ViewGroup 可以通过 addView 加载子布局
ViewGroup 有 LinearLayout、RelativeLayout 等
通过LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT)，可以设置 LinearLayout 相关属性值
通过继承一种 ViewGroup 自定义其组合控件
构造函数使用 LayoutInflater.from(context).inflate() 加载布局，或者使用 context： LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE) 或 activity：LayoutInflater inflater = activity.getLayoutInflater() 获得 inflater 实例，再使用 inflate() 方法
API 文档：
/**
* Instantiates a layout XML file into its corresponding {@link android.view.View}
* objects. It is never used directly. Instead, use
* {@link android.app.Activity#getLayoutInflater()} or
* {@link Context#getSystemService} to retrieve a standard LayoutInflater instance
* that is already hooked up to the current context and correctly configured
* for the device you are running on. For example:
*
* <pre>LayoutInflater inflater = (LayoutInflater)context.getSystemService
* (Context.LAYOUT_INFLATER_SERVICE);</pre>
*
* <p>
* To create a new LayoutInflater with an additional {@link Factory} for your
* own views, you can use {@link #cloneInContext} to clone an existing
* ViewFactory, and then call {@link #setFactory} on it to include your
* Factory.
*
* <p>
* For performance reasons, view inflation relies heavily on pre-processing of
* XML files that is done at build time. Therefore, it is not currently possible
* to use LayoutInflater with an XmlPullParser over a plain XML file at runtime;
* it only works with an XmlPullParser returned from a compiled resource
* (R.<em>something</em> file.)
*
* @see Context#getSystemService
*/
大致的意思是：将 XML 布局实例化到相关的 Oject 中，可使用 Activity#getLayoutInflater() 或 Context#getSystemService 检索一个标准 inflater 实例，实例已经和 activity 或 context 挂钩，和正在运行的设备挂钩
inflater 高度依赖提前处理的 XML 文件，XML 文件在编译资源时就已经给出，所以目前不可能使用 LayoutInflater 在运行时动态使用 XmlPullParser 将未经加工的 XML 布局进行实例化
inflate()：
参数1：xml 布局资源
参数2：父布局，指定生成布局的父布局，没有则生成布局作为 xml 布局的根布局
自定义控件：必须实现三个参数不同的构造函数
public XXX(Context context) {
super(context);
}
public XXX(Context context, AttributeSet attrs) {
super(context, attrs);
}
public XXX(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
参考：bug_ _ android.view.InflateException: Binary XML file line #2: Error inflating class <unknown
