如何刷新Android中ViewPager的中间页面数据

I am using view pager. In this view pager i have 3 page. When i am running the app. view pager create left center and right fragment instance and all life cycle method are called. my problem is that i need to show some data when i select middle page. but i am not able to get any callback method to do. please help me. thanks in advance.I am using view pager. In this view pager i hav