<%@page contentType="text/html"%> <%@page pageEncoding="UTF-8"%> <% int interval = 1; // in seconds String prefix = "ad"; String ext = "html"; if(request.getParameter("reset") != null){ application.setAttribute("lastDate",null); application.setAttribute("lastIndex","1"); } java.util.Date lastDate = (java.util.Date)application.getAttribute("lastDate"); if(lastDate == null){ lastDate = new java.util.Date(); application.setAttribute("lastDate",lastDate); } String lastIndex = (String)application.getAttribute("lastIndex"); if(lastIndex == null){ lastIndex = "1"; application.setAttribute("lastIndex",lastIndex); } java.util.Date now = new java.util.Date(); long lapse = (now.getTime() - lastDate.getTime()) / 1000; if(lapse > interval){ long idx = Long.parseLong(lastIndex) + 1; lastIndex = String.valueOf(idx); application.setAttribute("lastIndex",lastIndex); application.setAttribute("lastDate",now); } lastIndex = "00" + lastIndex; lastIndex = lastIndex.substring(lastIndex.length() - 2); String url = prefix + lastIndex + "." + ext; try{ String path = application.getRealPath(url); java.io.File file = new java.io.File(path); if(!file.exists()){ application.setAttribute("lastIndex","01"); lastIndex = "01"; url = prefix + lastIndex + "." + ext; } } catch(Exception ex){ application.setAttribute("lastIndex","01"); } %>