Paging mechanism in EJB

Question

I am trying to improve the performance of a huge report (around 80,000) records. The application uses stateless session bean and it fetches the records in a loop one at a time. I want to change it in such a way it uses oracle stored procedure that fetches 1000 records at a time. When a user wants to see the next set of 1000 records he/she should be able to see by clicking on a link. I�m pretty new to EJB. Before even I proceed I want to make sure that if I am taking the right approach. Now my question is, can I implement Paging mechanism in EJB. If so how feasible it is? Is there any other better way to do it?

Answer 1

hey how are you. I use following paging mechnism. There is paging method, which generates paging links.
public PagingInfo paging (String baseUrl , String currentPage , Long totalItems , Integer itemsPerPage)
          Integer cPage = getInteger (currentPage) ; // if currentPage is valid Integer, return Integer value, else returns null
          if (cPage == null || cPage < 1)
               cPage = 1 ;
          Long totalPages = 1L ;
          Integer i ;
          while (totalPages * itemsPerPage < totalItems)
               totalPages ++ ;
          Integer start = (cPage - 1) *  itemsPerPage ;
          if (baseUrl.lastIndexOf("?") == -1)
               baseUrl = baseUrl.concat("?") ;
          else
               baseUrl = baseUrl.concat("&") ;
          String output = "" ;
          if (totalPages > 1)
               List <String> pages = new ArrayList <String> () ;
               if (cPage > 1)
                    pages.add (li (link (baseUrl + "page=" + (cPage - 1) , "previous page"))) ;
               for (i = 1 ; i <= totalPages ; i ++)
                    if (cPage.equals(i))
                         pages.add (li (String.valueOf(cPage))) ;
                    else
                         pages.add (li (link (baseUrl + "page=" + i , String.valueOf(i)))) ;
               if (cPage < totalPages)
                    pages.add (li (link (baseUrl + "page=" + (cPage + 1) , "next page"))) ;
               Integer size = new Integer (pages.size()) ;
               for (i = 0 ; i < size ; i ++)
                    output = output.concat(pages.get(i)) ;
               output = div (ul (output) , "pages") ;
          return new PagingInfo (start , itemsPerPage , cPage , output) ;
     }PagingInfo declared like this :
public class PagingInfo {
     Integer start ;
     Integer itemsPerPage ;
     Integer currentPage ;
     String output ;
     public Integer getStart() {
          return start;
     public Integer getItemsPerPage() {
          return itemsPerPage;
     public Integer getCurrentPage() {
          return currentPage;
     public String getOutput() {
          return output;
     public PagingInfo(Integer start, Integer itemsPerPage, Integer currentPage,
               String output) {
          this.start = start;
          this.itemsPerPage = itemsPerPage;
          this.currentPage = currentPage;
          this.output = output;
     public PagingInfo() {}
}And your code should be like this
PagingInfo pi = paging ("servletname?action=view" , request.getParameter ("page") , itemCount , itemsPerPage) ;
Query ejbQuery = manager.createQuery("SELECT d FROM DataTable d");
ejbQuery.setMaxResults (pi.getItemsPerPage ()) ;
ejbQuery.setFirstResult (pi.getStart ()) ;
List result = ejbQuery.getResultList();
out.print (pi.getOutput ()) ; // paging links
while ()
// printing your item list
out.print (pi.getOutput()) ; // paging links