http://bbs.youkuaiyun.com/topics/110165909
http://blog.sina.com.cn/s/blog_590be5290100kaeg.html
http://fzhzhy.is-programmer.com/show/4070.html
http://www.cnblogs.com/xiaofengkang/archive/2011/05/20/2052452.html
http://zjf30366.blog.163.com/blog/static/411164582009615114928177/
http://www.cnblogs.com/charm/archive/2010/08/17/1801419.html good