AppCompat Toolbar控件去掉阴影设置高度

For Android 5.0, if you want to set it directly into a style use:

<item name="android:elevation">0dp</item>
and for Support library compatibility use:

<item name="elevation">0dp</item>
Example of style for a AppCompat light theme:

<style name="Theme.MyApp.ActionBar" parent="style/Widget.AppCompat.Light.ActionBar.Solid.Inverse">
    <!-- remove shadow below action bar -->
    <!-- <item name="android:elevation">0dp</item> -->
    <!-- Support library compatibility -->
    <item name="elevation">0dp</item>
</style>
Then apply this custom ActionBar style to you app theme:

<style name="Theme.MyApp" parent="Theme.AppCompat.Light">
<item name="actionBarStyle">@style/Theme.MyApp.ActionBar</item>

　　<item name="actionBarSize">@dimen/actionbar_size</item>

</style>

或者

<android.support.design.widget.AppBarLayout xmlns:andro
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:elevation="0dp"
    android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">
    <android.support.v7.widget.Toolbar
        android:
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="?attr/colorPrimary"
        app:popupTheme="@style/ThemeOverlay.AppCompat.Light">
    </android.support.v7.widget.Toolbar>
 </android.support.design.widget.AppBarLayout>