setContentView加载解析过程源码分析

public void setContentView(int layoutResID) {
	getWindow().setContentView(layoutResID);
	initWindowDecorActionBar();
}
public void setContentView(View view) {
	getWindow().setContentView(view);
	initWindowDecorActionBar();
}
public void setContentView(View view, ViewGroup.LayoutParams params) {
	getWindow().setContentView(view, params);
	initWindowDecorActionBar();
}

@Override
public void setContentView(View view) {
    //从这里就可以解释，为什么调用setContentView(View)时，被添加的View的宽高都是无效的，而是MATCH_PARENT
	setContentView(view, new ViewGroup.LayoutParams(MATCH_PARENT, MATCH_PARENT));
}
@Override
public void setContentView(View view, ViewGroup.LayoutParams params) {
	// Note: FEATURE_CONTENT_TRANSITIONS may be set in the process of installing the window
	// decor, when theme attributes and the like are crystalized. Do not check the feature before this happens.
	if (mContentParent == null) {
		installDecor();
	} else if (!hasFeature(FEATURE_CONTENT_TRANSITIONS)) {
		mContentParent.removeAllViews();
	}
	if (hasFeature(FEATURE_CONTENT_TRANSITIONS)) {
		view.setLayoutParams(params);
		final Scene newScene = new Scene(mContentParent, view);
		transitionTo(newScene);
	} else {
		mContentParent.addView(view, params);
	}
	final Callback cb = getCallback();
	if (cb != null && !isDestroyed()) {
		cb.onContentChanged();
	}
}

private void installDecor() {
	if (mDecor == null) {
		mDecor = generateDecor();
		mDecor.setDescendantFocusability(ViewGroup.FOCUS_AFTER_DESCENDANTS);
		mDecor.setIsRootNamespace(true);
		if (!mInvalidatePanelMenuPosted && mInvalidatePanelMenuFeatures != 0) {
			mDecor.postOnAnimation(mInvalidatePanelMenuRunnable);
		}
	}
	if (mContentParent == null) {
		//根据窗口的风格修饰，选择对应的修饰布局文件，并且将id为content的FrameLayout赋值给mContentParent
		mContentParent = generateLayout(mDecor);
		//......
		//初始化一堆属性值
	}
}

protected DecorView generateDecor() {
	return new DecorView(getContext(), -1);
}

protected ViewGroup generateLayout(DecorView decor) {
	// Apply data from current theme.从xml主题中获取窗口相关的属性
	TypedArray a = getWindowStyle();
	//......
	//获取代码中对主题style的设置
	// Inflate the window decor.
	int layoutResource;
	int features = getLocalFeatures();
	//......
	//根据设定好的features值选择不同的窗口修饰布局文件，得到layoutResource值
	//把选中的窗口修饰布局文件添加到DecorView对象里，并且指定contentParent值
	View in = mLayoutInflater.inflate(layoutResource, null);
	decor.addView(in, new ViewGroup.LayoutParams(MATCH_PARENT, MATCH_PARENT));
	mContentRoot = (ViewGroup) in;
	ViewGroup contentParent = (ViewGroup)findViewById(ID_ANDROID_CONTENT);
	if (contentParent == null) {
		throw new RuntimeException("Window couldn‘t find content container view");
	}
	//......
	//继续一堆属性设置，完事返回contentParent
	return contentParent;
}

/**
 * Return the current Callback interface for this window.
 */
public final Callback getCallback() {
	return mCallback;
}

public void setCallback(Callback callback) {
	mCallback = callback;
}

final void attach(Context context, ActivityThread aThread,
	......
	mWindow.setCallback(this);
	......
}