android 换肤框架详解2-LayoutInflater源码解析

前面已经讲解了换肤，换资源文件的逻辑，接下来需要讲解一下如何实现自动换肤的逻辑第一步

查看LayoutInflater源码

传送门android 换肤框架详解1-换肤逻辑基本-CSDN博客

要对自动换肤有更深的了解，这里就需要对LayoutInflater源码有所了解

1. LayoutInflater源码解析

从inflate进来

    public View inflate(@LayoutRes int resource, @Nullable ViewGroup root) {return inflate(resource, root, root != null);}

    public View inflate(@LayoutRes int resource, @Nullable ViewGroup root, boolean attachToRoot) {//这里可以知道，Resources是通过getContext()拿到的，我们可以直接改变getContext()中的Resourcesfinal Resources res = getContext().getResources();if (DEBUG) {Log.d(TAG, "INFLATING from resource: \"" + res.getResourceName(resource) + "\" ("+ Integer.toHexString(resource) + ")");}//尝试“预编译”路径（Android 12 以后增加的优化）// 如果系统把这个 layout 提前编译成了预置的 Java 类（precompiled layout），就直接 new 出来返回，不走传统 XML 解析。View view = tryInflatePrecompiled(resource, res, root, attachToRoot);if (view != null) {return view;}//通过 AssetManager 打开一个 XmlResourceParser，指向该 layout xml 文件XmlResourceParser parser = res.getLayout(resource);try {//解析布局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);final String name = parser.getName();//解析merge标签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//解析xml里面获取到的数据，进行创建Viewfinal 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 suppliedparams = 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.//如果存在VIewGroup，添加View到View上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) {final InflateException ie = new InflateException(e.getMessage(), e);ie.setStackTrace(EMPTY_STACK_TRACE);throw ie;} catch (Exception e) {final InflateException ie = new InflateException(getParserStateDescription(inflaterContext, attrs)+ ": " + e.getMessage(), e);ie.setStackTrace(EMPTY_STACK_TRACE);throw ie;} finally {// Don't retain static reference on context.mConstructorArgs[0] = lastContext;mConstructorArgs[1] = null;Trace.traceEnd(Trace.TRACE_TAG_VIEW);}return result;}}

正在创建View的地方

  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) {try {//通过注册回调创建，这里就是自动将资源文件布局到View上的关键，这里会通过接口回调，回调到自己创建的//监听上，在这个监听里面保存对应的参数和类，然后切换换肤的时候一键修部署到ViewView view = tryCreateView(parent, name, context, attrs);if (view == null) {final Object lastContext = mConstructorArgs[0];mConstructorArgs[0] = context;try {//没有通过监听创建View，走自己的解析方法if (-1 == name.indexOf('.')) {view = onCreateView(context, parent, name, attrs);} else {view = createView(context, name, null, attrs);}} finally {mConstructorArgs[0] = lastContext;}}return view;} catch (InflateException e) {throw e;} }

   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;//判断是否创建了回调类，如果创建了就走创建类的回调创建View，自动换肤的关键在这里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 setFactory2(Factory2 factory) {//在View解析的时候，会先执行这里，如果有创建监听，会执行这里的创建View，我们自定义的这个类，可以不走系统的解析//方法，在自己创建的factory中进行对应解析创建，并且保存对应View在xml中的状态，在换行的时候就可以将保存的类进行//换肤处理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);}}