全局修改一些view的属性的简单办法，就是标题的方法
需要在super.onCreate(savedInstanceState)之前添加，因为一个activity只能设置一个，而系统在super方法里也调用了这个方法。。所以我们需要在系统设置之前。

    override fun onCreate(savedInstanceState: Bundle?) {
        LayoutInflaterCompat.setFactory2(layoutInflater,object :LayoutInflater.Factory2{
            override fun onCreateView(parent: View?, name: String?, context: Context, attrs: AttributeSet): View? {
                var view=delegate.createView(parent,name,context,attrs);//调用系统的方法
                println("onCreateView56=====$name===========${view}")
                LinearLayout(context,attrs)
                return  view
            }

            override fun onCreateView(name: String?, context: Context?, attrs: AttributeSet?): View? {
                return  null
            }
        })
        super.onCreate(savedInstanceState)
    }

获取id的办法,打印下获取到的id就是 @+十进制id，比如这样id===============@2131296538

                (0 until attrs.attributeCount).forEach {
                    println("${name}=====$it==========${attrs.getAttributeName(it)}")
                    if(TextUtils.equals("id",attrs.getAttributeName(it))){
                        try {view.id
                            println("id===============${attrs.getAttributeValue(it)}")
                            if(TextUtils.equals(attrs.getAttributeValue(it),"@${android.R.id.message}")){
                                if(view!=null&& view is TextView){
                                    view.setTextColor(Color.RED)
                                }
                            }
                        }catch (e:Exception){
                            e.printStackTrace()
                        }
                    }
                }

然后先说下上边获取的view方法，最终是在这里AppCompatViewInflater类里
可以看到除了基本控件基本返回的view都是null

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 its android:onClick
            checkOnClickListener(view, attrs);
        }

        return view;
    }

我们看下系统的用法，在AppCompatActivity类里

protected void onCreate(@Nullable Bundle savedInstanceState) {
        final AppCompatDelegate delegate = getDelegate();
        delegate.installViewFactory();
        delegate.onCreate(savedInstanceState);


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

// public abstract class AppCompatDelegate

    public static AppCompatDelegate create(Activity activity, AppCompatCallback callback) {
        return create(activity, activity.getWindow(), callback);
    }

//
    private static AppCompatDelegate create(Context context, Window window,
            AppCompatCallback callback) {
        if (Build.VERSION.SDK_INT >= 24) {
            return new AppCompatDelegateImplN(context, window, callback);
        } else if (Build.VERSION.SDK_INT >= 23) {
            return new AppCompatDelegateImplV23(context, window, callback);
        } else if (Build.VERSION.SDK_INT >= 14) {
            return new AppCompatDelegateImplV14(context, window, callback);
        } else if (Build.VERSION.SDK_INT >= 11) {
            return new AppCompatDelegateImplV11(context, window, callback);
        } else {
            return new AppCompatDelegateImplV9(context, window, callback);
        }
    }

在AppCompatDelegateImplV9里实现了最开始的installViewFactory（）

另外在14里边实现了白天黑夜模式

class AppCompatDelegateImplV9 extends AppCompatDelegateImplBase
        implements MenuBuilder.Callback, LayoutInflater.Factory2

//可以看到只能设置一个factory

    public void installViewFactory() {
        LayoutInflater layoutInflater = LayoutInflater.from(mContext);
        if (layoutInflater.getFactory() == null) {
            LayoutInflaterCompat.setFactory2(layoutInflater, this);
        } else {
            if (!(layoutInflater.getFactory2() instanceof AppCompatDelegateImplV9)) {
                Log.i(TAG, "The Activity's LayoutInflater already has a Factory installed"
                        + " so we can not install AppCompat's");
            }
        }
    }

继续往下LayoutInflaterCompat

    @RequiresApi(21)
    static class LayoutInflaterCompatApi21Impl extends LayoutInflaterCompatBaseImpl {
        @SuppressWarnings("deprecation")
        @Override
        public void setFactory(LayoutInflater inflater, LayoutInflaterFactory factory) {
            inflater.setFactory2(factory != null ? new Factory2Wrapper(factory) : null);
        }

        @Override
        public void setFactory2(LayoutInflater inflater, LayoutInflater.Factory2 factory) {
            inflater.setFactory2(factory);
        }
    }
    static final LayoutInflaterCompatBaseImpl IMPL;
    static {
        if (Build.VERSION.SDK_INT >= 21) {
            IMPL = new LayoutInflaterCompatApi21Impl();
        } else {
            IMPL = new LayoutInflaterCompatBaseImpl();
        }
    }

    public static void setFactory2(
            @NonNull LayoutInflater inflater, @NonNull LayoutInflater.Factory2 factory) {
        IMPL.setFactory2(inflater, factory);
    }


//看下impl
    static class LayoutInflaterCompatBaseImpl {
        @SuppressWarnings("deprecation")
        public void setFactory(LayoutInflater inflater, LayoutInflaterFactory factory) {
            final LayoutInflater.Factory2 factory2 = factory != null
                    ? new Factory2Wrapper(factory) : null;
            setFactory2(inflater, factory2);
        }

        public void setFactory2(LayoutInflater inflater, LayoutInflater.Factory2 factory) {
            inflater.setFactory2(factory);

            final LayoutInflater.Factory f = inflater.getFactory();
            if (f instanceof LayoutInflater.Factory2) {
                // The merged factory is now set to getFactory(), but not getFactory2() (pre-v21).
                // We will now try and force set the merged factory to mFactory2
                forceSetFactory2(inflater, (LayoutInflater.Factory2) f);//通过反射把factory赋值给LayoutInflater。
            } else {
                // Else, we will force set the original wrapped Factory2
                forceSetFactory2(inflater, factory);
            }
        }

        @SuppressWarnings("deprecation")
        public LayoutInflaterFactory getFactory(LayoutInflater inflater) {
            LayoutInflater.Factory factory = inflater.getFactory();
            if (factory instanceof Factory2Wrapper) {
                return ((Factory2Wrapper) factory).mDelegateFactory;
            }
            return null;
        }
    }

我们知道我们的布局文件加载就是靠LayoutInflater的，现在看下它的加载

    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) + ")");
        }

        final XmlResourceParser parser = res.getLayout(resource);
        try {
            return inflate(parser, root, attachToRoot);
        } finally {
            parser.close();
        }
    }

//继续看下inflate方法，删掉一些代码，看下核心代码就行
    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 {
                // Look for the root node.
                int type;
                while ((type = parser.next()) != XmlPullParser.START_TAG &&
                        type != XmlPullParser.END_DOCUMENT) {
                    // Empty
                }

                if (type != XmlPullParser.START_TAG) {
                    throw new InflateException(parser.getPositionDescription()
                            + ": No start tag found!");
                }

                final String name = parser.getName();
              //处理merge标签的
                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");
                    }
                    //处理子控件的
                    rInflate(parser, root, inflaterContext, attrs, false);
                } else {
                    // Temp is the root view that was found in the xml 处理普通布局的
                    final View temp = createViewFromTag(root, name, inflaterContext, attrs);

                    ViewGroup.LayoutParams params = null;

                    if (root != null) {
              
                        // 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);
                        }
                    }

                    // Inflate all children under temp against its context.
                    rInflateChildren(parser, temp, attrs, true);

                    // 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;
                    }
                }

            } catch (XmlPullParserException e) {
            } catch (Exception e) {
            } finally {
            }

            return result;
        }
    }

下边分别说明下上边几个方法

对于merge布局走了这里，就是循环读取标签解析出对应的控件。

  /**
     * Recursive method used to descend down the xml hierarchy and instantiate
     * views, instantiate their children, and then call onFinishInflate().
     * <p>
     * <strong>Note:</strong> Default visibility so the BridgeInflater can
     * override it.
     */
    void rInflate(XmlPullParser parser, View parent, Context context,
            AttributeSet attrs, boolean finishInflate) throws XmlPullParserException, IOException {

        final int depth = parser.getDepth();
        int type;
        boolean pendingRequestFocus = false;

        while (((type = parser.next()) != XmlPullParser.END_TAG ||
                parser.getDepth() > depth) && type != XmlPullParser.END_DOCUMENT) {

            if (type != XmlPullParser.START_TAG) {
                continue;
            }

            final String name = parser.getName();

            if (TAG_REQUEST_FOCUS.equals(name)) {
                pendingRequestFocus = true;
                consumeChildElements(parser);
            } else if (TAG_TAG.equals(name)) {
                parseViewTag(parser, parent, attrs);
            } else if (TAG_INCLUDE.equals(name)) {
                if (parser.getDepth() == 0) {
                    throw new InflateException("<include /> cannot be the root element");
                }
                parseInclude(parser, context, parent, attrs);
            } else if (TAG_MERGE.equals(name)) {
                throw new InflateException("<merge /> must be the root element");
            } else {
                final View view = createViewFromTag(parent, name, context, attrs); //view的最后获取都是在这里的
                final ViewGroup viewGroup = (ViewGroup) parent;
                final ViewGroup.LayoutParams params = viewGroup.generateLayoutParams(attrs);
                rInflateChildren(parser, view, attrs, true);
                viewGroup.addView(view, params);
            }
        }

        if (pendingRequestFocus) {
            parent.restoreDefaultFocus();
        }

        if (finishInflate) {
            parent.onFinishInflate();
        }
    }

createViewFromTag

结论是先调用我们设置的factory的方法获取view，如果为空再调用系统原生的。

    private View createViewFromTag(View parent, String name, Context context, AttributeSet attrs) {
        return createViewFromTag(parent, name, context, attrs, false);
    }

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();
        }

        if (name.equals(TAG_1995)) {
            // Let's party like it's 1995!
            return new BlinkLayout(context, attrs);
        }

        try {
            View view;//可以看到先调用我们设置的factory的方法获取view
            if (mFactory2 != null) {
                view = mFactory2.onCreateView(parent, name, context, attrs);
            } else if (mFactory != null) {
                view = mFactory.onCreateView(name, context, attrs);
            } else {
                view = null;
            }
          //mPrivateFactory 也是个factory
            if (view == null && mPrivateFactory != null) {
                view = mPrivateFactory.onCreateView(parent, name, context, attrs);
            }

            if (view == null) {//如果我们factory的回调方法里返回的view是空的，那么这里处理
                final Object lastContext = mConstructorArgs[0];
                mConstructorArgs[0] = context;
                try {
                    if (-1 == name.indexOf('.')) {//这里2个就是系统创建view的过程了，不研究
                        view = onCreateView(parent, name, attrs);
                    } else {
                        view = createView(name, null, attrs);
                    }
                } finally {
                    mConstructorArgs[0] = lastContext;
                }
            }

            return view;
        } catch (InflateException e) {
        } catch (ClassNotFoundException e) {
        } catch (Exception e) {
        }
    }

在AppCompatDelegateImplV9 createView方法

可以看到调用了AppCompatViewInflater里的createView方法也就是对原始的控件，都改成了AppcompatXXXX的东西。

    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 */
        );
    }

最后稍微总结下：
AppCompatDelegate从v9开始就实现了Factory2，也就是它也是个factory。然后它通过反射赋值给了Layouinflator。 Layouinflator加载布局的过程我们也分析了，里边就有用到factory，先通过factory获取view【就是在这里完成了对原始view的修改】，获取 为空的话再用最原始的方法生成view。
看下v9下， mFactory2.onCreateView() 其实最终还是掉的createView方法，这个方法又跑到AppCompatViewInflater里的createView方法里的，这是最终修改view的地方。

    public final View onCreateView(View parent, String name, Context context, AttributeSet attrs) {
        // First let the Activity's Factory try and inflate the view
        final View view = callActivityOnCreateView(parent, name, context, attrs);
        if (view != null) {
            return view;
        }

        // If the Factory didn't handle it, let our createView() method try
        return createView(parent, name, context, attrs);
    }