http://blog.csdn.net/wangjinyu501/article/details/8169924
http://www.cnblogs.com/dwinter/archive/2012/02/27/AndroidViewPager%E5%A4%9A%E9%A1%B5%E9%9D%A2%E6%BB%91%E5%8A%A8%E5%88%87%E6%8D%A2%E4%BB%A5%E5%8F%8A%E5%8A%A8%E7%94%BB%E6%95%88%E6%9E%9C.html