In Java:

HttpServletResponse response = (HttpServletResponse)rep;
response.setDateHeader("Expires", -1);
response.setHeader("Cache_Control", "no-cache");
response.setHeader("Pragma", "no-cache");

In Jsp:

<% 
response.setHeader("Cache-Control","no-cache");
response.setHeader("Pragma","no-cache");
response.setHeader("Expires","-1");
%>