CarSystemBar不像Android手机那样固定的顶部“状态栏”和底部“导航栏”，而是将StatusBar和NavigationBar都统称为SystemBar，可以通过如下配置为每侧最多配置一个“系统栏”。

• packages/apps/Car/SystemUI/res/values/config.xml

    <!-- Configure which system bars should be displayed. -->
    <bool name="config_enableTopSystemBar">true</bool>
    <bool name="config_enableLeftSystemBar">false</bool>
    <bool name="config_enableRightSystemBar">false</bool>
    <bool name="config_enableBottomSystemBar">true</bool>

    <!-- Configure the type of each system bar. Each system bar must have a unique type. -->
    <!--    STATUS_BAR = 0-->
    <!--    NAVIGATION_BAR = 1-->
    <!--    STATUS_BAR_EXTRA = 2-->
    <!--    NAVIGATION_BAR_EXTRA = 3-->
    <integer name="config_topSystemBarType">0</integer>
    <integer name="config_leftSystemBarType">2</integer>
    <integer name="config_rightSystemBarType">3</integer>
    <integer name="config_bottomSystemBarType">1</integer>

•  默认显示Top&Bottom

• 显示左边栏

• 显示右边栏

代码解析

AAOS 13以前每个SystemUI服务还会依靠于Dependency类供