> 編寫:[K0ST](https://github.com/K0ST) - 原文:[http://developer.android.com/training/system-ui/visibility.html](http://developer.android.com/training/system-ui/visibility.html) 本節課將教你如果注冊監聽器來監聽系統UI可見性的變化。這個方法在將系統欄與你自己的UI控件進行同步操作時很有用。 ### 注冊監聽器 為了獲取系統UI可見性變化的通知，我們需要對View注冊`View.OnSystemUiVisibilityChangeListener`監聽器。通常上來說，這個View是用來控制導航的可見性的。 例如你可以添加如下代碼在onCreate中 ~~~ View decorView = getWindow().getDecorView(); decorView.setOnSystemUiVisibilityChangeListener (new View.OnSystemUiVisibilityChangeListener() { @Override public void onSystemUiVisibilityChange(int visibility) { // Note that system bars will only be "visible" if none of the // LOW_PROFILE, HIDE_NAVIGATION, or FULLSCREEN flags are set. if ((visibility & View.SYSTEM_UI_FLAG_FULLSCREEN) == 0) { // TODO: The system bars are visible. Make any desired // adjustments to your UI, such as showing the action bar or // other navigational controls. } else { // TODO: The system bars are NOT visible. Make any desired // adjustments to your UI, such as hiding the action bar or // other navigational controls. } } }); ~~~ 保持系統欄和UI同步是一種很好的實踐方式，比如當狀態欄顯示或隱藏的時候進行ActionBar的顯示和隱藏等等。