setContentView流程
setContentView
getDelegate
->AppCompatDelegate.Create
->AppCompatDelegateImplV9.setContentView
->ensureSubDecor
->createSubDecor
(->requestWindowFeature
->mWindow.getDecorView();// 就是创建DecorView
->subDecor inflate
-> mWindow.setContentView(subDecor);)
setContentView的过程就是通过PhoneWindow创建DecorView，然后创建SubDecor，最终将传递进来的布局add进来。
LayoutInflater
LayoutInflater.inflate()
->Xml.asAttributeSet(XmlPullParser parser)
->首先进行View的合理性校验，include、merge等标签
->createViewFromTag
(->final TypedArray ta = context.obtainStyledAttributes(attrs, ATTRS_THEME);
->Factory.onCreateView || onCreateView
(->clazz.getConstructor //反射获取这个View的构造器
->constructor.newInstance(args)))
->generateLayoutParams//根据当前标签的参数生成LayoutParams
->rInflateChildren
-> root.addView
LayoutInflater Factory
AppCompatActivity .onCreate
->delegate.installViewFactory
->AppCompatDelegateImpl.createView
->AppCompatViewInflater.createView
->switch (name) createView
