Single responsability example, step 2

form.cs

private void btnLoad_Click(object sender, EventArgs e)
{
    listView1.Items.Clear();

    var fileName = txtFileName.Text;
    foreach (Product product in productRepository.GetByFileName(fileName))
    {
        var item = new ListViewItem(new[] { 
            product.Id.ToString(), 
            product.Name,
            product.UnitPrice.ToString(), 
            product.Discontinued.ToString()
        });
        listView1.Items.Add(item);
    }
}

ProductRepository.cs

class ProductRepository : IProductRepository
{
    public IEnumerable<Product> GetByFileName(string fileName)
    {
        var products = new List<Product>(); 
        using (var fs = new FileStream(fileName, FileMode.Open))
        {
            var reader = XmlReader.Create(fs);
            while (reader.Read())
            {
                if (reader.Name != "product") continue;
                var product = new Product();
                product.Id = int.Parse(reader.GetAttribute("id"));
                product.Name = reader.GetAttribute("name");
                product.UnitPrice = decimal.Parse(reader.GetAttribute("unitPrice"));
                product.Discontinued = bool.Parse(reader.GetAttribute("discontinued"));
                products.Add(product);
            }
        }
        return products;
    }
}