1.使用rectangle
<dimen name="cardPadding">1px</dimen>
<dimen name="cardPadding">1px</dimen>
<dimen name="cardRadius">7dp</dimen>
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item>
<shape android:shape="rectangle">
<solid android:color="@color/cardShadowColor" />
<corners android:radius="@dimen/cardRadius" />
<padding
android:bottom="@dimen/cardPadding"
android:left="@dimen/cardPadding"
android:top="@dimen/cardPadding"
android:right="@dimen/cardPadding" />
</shape>
</item>
<item>
<shape android:shape="rectangle">
<solid android:color="@color/cardShadowColor" />
<corners android:radius="@dimen/cardRadius" />
<padding
android:bottom="@dimen/cardPadding"
android:left="@dimen/cardPadding"
android:top="@dimen/cardPadding"
android:right="@dimen/cardPadding" />
</shape>
</item>
<item>
<shape android:shape="rectangle">
<solid android:color="@color/cardShadowColor" />
<corners android:radius="@dimen/cardRadius" />
<padding
android:bottom="@dimen/cardPadding"
android:left="@dimen/cardPadding"
android:top="@dimen/cardPadding"
android:right="@dimen/cardPadding" />
</shape>
</item>
<item>
<shape android:shape="rectangle">
<solid android:color="@color/cardShadowColor" />
<corners android:radius="@dimen/cardRadius" />
<padding
android:bottom="@dimen/cardPadding"
android:left="@dimen/cardPadding"
android:top="@dimen/cardPadding"
android:right="@dimen/cardPadding" />
</shape>
</item>
<item>
<shape android:shape="rectangle">
<solid android:color="@color/cardShadowColor" />
<corners android:radius="@dimen/cardRadius" />
<padding
android:bottom="@dimen/cardPadding"
android:left="@dimen/cardPadding"
android:top="@dimen/cardPadding"
android:right="@dimen/cardPadding" />
</shape>
</item>
<item>
<shape android:shape="rectangle">
<solid android:color="@color/cardShadowColor" />
<corners android:radius="@dimen/cardRadius" />
<padding
android:bottom="@dimen/cardPadding"
android:left="@dimen/cardPadding"
android:top="@dimen/cardPadding"
android:right="@dimen/cardPadding" />
</shape>
</item>
<item>
<shape android:shape="rectangle">
<solid android:color="@color/cardShadowColor" />
<corners android:radius="@dimen/cardRadius" />
<padding
android:bottom="@dimen/cardPadding"
android:left="@dimen/cardPadding"
android:top="@dimen/cardPadding"
android:right="@dimen/cardPadding" />
</shape>
</item>
<item>
<shape android:shape="rectangle">
<solid android:color="@color/cardShadowColor" />
<corners android:radius="@dimen/cardRadius" />
<padding
android:bottom="@dimen/cardPadding"
android:left="@dimen/cardPadding"
android:top="@dimen/cardPadding"
android:right="@dimen/cardPadding" />
</shape>
</item>
<item>
<shape android:shape="rectangle">
<corners android:radius="7dp" />
<solid android:color="@color/white" />
<padding
android:bottom="@dimen/cardRadius"
android:top="@dimen/cardRadius"
android:left="@dimen/cardRadius"
android:right="@dimen/cardRadius" />
</shape>
</item>
</layer-list>
2.使用網站制作shadow背景
http://inloop.github.io/shadow4android/
3.使用Shadow第三方
https://github.com/wangjiegulu/ShadowViewHelper