jsp code:
  :
  :
  <% this.pageContext.getSession().setAttribute("test_attrib",obj); %>
   :
   :
<form method="post" action="testServlet">
   :
   :
</form>
(不用form submit也沒差,直接用urlconnection送request到你的servlet也可以)
----------------------------------
test servlet  code:
  public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
     :
   Object obj= request.getSession().getAttribute("test_attrib");
     :
     :
  }
-----------------------------------------------------