首先，Activity会在onCreate中初始化Factory，我们没有设置就返回系统默认的：

@Override

public void installViewFactory() {

LayoutInflater layoutInflater = LayoutInflater.from(mContext);

if (layoutInflater.getFactory() == null) {

LayoutInflaterCompat.setFactory(layoutInflater, this); //系统默认的

} else {

if (!(LayoutInflaterCompat.getFactory(layoutInflater)

instanceof AppCompatDelegateImplV9)) {

Log.i(TAG, "The Activity's LayoutInflater already has a Factory installed"

+ " so we can not install AppCompat's");

}

}

}

Factory会在layoutInflater.inflate，最终会走Factory.createView，看看系统的：

@Override

public View createView(View parent, final String name, @NonNull Context context,

@NonNull AttributeSet attrs) {

if (mAppCompatViewInflater == null) {

mAppCompatViewInflater = new AppCompatViewInflater();

}

boolean inheritContext = false;

if (IS_PRE_LOLLIPOP) {

inheritContext = (attrs instanceof XmlPullParser)

// If we have a XmlPullParser, we can detect where we are in the layout

? ((XmlPullParser) attrs).getDepth() > 1

// Otherwise we have to use the old heuristic

: shouldInheritContext((ViewParent) parent);

}

return mAppCompatViewInflater.createView(parent, name, context, attrs, inheritContext,

IS_PRE_LOLLIPOP, /* Only read android:theme pre-L (L+ handles this anyway) */

true, /* Read read app:theme as a fallback at all times for legacy reasons */

VectorEnabledTintResources.shouldBeUsed() /* Only tint wrap the context if enabled */

);

}

再看下去：

public final View createView(View parent, final String name, @NonNull Context context,

@NonNull AttributeSet attrs, boolean inheritContext,

boolean readAndroidTheme, boolean readAppTheme, boolean wrapContext) {

final Context originalContext = context;

// We can emulate Lollipop's android:theme attribute propagating down the view hierarchy

// by using the parent's context

if (inheritContext && parent != null) {

context = parent.getContext();

}

if (readAndroidTheme || readAppTheme) {

// We then apply the theme on the context, if specified

context = themifyContext(context, attrs, readAndroidTheme, readAppTheme);

}

if (wrapContext) {

context = TintContextWrapper.wrap(context);

}

View view = null;

// We need to 'inject' our tint aware Views in place of the standard framework versions

switch (name) {

case "TextView":

view = new AppCompatTextView(context, attrs);

break;

case "ImageView":

view = new AppCompatImageView(context, attrs);

break;

case "Button":

view = new AppCompatButton(context, attrs);

break;

case "EditText":

view = new AppCompatEditText(context, attrs);

break;

case "Spinner":

view = new AppCompatSpinner(context, attrs);

break;

case "ImageButton":

view = new AppCompatImageButton(context, attrs);

break;

case "CheckBox":

view = new AppCompatCheckBox(context, attrs);

break;

case "RadioButton":

view = new AppCompatRadioButton(context, attrs);

break;

case "CheckedTextView":

view = new AppCompatCheckedTextView(context, attrs);

break;

case "AutoCompleteTextView":

view = new AppCompatAutoCompleteTextView(context, attrs);

break;

case "MultiAutoCompleteTextView":

view = new AppCompatMultiAutoCompleteTextView(context, attrs);

break;

case "RatingBar":

view = new AppCompatRatingBar(context, attrs);

break;

case "SeekBar":

view = new AppCompatSeekBar(context, attrs);

break;

}

if (view == null && originalContext != context) {

// If the original context does not equal our themed context, then we need to manually

// inflate it using the name so that android:theme takes effect.

view = createViewFromTag(context, name, attrs);

}

if (view != null) {

// If we have created a view, check it's android:onClick

checkOnClickListener(view, attrs);

}

return view;

}

可以看到系统也是根据XML解析的名字new出控件，但上面都是AppCompat类型，其他类型其实的通过类加载器创建出来的，那么XML使用TextView其实是AppCompatTextView，利用这一个原理，看看Android-skin-support：

private View createViewFromFV(Context context, String name, AttributeSet attrs) {

View view = null;

if (name.contains(".")) {

return null;

}

switch (name) {

case "View":

view = new SkinCompatView(context, attrs);

break;

case "LinearLayout":

view = new SkinCompatLinearLayout(context, attrs);

break;

case "RelativeLayout":

view = new SkinCompatRelativeLayout(context, attrs);

break;

case "FrameLayout":

view = new SkinCompatFrameLayout(context, attrs);

break;

case "TextView":

view = new SkinCompatTextView(context, attrs);

break;

case "ImageView":

view = new SkinCompatImageView(context, attrs);

break;

case "Button":

view = new SkinCompatButton(context, attrs);

break;

case "EditText":

view = new SkinCompatEditText(context, attrs);

break;

case "Spinner":

view = new SkinCompatSpinner(context, attrs);

break;

case "ImageButton":

view = new SkinCompatImageButton(context, attrs);

break;

case "CheckBox":

view = new SkinCompatCheckBox(context, attrs);

break;

case "RadioButton":

view = new SkinCompatRadioButton(context, attrs);

break;

case "RadioGroup":

view = new SkinCompatRadioGroup(context, attrs);

break;

case "CheckedTextView":

view = new SkinCompatCheckedTextView(context, attrs);

break;

case "AutoCompleteTextView":

view = new SkinCompatAutoCompleteTextView(context, attrs);

break;

case "MultiAutoCompleteTextView":

view = new SkinCompatMultiAutoCompleteTextView(context, attrs);

break;

case "RatingBar":

view = new SkinCompatRatingBar(context, attrs);

break;

case "SeekBar":

view = new SkinCompatSeekBar(context, attrs);

break;

case "ProgressBar":

view = new SkinCompatProgressBar(context, attrs);

break;

case "ScrollView":

view = new SkinCompatScrollView(context, attrs);

break;

}

return view;

}

这就返回了自己定制好的View了，那么回到前面，我们需要在super.onCreate前设置自己的Factory，不可能每个Activity都设置一遍，那么利用Application.ActivityLifecycleCallbacks统一设置：

@Override

public void onActivityCreated(Activity activity, Bundle savedInstanceState) {

if (activity instanceof AppCompatActivity) {

LayoutInflater layoutInflater = activity.getLayoutInflater();

try {

Field field = LayoutInflater.class.getDeclaredField("mFactorySet");

field.setAccessible(true);

field.setBoolean(layoutInflater, false);

LayoutInflaterCompat.setFactory(activity.getLayoutInflater(),

getSkinDelegate((AppCompatActivity) activity));

} catch (NoSuchFieldException | IllegalArgumentException | IllegalAccessException e) {

e.printStackTrace();

}

updateStatusBarColor(activity);

updateWindowBackground(activity);

}

}