Android5.x中的阴影效果elevation和translationZ的实现方法

<ImageView 
   android:id="@+id/me_daijjBack" 
   android:layout_width="27dp" 
   android:layout_height="27dp" 
   android:elevation="3dp"  
   android:translationZ="5dp" 
 android:src="@drawable/shape_back" /> 

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) { 
 btn.setElevation(3f); 
} 
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) { 
 btn.setTranslationZ(5f); 
}