linearlayout背景白色，元素的字体却成灰色
我需要得到白色背景和黑色字体，却发现如题所说，具体布局如下：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#FFFFFF"
android:orientation="vertical" >
<RelativeLayout
android:layout_width="fill_parent"
android:layout_height="50dip"
android:layout_marginLeft="5dip"
android:layout_marginRight="5dip"
android:layout_marginTop="5dip" >
<ImageButton
android:id="@+id/searchBtn"
android:layout_width="50dip"
android:layout_height="fill_parent"
android:layout_alignParentRight="true"
android:scaleType="centerInside"
android:src="@drawable/search" />
<EditText
android:id="@+id/searchText"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_marginRight="0dip"
android:layout_toLeftOf="@id/searchBtn"
android:focusable="true"
android:focusableInTouchMode="true"
android:hint="请输入关键字"
android:selectAllOnFocus="true"
android:singleLine="true" />
</RelativeLayout>
<ListView
android:id="@+id/searchList"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:cacheColorHint="#00000000" />
</LinearLayout>
