继Android View 相关源码分析之一 从setContentView说起继续说
之前我们分析了setContentView方法的相关代码 接下来说说LayoutInflater的方法
LayoutInflater源码分析
- 与setContentView相关
在PhoneWindow的generateLayout中调用了
View in = mLayoutInflater.inflate(layoutResource, null);
- LayoutInflater中获取实例化方法
/**
* 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;
}
- inflate方法相关
public View inflate(@LayoutRes int resource, @Nullable ViewGroup root) {
return inflate(resource, root, root != null);
}
public View inflate(XmlPullParser parser, @Nullable ViewGroup root) {
return inflate(parser, root, root != null);
}
public View inflate(@LayoutRes int resource, @Nullable ViewGroup root, boolean attachToRoot) {
final Resources res = getContext().getResources();
if (DEBUG) {
Log.d(TAG, "INFLATING from resource: \"" + res.getResourceName(resource) + "\" ("
+ Integer.toHexString(resource) + ")");
}
final XmlResourceParser parser = res.getLayout(resource);
try {
return inflate(parser, root, attachToRoot);
} finally {
parser.close();
}
}
最后发现都需要调用
public View inflate(XmlPullParser parser, @Nullable ViewGroup root, boolean attachToRoot) {
synchronized (mConstructorArgs) {
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;
//定义返回值 初始化传入形参 root
View result = root;
try {
// 找到根节点
int type;
while ((type = parser.next()) != XmlPullParser.START_TAG &&
type != XmlPullParser.END_DOCUMENT) {
}
//验证type是否为Start_Tag 保证xml文件正确
if (type != XmlPullParser.START_TAG) {
throw new InflateException(parser.getPositionDescription()
+ ": No start tag found!");
}
//type为 root node
final String name = parser.getName();
if (DEBUG) {
System.out.println("**************************");
System.out.println("Creating root view: "
+ name);
System.out.println("**************************");
}
if (TAG_MERGE.equals(name)) {
//处理 merge相关
//root需要非空 且attachToRoot为空
if (root == null || !attachToRoot) {
throw new InflateException("<merge /> can be used only with a valid "
+ "ViewGroup root and attachToRoot=true");
}
//递归inflate 方法调用
rInflate(parser, root, inflaterContext, attrs, false);
} else {
//根据tag节点创建view对象
final View temp = createViewFromTag(root, name, inflaterContext, attrs);
ViewGroup.LayoutParams params = null;
if (root != null) {
if (DEBUG) {
System.out.println("Creating params from root: " +
root);
}
//根据root生成LayoutParams
params = root.generateLayoutParams(attrs);
if (!attachToRoot) {
//如果attachToRoot为flase 则调用setLayoutParams
temp.setLayoutParams(params);
}
}
if (DEBUG) {
System.out.println("-----> start inflating children");
}
//递归inflate剩下的children
rInflateChildren(parser, temp, attrs, true);
if (DEBUG) {
System.out.println("-----> done inflating children");
}
// We are supposed to attach all the views we found (int temp)
// to root. Do that now.
if (root != null && attachToRoot) {
//root非空且attachToRoot=true则将xml文件的root view加到形参提供的root里
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) {
//返回xml里解析的root view
result = temp;
}
}
} catch (XmlPullParserException e) {
InflateException ex = new InflateException(e.getMessage());
ex.initCause(e);
throw ex;
} catch (Exception e) {
InflateException ex = new InflateException(
parser.getPositionDescription()
+ ": " + e.getMessage());
ex.initCause(e);
throw ex;
} finally {
// Don't retain static reference on context.
mConstructorArgs[0] = lastContext;
mConstructorArgs[1] = null;
}
Trace.traceEnd(Trace.TRACE_TAG_VIEW);
//返回参数root或xml文件里的root view
return result;
}
}
相关inflate参数的结果
inflate参数分析
- 相关方法解析
在Inflate中多次被调用的rInflate
void rInflate(XmlPullParser parser, View parent, Context context,
AttributeSet attrs, boolean finishInflate) throws XmlPullParserException, IOException {
final int depth = parser.getDepth();
int type;
//XmlPullParser解析器的标准解析模式
while (((type = parser.next()) != XmlPullParser.END_TAG ||
parser.getDepth() > depth) && type != XmlPullParser.END_DOCUMENT) {
//找到start_tag节点
if (type != XmlPullParser.START_TAG) {
continue;
}
//获取Name标记
final String name = parser.getName();
//private static final String TAG_REQUEST_FOCUS = "requestFocus";
//处理requestFocus
if (TAG_REQUEST_FOCUS.equals(name)) {
parseRequestFocus(parser, parent);
// private static final String TAG_TAG = "tag";
//处理tag
} else if (TAG_TAG.equals(name)) {
parseViewTag(parser, parent, attrs);
//private static final String TAG_INCLUDE = "include";
//处理include
} else if (TAG_INCLUDE.equals(name)) {
//如果是根节点则抛出异常
if (parser.getDepth() == 0) {
throw new InflateException("<include /> cannot be the root element");
}
parseInclude(parser, context, parent, attrs);
//private static final String TAG_MERGE = "merge";
//处理merge merge需要是xml中的根节点
} else if (TAG_MERGE.equals(name)) {
throw new InflateException("<merge /> must be the root element");
} else {
final View view = createViewFromTag(parent, name, context, attrs);
final ViewGroup viewGroup = (ViewGroup) parent;
final ViewGroup.LayoutParams params = viewGroup.generateLayoutParams(attrs);
rInflateChildren(parser, view, attrs, true);
viewGroup.addView(view, params);
}
}
//parent的所有子节点都处理完毕的时候回onFinishInflate方法
if (finishInflate) {
parent.onFinishInflate();
}
}
//可以添加自定义逻辑
protected void onFinishInflate() {
}
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