager.addService(Context.CLIPBOARD_SERVICE, new ClipboardService(context)); } catch (Throwable e) { } } if (!disableNetwork) { try { networkManagement = NetworkManagementService.create(context); ServiceManager.addService(Context.NETWORKMANAGEMENT_SERVICE, networkManagement); } catch (Throwable e) { } } if (!disableNonCoreServices && !disableTextServices) { mSystemServiceManager.startService(TextServicesManagerService.Lifecycle.class); } if (!disableNetwork) { traceBeginAndSlog("StartNetworkScoreService"); try { networkScore = new NetworkScoreService(context); ServiceManager.addService(Context.NETWORK_SCORE_SERVICE, networkScore); } catch (Throwable e) { } try { networkStats = NetworkStatsService.create(context, networkManagement); ServiceManager.addService(Context.NETWORK_STATS_SERVICE, networkStats); } catch (Throwable e) { } try { networkPolicy = new NetworkPolicyManagerService( context, mActivityManagerService, (IPowerManager)ServiceManager.getService(Context.POWER_SERVICE), networkStats, networkManagement); ServiceManager.addService(Context.NETWORK_POLICY_SERVICE, networkPolicy); } catch (Throwable e) { } if (context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_WIFI_NAN)) { mSystemServiceManager.startService(WIFI_NAN_SERVICE_CLASS); } else { Slog.i(TAG, "No Wi-Fi NAN Service (NAN support Not Present)"); } mSystemServiceManager.startService(WIFI_P2P_SERVICE_CLASS); mSystemServiceManager.startService(WIFI_SERVICE_CLASS); mSystemServiceManager.startService( "com.android.server.wifi.scanner.WifiScanningService"); if (!disableRtt) { mSystemServiceManager.startService("com.android.server.wifi.RttService"); } if (mPackageManager.hasSystemFeature(PackageManager.FEATURE_ETHERNET) || mPackageManager.hasSystemFeature(PackageManager.FEATURE_USB_HOST)) { mSystemServiceManager.startService(ETHERNET_SERVICE_CLASS); } traceBeginAndSlog("StartConnectivityService"); try { connectivity = new ConnectivityService( context, networkManagement, networkStats, networkPolicy); ServiceManager.addService(Context.CONNECTIVITY_SERVICE, connectivity); networkStats.bindConnectivityManager(connectivity); networkPolicy.bindConnectivityManager(connectivity); } catch (Throwable e) { } try { serviceDiscovery = NsdService.create(context); ServiceManager.addService( Context.NSD_SERVICE, serviceDiscovery); } catch (Throwable e) { reportWtf("starting Service Discovery Service", e); } if (!disableNonCoreServices) { try { ServiceManager.addService(Context.UPDATE_LOCK_SERVICE, new UpdateLockService(context)); } catch (Throwable e) { } } if (!disableNonCoreServices) { mSystemServiceManager.startService(RecoverySystemService.class); } ...... mSystemServiceManager.startService(NotificationManagerService.class); notification = INotificationManager.Stub.asInterface( ServiceManager.getService(Context.NOTIFICATION_SERVICE)); networkPolicy.bindNotificationManager(notification); mSystemServiceManager.startService(DeviceStorageMonitorService.class); if (!disableLocation) { try { location = new LocationManagerService(context); ServiceManager.addService(Context.LOCATION_SERVICE, location); } catch (Throwable e) { } try { countryDetector = new CountryDetectorService(context); ServiceManager.addService(Context.COUNTRY_DETECTOR, countryDetector); } catch (Throwable e) { } } if (!disableNonCoreServices && !disableSearchManager) { traceBeginAndSlog("StartSearchManagerService"); try { mSystemServiceManager.startService(SEARCH_MANAGER_SERVICE_CLASS); } catch (Throwable e) { } } mSystemServiceManager.startService(DropBoxManagerService.class); if (!disableNonCoreServices && context.getResources().getBoolean( R.bool.config_enableWallpaperService)) { mSystemServiceManager.startService(WALLPAPER_SERVICE_CLASS); } mSystemServiceManager.startService(AudioService.Lifecycle.class); if (!disableNonCoreServices) { mSystemServiceManager.startService(DockObserver.class); if (context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_WATCH)) { mSystemServiceManager.startService(THERMAL_OBSERVER_CLASS); } } try { // Listen for wired headset changes inputManager.setWiredAccessoryCallbacks( new WiredAccessoryManager(context, inputManager)); } catch (Throwable e) { } if (!disableNonCoreServices) { if (mPackageManager.hasSystemFeature(PackageManager.FEATURE_MIDI)) { // Start MIDI Manager service mSystemServiceManager.startService(MIDI_SERVICE_CLASS); } if (mPackageManager.hasSystemFeature(PackageManager.FEATURE_USB_HOST) || mPackageManager.hasSystemFeature( PackageManager.FEATURE_USB_ACCESSORY)) { mSystemServiceManager.startService(USB_SERVICE_CLASS); } if (!disableSerial) { try { // Serial port support serial = new SerialService(context); ServiceManager.addService(Context.SERIAL_SERVICE, serial); } catch (Throwable e) { } } "StartHardwarePropertiesManagerService"); try { hardwarePropertiesService = new HardwarePropertiesManagerService(context); ServiceManager.addService(Context.HARDWARE_PROPERTIES_SERVICE, hardwarePropertiesService); } catch (Throwable e) { Slog.e(TAG, "Failure starting HardwarePropertiesManagerService", e); } } mSystemServiceManager.startService(TwilightService.class); mSystemServiceManager.startService(JobSchedulerService.class); mSystemServiceManager.startService(SoundTriggerService.class); if (!disableNonCoreServices) { if (mPackageManager.hasSystemFeature(PackageManager.FEATURE_BACKUP)) { mSystemServiceManager.startService(BACKUP_MANAGER_SERVICE_CLASS); } if (mPackageManager.hasSystemFeature(PackageManager.FEATURE_APP_WIDGETS) || context.getResources().getBoolean(R.bool.config_enableAppWidgetService)) { mSystemServiceManager.startService(APPWIDGET_SERVICE_CLASS); } if (mPackageManager.hasSystemFeature(PackageManager.FEATURE_VOICE_RECOGNIZERS)) { mSystemServiceManager.startService(VOICE_RECOGNITION_MANAGER_SERVICE_CLASS); } if (GestureLauncherService.isGestureLauncherEnabled(context.getResources())) { Slog.i(TAG, "Gesture Launcher Service"); mSystemServiceManager.startService(GestureLauncherService.class); } mSystemServiceManager.startService(SensorNotificationService.class); mSystemServiceManager.startService(ContextHubSystemService.class); } try { ServiceManager.addService("diskstats", new DiskStatsService(context)); } catch (Throwable e) { } if (!disableSamplingProfiler) { traceBeginAndSlog("StartSamplingProfilerService"); try { ServiceManager.addService("samplingprofiler", new SamplingProfilerService(context)); } catch (Throwable e) { } } if (!disableNetwork && !disableNetworkTime) { traceBeginAndSlog("StartNetworkTimeUpdateService"); try { networkTimeUpdater = new NetworkTimeUpdateService(context); ServiceManager.addService("network_time_update_service", networkTimeUpdater); } catch (Throwable e) { } } traceBeginAndSlog("StartCommonTimeManagementService"); try { commonTimeMgmtService = new CommonTimeManagementService(context); ServiceManager.addService("commontime_management", commonTimeMgmtService); } catch (Throwable e) { } Trace.traceEnd(Trace.TRACE_TAG_SYSTEM_SERVER); if (!disableNetwork) { try { CertBlacklister blacklister = new CertBlacklister(context); } catch (Throwable e) { } } if (!disableNonCoreServices) { mSystemServiceManager.startService(DreamManagerService.class); } if (!disableNonCoreServices && ZygoteInit.PRELOAD_RESOURCES) { traceBeginAndSlog("StartAssetAtlasService"); try { atlas = new AssetAtlasService(context); ServiceManager.addService(AssetAtlasService.ASSET_ATLAS_SERVICE, atlas); } catch (Throwable e) { } } if (!disableNonCoreServices) { ServiceManager.addService(GraphicsStatsService.GRAPHICS_STATS_SERVICE, new GraphicsStatsService(context)); } if (mPackageManager.hasSystemFeature(PackageManager.FEATURE_PRINTING)) { mSystemServiceManager.startService(PRINT_MANAGER_SERVICE_CLASS); } mSystemServiceManager.startService(RestrictionsManagerService.class); mSystemServiceManager.startService(MediaSessionService.class); if (mPackageManager.hasSystemFeature(PackageManager.FEATURE_HDMI_CEC)) { mSystemServiceManager.startService(HdmiControlService.class); } if (mPackageManager.hasSystemFeature(PackageManager.FEATURE_LIVE_TV)) { mSystemServiceManager.startService(TvInputManagerService.class); } if (mPackageManager.hasSystemFeature(PackageManager.FEATURE_PICTURE_IN_PICTURE)) { mSystemServiceManager.startService(MediaResourceMonitorService.class); } if (mPackageManager.hasSystemFeature(PackageManager.FEATURE_LEANBACK)) { mSystemServiceManager.startService(TvRemoteService.class); } if (!disableNonCoreServices) { traceBeginAndSlog("StartMediaRouterService"); try { mediaRouter = new MediaRouterService(context); ServiceManager.addService(Context.MEDIA_ROUTER_SERVICE, mediaRouter); } catch (Throwable e) { } if (!disableTrustManager) { mSystemServiceManager.startService(TrustManagerService.class); } if (mPackageManager.hasSystemFeature(PackageManager.FEATURE_FINGERPRINT)) { mSystemServiceManager.startService(FingerprintService.class); } } // LauncherAppsService uses ShortcutService. mSystemServiceManager.startService(ShortcutService.Lifecycle.class); mSystemServiceManager.startService(LauncherAppsService.class); } if (!disableNonCoreServices && !disableMediaProjection) { mSystemServiceManager.startService(MediaProjectionManagerService.class); } if (context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_WATCH)) { mSystemServiceManager.startService(WEAR_BLUETOOTH_SERVICE_CLASS); } mmsService = mSystemServiceManager.startService(MmsServiceBroker.class); // It is now time to start up the app processes... try { vibrator.systemReady(); } catch (Throwable e) { } if (lockSettings != null) { try { lockSettings.systemReady(); } catch (Throwable e) { } } // Needed by DevicePolicyManager for initialization mSystemServiceManager.startBootPhase(SystemService.PHASE_LOCK_SETTINGS_READY); mSystemServiceManager.startBootPhase(SystemService.PHASE_SYSTEM_SERVICES_READY); Trace.traceBegin(Trace.TRACE_TAG_SYSTEM_SERVER, "MakeWindowManagerServiceReady"); try { wm.systemReady(); } catch (Throwable e) { } try { // TODO: use boot phase mPowerManagerService.systemReady(mActivityManagerService.getAppOpsService()); } catch (Throwable e) { } try { mPackageManagerService.systemReady(); } catch (Throwable e) { } try { // TODO: use boot phase and communicate these flags some other way mDisplayManagerService.systemReady(safeMode, mOnlyCore); } catch (Throwable e) { } mActivityManagerService.systemReady(new Runnable() { @Override public void run() { try { startSystemUi(context); } catch (Throwable e) { } "MakeNetworkManagementServiceReady"); try { if (networkManagementF != null) networkManagementF.systemReady(); } catch (Throwable e) { reportWtf("making Network Managment Service ready", e); } "MakeNetworkStatsServiceReady"); try { if (networkStatsF != null) networkStatsF.systemReady(); } catch (Throwable e) { } try { if (networkPolicyF != null) networkPolicyF.systemReady(); } catch (Throwable e) { reportWtf("making Network Policy Service ready", e); } "MakeConnectivityServiceReady"); try { if (connectivityF != null) connectivityF.systemReady(); } catch (Throwable e) { } Watchdog.getInstance().start(); try { if (locationF != null) locationF.systemRunning(); } catch (Throwable e) { } try { if (countryDetectorF != null) countryDetectorF.systemRunning(); } catch (Throwable e) { } try { if (networkTimeUpdaterF != null) networkTimeUpdaterF.systemRunning(); } catch (Throwable e) { } try { if (commonTimeMgmtServiceF != null) { commonTimeMgmtServiceF.systemRunning(); } } catch (Throwable e) { } try { if (atlasF != null) atlasF.systemRunning(); } catch (Throwable e) { } try { // TODO(BT) Pass parameter to input manager if (inputManagerF != null) inputManagerF.systemRunning(); } catch (Throwable e) { } try { if (telephonyRegistryF != null) telephonyRegistryF.systemRunning(); } catch (Throwable e) { reportWtf("Notifying TelephonyRegistry running", e); } try { if (mediaRouterF != null) mediaRouterF.systemRunning(); } catch (Throwable e) { } try { if (mmsServiceF != null) mmsServiceF.systemRunning(); } catch (Throwable e) { } try { if (networkScoreF != null) networkScoreF.systemRunning(); } catch (Throwable e) { } } });}这个方法中启动的service非常多，代码量非常巨大，所以可见，这个方法对于Android系统而言，不言也可知其重要性。由于代码量巨大，将startOtherServices()分成三部分解说：
1.startOtherServices()中启动了那些服务
- SchedulingPolicyService
- TelecomLoaderService
- TelephonyRegistry
- CameraService
- AccountManagerService$Lifecycle
- ContentService$Lifecycle
- VibratorService
- ConsumerIrService
- AlarmManagerService
- InputManagerService
- WindowManagerService
- VrManagerService
- MetricsLoggerService
- PinnerService
- InputMethodManagerService
- AccessibilityManagerService
- MountService$Lifecycle
- UiModeManagerService
- LockSettingsService$Lifecycle
- PersistentDataBlockService
- DeviceIdleController
- DevicePolicyManagerService
- StatusBarManagerService
- ClipboardService
- NetworkManagementService
- TextServicesManagerService
- NetworkScoreService
- NetworkStatsService
- NetworkPolicyManagerService
- WifiNanService
- WifiP2pService
- WifiService
- WifiScanningService
- RttService
- EthernetService
- ConnectivityService
- NsdService
- UpdateLockService
- RecoverySystemService
- NotificationManagerService
- DeviceStorageMonitorService
- LocationManagerService
- CountryDetectorService
- SearchManagerService$Lifecycle
- DropBoxManagerService
- WallpaperManagerService$Lifecycle
- AudioService.Lifecycle
- DockObserver
- ThermalObserver
- MidiService$Lifecycle
- UsbService$Lifecycle
- SerialService
- HardwarePropertiesManagerService
- TwilightService
- JobSchedulerService
- SoundTriggerService
- BackupManagerService$Lifecycle
- AppWidgetService
- VoiceInteractionManagerService
- GestureLauncherService
- SensorNotificationService
- ContextHubSystemService
- DiskStatsService
- SamplingProfilerService
- NetworkTimeUpdateService
- CommonTimeManagementService
- DreamManagerService
- AssetAtlasService
- GraphicsStatsService
- PrintManagerService
- RestrictionsManagerService
- MediaSessionService
- HdmiControlService
- TvInputManagerService
- MediaResourceMonitorService
- TvRemoteService
- MediaRouterService
- TrustManagerService
- FingerprintService
- ShortcutService.Lifecycle
- LauncherAppsService
- MediaProjectionManagerService
- WearBluetoothService
- MmsServiceBroker
所列的这些服务，不一定全部都启动，系统会依照一些配置，选择性启动某些服务。如，因为Android系统会用于众多设备，手机，电视等等，当Android安装到电视设备是，TvInputManagerService、TvRemoteService这些service才会被启动，相反，手机设备时，这两个服务就不会被启动了。
2.不同的启动服务的方式
不知读者是否注意到，在startOtherServices()中存在和startBootstrapServices()、startCoreServices()中不同的启动service的方法，在startBootstrapServices()、startCoreServices()中见到SystemServiceManager.startService()和LocalServices.addService()的方式，而startOtherServices()中又多了ServiceManager.addService()，这三种方式有什么不同呢？
类型不同
SystemServiceManager.startService()和LocalServices.addService()启动的系统服务是SystemService的子类，启动这些服务后会回调SystemService的onStart()方法。ServiceManager.addService()启动的系统服务是实现了Android IPC 的Binder的子类，这些服务启动后会调用systemReady()或systemRunning()方法。SystemServiceManager.startService()和ServiceManager.addService()中启动的服务需要Binder对象，而LocalServices.addService()却没有Binder对象。
SystemServiceManager.startService()中启动的是需要关心lifecycle events的服务，而ServiceManager.addService()和LocalServices.addService()不关心lifecycle events。
ServiceManager.addService()启动的服务本身是实现Binder通信的子类，而一般SystemServiceManager.startService()启动的服务是某个服务的内部类且这个内部类是SystemService的子类，如BackupManagerService$Lifecycle，在启动这个Lifecycle的内部类服务时，当回调onStart()方法时通过SystemService的publishBinderService()方法应用某个服务的Binder对象，且这个Binder的实现类也是某个服务的内部类。也就是说需要启动服务，而这个服务需要关心lifecycle events，所以不能通过ServiceManager.addService()的方式启动，然后在这个服务中声明一个实现了SystemService的子类Lifecycle，来接受lifecycle events，通过SystemServiceManager.startService()的方式启动这个服务，在SystemService的回调方法onStart()中应用这个服务的Binder对象。所以通过SystemServiceManager.startService()启动的服务，实际是启动了一个即需要关心lifecycle events，也需要像ServiceManager.addService()那样需要Binder对象的服务。
所以，其实在startBootstrapServices()中就已经通过ServiceManager.addService()的方式启动了一些特别特别重要的服务，如：
private void startBootstrapServices() { mPackageManagerService = PackageManagerService.main(mSystemContext, installer, mFactoryTestMode != FactoryTest.FACTORY_TEST_OFF, mOnlyCore); } public static PackageManagerService main(Context context, Installer installer, boolean factoryTest, boolean onlyCore) { ...... ServiceManager.addService("package", m); return m; }3.通过ServiceManager.addService()启动的服务，会调用服务的systemReady()或systemRunning()方法，初始化一些需要在系统服务启动后的其它代码。如启动SystemUI。
全部启动所需要的服务以后，SystemServer便要进入了接受Message的循环中，等待Message的事件。
总结
在本大纲中，认识了Android系统启动时需要启动的服务，以及
- SystemServiceManager.startService()
- ServiceManager.addService()
- LocalServices.addService()
三种不同的启动系统服务的方式，通过这三种启动的服务各有什么不同。另外，Android系统除了在启动的时候可以初始化服务，在运行中，也可能有新的服务被加进来，如某些APP启动时，会增加一些服务，如Phone APP（Telephony）
public void onCreate() { phoneMgr = PhoneInterfaceManager.init(this, PhoneFactory.getDefaultPhone());}static PhoneInterfaceManager init(PhoneGlobals app, Phone phone) { synchronized (PhoneInterfaceManager.class) { if (sInstance == null) { sInstance = new PhoneInterfaceManager(app, phone); ...... return sInstance; }}private PhoneInterfaceManager(PhoneGlobals app, Phone phone) { publish();}private void publish() { ServiceManager.addService("phone", this);}到此，System Server的大纲介绍到这里，在本大纲的牵引下，一一以分文章（文档）的形式对各个系统服务进入全面的了解。
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