request的get/setParameter和get/setAttribute()

request.getParameter()是获得通过get或者post获得来的数据，类型只能是String,不能cast成List
getAttribute()是之前自己设定的，类型可以是多种
比如request.setAttribute("name","小强");
然后另一页面
String name=request.getAttribute("name");
name就是小强喽

Attribute用作servlet向jsp传参，不限对象类型
servlet代码：

List<Map<String, Object>> list = service.listProduct(proname, start,
end);
request.setAttribute("listproduct", list);
request.getRequestDispatcher("/product.jsp").forward(request,
response);

<%
String path = request.getContextPath();List<Map<String, Object>> list = (List<Map<String, Object>>)request.getAttribute("listproduct");
%>