Activity中的setContentView(R.layout.xxx)源码分析

阳光穿透心脏的1/2处 2021-11-09 12:36 189阅读 0赞

点进去会看到下图：

![894642-20190724145554780-687804364.png][]

其中getWindow()是获取到Window类的唯一子类PhoneWindow的对象

![894642-20190724145936352-275895746.png][]

找到PhoneWindow的`setContentView`()方法点进去：

1 @Override
     2     public void setContentView(int layoutResID) {
     3         // Note: FEATURE_CONTENT_TRANSITIONS may be set in the process of installing the window
     4         // decor, when theme attributes and the like are crystalized. Do not check the feature
     5         // before this happens.
     6         if (mContentParent == null) {
     7             installDecor();
     8         } else if (!hasFeature(FEATURE_CONTENT_TRANSITIONS)) {
     9             mContentParent.removeAllViews();
    10         }
    11 
    12         if (hasFeature(FEATURE_CONTENT_TRANSITIONS)) {
    13             final Scene newScene = Scene.getSceneForLayout(mContentParent, layoutResID,
    14                     getContext());
    15             transitionTo(newScene);
    16         } else {
    17             mLayoutInflater.inflate(layoutResID, mContentParent);
    18         }
    19         mContentParent.requestApplyInsets();
    20         final Callback cb = getCallback();
    21         if (cb != null && !isDestroyed()) {
    22             cb.onContentChanged();
    23         }
    24     }

从上述代码中可以看出：把我们的layoutResID放在了mContentParent里面

在类中可以看出mContentParent是一个ViewGroup

点进去查看：installDecor()方法

![894642-20190724150752899-2054125786.png][]

![894642-20190724151025211-1526250370.png][]

继续跟进：generateLayout（）方法

protected ViewGroup generateLayout(DecorView decor) { // Apply data from current theme. TypedArray a = getWindowStyle(); if (false) { System.out.println("From style:"); String s = "Attrs:"; for (int i = 0; i < R.styleable.Window.length; i++) { s = s + " " + Integer.toHexString(R.styleable.Window[i ![无标题.png](http://upload-images.jianshu.io/upload_images/4658633-9a3a758cbac9f8aa.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240) ]) + "=" + a.getString(i); } System.out.println(s); } //根据style属性做一些列的判断... //在做一些列的判断得到layoutResource layoutResource = R.layout.screen_swipe_dismiss; //这里用R.layout.screen_simple来分析 mDecor.startChanging(); View in = mLayoutInflater.inflate(layoutResource, null); //把layoutResource放进decor中去 decor.addView(in, new ViewGroup.LayoutParams(MATCH_PARENT, MATCH_PARENT)); mContentRoot = (ViewGroup) in; ViewGroup contentParent = (ViewGroup)findViewById(ID_ANDROID_CONTENT); if (contentParent == null) { throw new RuntimeException("Window couldn't find content container view"); } //...... mDecor.finishChanging(); //返回创建的这个布局 return contentParent; } //贴出这个布局文件

if (mDecor == null) {
                mDecor = generateDecor();
                mDecor.setDescendantFocusability(ViewGroup.FOCUS_AFTER_DESCENDANTS);
                mDecor.setIsRootNamespace(true);
                if (!mInvalidatePanelMenuPosted && mInvalidatePanelMenuFeatures != 0) {
                    mDecor.postOnAnimation(mInvalidatePanelMenuRunnable);
                }
            }

protected DecorView generateDecor() { return new DecorView(getContext(), -1); }

mDecor 就是DecorView（FragmentLayout）的一个实例
    所以最终的图形就是

![894642-20190724152604260-808222452.png][]

转载于:https://www.cnblogs.com/lianzhen/p/11238301.html

[894642-20190724145554780-687804364.png]: /images/20211109/3b928991c55f454695a9a5580b389819.png
[894642-20190724145936352-275895746.png]: /images/20211109/3bcde8eafbd7473492a8284ddcabdd6b.png
[894642-20190724150752899-2054125786.png]: /images/20211109/decd06eedcfc486ba133c01ab004ec61.png
[894642-20190724151025211-1526250370.png]: /images/20211109/e178ed32bdd1478dad5efda2abf63d8b.png
[894642-20190724152604260-808222452.png]: /images/20211109/5ee6b4aa355e48b388c22d90cb6b2e29.png