LayoutInflater的inflate方法,在fragment的onCreateView方法中经经常使用到:
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {LayoutInflater的inflate方法一共同拥有四种,但我们日经常使用经经常使用到的就仅仅有这两种:
public View inflate(int resource, ViewGroup root) { return inflate(resource, root, root != null); }
public View inflate(int resource, ViewGroup root, boolean attachToRoot) { if (DEBUG) System.out.println("INFLATING from resource: " + resource); XmlResourceParser parser = getContext().getResources().getLayout(resource); try { return inflate(parser, root, attachToRoot); } finally { parser.close(); } }
所以,这里直接介绍里面调用这种方法就可以:
public View inflate(XmlPullParser parser, ViewGroup root, boolean attachToRoot)在这种方法里面,上半部分为xml解析的代码,这里就不贴出来,确实没什么东西可看。直接看中间部分的代码:
ViewGroup.LayoutParams params = null; if (root != null) { if (DEBUG) { System.out.println("Creating params from root: " + root); } // Create layout params that match root, if supplied params = root.generateLayoutParams(attrs); if (!attachToRoot) { // Set the layout params for temp if we are not // attaching. (If we are, we use addView, below) temp.setLayoutParams(params); } }
params = root.generateLayoutParams(attrs);
这段的意思是:假设调用inflate方法,传入了ViewGroup root參数,则会从root中得到由layout_width和layout_height组成的LayoutParams,在attachToRoot设置为false的话,就会对我们载入的视图View设置该LayoutParams。
接着往下看:
// We are supposed to attach all the views we found (int temp) // to root. Do that now. 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; }
root.addView(temp, params);
假设设置了ViewGroup root參数,且attachToRoot设置为true的话,则将我们载入的视图做为子视图加入到root视图中。
假设我们ViewGroup root设置为空的话,就直接返回我们创建的视图;假设root不为空,且attachToRoot设置为false的话,就返回上面那段:对我们载入的视图View设置该LayoutParams。
以上就是该方法内容,可能你还有点看不太懂吧,下一篇文章,我将会做几个样例,来详细说明一下。