Android5.0系统：一个属性搞定3D效果

android:elevation="10dp"

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context="com.demo.monty.androidstudiodemo.Activity2">

<RelativeLayout
android:layout_width="100dp"
android:layout_height="100dp"
android:elevation="10dp"
android:background="#3a3e55"
android:layout_centerVertical="true"
android:layout_centerHorizontal="true"
android:id="@+id/relative"></RelativeLayout>
</RelativeLayout>