最近经常处理这个，所以直接写成了扩展函数，在kotlin中挺好用的。记录下：

/**
 * 隐藏状态栏、虚拟按键
 * 锁屏后打开屏幕依旧隐藏 需要配和监听setOnSystemUiVisibilityChangeListener
 */
fun Window.makeFullScreenBottomSheet() {
    val uiOptions = View.SYSTEM_UI_FLAG_HIDE_NAVIGATION.or(View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION)
            .or(View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN)
            .or(View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY)
    decorView.systemUiVisibility = uiOptions
    addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN)
}

/**
 * 隐藏状态栏、虚拟按键
 * 锁屏后打开屏幕虚拟按键会弹出
 */
fun Window.makeFullScreen() {
    val uiOptions = View.SYSTEM_UI_FLAG_HIDE_NAVIGATION.or(View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION)
            .or(View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN)
            .or(View.SYSTEM_UI_FLAG_IMMERSIVE)
    decorView.systemUiVisibility = uiOptions
    addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN)
}

/**
 * 退出全屏模式
 */
fun Window.exitFullScreen() {
    val uiOptions = View.SYSTEM_UI_FLAG_VISIBLE
    decorView.systemUiVisibility = uiOptions
    clearFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN)
}

/**
 * 隐藏状态栏
 */
fun Window.hideStatusBar() {
    addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN)
}

/**
 * 显示状态栏
 */
fun Window.showStatusBar() {
    clearFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN)
}

/**
 * 只隐藏虚拟按键
 */
fun Window.makeHideNaviBottomSheet() {
    val uiOptions = View.SYSTEM_UI_FLAG_HIDE_NAVIGATION.or(View.SYSTEM_UI_FLAG_IMMERSIVE)
    decorView.systemUiVisibility = uiOptions
}

参考文章直接看谷歌的即可：

https://developer.android.com/training/system-ui/immersive