问ASP.Net中的GridView行单击事件我要获取id，并在单击行时将其发送到另一个页面

EN

{
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        e.Row.Attributes["onclick"] = "location.href='MailsByOne.aspx?id=" + DataBinder.Eval(e.Row.DataItem, "id") + "'";
        e.Row.Attributes["style"] = "cursor:pointer";
    }
}
protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)
{
    contacts connn = new contacts();
    int index = GridView1.SelectedRow.RowIndex;
    int ID = Convert.ToInt32(GridView1.SelectedRow.Cells[0].Text);
    string message = "Row Index: " + index + "\\ContactID: " + connn.ContactID;
    ClientScript.RegisterStartupScript(this.GetType(), "alert", "alert('" + message + "');", true);
}