Using HttpServletRequest object to share variables between static methods.

Question

Does anyone know of the overhead/performance implications of using the HttpServletRequest object to share variables between a static method and the calling code?
First, let me explain why I am doing it.
I have some pagination code that I would like to share across multiple servlets. So I pulled the pagination code out, and created a static method that these servlets could all use for their pagination.
public class Pagination {
     public static void setPagination (HttpServletRequest request, Config conf, int totalRows) {
          int page = 0;
          if (request.getParameter("page") != null) {
               page = new Integer(request.getParameter("page")).intValue();
          int articlesPerPage = conf.getArticlesPerPage();
          int pageBoundary = conf.getPageBoundary();
            int numOfPages = totalRows / articlesPerPage;  
            // Checks if the page variable is empty (not set)
            if (page == 0 || (page > numOfPages && (totalRows % articlesPerPage) == 0 && page < numOfPages + 1)) {    
             page = 1;  // If it is empty, we're on page 1
          // Ex: (2 * 25) - 25 = 25 <- data starts at 25
         int startRow = page * articlesPerPage - (articlesPerPage);
         int endRow = startRow + (articlesPerPage);           
         // Set array of page numbers.
         int minDisplayPage = page - pageBoundary;
         if (minDisplayPage < 1) {
              minDisplayPage = 1;     
         int maxDisplayPage = page + pageBoundary;
         if (maxDisplayPage > numOfPages) {
              maxDisplayPage = numOfPages;     
         int arraySize = (maxDisplayPage - minDisplayPage) + 1;
         // Check if there is a remainder page (partially filled page).
         if ((totalRows % articlesPerPage) != 0) arraySize++;
         // Set array to correct size.
         int[] pages = new int[arraySize];
         // Fill the array.
         for (int i = 1; i <= pages.length; i++) {
              pages[i - 1] = i;
         // Set pageNext and pagePrev variables.
         if (page != 1) {
              int pagePrev = page - 1;
              request.setAttribute("pagePrev", pagePrev);
         if ((totalRows - (articlesPerPage * page)) > 0) {
             int pageNext = page + 1;
             request.setAttribute("pageNext", pageNext);
         // These will be used by calling code for SQL query.
         request.setAttribute("startRow", startRow);
         request.setAttribute("endRow", endRow);
         // These will be used in JSP page.
         request.setAttribute("totalRows", totalRows);
         request.setAttribute("numOfPages", numOfPages);
         request.setAttribute("page", page);
         request.setAttribute("pages", pages);          
}I need two parameters from this method (startrow and endrow) so I can perform my SQL queries. Since this is a multithreaded app, I do not want to use class variables that I will later retrieve through methods.
So my solution was to just set the two parameters in the request and grab them later with the calling code like this:
// Set pagination
Pagination.setPagination(request, conf, tl.getTotalRows());
// Grab variables set into request by static method
int startRow = new Integer(request.getAttribute("startRow").toString());
int endRow = new Integer(request.getAttribute("endRow").toString());
// Use startRow and endRow for SQL query below...Does anyone see any problem with this from a resource/performance standpoint? Any idea on what the overhead is in using the HttpServletRequest object like this to pass variables around?
Thanks for any thoughts.

Answer 1

You could either
- create instance vars in both controllers and set them accordingly to point to the same object (from the App Delegate) OR
- create an instance variable on the App Delegate and access it from within the view controllers
Hope this helps!