加在onCreate中

//全屏开始
supportActionBar?.hide() // 隐藏标题栏
window.setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN) //设置全屏
//设置屏幕长亮
window.setFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON,
WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON)
setContentView(R.layout.activity_main)

// 这个组合不好用，当在触摸屏幕时还是会出现系统导航栏（home, back等）
val mUIFlag = (View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
or View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
or View.SYSTEM_UI_FLAG_LAYOUT_STABLE
or View.SYSTEM_UI_FLAG_LOW_PROFILE
or View.SYSTEM_UI_FLAG_FULLSCREEN
or View.SYSTEM_UI_FLAG_HIDE_NAVIGATION)

// 4.4以及上全屏
val mUIFlag2 =(
View.SYSTEM_UI_FLAG_LAYOUT_STABLE
or View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
or View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
or View.SYSTEM_UI_FLAG_HIDE_NAVIGATION // hide nav bar

or View.SYSTEM_UI_FLAG_FULLSCREEN // hide status bar

or View.SYSTEM_UI_FLAG_IMMERSIVE)

//取消全屏
val cancelFullScreenFlag = (View.SYSTEM_UI_FLAG_LAYOUT_STABLE
or View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
or View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN)

window.decorView.systemUiVisibility = mUIFlag2
// 全屏结束

项目中的代码

override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)

//全屏开始
supportActionBar?.hide() // 隐藏标题栏
window.setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN) //设置全屏
//设置屏幕长亮
window.setFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON,
WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON)
setContentView(R.layout.activity_main)

// 这个组合不好用，当在触摸屏幕时还是会出现系统导航栏（home, back等）
val mUIFlag = (View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
or View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
or View.SYSTEM_UI_FLAG_LAYOUT_STABLE
or View.SYSTEM_UI_FLAG_LOW_PROFILE
or View.SYSTEM_UI_FLAG_FULLSCREEN
or View.SYSTEM_UI_FLAG_HIDE_NAVIGATION)

// 4.4以及上全屏
val mUIFlag2 =(
View.SYSTEM_UI_FLAG_LAYOUT_STABLE
or View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
or View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
or View.SYSTEM_UI_FLAG_HIDE_NAVIGATION // hide nav bar

or View.SYSTEM_UI_FLAG_FULLSCREEN // hide status bar

or View.SYSTEM_UI_FLAG_IMMERSIVE)

//取消全屏
val cancelFullScreenFlag = (View.SYSTEM_UI_FLAG_LAYOUT_STABLE
or View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
or View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN)

window.decorView.systemUiVisibility = mUIFlag2
// 全屏结束


//注册onLongClick监听器
super.findViewById<LinearLayout>(R.id.changeBkgArea).setOnLongClickListener(PicOnLongClick())
super.findViewById<LinearLayout>(R.id.settingArea).setOnLongClickListener(OnLongClickSetting())

loadConfig()
loadBackgroundImage()
startGetCommandLoop()
}