<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical">
    <TextView
        android:layout_width="match_parent"
        android:layout_height="80dp"
        android:background="#2196F3"
        android:text="這是頂部TextView"
        android:gravity="center"
        android:textColor="#FFFFFF"
        app:layout_behavior=".behavior.ScrollBehavior"/>
    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/rv_child"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="80dp"
        app:layout_behavior=".behavior.RecyclerViewBehavior"/>
</androidx.coordinatorlayout.widget.CoordinatorLayout>

setContentView(R.layout.activity_main)

@Override
public void setContentView(@LayoutRes int layoutResID) {
    initViewTreeOwners();
    getDelegate().setContentView(layoutResID);
}

@NonNull
public AppCompatDelegate getDelegate() {
    if (mDelegate == null) {
        mDelegate = AppCompatDelegate.create(this, this);
    }
    return mDelegate;
}

@Override
public void setContentView(int resId) {
    ensureSubDecor();
    ViewGroup contentParent = mSubDecor.findViewById(android.R.id.content);
    contentParent.removeAllViews();
    LayoutInflater.from(mContext).inflate(resId, contentParent);
    mAppCompatWindowCallback.bypassOnContentChanged(mWindow.getCallback());
}

<androidx.appcompat.widget.ActionBarOverlayLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:id="@+id/decor_content_parent"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:fitsSystemWindows="true">
    <!--布局id為 action_bar_activity_content---->
    <include layout="@layout/abc_screen_content_include"/>
    <androidx.appcompat.widget.ActionBarContainer
            android:id="@+id/action_bar_container"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_alignParentTop="true"
            style="?attr/actionBarStyle"
            android:touchscreenBlocksFocus="true"
            android:gravity="top">
        <androidx.appcompat.widget.Toolbar
                android:id="@+id/action_bar"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                app:navigationContentDescription="@string/abc_action_bar_up_description"
                style="?attr/toolbarStyle"/>
        <androidx.appcompat.widget.ActionBarContextView
                android:id="@+id/action_context_bar"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:visibility="gone"
                android:theme="?attr/actionModeTheme"
                style="?attr/actionModeStyle"/>
    </androidx.appcompat.widget.ActionBarContainer>
</androidx.appcompat.widget.ActionBarOverlayLayout>

final ContentFrameLayout contentView = (ContentFrameLayout) subDecor.findViewById(
        R.id.action_bar_activity_content);
final ViewGroup windowContentView = (ViewGroup) mWindow.findViewById(android.R.id.content);
if (windowContentView != null) {
    // There might be Views already added to the Window's content view so we need to
    // migrate them to our content view
    while (windowContentView.getChildCount() > 0) {
        final View child = windowContentView.getChildAt(0);
        windowContentView.removeViewAt(0);
        contentView.addView(child);
    }
    // Change our content FrameLayout to use the android.R.id.content id.
    // Useful for fragments.
    windowContentView.setId(View.NO_ID);
    contentView.setId(android.R.id.content);
    // The decorContent may have a foreground drawable set (windowContentOverlay).
    // Remove this as we handle it ourselves
    if (windowContentView instanceof FrameLayout) {
        ((FrameLayout) windowContentView).setForeground(null);
    }
}

public View inflate(@LayoutRes int resource, @Nullable ViewGroup root, boolean attachToRoot) {
    final Resources res = getContext().getResources();
    if (DEBUG) {
        Log.d(TAG, "INFLATING from resource: "" + res.getResourceName(resource) + "" ("
              + Integer.toHexString(resource) + ")");
    }
    View view = tryInflatePrecompiled(resource, res, root, attachToRoot);
    if (view != null) {
        return view;
    }
    // 這里是進(jìn)行XML布局解析
    XmlResourceParser parser = res.getLayout(resource);
    try {
        return inflate(parser, root, attachToRoot);
    } finally {
        parser.close();
    }
}

public View inflate(XmlPullParser parser, @Nullable ViewGroup root, boolean attachToRoot) {
    synchronized (mConstructorArgs) {
        Trace.traceBegin(Trace.TRACE_TAG_VIEW, "inflate");
        final Context inflaterContext = mContext;
        final AttributeSet attrs = Xml.asAttributeSet(parser);
        Context lastContext = (Context) mConstructorArgs[0];
        mConstructorArgs[0] = inflaterContext;
        View result = root;
        try {
            advanceToRootNode(parser);
            // 代碼 - 1
            final String name = parser.getName();
            // ...... 省略部分代碼
            if (TAG_MERGE.equals(name)) {
                if (root == null || !attachToRoot) {
                    throw new InflateException("<merge /> can be used only with a valid "
                            + "ViewGroup root and attachToRoot=true");
                }
                rInflate(parser, root, inflaterContext, attrs, false);
            } else {
                // Temp is the root view that was found in the xml
                // 代碼 - 2
                final View temp = createViewFromTag(root, name, inflaterContext, attrs);
                ViewGroup.LayoutParams params = null;
                if (root != null) {
                    if (DEBUG) {
                        System.out.println("Creating params from root: " +
                                root);
                    }
                    // Create layout params that match root, if supplied
                    params = root.generateLayoutParams(attrs);
                    if (!attachToRoot) {
                        // Set the layout params for temp if we are not
                        // attaching. (If we are, we use addView, below)
                        temp.setLayoutParams(params);
                    }
                }
                if (DEBUG) {
                    System.out.println("-----> start inflating children");
                }
                // Inflate all children under temp against its context.
                rInflateChildren(parser, temp, attrs, true);
                if (DEBUG) {
                    System.out.println("-----> done inflating children");
                }
                // We are supposed to attach all the views we found (int temp)
                // to root. Do that now.
                if (root != null && attachToRoot) {
                    root.addView(temp, params);
                }
                // Decide whether to return the root that was passed in or the
                // top view found in xml.
                if (root == null || !attachToRoot) {
                    result = temp;
                }
            }
        }
        return result;
    }
}

View createViewFromTag(View parent, String name, Context context, AttributeSet attrs,
        boolean ignoreThemeAttr) {
    if (name.equals("view")) {
        name = attrs.getAttributeValue(null, "class");
    }
    // Apply a theme wrapper, if allowed and one is specified.
    if (!ignoreThemeAttr) {
        final TypedArray ta = context.obtainStyledAttributes(attrs, ATTRS_THEME);
        final int themeResId = ta.getResourceId(0, 0);
        if (themeResId != 0) {
            context = new ContextThemeWrapper(context, themeResId);
        }
        ta.recycle();
    }
    try {
        // 代碼 - 3
        View view = tryCreateView(parent, name, context, attrs);
        // 代碼 - 4
        if (view == null) {
            final Object lastContext = mConstructorArgs[0];
            mConstructorArgs[0] = context;
            try {
                if (-1 == name.indexOf('.')) {
                    view = onCreateView(context, parent, name, attrs);
                } else {
                    view = createView(context, name, null, attrs);
                }
            } finally {
                mConstructorArgs[0] = lastContext;
            }
        }
        return view;
    }
}

public final View tryCreateView(@Nullable View parent, @NonNull String name,
    @NonNull Context context,
    @NonNull AttributeSet attrs) {
    if (name.equals(TAG_1995)) {
        // Let's party like it's 1995!
        return new BlinkLayout(context, attrs);
    }
    View view;
    if (mFactory2 != null) {
        view = mFactory2.onCreateView(parent, name, context, attrs);
    } else if (mFactory != null) {
        view = mFactory.onCreateView(name, context, attrs);
    } else {
        view = null;
    }
    if (view == null && mPrivateFactory != null) {
        view = mPrivateFactory.onCreateView(parent, name, context, attrs);
    }
    return view;
}

public void setFactory(Factory factory) {
    if (mFactorySet) {
        throw new IllegalStateException("A factory has already been set on this LayoutInflater");
    }
    if (factory == null) {
        throw new NullPointerException("Given factory can not be null");
    }
    mFactorySet = true;
    if (mFactory == null) {
        mFactory = factory;
    } else {
        mFactory = new FactoryMerger(factory, null, mFactory, mFactory2);
    }
}
/**
 * Like {@link #setFactory}, but allows you to set a {@link Factory2}
 * interface.
 */
public void setFactory2(Factory2 factory) {
    if (mFactorySet) {
        throw new IllegalStateException("A factory has already been set on this LayoutInflater");
    }
    if (factory == null) {
        throw new NullPointerException("Given factory can not be null");
    }
    mFactorySet = true;
    if (mFactory == null) {
        mFactory = mFactory2 = factory;
    } else {
        mFactory = mFactory2 = new FactoryMerger(factory, factory, mFactory, mFactory2);
    }
}

protected LayoutInflater(LayoutInflater original, Context newContext) {
    StrictMode.assertConfigurationContext(newContext, "LayoutInflater");
    mContext = newContext;
    mFactory = original.mFactory;
    mFactory2 = original.mFactory2;
    mPrivateFactory = original.mPrivateFactory;
    setFilter(original.mFilter);
    initPrecompiledViews();
}

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/cs_root"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <TextView
        android:id="@+id/tv_skin"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="開啟換膚"
        android:textColor="#000000"
        android:textStyle="bold"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"/>
</androidx.constraintlayout.widget.ConstraintLayout>

class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
    // 代碼 - 5
    super.onCreate(savedInstanceState)
    val inflater = LayoutInflater.from(this)
    inflater.factory2 = object : LayoutInflater.Factory2 {
        override fun onCreateView(
            parent: View?,
            name: String,
            context: Context,
            attrs: AttributeSet
        ): View? {
            if (name == "TextView") {
                val button = Button(context)
                button.setText("換膚")
                return button
            }
            return null
        }
        override fun onCreateView(name: String, context: Context, attrs: AttributeSet): View? {
            return null
        }
    }
    val view = inflater.inflate(R.layout.layout_skin, findViewById(R.id.cs_root), false)
    setContentView(view)
}

@ContentView
public AppCompatActivity(@LayoutRes int contentLayoutId) {
    super(contentLayoutId);
    initDelegate();
}
private void initDelegate() {
    // TODO: Directly connect AppCompatDelegate to SavedStateRegistry
    getSavedStateRegistry().registerSavedStateProvider(DELEGATE_TAG,
            new SavedStateRegistry.SavedStateProvider() {
                @NonNull
                @Override
                public Bundle saveState() {
                    Bundle outState = new Bundle();
                    getDelegate().onSaveInstanceState(outState);
                    return outState;
                }
            });
    addOnContextAvailableListener(new OnContextAvailableListener() {
        @Override
        public void onContextAvailable(@NonNull Context context) {
            final AppCompatDelegate delegate = getDelegate();
            delegate.installViewFactory();
            delegate.onCreate(getSavedStateRegistry()
                    .consumeRestoredStateForKey(DELEGATE_TAG));
        }
    });
}

@Override
public void installViewFactory() {
    LayoutInflater layoutInflater = LayoutInflater.from(mContext);
    if (layoutInflater.getFactory() == null) {
        LayoutInflaterCompat.setFactory2(layoutInflater, this);
    } else {
        if (!(layoutInflater.getFactory2() instanceof AppCompatDelegateImpl)) {
            Log.i(TAG, "The Activity's LayoutInflater already has a Factory installed"
                    + " so we can not install AppCompat's");
        }
    }
}

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="Skinable">
        <attr name="isSupport" format="boolean"/>
    </declare-styleable>
</resources>

class SkinFactory : LayoutInflater.Factory2 {
    override fun onCreateView(
        parent: View?,
        name: String,
        context: Context,
        attrs: AttributeSet
    ): View? {
        //創(chuàng)建View
        //收集可以換膚的組件
        return null
    }
    override fun onCreateView(name: String, context: Context, attrs: AttributeSet): View? {
        return null
    }
}

override fun onCreateView(
    parent: View?,
    name: String,
    context: Context,
    attrs: AttributeSet
): View? {
    //創(chuàng)建View
    val view = delegate.createView(parent, name, context, attrs)
    if (view == null) {
        //TODO 沒有創(chuàng)建成功，需要通過反射來創(chuàng)建
    }
    //收集可以換膚的組件
    if (view != null) {
        collectSkinComponent(attrs, context, view)
    }
    return view
}
/**
 * 收集能夠進(jìn)行換膚的控件
 */
private fun collectSkinComponent(attrs: AttributeSet, context: Context, view: View) {
    //獲取屬性
    val skinAbleAttr = context.obtainStyledAttributes(attrs, R.styleable.Skinable, 0, 0)
    val isSupportSkin = skinAbleAttr.getBoolean(R.styleable.Skinable_isSupport, false)
    if (isSupportSkin) {
        val attrsMap: MutableMap<String, String> = mutableMapOf()
        //收集起來
        for (index in 0 until attrs.attributeCount) {
            val name = attrs.getAttributeName(index)
            val value = attrs.getAttributeValue(index)
            attrsMap[name] = value
        }
        val skinView = SkinView(view, attrsMap)
        skinList.add(skinView)
    }
    skinAbleAttr.recycle()
}

sealed class SkinType{
    /**
     * 更換背景顏色
     * @param color 背景顏色
     */
    class BackgroundSkin(val color:Int):SkinType()
    /**
     * 更換背景圖片
     * @param drawable 背景圖片資源id
     */
    class BackgroundDrawableSkin(val drawable:Int):SkinType()
    /**
     * 更換字體顏色
     * @param color 字體顏色
     * NOTE 這個(gè)只能TextView才能是用
     */
    class TextColorSkin(val color: Int):SkinType()
    /**
     * 更換字體類型
     * @param textStyle 字體型號(hào)
     * NOTE 這個(gè)只能TextView才能是用
     */
    class TextStyleSkin(val textStyle: Typeface):SkinType()
}

/**
 * 一鍵換膚
 */
fun changedSkin(vararg skinType: SkinType) {
    Log.e("TAG","skinList $skinList")
    skinList.forEach { skinView ->
        changedSkinInner(skinView, skinType)
    }
}
/**
 * 換膚的內(nèi)部實(shí)現(xiàn)類
 */
private fun changedSkinInner(skinView: SkinView, skinType: Array<out SkinType>) {
    skinType.forEach { type ->
        Log.e("TAG", "changedSkinInner $type")
        when (type) {
            is SkinType.BackgroundSkin -> {
                skinView.view.setBackgroundColor(type.color)
            }
            is SkinType.BackgroundDrawableSkin -> {
                skinView.view.setBackgroundResource(type.drawable)
            }
            is SkinType.TextStyleSkin -> {
                if (skinView.view is TextView) {
                    //只有TextView可以換
                    skinView.view.typeface = type.textStyle
                }
            }
            is SkinType.TextColorSkin -> {
                if (skinView.view is TextView) {
                    //只有TextView可以換
                    skinView.view.setTextColor(type.color)
                }
            }
        }
    }
}

abstract class SkinActivity : AppCompatActivity() {
    private lateinit var skinFactory: SkinFactory
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        Log.e("TAG", "onCreate")
        val inflate = LayoutInflater.from(this)
        //恢復(fù)標(biāo)志位
        resetmFactorySet(inflate)
        //開啟換膚模式
        skinFactory = SkinFactory(delegate)
        inflate.factory2 = skinFactory
        setContentView(inflate.inflate(getLayoutId(), getViewRoot(), false))
        initView()
    }
    open fun initView() {
    }
    protected fun changedSkin(vararg skinType: SkinType) {
        Log.e("TAG", "changedSkin")
        skinFactory.changedSkin(*skinType)
    }
    @SuppressLint("SoonBlockedPrivateApi")
    private fun resetmFactorySet(instance: LayoutInflater) {
        val mFactorySetField = LayoutInflater::class.java.getDeclaredField("mFactorySet")
        mFactorySetField.isAccessible = true
        mFactorySetField.set(instance, false)
    }
    abstract fun getLayoutId(): Int
    abstract fun getViewRoot(): ViewGroup?
}

class SkinChangeActivity : SkinActivity() {
    override fun initView() {
        findViewById<Button>(R.id.btn_skin).setOnClickListener {
            Toast.makeText(this,"更換背景",Toast.LENGTH_SHORT).show()
            changedSkin(
                SkinType.BackgroundSkin(Color.parseColor("#B81A1A"))
            )
        }
        findViewById<Button>(R.id.btn_skin_textColor).setOnClickListener {
            Toast.makeText(this,"更換字體顏色",Toast.LENGTH_SHORT).show()
            changedSkin(
                SkinType.TextColorSkin(Color.parseColor("#FFEB3B")),
                SkinType.BackgroundSkin(Color.WHITE)
            )
        }
        findViewById<Button>(R.id.btn_skin_textStyle).setOnClickListener {
            Toast.makeText(this,"更換字體樣式",Toast.LENGTH_SHORT).show()
            changedSkin(
                SkinType.TextStyleSkin(Typeface.DEFAULT_BOLD),
            )
        }
    }
    override fun getLayoutId(): Int {
        return R.layout.activity_skin_change
    }
    override fun getViewRoot(): ViewGroup? {
        return findViewById(R.id.cs_root)
    }
}