页面中使用cache缓存对象

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.IO;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
    }
    protected void btnLogin_Click(object sender, EventArgs e)
    {
        DataSet ds = new DataSet();
        FileStream fs = new FileStream(Server.MapPath("LoginMsg.xml"), FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
        StreamReader reader = new StreamReader(fs);
        ds.ReadXml(reader);
        fs.Close();

        DataTable dt = ds.Tables[0];
        DataRow dr = dt.NewRow();
        dr["custom_email"] = this.TextBox1.Text;
        dr["custom_pass"] = this.TextBox2.Text;
        dr["login_time"] = DateTime.Now.ToString();

        fs = new FileStream(Server.MapPath("LoginMsg.xml"), FileMode.Create, FileAccess.ReadWrite, FileShare.ReadWrite);
        TextWriter writer = new StreamWriter(fs);
        writer = TextWriter.Synchronized(writer);
        ds.Tables[0].Rows.Add(dr);
        ds.WriteXml(writer);
        writer.Close();
        Cache.Remove("myData");
        LoadData();
       
    }

    public void LoadData()
    {
        DataView source = (DataView)Cache["myData"];
        if (source == null)
        {
            DataSet ds = new DataSet();
            FileStream fs = new FileStream(Server.MapPath("LoginMsg.xml"), FileMode.Open, FileAccess.Read);
            StreamReader reader = new StreamReader(fs);
            ds.ReadXml(reader);
            fs.Close();
            source = new DataView(ds.Tables[0]);
            Cache.Insert("myData", source, new System.Web.Caching.CacheDependency(Server.MapPath("LoginMsg.xml")));
            this.Label1.Text = "read from file";
        }
        else
        {
            this.Label1.Text = "read form cache";
        }
        this.GridView1.DataSource = source;
        this.GridView1.DataBind();
   
    }
    protected void btnRefresh_Click(object sender, EventArgs e)
    {
        LoadData();
    }
}