shape

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <corners android:radius="8dp" />
    <gradient
        android:centerColor="#cccc00"
        android:endColor="#00cccc"
        android:startColor="#cc00cc" />

    <padding
        android:bottom="7dp"
        android:left="7dp"
        android:right="7dp"
        android:top="7dp" />

</shape>

shape

原文：http://www.cnblogs.com/guozhiping/p/5019645.html