参考
http://www.cnblogs.com/wsklt/articles/1057539.html
http://www.cnblogs.com/fjchenq/archive/2006/06/20/430379.aspx
http://www.cnblogs.com/wsklt/articles/1057539.html
http://www.cnblogs.com/fjchenq/archive/2006/06/20/430379.aspx
http://www.cnblogs.com/wsklt/articles/1057539.html