看到一篇文章,讲得不错:
http://forum.zatan.bbs.sina.com.cn/cgi-bin/view.cgi?gid=115&fid=6578&thread=301550&date=20061026
转载于:https://www.cnblogs.com/fortest/archive/2006/10/28/2057043.html
转载于:https://www.cnblogs.com/fortest/archive/2006/10/28/2057043.html