Android Shadow阴影

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.使用网站制作shadow背景

http://inloop.github.io/shadow4android/

3.使用Shadow第三方

https://github.com/wangjiegulu/ShadowViewHelper