Use Xxradius to set the rounded background picture in Android L cannot be displayed

Example of setting the background of a control:

<button        android:id= "@+id/btn1"        android:layout_width= "100DP"        android:layout_height= "50DP"        android:text= "BTN1"        android:background= "@drawable/btn1"/><?xml version= "1.0" encoding= "Utf-8"?>< Shape xmlns:android= "http://schemas.android.com/apk/res/android" android:shape= "Rectangle" >    <solid Android:color= "#ffffffff"/>    <corners android:topleftradius= "5DP" android:toprightradius= "5DP"  / >    <padding android:top= "5DP"/> </shape><!--not visible in Android L

<button        android:id= "@+id/btn2"        android:layout_width= "100DP"        android:layout_height= "50DP"        android:text= "BTN2"        android:background= "@drawable/btn2"/><shape xmlns:android= "/http/ Schemas.android.com/apk/res/android "android:shape=" Rectangle ">    <solid android:color=" #ffffffff "/>    <corners android:topleftradius= "5DP" android:toprightradius= "5DP" android:bottomleftradius= "5DP" Android: bottomrightradius= "5DP"/>    <padding android:top= "5DP"/> </shape><!--cannot be displayed under Android L

<button        android:id= "@+id/btn3"        android:layout_width= "100DP"        android:layout_height= "50DP"        android:text= "Btn3"        android:background= "@drawable/btn3"/><shape xmlns:android= "/http/ Schemas.android.com/apk/res/android "android:shape=" Rectangle ">    <solid android:color=" #ffffffff "/>    <corners android:radius= "5DP"/>    <padding android:top= "5DP"/> </shape><!--Normal---

<button        android:id= "@+id/btn4"        android:layout_width= "100DP"        android:layout_height= "50DP"        android:text= "Btn4"        android:background= "@drawable/btn4"/><?xml version= "1.0" encoding= "Utf-8"?>< Selector xmlns:android= "Http://schemas.android.com/apk/res/android" >    <item>        <shape android: Shape= "Rectangle" >            <solid android:color= "@android: Color/white"/> <corners            android: bottomleftradius= "5DP" android:bottomrightradius= "5DP"/>            <padding android:bottom= "5DP"/>        </ shape>    </item></selector><!--Normal---

Summary below:
(1) shape with Xxradius, cannot be displayed under Android L.
(2) selector inside with Xxradius, under the Android L can display normally.
(3) shape inside with Android:radius, under the Android L can display normally.
(4) For compatibility, shape can be changed to selector.

Setting a rounded background picture with Xxradius under Android l cannot be displayed