<select name=productionName id="textfield2" size=1>
</select>

public class selectProduct extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doPost(request, response);
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        Connection conn=null;
        Statement stmt=null;
        ResultSet rs=null;
        List<String> list = new ArrayList<String>();
        String sql = "select product_name from product";

        ConnectionFactory newconn = new ConnectionFactory();
        conn = newconn.getConnection();
        try {
            stmt = conn.createStatement();
            rs = stmt.executeQuery(sql);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        try {
            while (rs.next()) {
                String st1 =rs.getString("product_name");
                list.add(st1);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }

        request.setAttribute("list", list);
        String URL = "/jsp/ReleaseDepend.jsp";
        request.getRequestDispatcher(URL).forward(request, response);
    }
}

<select name=productionName id="textfield2" size=1>
     <c:forEach items="${list}" var="data">
             <option value="${data}">${data}</option>
     </c:forEach>
</select>

------解决方案--------------------
   你的结果不是都在request中存好了   直接在页面拿出来循环显示就行了~

------解决方案--------------------
你可以在jsp页面中把存好的list打印出来，如果没有数据显示那就说明你的list里面的值没有放进去。list里面有值你就直接循环赋给select
<%
  for(int i=0;i<list.size();++i)
  {
%>
option value="<%=list.get(i)%>"><%=list.get(i)