layer-list

 <?xml version="1.0" encoding="utf-8"?>
 <layer-list xmlns:android="http://schemas.android.com/apk/res/android" >
     <item>
         <shape>
             <corners
                 android:topLeftRadius="5dp"
                 android:topRightRadius="5dp" />
             <solid android:color="#ff66ff66" />
         </shape>
     </item>
     <!-- 上层 -->
     <item
         android:left="1dp"
         android:right="1dp"
         android:top="1dp">
         <shape>
             <corners
                 android:topLeftRadius="5dp"
                 android:topRightRadius="5dp" />
             <solid android:color="#ffffffff" />
         </shape>
     </item>
 </layer-list>