request.getParameter("v1")取值为空问题

Question

for (Vote v : list) { request.setAttribute("v"+v.getVno(), df.format(v.getNum()*100.0/num)+"%"); } request.getRequestDispatcher("Result.jsp").forward(request, response);将数据传入Result.jsp之后，如果使用  <%=request.getParameter("v1") %>取值为null而${v1}  却可以取到对于的数值。 

Answer 1

应该用getAttribute("v1");