XML增\删、改、查简单操作

  protected void Page_Load(object sender, EventArgs e)
    {
        lblValue.Text = string.Format("{0:N}", 2500000);
        lblValue.Text = string.Format("{0:C3}", 2);
        // 加载时不缓存数据
        Response.Cache.SetNoStore();
        if (!IsPostBack)
        {
            // 初始化页面显示
            ShowXml();
        }
    }
    // 初始化页面显示
    private void ShowXml()
    {
        // 获取xml数据
        string url = Server.MapPath("user.xml");
        StreamReader sr = new StreamReader(url, System.Text.Encoding.GetEncoding("GB2312"));
        // 操作xml文档
        XmlDataDocument xmlDataDocument = new XmlDataDocument();
        // 将读取的字节流保存到DataSet中
        xmlDataDocument.DataSet.ReadXml(sr);
        this.DataGrid1.DataSource = xmlDataDocument.DataSet.Tables[0].DefaultView;
        // 定义显示ID
        this.DataGrid1.DataKeyField = "username";
        this.DataGrid1.DataBind();
        xmlDataDocument = null;
        sr.Close();
    }
    protected override void OnInit(EventArgs e)
    {