View createViewFromTag(View parent, String name, AttributeSet attrs) {
if (name.equals("view")) {
name = attrs.getAttributeValue(null, "class");
}
if (DEBUG) System.out.println("******** Creating view: " + name);
try {
View view;
if (mFactory2 != null) view = mFactory2.onCreateView(parent, name, mContext, attrs);
else if (mFactory != null) view = mFactory.onCreateView(name, mContext, attrs);
else view = null;
if (view == null && mPrivateFactory != null) {
view = mPrivateFactory.onCreateView(parent, name, mContext, attrs);
}
if (view == null) {
if (-1 == name.indexOf('.')) {
view = onCreateView(parent, name, attrs);
} else {
view = createView(name, null, attrs);
}
}
if (DEBUG) System.out.println("Created view is: " + view);
return view;
} catch (InflateException e) {
throw e;
} catch (ClassNotFoundException e) {
InflateException ie = new InflateException(attrs.getPositionDescription()
+ ": Error inflating class " + name);
ie.initCause(e);
throw ie;
} catch (Exception e) {
InflateException ie = new InflateException(attrs.getPositionDescription()
+ ": Error inflating class " + name);
ie.initCause(e);
throw ie;
}
}
里面根据不同情况，调用了onCreateView方法，利用反射来创建view。其中可以使用指定的factory来创建view，这样的钩子设计使得inflate方法变得十分灵活。
然后调用rInflate(parser, temp, attrs, true)方法来递归查找temp中的子view，并添加到上层view中：
void rInflate(XmlPullParser parser, View parent, final AttributeSet attrs,
boolean finishInflate) throws XmlPullParserException, IOException {
final int depth = parser.getDepth();
int type;
while (((type = parser.next()) != XmlPullParser.END_TAG ||
parser.getDepth() > depth) && type != XmlPullParser.END_DOCUMENT) {
if (type != XmlPullParser.START_TAG) {
continue;
}
final String name = parser.getName();
if (TAG_REQUEST_FOCUS.equals(name)) {
parseRequestFocus(parser, parent);
} else if (TAG_INCLUDE.equals(name)) {
if (parser.getDepth() == 0) {
throw new InflateException("<include /> cannot be the root element");
}
parseInclude(parser, parent, attrs);
} else if (TAG_MERGE.equals(name)) {
throw new InflateException("<merge /> must be the root element");
} else if (TAG_1995.equals(name)) {
final View view = new BlinkLayout(mContext, attrs);
final ViewGroup viewGroup = (ViewGroup) parent;
final ViewGroup.LayoutParams params = viewGroup.generateLayoutParams(attrs);
rInflate(parser, view, attrs, true);
viewGroup.addView(view, params);
} else {
final View view = createViewFromTag(parent, name, attrs);
final ViewGroup viewGroup = (ViewGroup) parent;
final ViewGroup.LayoutParams params = viewGroup.generateLayoutParams(attrs);
rInflate(parser, view, attrs, true);
viewGroup.addView(view, params);
}
}
if (finishInflate) parent.onFinishInflate();
}
里面也用到onCreateView方法创建子view，然后将其加入到父view中返回。
通过查看上面的源码，我们可以发现inflate方法中的三个参数int resource, ViewGroup root, boolean attachToRoot的作用如下：
resource指定了要加载的view，root作为view外面一层的父容器，attachToRoot表示是否将view加入到父容器。
当指定了父容器，并且attachToRoot为true，则将view加入到父容器中。
如果指定了父容器，却将attachToRoot设置为false，那么只是从父容器中生成了view布局的参数并设置给view
当未指定父容器时，直接返回view本身。
总结
通过研究LayoutInflater源码的设计，我们了解到代码的执行细节的同时，也可以发现：
LayoutInflater创建view对象时候使用了简单工厂模式，并通过加入钩子方法，利用抽象工厂模式让coder可以使用自定义的工厂方法来创建view。