Fragment.getView返回FrameLayout

Question

当我调用getView（）insiede一个片段时，它返回一个FrameLayout，但是片段根是RelativeLayout，怎么会发生这种情况呢？经过一些测试后，我还发现getView（）返回不同的值，而不是onCreateView返回的值。

fragment_message.xml：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="500dp"


     >
    <View
        android:layout_width="fill_parent"
        android:layout_height="2dp"
        android:background="@android:color/darker_gray"/>
    <ImageView
        android:id="@+id/imageView1"
        android:contentDescription="@string/hello_world"
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:layout_marginTop="20dp"
        android:layout_alignParentLeft="true"
        android:src="@drawable/seele" />


    <WebView 
    android:id="@+id/webView1"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:layout_below="@id/imageView1"
/>
</RelativeLayout>

MessageFragment.java：

public void onResume() {

        RelativeLayout rl = relativeLayout;
        WebView webView = (WebView) rl.getChildAt(rl.getChildCount() - 1);
        webView.getSettings().setJavaScriptEnabled(true);

        //getView();
        //RelativeLayout rl2 = (RelativeLayout) getView();

        //Toast.makeText(getActivity(), rl.getChildCount(), Toast.LENGTH_SHORT)
        //.show();

        FrameLayout fl = (FrameLayout) getView();


        Toast.makeText(getActivity(), Integer.toString(((RelativeLayout)fl.getChildAt(0)).getChildCount()), Toast.LENGTH_SHORT).show();

        //Toast.makeText(getActivity(), fl.getChildAt(0).getClass().toString(), Toast.LENGTH_SHORT).show();
        //webView.loadUrl("http://www.google.com");
        super.onResume();
    }