獲取方式
LayoutInflater inflater = (LayoutInflater)context.getSystemService
(Context.LAYOUT_INFLATER_SERVICE);
或者
LayoutInflater layoutInflater = LayoutInflater.from(context);
LayoutInflater方法
參數(shù)說(shuō)明
resource:布局文件id狂魔。
root:根視圖不為空時(shí)，如果attachToRoot為true，則將inflate視圖添加到根視圖上，為false榆综，則將根視圖的布局參數(shù)（LayoutParams）設(shè)置給inflate視圖。
attachToRoot:是否添加到根視圖上铸史。
public View inflate(XmlPullParser parser, ViewGroup root) {
return inflate(parser, root, root != null);
}
public View inflate(int resource, ViewGroup root, boolean attachToRoot) {
final Resources res = getContext().getResources();
final XmlResourceParser parser = res.getLayout(resource);
try {
return inflate(parser, root, attachToRoot);
} finally {
parser.close();
}
}
public View inflate(XmlPullParser parser, ViewGroup root) {
return inflate(parser, root, root != null);
}
public View inflate(XmlPullParser parser, ViewGroup root, boolean attachToRoot) {
// mConstructorArgs為長(zhǎng)度2的Object數(shù)組鼻疮，mConstructorArgs[0]當(dāng)前Context對(duì)象，mConstructorArgs[1]為當(dāng)前布局的AttributeSet琳轿。
synchronized (mConstructorArgs) {
// Trace事件
Trace.traceBegin(Trace.TRACE_TAG_VIEW, "inflate");
final Context inflaterContext = mContext;
final AttributeSet attrs = Xml.asAttributeSet(parser);
Context lastContext = (Context) mConstructorArgs[0];
mConstructorArgs[0] = inflaterContext;
View result = root;
try {
// Pull解析文章判沟，http://www.reibang.com/p/189b91ef5d61
int type;
// 跳過(guò)START_DOCUMENT類型，直接處理START_TAG
while ((type = parser.next()) != XmlPullParser.START_TAG &&
type != XmlPullParser.END_DOCUMENT) {
// Empty
}
if (type != XmlPullParser.START_TAG) {
throw new InflateException(parser.getPositionDescription()
+ ": No start tag found!");
}
final String name = parser.getName();
// 判斷merge標(biāo)簽崭篡，如果存在根視圖不能為空挪哄，attachToRoot不能為false
if (TAG_MERGE.equals(name)) {
if (root == null || !attachToRoot) {
throw new InflateException("<merge /> can be used only with a valid "
+ "ViewGroup root and attachToRoot=true");
}
// 參考下面rInflate源碼，此時(shí)parser為merge標(biāo)簽內(nèi)容
rInflate(parser, root, inflaterContext, attrs, false);
} else {
// Temp is the root view that was found in the xml
// 創(chuàng)建inflate視圖
final View temp = createViewFromTag(root, name, inflaterContext, attrs);
ViewGroup.LayoutParams params = null;
// 獲取根視圖布局參數(shù)
if (root != null) {
// Create layout params that match root, if supplied
params = root.generateLayoutParams(attrs);
// 如果attachToRoot為false琉闪，把根視圖布局參數(shù)賦給inflate視圖
if (!attachToRoot) {
// Set the layout params for temp if we are not
// attaching. (If we are, we use addView, below)
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.
// 如果attachToRoot為true并且根視圖不為空迹炼，添加inflate視圖到根視圖上，root和result是同一對(duì)象
if (root != null && attachToRoot) {
root.addView(temp, params);
}
// Decide whether to return the root that was passed in or the
// top view found in xml.
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 {
// Don't retain static reference on context.
mConstructorArgs[0] = lastContext;
mConstructorArgs[1] = null;
Trace.traceEnd(Trace.TRACE_TAG_VIEW);
}
return result;
}
}
rInflate方法
void rInflate(XmlPullParser parser, View parent, Context context,
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)) {
// 處理requestFocus標(biāo)簽
parseRequestFocus(parser, parent);
} else if (TAG_TAG.equals(name)) {
// 處理tag標(biāo)簽
parseViewTag(parser, parent, attrs);
} else if (TAG_INCLUDE.equals(name)) {
// 處理include標(biāo)簽
if (parser.getDepth() == 0) {
throw new InflateException("<include /> cannot be the root element");
}
parseInclude(parser, context, parent, attrs);
} else if (TAG_MERGE.equals(name)) {
// merge標(biāo)簽不能嵌套merge標(biāo)簽
throw new InflateException("<merge /> must be the root element");
} else {
// 處理merge標(biāo)簽
// 創(chuàng)建視圖
final View view = createViewFromTag(parent, name, context, attrs);
// 獲取根視圖
final ViewGroup viewGroup = (ViewGroup) parent;
// 獲取根視圖布局參數(shù)
final ViewGroup.LayoutParams params = viewGroup.generateLayoutParams(attrs);
// Inflate子視圖
rInflateChildren(parser, view, attrs, true);
// 添加子視圖
viewGroup.addView(view, params);
}
}
if (finishInflate) {
parent.onFinishInflate();
}
}
