想设计一个FrameLayout,里面有一个WebView,WebView上方叠着一个透明的LinearLayout(id为middleLayout),当在无网的情况下,将LinearLayout变为不透明,挡住WebView,提示用户无法联网。布局如下:<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >    <WebView
        android:id="@+id/detailWebView"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:layout_marginTop="48dip" />    <LinearLayout
        android:id="@+id/middleLayout"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:layout_marginTop="48dip"
        android:background="#00000000"
        android:orientation="vertical" />    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="48dip"
        android:layout_gravity="top"
        android:background="@drawable/title_bg"
        android:orientation="horizontal" >        <ImageButton
            android:id="@+id/back"
            android:layout_width="48dip"
            android:layout_height="fill_parent"
            android:background="#00000000"
            android:scaleType="fitCenter"
            android:src="@drawable/back" />
    </LinearLayout>    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:background="#00000000"
        android:orientation="vertical" /></FrameLayout>无网时触发后台的callQuestion函数:private void callQuestion(String result) {
if (result == "No result") {
LinearLayout middleLayout = (LinearLayout) findViewById(R.id.middleLayout);
middleLayout.setBackgroundColor(Color.WHITE);

View view = LayoutInflater.from(this).inflate(
R.layout.detail_no_result, null);
middleLayout.addView(view);
}
}当中的R.layout.detail_no_result如下:<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/txt1"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="#ff0"
    android:gravity="center"
    android:text="网络出问题了,点我刷新..."
    android:textSize="30sp" />为何这个TextView无法占满(fill_parent)整个middleLayout???android布局