android用shape给linearLayout设置边框，怎样只保留底部或顶部的边框，把其它三个方向的边框去掉呢？

<?xml version="1.0" encoding="utf-8"?>

<shape xmlns:android="http://schemas.android.com/apk/res/android" >



    <stroke  

        android:width="0.01dp"  

        android:color="#C6C7CE" />

    <padding  

        android:bottom="5dp"   

        android:top="5dp"

        android:left="5dp"

        android:right="5dp" />



</shape>

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

     android:orientation="vertical"

     android:layout_width="fill_parent"

     android:layout_height="fill_parent" >



    <LinearLayout android:layout_width="fill_parent" android:layout_height="wrap_content"

        android:orientation="vertical" android:gravity="center"

        android:background="@drawable/boder" >

        

        <TextView android:layout_width="fill_parent" android:layout_height="wrap_content"

            android:text="@string/log_name"/>

            

    </LinearLayout>



 </LinearLayout>