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這篇文章主要介紹“Android framework ATMS啟動(dòng)流程是什么”的相關(guān)知識(shí),小編通過實(shí)際案例向大家展示操作過程,操作方法簡(jiǎn)單快捷,實(shí)用性強(qiáng),希望這篇“Android framework ATMS啟動(dòng)流程是什么”文章能幫助大家解決問題。
ATMS 即 ActivityTaskManagerService,用于管理 Activity 及其容器(任務(wù)、堆棧、顯示等)。ATMS 在 Android 10 中才出現(xiàn),由原來的 AMS(ActivityManagerService)分離而來,承擔(dān)了 AMS 的部分職責(zé)。因此,在 AMS初始化過程中(AMS啟動(dòng)流程),也伴隨著了 ATMS 的初始化。
SystemServer:依次調(diào)用 main()、run()、startBootstrapServices(),再調(diào)用 SystemServiceManager 的 startService() 方法,并將 Lifecyle.class 傳入;
SystemServiceManager :startService() 方法通過反射調(diào)用 Lifecyle 的構(gòu)造方法,生成 Lifecyle 對(duì)象;
Lifecyle:構(gòu)造方法中調(diào)用 ATMS 的構(gòu)造方法創(chuàng)建 ATMS 對(duì)象,并通過 getService() 方法返回 ATMS 對(duì)象。
如圖,ATMS 在初始化時(shí)創(chuàng)建了圖中藍(lán)色類的對(duì)象。
/frameworks/base/services/java/com/android/server/SystemServer.java
public static void main(String[] args) { new SystemServer().run(); }
/frameworks/base/services/java/com/android/server/SystemServer.java
private void run() { try { ... // 創(chuàng)建Looper Looper.prepareMainLooper(); // 加載libandroid_servers.so System.loadLibrary("android_servers"); // 創(chuàng)建系統(tǒng)的 Context:ContextImpl.createSystemContext(new ActivityThread()) createSystemContext(); // 創(chuàng)建 SystemServiceManager mSystemServiceManager = new SystemServiceManager(mSystemContext); LocalServices.addService(SystemServiceManager.class, mSystemServiceManager); ... } ... try { //啟動(dòng)引導(dǎo)服務(wù),ActivityManagerService、ActivityTaskManagerService、PackageManagerService、PowerManagerService、DisplayManagerService 等 startBootstrapServices(); //啟動(dòng)核心服務(wù),BatteryService、UsageStatusService 等 startCoreServices(); //啟動(dòng)其他服務(wù),InputManagerService、WindowManagerService、CameraService、AlarmManagerService 等 startOtherServices(); ... } ... // 開啟消息循環(huán) Looper.loop(); }
/frameworks/base/services/java/com/android/server/SystemServer.java
private void startBootstrapServices() { ... //啟動(dòng) ATMS ActivityTaskManagerService atm = mSystemServiceManager.startService(ActivityTaskManagerService.Lifecycle.class).getService(); //啟動(dòng) AMS,并將 ATMS 注入 mActivityManagerService = ActivityManagerService.Lifecycle.startService(mSystemServiceManager, atm); ... }
/frameworks/base/services/core/java/com/android/server/SystemServiceManager.java
public <T extends SystemService> T startService(Class<T> serviceClass) { try { final String name = serviceClass.getName(); ... final T service; try { //通過反射調(diào)用 serviceClass 的構(gòu)造方法 創(chuàng)建 Lifecycle 對(duì)象 Constructor<T> constructor = serviceClass.getConstructor(Context.class); service = constructor.newInstance(mContext); } ... startService(service); return service; } ... } public void startService(SystemService service) { mServices.add(service); //mServices: ArrayList<SystemService> ... try { service.onStart(); //調(diào)用 Lifecycle 的 onStart 方法 } ... }
/frameworks/base/services/core/java/com/android/server/wm/ActivityTaskManagerService.Lifecycle.java
public static final class Lifecycle extends SystemService { private final ActivityTaskManagerService mService; public Lifecycle(Context context) {//被 SystemServiceManager 的 startService() 方法調(diào)用 super(context); mService = new ActivityTaskManagerService(context); } public void onStart() { //添加 ATMS 服務(wù),方便跨進(jìn)程調(diào)用:ServiceManager.addService(Context.ACTIVITY_TASK_SERVICE, mService, false, DUMP_FLAG_PRIORITY_DEFAULT) publishBinderService(Context.ACTIVITY_TASK_SERVICE, mService); mService.start(); //調(diào)用 ATMS 的 start() 方法 } ... public ActivityTaskManagerService getService() { return mService; } }
注意:onStart() 方法中調(diào)用 ATMS 的 start() 方法初始化(下文還會(huì)介紹)。 已通過 ServiceManager.addService() 將 Context.ACTIVITY_TASK_SERVICE 與 ATMS 綁定,因此在其他進(jìn)程中可以通過如下方式獲取 ATMS。
IBinder b = ServiceManager.getService(Context.ACTIVITY_TASK_SERVICE); IActivityTaskManager atm = IActivityTaskManager.Stub.asInterface(b);
/frameworks/base/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
public ActivityTaskManagerService(Context context) { mContext = context; ... mSystemThread = ActivityThread.currentActivityThread(); mUiContext = mSystemThread.getSystemUiContext(); //ContextImpl.createSystemUiContext(getSystemContext()) mLifecycleManager = new ClientLifecycleManager(); mInternal = new LocalService(); //ActivityTaskManagerInternal 的子類 ... }
start() 方法被 Lifecycle 的 onStart() 方法調(diào)用,onStart() 方法又被 SystemServiceManager 的 startService() 方法調(diào)用。
/frameworks/base/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
private void start() { LocalServices.addService(ActivityTaskManagerInternal.class, mInternal); }
mInternal 屬于 LocalService 類(ActivityTaskManagerInternal 的子類),在 ATMS 的構(gòu)造方法中創(chuàng)建。
在 AMS 的構(gòu)造方法中,調(diào)用了 ATMS 的 initialize() 方法進(jìn)一步初始化。
/frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java
public ActivityManagerService(Context systemContext, ActivityTaskManagerService atm) { ... mHandlerThread = new ServiceThread(TAG, THREAD_PRIORITY_FOREGROUND, false); ... mUserController = new UserController(this); mPendingIntentController = new PendingIntentController(mHandlerThread.getLooper(), mUserController); ... mIntentFirewall = new IntentFirewall(new IntentFirewallInterface(), mHandler); mActivityTaskManager = atm; //進(jìn)一步初始化 ATMS mActivityTaskManager.initialize(mIntentFirewall, mPendingIntentController, DisplayThread.get().getLooper()); ... }
/frameworks/base/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
public void initialize(IntentFirewall intentFirewall, PendingIntentController intentController, Looper looper) { mH = new H(looper); mUiHandler = new UiHandler(); mIntentFirewall = intentFirewall; ... mPendingIntentController = intentController; mTempConfig.setToDefaults(); //定義時(shí)即被創(chuàng)建:mTempConfig = new Configuration() ... //new ActivityStackSupervisor(this, mH.getLooper()) mStackSupervisor = createStackSupervisor(); mRootActivityContainer = new RootActivityContainer(this); mRootActivityContainer.onConfigurationChanged(mTempConfig); ... mLockTaskController = new LockTaskController(mContext, mStackSupervisor, mH); mActivityStartController = new ActivityStartController(this); mRecentTasks = createRecentTasks(); //new RecentTasks(this, mStackSupervisor) mStackSupervisor.setRecentTasks(mRecentTasks); ... }
在 AMS 的 start() 方法中,調(diào)用了 ATMS 的 onActivityManagerInternalAdded() 方法進(jìn)一步初始化。
/frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java
private void start() { ... LocalServices.addService(ActivityManagerInternal.class, new LocalService()); //調(diào)用 ATMS 的 onActivityManagerInternalAdded 方法進(jìn)一步初始化 mActivityTaskManager.onActivityManagerInternalAdded(); mUgmInternal.onActivityManagerInternalAdded(); mPendingIntentController.onActivityManagerInternalAdded(); ... }
/frameworks/base/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
public void onActivityManagerInternalAdded() { synchronized (mGlobalLock) { mAmInternal = LocalServices.getService(ActivityManagerInternal.class); mUgmInternal = LocalServices.getService(UriGrantsManagerInternal.class); } }
ActivityStartController 作為 ATMS 的一個(gè)重要成員,控制了 Activity 的啟動(dòng),因此我們繼續(xù)跟進(jìn) ActivityStartController 的構(gòu)造方法。
/frameworks/base/services/core/java/com/android/server/am/ActivityStartController.java
ActivityStartController(ActivityTaskManagerService service) { this(service, service.mStackSupervisor, new DefaultFactory(service, service.mStackSupervisor, new ActivityStartInterceptor(service, service.mStackSupervisor))); } ActivityStartController(ActivityTaskManagerService service, ActivityStackSupervisor supervisor, Factory factory) { mService = service; mSupervisor = supervisor; mHandler = new StartHandler(mService.mH.getLooper()); mFactory = factory; mFactory.setController(this); ... }
DefaultFactory 是 ActivityStarter 的靜態(tài)內(nèi)部類,負(fù)責(zé) ActivityStarter 的創(chuàng)建和回收。因此我們繼續(xù)跟進(jìn) DefaultFactory 類。
/frameworks/base/services/core/java/com/android/server/wm/ActivityStarter.DefaultFactory.java
static class DefaultFactory implements Factory { ... private ActivityStartController mController; private ActivityTaskManagerService mService; private ActivityStackSupervisor mSupervisor; private ActivityStartInterceptor mInterceptor; //MAX_STARTER_COUNT = 3 private SynchronizedPool<ActivityStarter> mStarterPool = new SynchronizedPool<>(MAX_STARTER_COUNT); DefaultFactory(ActivityTaskManagerService service, ActivityStackSupervisor supervisor, ActivityStartInterceptor interceptor) { mService = service; mSupervisor = supervisor; mInterceptor = interceptor; } public ActivityStarter obtain() { ActivityStarter starter = mStarterPool.acquire(); if (starter == null) { starter = new ActivityStarter(mController, mService, mSupervisor, mInterceptor); } return starter; } @Override public void recycle(ActivityStarter starter) { mStarterPool.release(starter); } }
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