Insert and then show the result and refresh page problem

Question

hi all,
I collect the form value and put them into db, and then display this student 's inform out from db including the one we just submit, first I do it on this way
  insertpayment(UserId, FeeType, DuteDate, OfficerReason, OtherReason, CompleteDate,
                        InterviewDate, ApprovalDate,PaymentYear);
               studentRecords= getFound(UserId);
                 userSession.setAttribute("studentRecords", studentRecords);
                 RequestDispatcher disp;
               // disp = getServletContext().getRequestDispatcher("/WEB-INF/jsp/   studentRecords= getFound(UserId);");
                 disp = getServletContext().getRequestDispatcher("/showPayment");
                disp.forward(req, res); then whenever I refresh my showRecords.jsp" I call the insert function. THAT IS HORRIABLE.
I try to move the studentRecords= getFound(UserId); to my showPayment servlet and then forward the result to showRecords.jsp, but I alwarys get error
PWC4011: Unable to set request character encoding to UTF-8 from context /report, because request parameters have already been read, or ServletRequest.getReader() has already been called
How should I handle this kind of problem??

Answer 1

Karan, thank you for the link, i read a few articles, I only get the sample part part use res.sendRedirect("/myfolder/showPayment"); in my insert servlet and use forward to display the page
userSession.setAttribute("studentRecords", studentRecords);
              RequestDispatcher disp;
              disp = getServletContext().getRequestDispatcher("/WEB-INF/jsp/secure/admin/showRecords.jsp");
               disp.forward(req, res);   
this solute the refresh page problem, but bring the new problem I can't use the following way to disable the back button. not the perter solution
maybe I did not understand PRC more advice!!
response.setHeader("Cache-Control","no-cache"); //Forces caches to obtain a new copy of the page from the origin server
response.setHeader("Cache-Control","no-store"); //Directs caches not to store the page under any circumstance
response.setDateHeader("Expires", 0); //Causes the proxy cache to see the page as "stale"
response.setHeader("Pragma","no-cache"); //HTTP 1.0 backward compatibility