这个跳转页面的方法跳转的速度不快，因为它要走2个来回（2次postback），但他可以跳 转到任何页面，没有站点页面限制（即可以由雅虎跳到新浪），同时不能跳过登录保护。但速度慢是其最大缺陷！redirect跳转机制：首先是发送一个http请求到客户端，通知需要跳转到新页面，然后客户端在发送跳转请求到服务器端。(Methods the jump page Jump speed is not fast, because it has to go back and forth 2 (2 postback), but he can jump to any page, no web page (which can be restricted by YAHOO at the same time, jump to Sina) can't skip the login protection. But slow speed is its biggest drawback! Redirect jump mechanism: first, send a HTTP request to the client, the notification needs to jump to the new page, and then the client sends the jump request to the server.)