<div>

        <asp:ListBox ID="ListBox1" runat="server"></asp:ListBox>  <br />

        <asp:Button ID="Button1" runat="server" Text="Get Selected Values" OnClick="Button1_Click" />

    </div>

 protected void Page_Load(object sender, EventArgs e)

        {

            if (!IsPostBack)

            {

                   //填充数据

                    DataTable dt = new DataTable();

                    dt.Columns.Add(new DataColumn() { ColumnName = "Id", DataType = typeof(int) });

                    dt.Columns.Add(new DataColumn() { ColumnName = "Name", DataType = typeof(string) });

                    dt.Rows.Add(, "Scott");

                    dt.Rows.Add(, "John");

                    dt.Rows.Add(, "Tom");

                    dt.Rows.Add(, "Ross");

                    ListBox1.DataValueField = "Id";

                    ListBox1.DataTextField = "Name";

                    ListBox1.DataSource = dt;

                    ListBox1.DataBind();

            }

        }

        protected void Button1_Click(object sender, EventArgs e)

        {

            int id = int.Parse(ListBox1.SelectedItem.Value);

            Response.Write(id);

        }