1.xml设置fitsSystemWindows = false
2.配置themes
3.onCreate中配置全面屏:
```java
window.decorView.systemUiVisibility=View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATIONor View.SYSTEM_UI_FLAG_LAYOUT_STABLE
// 设置状态栏和导航栏为透明
if (Build.VERSION.SDK_INT >=Build.VERSION_CODES.LOLLIPOP) {
window.statusBarColor =Color.TRANSPARENT
window.navigationBarColor =Color.TRANSPARENT
}
```