当访问默认首页default.aspx时，会自动跳转到login.aspx页面上请求登录，随便输入用户名和密码，点击“登录”按钮，会回到首页，并显示当前登录的用户名。
web.config
<configuration>
<system.web>
<compilation debug="true"/>
<authentication mode="forms">
<forms loginurl="login.aspx" name = ".aspxformsauth" />
</authentication>
<authorization>
<deny users="?"/>
</authorization>
</system.web>
</configuration>
default.aspx
<html>
<head>
<title>首页</title>
<script language="vb" runat="server">
sub page_load(sender as object, e as eventargs)
message.text = string.format("你好，{0}", context.user.identity.name)
end sub
sub btnsignout_click(sender as object, e as eventargs)
formsauthentication.signout()
response.redirect("login.aspx")
end sub
</script>
</head>
<body>
<asp:label id="message" runat="server"/>
<br>
<form method="post" runat="server">
<asp:button id="btnsignout" text="退出登录" runat="server" onclick="btnsignout_click"/>
</form>
</body>
</html>
login.aspx
<head>
<title>首页</title>
<script lanugage="c#" runat="server">
private void page_load(object sender, eventargs e)
{
if (request.isauthenticated)
response.redirect("default.aspx");
}
void btnlogin_click(object sender, eventargs e)
{
if (txtusername.text != null && txtusername.text != string.empty && txtpassword.text != null && txtpassword.text != string.empty)
formsauthentication.redirectfromloginpage(txtusername.text, true);
else
lblerror.text = "错误的用户名/密码";
}
</script>
</head>
<body>
<form method="post" runat="server">
<asp:label id="lblusername" runat="server" text="用户名："/>
<asp:textbox id="txtusername" runat="server"/>
<br>
<br>
<asp:label id="lblpassword" runat="server" text="密 码："/>
<asp:textbox id="txtpassword" runat="server" textmode="password"/>
<br>
<asp:button id="btnlogin" runat="server" text="登录" onclick="btnlogin_click" />
</form>
<hr>
<br>
<asp:label id="lblerror" forecolor="red" runat="server"/>
</body>
</html>
