C#结合xml制作简单的用户登录？

C#结合xml制作简单的用户登录？

后台代码： XmlDocument xmldoc;
protected void Page_Load(object sender, EventArgs e)
{ }
protected void Button1_Click(object sender, EventArgs e)
{
xmllod();
foreach (XmlNode xnode in xmldoc.SelectSingleNode("UserDataList").ChildNodes)
{
if (xnode.ChildNodes[0].InnerText == TextBox1.Text && xnode.ChildNodes[1].InnerText == TextBox2.Text)
{
Page.ClientScript.RegisterStartupScript(this.GetType(), "", "");
return;
}
}
Page.ClientScript.RegisterStartupScript(this.GetType(), "", "");
}
protected void Button3_Click(object sender, EventArgs e)
{
AddUser();
}
protected void xmllod()
{
xmldoc = new XmlDocument();
xmldoc.Load(Server.MapPath("~/xml/UserInfo.xml"));
}
protected void AddUser()
{
xmllod();
XmlNode xml = xmldoc.SelectSingleNode("UserDataList");
XmlElement xmle = xmldoc.CreateElement("user");
XmlElement xmlenode1 = xmldoc.CreateElement("username");
xmlenode1.InnerText = TextBox3.Text;
XmlElement xmlenode2 = xmldoc.CreateElement("password");
xmlenode2.InnerText = TextBox4.Text; xmle.AppendChild(xmlenode1);
xmle.AppendChild(xmlenode2);
xml.AppendChild(xmle);
xmldoc.Save(Server.MapPath("~/xml/UserInfo.xml"));//保存
Page.ClientScript.RegisterStartupScript(this.GetType(), "", "");
}前台：