内容简介:在 zygote 启动流程分析中,zygote最后会调用 SystemServer 的main函数,这篇就来介绍SystemServer的流程SystemServer 有点CPU的感觉,我们应用层用到的很多服务都是运行在该进程中的,比如WMS,AMS,PMS该过程会创建对象有ActivityThread,Instrumentation, ContextImpl,LoadedApk,Application
在 zygote 启动流程分析中,zygote最后会调用 SystemServer 的main函数,这篇就来介绍SystemServer的流程
时序图
SystemServer介绍
SystemServer 有点CPU的感觉,我们应用层用到的很多服务都是运行在该进程中的,比如WMS,AMS,PMS
入口main函数
public static void main(String[] args) { new SystemServer().run(); } private void run() { try { ...... // Prepare the main looper thread (this thread). android.os.Process.setThreadPriority( android.os.Process.THREAD_PRIORITY_FOREGROUND); android.os.Process.setCanSelfBackground(false); //主线程looper就在当前线程运行 Looper.prepareMainLooper(); //加载android_servers.so库,该库包含的源码在frameworks/base/services/目录下 System.loadLibrary("android_servers"); //检测上次关机过程是否失败,该方法可能不会返回 performPendingShutdown(); //初始化系统上下文 createSystemContext(); //创建系统服务管理 mSystemServiceManager = new SystemServiceManager(mSystemContext); mSystemServiceManager.setRuntimeRestarted(mRuntimeRestart); LocalServices.addService(SystemServiceManager.class, mSystemServiceManager); // Prepare the thread pool for init tasks that can be parallelized SystemServerInitThreadPool.get(); } finally { traceEnd(); // InitBeforeStartServices } //启动各种系统服务 try { traceBeginAndSlog("StartServices"); startBootstrapServices(); startCoreServices(); startOtherServices(); SystemServerInitThreadPool.shutdown(); } catch (Throwable ex) { ...... } finally { traceEnd(); } // Loop forever. 一直处于循环状态 Looper.loop(); throw new RuntimeException("Main thread loop unexpectedly exited"); } 复制代码
createSystemContext
该过程会创建对象有ActivityThread,Instrumentation, ContextImpl,LoadedApk,Application
startBootstrapServices
private void startBootstrapServices() { //阻塞等待与installd建立socket通道 Installer installer = mSystemServiceManager.startService(Installer.class); //启动服务ActivityManagerService mActivityManagerService = mSystemServiceManager.startService( ActivityManagerService.Lifecycle.class).getService(); mActivityManagerService.setSystemServiceManager(mSystemServiceManager); mActivityManagerService.setInstaller(installer); //启动服务PowerManagerService mPowerManagerService = mSystemServiceManager.startService(PowerManagerService.class); ...... //启动服务PackageManagerService mPackageManagerService = PackageManagerService.main(mSystemContext, installer, mFactoryTestMode != FactoryTest.FACTORY_TEST_OFF, mOnlyCore); mFirstBoot = mPackageManagerService.isFirstBoot(); mPackageManager = mSystemContext.getPackageManager(); //启动服务UserManagerService,新建目录/data/user/ ServiceManager.addService(Context.USER_SERVICE, UserManagerService.getInstance()); AttributeCache.init(mSystemContext); //设置AMS mActivityManagerService.setSystemProcess(); //启动传感器服务 startSensorService(); } 复制代码
该方法所创建的服务:
- ActivityManagerService
- PowerManagerService
- LightsService
- DisplayManagerService
- PackageManagerService
- UserManagerService
- SensorService
startCoreServices
private void startCoreServices() { //启动服务BatteryService,用于统计电池电量,需要LightService. mSystemServiceManager.startService(BatteryService.class); //启动服务UsageStatsService,用于统计应用使用情况 mSystemServiceManager.startService(UsageStatsService.class); mActivityManagerService.setUsageStatsManager( LocalServices.getService(UsageStatsManagerInternal.class)); mPackageManagerService.getUsageStatsIfNoPackageUsageInfo(); //启动服务WebViewUpdateService mSystemServiceManager.startService(WebViewUpdateService.class); } 复制代码
通过传入的类名进行实例化后添加到 mServices 中并调用自身的 onStart
public void startService(@NonNull final SystemService service) { // Register it. mServices.add(service); // Start it. long time = SystemClock.elapsedRealtime(); try { service.onStart(); } catch (RuntimeException ex) { ...... } warnIfTooLong(SystemClock.elapsedRealtime() - time, service, "onStart"); } 复制代码
该方法所创建的服务:
- BatteryService
- UsageStatsService
- WebViewUpdateService
startOtherServices
// 和SettingsProvider关联 mActivityManagerService.installSystemProviders(); // 设置对象关联 mActivityManagerService.setWindowManager(wm); ...... // 准备好window, power, package, display服务 wm.systemReady(); mPowerManagerService.systemReady(...); mPackageManagerService.systemReady(); mDisplayManagerService.systemReady(...); mActivityManagerService.systemReady(new Runnable() { public void run() { ...... } }); 复制代码
AMS.systemReady
在服务启动完毕后,会调用各个服务的 systemReady
AMS是最后一个启动的服务,会调用 mActivityManagerService.systemReady
mActivityManagerService.systemReady(new Runnable() { public void run() { //启动WebView WebViewFactory.prepareWebViewInSystemServer(); //启动系统UI startSystemUi(context); // 执行一系列服务的systemReady方法 networkScoreF.systemReady(); networkManagementF.systemReady(); networkStatsF.systemReady(); ...... //执行一系列服务的systemRunning方法 wallpaper.systemRunning(); inputMethodManager.systemRunning(statusBarF); location.systemRunning(); } }); 复制代码
这个函数里进行了大量的systemRunning调用,主要是注册广播等等
比如 TelephonyRegistry
try { if (telephonyRegistryF != null) telephonyRegistryF.systemRunning(); } catch (Throwable e) { reportWtf("Notifying TelephonyRegistry running", e); } public void systemRunning() { // Watch for interesting updates final IntentFilter filter = new IntentFilter(); filter.addAction(Intent.ACTION_USER_SWITCHED); filter.addAction(Intent.ACTION_USER_REMOVED); filter.addAction(TelephonyIntents.ACTION_DEFAULT_SUBSCRIPTION_CHANGED); log("systemRunning register for intents"); mContext.registerReceiver(mBroadcastReceiver, filter); } 复制代码
startSystemUi
static final void startSystemUi(Context context) { Intent intent = new Intent(); intent.setComponent(new ComponentName("com.android.systemui", "com.android.systemui.SystemUIService")); context.startServiceAsUser(intent, UserHandle.OWNER); } 复制代码
该函数的主要作用是启动服务 ”com.android.systemui.SystemUIService”
AMS简单流程
这里需要介绍下AMS的流程,因为后续的代码就是和AMS有关了
在前面 startBootstrapServices 的流程中有一段代码
ams.setSystemProcess()
在 startOtherServices 中有段代码
ams.installSystemProviders()
这些都是AMS的大致流程
- 创建AMS对象
- 调用ams.setSystemProcess
- 调用ams.installSystemProviders
- 调用ams.systemReady
在 systemReady 的最后它会调用到 ams 中的 startHomeActivityLocked 函数,他的主要作用就是启动桌面Activity
boolean startHomeActivityLocked(int userId, String reason) { //home intent有CATEGORY_HOME Intent intent = getHomeIntent(); ActivityInfo aInfo = resolveActivityInfo(intent, STOCK_PM_FLAGS, userId); if (aInfo != null) { intent.setComponent(new ComponentName( aInfo.applicationInfo.packageName, aInfo.name)); aInfo = new ActivityInfo(aInfo); aInfo.applicationInfo = getAppInfoForUser(aInfo.applicationInfo, userId); ProcessRecord app = getProcessRecordLocked(aInfo.processName, aInfo.applicationInfo.uid, true); if (app == null || app.instrumentationClass == null) { intent.setFlags(intent.getFlags() | Intent.FLAG_ACTIVITY_NEW_TASK); //启动桌面Activity mStackSupervisor.startHomeActivity(intent, aInfo, reason); } } return true; } 复制代码
systemReady大致流程
public final class ActivityManagerService{ public void systemReady(final Runnable goingCallback) { ...//更新操作 mSystemReady = true; //系统处于ready状态 removeProcessLocked(proc, true, false, "system update done");//杀掉所有非persistent进程 mProcessesReady = true; //进程处于ready状态 goingCallback.run(); //这里有可能启动进程 addAppLocked(info, false, null); //启动所有的persistent进程 mBooting = true; //正在启动中 startHomeActivityLocked(mCurrentUserId, "systemReady"); //启动桌面 mStackSupervisor.resumeTopActivitiesLocked(); //恢复栈顶的Activity } } 复制代码
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