Android中LayoutInflater.inflater()的正确打开方式

/**
 * Obtains the LayoutInflater from the given context.
 */
public static LayoutInflater from(Context context) {
 LayoutInflater LayoutInflater =
  (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
 if (LayoutInflater == null) {
 throw new AssertionError("LayoutInflater not found.");
 }
 return LayoutInflater;
}

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) {
 final Resources res = getContext().getResources();
 //省略代码
 final XmlResourceParser parser = res.getLayout(resource);
 try {
 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;
 //1.通过XmlResourceParser对象转换成AttributeSet
 final AttributeSet attrs = Xml.asAttributeSet(parser);
 Context lastCOntext= (Context) mConstructorArgs[0];
 mConstructorArgs[0] = inflaterContext;
 View result = root;

 try {
  //2.在xml中寻找根节点，如果类型是XmlPullParser.START_TAG或者XmlPullParser.END_DOCUMENT就会退出循环
  int type;
  while ((type = parser.next()) != XmlPullParser.START_TAG &&
   type != XmlPullParser.END_DOCUMENT) {
  // Empty
  }
  //3.如果根节点类型不是XmlPullParser.START_TAG将抛出异常
  if (type != XmlPullParser.START_TAG) {
  throw new InflateException(parser.getPositionDescription()
   + ": No start tag found!");
  }

  final String name = parser.getName();

  //4.判断根节点是否是merge标签
  if (TAG_MERGE.equals(name)) {
  if (root == null || !attachToRoot) {
   throw new InflateException(" can be used only with a valid "
    + "ViewGroup root and attachToRoot=true");
  }

  rInflate(parser, root, inflaterContext, attrs, false);
  } else {
  //5.通过根节点创建临时的view对象
  final View temp = createViewFromTag(root, name, inflaterContext, attrs);

  ViewGroup.LayoutParams params = null;

  if (root != null) {
   //6.如果root不为空，则调用generateLayoutParams(attrs)获取root所对应LayoutParams对象
   params = root.generateLayoutParams(attrs);
   //是否attachToRoot
   if (!attachToRoot) {
   //7.如果attachToRoot为false，则使用root默认的LayoutParams作为临时view对象的属性
   temp.setLayoutParams(params);
   }
  }

  //8.inflate xml的所有子节点
  rInflateChildren(parser, temp, attrs, true);

  //9.判断是否需要将创建的临时view attach到root中
  if (root != null && attachToRoot) {
   root.addView(temp, params);
  }

  //10.决定方法的返回值是root还是临时view
  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(parser.getPositionDescription()
   + ": " + e.getMessage(), e);
  ie.setStackTrace(EMPTY_STACK_TRACE);
  throw ie;
 } finally {
  mConstructorArgs[0] = lastContext;
  mConstructorArgs[1] = null;

  Trace.traceEnd(Trace.TRACE_TAG_VIEW);
 }

 return result;
 }
}