Application和Activity创建

此源码基于 API 30

一：Android main   Application和Activity创建

1. ActivityThread extends ClientTransactionHandler

   main()->
    Looper.prepareMainLooper();
    ActivityThread thread = new ActivityThread();
        thread.attach(false, startSeq);
    Looper.loop();

   attach() ->
    final IActivityManager mgr = ActivityManager.getService();
            try {
                mgr.attachApplication(mAppThread, startSeq);
            } catch (RemoteException ex) {
                throw ex.rethrowFromSystemServer();
            }

2. ActivityManagerService
   
    attachApplication()->attachApplicationLocked()->
            
            1.thread.bindApplication() ->sendMessage(H.BIND_APPLICATION, data);
            ->handleBindApplication()->LoadedApk.makeApplication()
                    ->mActivityThread.mInstrumentation.newApplication();
                    ->Application app = getFactory(context.getPackageName()) 
                            .instantiateApplication(cl, className);
                            app.attach(context);
            ->mInstrumentation.callApplicationOnCreate(app);
            -> Application.onCreate();
            
            2. ActivityTaskManagerService.attachApplication()->
                RootWindowContainer.attachApplication()->
                startActivityForAttachedApplicationIfNeeded()->
                ActivityStackSupervisor .realStartActivityLocked()->
                    ClientTransaction.obtain()->
                    clientTransaction.addCallback(LaunchActivityItem);  ****
                    if (andResume) {
                                      lifecycleItem = ResumeActivityItem .obtain(dc.isNextTransitionForward());  ****
                                 } else {
                                      lifecycleItem = PauseActivityItem.obtain();
                                }
                ClientLifecycleManager.scheduleTransaction(clientTransaction)->
                    transaction.schedule();->
                    ApplicationThread.scheduleTransaction()->
                    (ActivityThread | ClientTransactionHandler).scheduleTransaction()->
                    sendMessage(ActivityThread.H.EXECUTE_TRANSACTION, transaction);->
                    mTransactionExecutor.execute(transaction);->
                        executeCallbacks(transaction);
                        executeLifecycleState(transaction);
                                        

                    
                    executeCallbacks()-> LaunchActivityItem .execute()->client.handleLaunchActivity()->
                            performLaunchActivity()->
                                activity = mInstrumentation.newActivity();                              
                                Application app = r.packageInfo.makeApplication(false, mInstrumentation);
                                
                                activity.attach()  ***
                                    mWindow = new PhoneWindow window view 
                                    installDecor();->generateDecor()->new DecorView()
                                    
                                mInstrumentation.callActivityOnCreate(activity, r.state);
                                activity.performCreate(icicle, persistentState);  ****
                                    if (persistentState != null) {
                                                    onCreate(icicle, persistentState);
                                         } else {
                                                    onCreate(icicle);
                                         }
                                    onCreate() -> dispatchActivityCreated(savedInstanceState);
                                setState(ON_CREATE);

                        
                    executeLifecycleState()->ResumeActivityItem.execute()->
                                  ActivityThread. handleResumeActivity()->
                                    performResumeActivity()->
                                        r.activity.performResume()  *** 
                                            callActivityOnResume()->activity.onResume();->
                                        setState(ON_RESUME)->
                            //window 添加 DecorView
                               r.window = r.activity.getWindow();
                                     View decor = r.window.getDecorView();
                                        decor.setVisibility(View.INVISIBLE);
                                        ViewManager wm = a.getWindowManager();  
                                     wm.addView(decor, l);    ***
                                      //最后显示                
                                    activity.makeVisible(); ->mDecor.setVisibility(View.VISIBLE);
                                //****
                                ViewManager wm = a.getWindowManager();
                                        mWindowManager = mWindow.getWindowManager();
                                         PhoneWindow.getWindowManager() -> mWindowManager 
                                         mWindowManager = ((WindowManagerImpl)wm).createLocalWindowManager(this);
                                        createLocalWindowManager() ->new WindowManagerImpl->
                                            WindowManagerGlobal mGlobal = WindowManagerGlobal.getInstance() 
                                        addView()->mGlobal.addView
                            //最终wm.addView -> mGlobal.addView  ****
                                mGlobal.addView()->
                                    1.ViewRootImpl root; 创建 
                                        root = new ViewRootImpl(view.getContext(), display);
                                    2.
                                    mViews.add(view);
                                                mRoots.add(root);
                                                mParams.add(wparams);
                                    //ViewRootImpl 和DecorView() 关联  
                                    3.root. setView(view, wparams, panelParentView);
                                        1.requestLayout()
                                        2.mWindowSession.addToDisplayAsUser(): 
                                            WindowManagerService .addWindow()
                                            //添加到WindowManagerService 管理
                                    
                                        //View 测量 布局 绘制 
                                        requestLayout();   ****
                                              1.checkThread();//检查是不是在主线程
                                               2.scheduleTraversals()
                                            //开启同步屏障                    
                                            mTraversalBarrier = mHandler.getLooper().getQueue().postSyncBarrier();
                                                        //编舞者执行 mTraversalRunnable,
                                            mChoreographer.postCallback(
                                                                 Choreographer.CALLBACK_TRAVERSAL, mTraversalRunnable, null);
                                            
                                            mChoreographer
                                                //threadLocal存储
                                                sSfThreadInstance.get()                                             
                                                ThreadLocal<Choreographer> sSfThreadInstance =  new ThreadLocal<Choreographer>()
                                                mHandler = new FrameHandler(looper);                                                    
                                                //接收底层vsync信号
                                                mDisplayEventReceiver  =FrameDisplayEventReceiver
                                                CallbackQueue[]         
                                                ///放入队列
                                                postCallback()->postCallbackDelayedInternal()->
                                                mCallbackQueues[callbackType].addCallbackLocked(dueTime, action, token);        
                                                 if (dueTime <= now) {
                                                    //每16ms刷新一次
                                                                  scheduleFrameLocked(now);->scheduleVsync()->nativeScheduleVsync()
                                                    
                                                         } else {
                                                                Message msg = mHandler.obtainMessage(MSG_DO_SCHEDULE_CALLBACK, action);
                                                                 msg.arg1 = callbackType;
                                                                  msg.setAsynchronous(true);
                                                                   mHandler.sendMessageAtTime(msg, dueTime);
                                                          }
                                            FrameDisplayEventReceiver
                                                //接收 底层信号
                                                onVsync()->Message msg = Message.obtain(mHandler, this);->
                                                mHandler.sendMessageAtTime(msg,no)
                                                run()->doFrame()->
                                                //取出CallbackQueue里的  最终执行 TraversalRunnable的run方法
                                                ->doCallbacks ->CallbackRecord.run()  ->TraversalRunnable.run

                                            TraversalRunnable
                                                doTraversal()-
                                                //移除同步屏障
                                                -> mHandler.getLooper().getQueue().removeSyncBarrier(mTraversalBarrier);
                                                ->performTraversals();->
                                                    performMeasure()->
                                                        mView.measure()
                                                    performLayout()->
                                                        host.layout(0, 0, host.getMeasuredWidth(), host.getMeasuredHeight());
                                                    performDraw()->
                                                        draw()
                            ViewRootImpl impl = r.window.getDecorView().getViewRootImpl();