system_server_AMS类图.png

Activity_Window_相关类图.png

system_server_AMS类图.png

总体类图.png

流程图.png

    public final class ActivityThread {
      private void handleLaunchActivity(ActivityClientRecord r, Intent customIntent, String reason) {
        // Initialize before creating the activity
        WindowManagerGlobal.initialize();
        Activity a = performLaunchActivity(r, customIntent);
        if (a != null) {
            r.createdConfig = new Configuration(mConfiguration);
            reportSizeConfigurations(r);
            Bundle oldState = r.state;
            handleResumeActivity(r.token, false, r.isForward,
                    !r.activity.mFinished && !r.startsNotResumed, r.lastProcessedSeq, reason);
        ...
        } 
    }
}

其中WindowManagerGlobal.initialize;是先取到WMS(WindowManagerService)的远程代理IWindowManager

WindowManagerGlobal.java

public final class WindowManagerGlobal {
    public static void initialize() {
        getWindowManagerService();
    }
    public static IWindowManager getWindowManagerService() {
        synchronized (WindowManagerGlobal.class) {
            if (sWindowManagerService == null) {
                sWindowManagerService = IWindowManager.Stub.asInterface(
                        ServiceManager.getService("window"));
                try {
                    sWindowManagerService = getWindowManagerService();
                    ValueAnimator.setDurationScale(sWindowManagerService.getCurrentAnimatorScale());
                } catch (RemoteException e) {
                    throw e.rethrowFromSystemServer();
                }
            }
            return sWindowManagerService;
        }
    }
}

Activity a = performLaunchActivity(r, customIntent);使用ClassLoader加载XXXActivity，这其中会创建ContextImpl、如果Application还没启动过，会先把Applicaition创建并onCreate,然后调用XXXActivity的attach();
在attach中：会创建改activity的对应的window即PhoneWindow，以及phoneWindow和WindowManagerImpl关联：
Activity:

final void attach(Context context, ActivityThread aThread,
            Instrumentation instr, IBinder token, int ident,
            Application application, Intent intent, ActivityInfo info,
            CharSequence title, Activity parent, String id,
            NonConfigurationInstances lastNonConfigurationInstances,
            Configuration config, String referrer, IVoiceInteractor voiceInteractor,
            Window window) {
        attachBaseContext(context);
        mFragments.attachHost(null /*parent*/);
        mWindow = new PhoneWindow(this, window);
        mWindow.setWindowControllerCallback(this);
        mWindow.setCallback(this);
        mWindow.setOnWindowDismissedCallback(this);
        mWindow.getLayoutInflater().setPrivateFactory(this);
        mMainThread = aThread;
        mInstrumentation = instr;
        mWindow.setWindowManager(
                (WindowManager)context.getSystemService(Context.WINDOW_SERVICE),
                mToken, mComponent.flattenToString(),
                (info.flags & ActivityInfo.FLAG_HARDWARE_ACCELERATED) != 0);
        if (mParent != null) {
            mWindow.setContainer(mParent.getWindow());
        }
        mWindowManager = mWindow.getWindowManager();
        mCurrentConfig = config;
}

其中：(WindowManager)context.getSystemService(Context.WINDOW_SERVICE)获取到是WindowManagerImpl：
这边会走到ContextImpl.getSystemService：

class ContextImpl extends Context {   
  @Override
    public Object getSystemService(String name) {
        return SystemServiceRegistry.getSystemService(this, name);
    }
}

SystemServiceRegistry:

final class SystemServiceRegistry {
  public static Object getSystemService(ContextImpl ctx, String name) {
        ServiceFetcher<?> fetcher = SYSTEM_SERVICE_FETCHERS.get(name);
        return fetcher != null ? fetcher.getService(ctx) : null;
    }
  private static final HashMap<Class<?>, String> SYSTEM_SERVICE_NAMES =
            new HashMap<Class<?>, String>();
    private static final HashMap<String, ServiceFetcher<?>> SYSTEM_SERVICE_FETCHERS =
            new HashMap<String, ServiceFetcher<?>>();
    private static int sServiceCacheSize;
    static {
        registerService(Context.ACCESSIBILITY_SERVICE, AccessibilityManager.class,
                new CachedServiceFetcher<AccessibilityManager>() {
            @Override
            public AccessibilityManager createService(ContextImpl ctx) {
                return AccessibilityManager.getInstance(ctx);
            }});
    registerService(Context.WINDOW_SERVICE, WindowManager.class,
                new CachedServiceFetcher<WindowManager>() {
            @Override
            public WindowManager createService(ContextImpl ctx) {
                return new WindowManagerImpl(ctx);
            }});
}

返回是new WindowManagerImpl(ctx);在performLaunchActivity函数中，走完attach后，继续调用mInstrumentation.callActivityOnCreate去实行XXXActivity的onCreate，这时候大家会写setContentView(R.layout.xxx)
Step3:
Activity.setContentView():
会调用getWindow().setContentView(layoutResID),即PhoneWindow类中的setContentView：主要是在PhoneWindow创建DecorView mDecor(This is the top-level view of the window, containing the window decor),然后从mDecor找出android.R.id.content: mContentParent(ViewGroup), 然后把activity设置的View添加到mContentParent.addView(view, params);

public void setContentView(@LayoutRes int layoutResID) {
        getWindow().setContentView(layoutResID);
        initWindowDecorActionBar();
}

PhoneWindow:

public class PhoneWindow extends Window implements MenuBuilder.Callback {
  public void setContentView(int layoutResID) {
        
        if (mContentParent == null) {
            installDecor();
        } else if (!hasFeature(FEATURE_CONTENT_TRANSITIONS)) {
            mContentParent.removeAllViews();
        }

        if (hasFeature(FEATURE_CONTENT_TRANSITIONS)) {
            final Scene newScene = Scene.getSceneForLayout(mContentParent, layoutResID,
                    getContext());
            transitionTo(newScene);
        } else {
            mLayoutInflater.inflate(layoutResID, mContentParent);
        }
        mContentParent.requestApplyInsets();
        final Callback cb = getCallback();
        if (cb != null && !isDestroyed()) {
            cb.onContentChanged();
        }
        mContentParentExplicitlySet = true;
    }
}

Step4：
在ActivitThread.handleLaunchActivity函数走完performLaunchActivity后，接着走handleResumeActivity函数中，显示启动r = performResumeActivity(token, clearHide, reason);去走XXXActivity的onResume。
接着会对Activity的对应的window设置窗口类型：l.type = WindowManager.LayoutParams.TYPE_BASE_APPLICATION，WMS是对窗口进行操作，每个activity对应一个窗口，Framework会定义好几种窗口类型，比如系统Window、应用程序window、子Window等。这边的type类型很重要，没有这个，window显示不出来的。
接着会调用到ViewManager wm = a.getWindowManager();wm.addView(decor, l);走到WindowManagerImpl.addView：
ActivityThread:

final void handleResumeActivity(IBinder token,
            boolean clearHide, boolean isForward, boolean reallyResume, int seq, String reason) {
        ActivityClientRecord r = mActivities.get(token);
        ...
        r = performResumeActivity(token, clearHide, reason);
        ...
            if (r.window == null && !a.mFinished && willBeVisible) {
                r.window = r.activity.getWindow();
                View decor = r.window.getDecorView();
                decor.setVisibility(View.INVISIBLE);
                ViewManager wm = a.getWindowManager();
                WindowManager.LayoutParams l = r.window.getAttributes();
                a.mDecor = decor;
                l.type = WindowManager.LayoutParams.TYPE_BASE_APPLICATION;
                l.softInputMode |= forwardBit;
                if (r.mPreserveWindow) {
                    a.mWindowAdded = true;
                    r.mPreserveWindow = false;
                   
                    ViewRootImpl impl = decor.getViewRootImpl();
                    if (impl != null) {
                        impl.notifyChildRebuilt();
                    }
                }
                if (a.mVisibleFromClient && !a.mWindowAdded) {
                    a.mWindowAdded = true;
                    wm.addView(decor, l);
                }
             ...
    }

Step5：
WindowManagerImpl的addView又调用到WindowManagerGlobal.getInstance()的addView：
这个函数会创建root = new ViewRootImpl(view.getContext(), display);然后保存到mRoots.add(root)
接着调用到 root.setView(view, wparams, panelParentView);

public final class WindowManagerImpl implements WindowManager {
    private final WindowManagerGlobal mGlobal = WindowManagerGlobal.getInstance();
    @Override
    public void addView(@NonNull View view, @NonNull ViewGroup.LayoutParams params) {
        applyDefaultToken(params);
        mGlobal.addView(view, params, mContext.getDisplay(), mParentWindow);
    }
}

public final class WindowManagerGlobal {
    public void addView(View view, ViewGroup.LayoutParams params,
            Display display, Window parentWindow) {
        ...
        ViewRootImpl root;
        View panelParentView = null;
        synchronized (mLock) {
            ...
            root = new ViewRootImpl(view.getContext(), display);
            view.setLayoutParams(wparams);
            mViews.add(view);
            mRoots.add(root);
            mParams.add(wparams);
        }
        // do this last because it fires off messages to start doing things
        try {
            root.setView(view, wparams, panelParentView);
        } catch (RuntimeException e) {
           
        }
    }
}

Step6：
ViewRootImpl.setView():
这个函数中，通过WindowManagerGloabl拿到IWindowSession mWindowSession及远程WMS的Seesion的对象，进行mWindowSession.addToDisplay，到system_server进程的Session中。

public final class ViewRootImpl implements ViewParent,
        View.AttachInfo.Callbacks, ThreadedRenderer.HardwareDrawCallbacks {
    public void setView(View view, WindowManager.LayoutParams attrs, View panelParentView) {
        synchronized (this) {
                ....
                try {
                    res = mWindowSession.addToDisplay(mWindow, mSeq, mWindowAttributes,
                            getHostVisibility(), mDisplay.getDisplayId(),
                            mAttachInfo.mContentInsets, mAttachInfo.mStableInsets,
                            mAttachInfo.mOutsets, mInputChannel);
                }            
            }
        ...
    }
}

这个mWindowSession是

public static IWindowSession getWindowSession() {
        synchronized (WindowManagerGlobal.class) {
            if (sWindowSession == null) {
                try {
                    InputMethodManager imm = InputMethodManager.getInstance();
                    IWindowManager windowManager = getWindowManagerService();
                    sWindowSession = windowManager.openSession(
                            new IWindowSessionCallback.Stub() {
                                @Override
                                public void onAnimatorScaleChanged(float scale) {
                                    ValueAnimator.setDurationScale(scale);
                                }
                            },
                            imm.getClient(), imm.getInputContext());
                } catch (RemoteException e) {
                    throw e.rethrowFromSystemServer();
                }
            }
            return sWindowSession;
        }
    }

调用到WindowManagerService的openSession方法：

public class WindowManagerService extends IWindowManager.Stub
        implements Watchdog.Monitor, WindowManagerPolicy.WindowManagerFuncs {
   @Override
    public IWindowSession openSession(IWindowSessionCallback callback, IInputMethodClient client,
            IInputContext inputContext) {
        if (client == null) throw new IllegalArgumentException("null client");
        if (inputContext == null) throw new IllegalArgumentException("null inputContext");
        Session session = new Session(this, callback, client, inputContext);
        return session;
    }
}