ViewPager
PagerAdapter
//instantiateItem(ViewGroup container, int position) ：初始化一个子View
//destroyItem(ViewGroup container, int position,Object object)：销毁一个子View
//getCount()：返回子View的个数
//isViewFromObject(View arg0, Object arg1)：判断子View是否来自Objects
//instantiateItem(ViewGroup container, int position) ：初始化一个子View
//destroyItem(ViewGroup container, int position,Object object)：销毁一个子View
//getCount()：返回子View的个数
//isViewFromObject(View arg0, Object arg1)：判断子View是否来自Objects