activity window 获取setContentView的基视图（getContentView）

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android setContentView后如何get回来

setContentView 流程（window DecorView 装载流程）

一、activity window 引出 PhoneWindow类

setContentView -> getWindow().setContentView(view)
getWindow() -> mWindow = new PhoneWindow(this);

二、 PhoneWindow 类分析

分析setContentView 知道里主要做两步操作：
->1 装载DecorView 基础布局 installDecor()
->2 装载setContentView的具体布局 mLayoutInflater.inflate(layoutResID, mContentParent);

@Override    public void setContentView(int layoutResID) {        if (mContentParent == null) {            //1、装载 DecorView            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 {            //2、把layoutResID 装载到 R.id.content对应的ViewGroup            mLayoutInflater.inflate(layoutResID, mContentParent);        }        mContentParent.requestApplyInsets();        final Callback cb = getCallback();        if (cb != null && !isDestroyed()) {            cb.onContentChanged();        }    }

布局装载图如下，后面详细描述加载的2步：

这里写图片描述

2.1、装载过程（基础模板layoutId, 与activity 传入的layout）

->1、generateDecor() 加载DecorView 作为最外层布局。比较简单该函数不展开
->2.1、generateLayout(mDecor) 装载基础模板布局(如：R.layout.screen_title 或者 R.layout.screen_simple)
->2.2、generateLayout(mDecor) 找到R.id.content 的viewGroup 作为 mContentParent
->补充 findViewById -> getDecorView().findViewById(id) -> (getDecorView() 就是 mDecor)

private void installDecor() {    if (mDecor == null) {        //1、加载DecorView(extends FrameLayout) 作为最外层布局        mDecor = generateDecor();        mDecor.setDescendantFocusability(ViewGroup.FOCUS_AFTER_DESCENDANTS);        mDecor.setIsRootNamespace(true);        if (!mInvalidatePanelMenuPosted && mInvalidatePanelMenuFeatures != 0) {            mDecor.postOnAnimation(mInvalidatePanelMenuRunnable);        }    }    if (mContentParent == null) {        //2.1、装载基础模板布局(如：R.layout.screen_title 或者 R.layout.screen_simple)        //2.2、找到R.id.content 的viewGroup 作为 mContentParent        mContentParent = generateLayout(mDecor);    }    ...}protected ViewGroup generateLayout(DecorView decor) {        ...        else if ((features & (1 << FEATURE_NO_TITLE)) == 0) {            // If no other features and not embedded, only need a title.            // If the window is floating, we need a dialog layout            if (mIsFloating) {                TypedValue res = new TypedValue();                getContext().getTheme().resolveAttribute(                        R.attr.dialogTitleDecorLayout, res, true);                layoutResource = res.resourceId;            } else if ((features & (1 << FEATURE_ACTION_BAR)) != 0) {                layoutResource = a.getResourceId(                        R.styleable.Window_windowActionBarFullscreenDecorLayout,                        R.layout.screen_action_bar);            } else {                layoutResource = R.layout.screen_title;            }            // System.out.println("Title!");        } else if ((features & (1 << FEATURE_ACTION_MODE_OVERLAY)) != 0) {            layoutResource = R.layout.screen_simple_overlay_action_mode;        } else {            // Embedded, so no decoration is needed.            layoutResource = R.layout.screen_simple;            // System.out.println("Simple!");        }        mDecor.startChanging();        //2.1、装载基础模板layoutId 到decor (mDecor)        View in = mLayoutInflater.inflate(layoutResource, null);        decor.addView(in, new ViewGroup.LayoutParams(MATCH_PARENT, MATCH_PARENT));        mContentRoot = (ViewGroup) in;        //2.2、找到R.id.content 对应的ViewGroup 作为contentParent(mContentParent)         //ID_ANDROID_CONTENT = com.android.internal.R.id.content;        //findViewById -> getDecorView().findViewById(id) -> (getDecorView() -> mDecor)        ViewGroup contentParent = (ViewGroup)findViewById(ID_ANDROID_CONTENT);        if (contentParent == null) {            throw new RuntimeException("Window couldn't find content container view");        }        ...        return contentParent;}

三、获取setContentView的layout

public static View getContentView(Activity context){    return ((ViewGroup)context.findViewById(android.R.id.content)).getChildAt(0);}

参考
[1] http://blog.csdn.net/qinjuning/article/details/7226787

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