购物网站是如何一个个放入SESSION,又是如何一个个取出

//提交后转入SERVLET
String shangp=request.getParameter("shangp");
String price=request.getParameter("price");
ArrayList <Shop_items> list=new ArrayList <Shop_items>();
Shop_items shitem=new Shop_items();
shitem.setShangp(shangp);
shitem.setPrice(price);
if(list.isEmpty()==true){
list.add(shitem);

}else{
list.addAll(list);
}

if(list==null||list.size() <=0){
response.sendRedirect("../fun/image_info.jsp");
}else{

HttpSession session=request.getSession();
session.setAttribute("list", list);
response.sendRedirect("../fun/shopping.jsp");

}
//JSP取出，取出来只有一个，是不是放入SESSION的问题，请高手指点下
<%
try{
ArrayList <Shop_items> list2=new ArrayList <Shop_items>();
list2=(ArrayList)session.getAttribute("list");

if(list2!=null){
for(int i=0;i <list2.size();i++){

%>
<TR>
<td align="center"> <%=list2.get(i).getShangp()%> </td> <td > <%=list2.get(i).getPrice()%> </td>
</TR>
<%} }}catch(Exception e){}%>