<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle" >

    <!-- 填充颜色 -->
    <solid android:color="@color/gray_4" >
    </solid>

    <!-- 矩形的圆角半径 -->
    <corners android:radius="4dp" />

</shape>