参考学习：依次
http://blog.csdn.net/xiaanming/article/details/26810303
http://blog.csdn.net/xiaanming/article/details/27525741
http://blog.csdn.net/liu1164316159/article/details/38728259
imageLoader学习
原文：http://www.cnblogs.com/chuiyuan/p/4081858.html
