Iprincipal myprincipal = this.user 出现错误
protected void btnsubmit_click(object sender, EventArgs e)
{
Iprincipal myprincipal = this.User; 是错的吗？
string tablestring = "<table border=1><tr><td>Name</td><td>";
tablestring += Server.HtmlEncode(myprincipal.identity.name) + "</td></tr>";
Response.Write(tablestring);
}

[解决办法]
路过,up