http://www.cnblogs.com/ok123/articles/2155732.html
http://www.cnblogs.com/temptation/archive/2007/02/22/653838.html
http://hi.baidu.com/gnilling/blog/item/8a2fa772b18a2b168601b049.html
http://5791823-163.blog.163.com/blog/static/3360540220121941814921/