Hides or shows the status bar, optionally animating the transition.
显示或隐藏状态栏，可选择动画效果过渡。
2
Sets the application's status bar to the specified orientation, optionally animating the transition.
设置应用程序状态栏旋转到指定的方位，可选择动画过渡。
3
This obscures some of the layout at the top, but now when the action bar hides or appears, the system does not need to resize your layout and the transition is seamless.