http://blog.csdn.net/azloong/article/details/6140824
http://blog.csdn.net/tianshuai1111/article/details/8191711
http://blog.csdn.net/ljclx1748/article/details/8606831
http://wenku.baidu.com/view/6563ea8483d049649b665876.html
http://blog.csdn.net/sxwenpan/article/details/10930587