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获取LayoutInflater实例的常规方法

//方法1LayoutInflater layoutInflater = LayoutInflater.from(context);  //方法2LayoutInflater layoutInflater = (LayoutInflater) context          .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

注意inflate方法的第二，第三个参数的使用

如下是关键的源码(View inflate(XmlPullParser parser, @Nullable ViewGroup root, boolean attachToRoot)中的代码)

//一开始 View result = root; ..... // Temp is the root view that was found in the xml final View temp = createViewFromTag(root, name, inflaterContext, attrs); // Decide whether to return the root that was passed in or the // top view found in xml. if (root == null || !attachToRoot) {     result = temp; }

最常遇到的问题-布局文件的根View排版参数丢失了

如第二点提到的，如果第二个参数没有赋值，布局文件的排版版参数(LayoutParams)是不生效的（会丢失），关键代码如下图所示

// Temp is the root view that was found in the xmlfinal 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)        //设备布局文件的根节点的排版参数        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) {    //addView的内部也会设置布局文件的根view的排版参数    root.addView(temp, params);}