http://www.iteye.com/topic/1116829
http://blog.csdn.net/myjava_024/article/details/3220319
http://www.cnblogs.com/zabery/archive/2011/07/26/2117103.html
http://www.cnblogs.com/biyeymyhjob/archive/2012/07/17/2591457.html
http://student.zjzk.cn/course_ware/data_structure/web/paixu/paixu8.5.1.1.htm