activity window 获取setContentView的基视图（getContentView）

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：



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