Use a variable in different classes in webforms c#

I am stack in something simple i think.

I have the following code:

public void Button1Click(object sender, EventArgs e)
{
    if (FileUpload1.HasFile)
    {
        if (FileUpload1.PostedFile.ContentType == "text/xml")
            {

                    string filename = Path.GetFileName(FileUpload1.FileName);
                    FileUpload1.SaveAs(Server.MapPat开发者_运维技巧h("~/") + filename);
                    StatusLabel.Text = "Upload status: File uploaded!";

                    DataSet ds = new DataSet();
                    ds.ReadXml((Server.MapPath(filename)));
                    GridView1.DataSource = ds;
                    GridView1.DataBind();
            }
            else
                StatusLabel.Text = "Only xml files are accepted!";

    }
}

public void Button2_Click1(object sender, EventArgs e)
{

}    

What i want is the user the execute this code in button2

                    DataSet ds = new DataSet();
                    ds.ReadXml((Server.MapPath(filename)));
                    GridView1.DataSource = ds;
                    GridView1.DataBind();

My problem is that the variable filename is not available outside

public void Button1Click(object sender, EventArgs e)

Thanks in advance for your help! Chris

---

you can persist the variable in the page ViewState like this:

private string fileName
{
    get { return ViewState["fileName"] != null ? (string)ViewState["fileName"] : String.Empty; }
    set { ViewState["fileName"] = value; }
}

---

Save the filename into Session or ViewState while uploading a file.

public void Button1Click(object sender, EventArgs e)
{
    ..
    string filename = Path.GetFileName(FileUpload1.FileName);
    ...
    Session["filename"]=filename;
}

Code in Button2 click handler,

public void Button2_Click1(object sender, EventArgs e)
{
 if(Session["filename"]!=null)
 { 
  string filename=Session["filename"].ToString();
  DataSet ds = new DataSet();
  ds.ReadXml((Server.MapPath("~/" + filename)));
  GridView1.DataSource = ds;
  GridView1.DataBind();
}  

---

Actually here you can have huge amount of variants:

1. You can get this value from file upload control, juts simply using same method as it was used in Button1Click:

   string filename = Path.GetFileName(FileUpload1.FileName);
   

2. More correctly, is to store in ViewState as it was told before.

3. If you want to use this in other pages, just save this to session.