I’m inheriting a codebase that has largely JSP scriplets that quickly become less than readable, for instance here’s the fragment that does pagination links:
Visa:
<a class="link" href="javascript:doSubmit('MenyNavigation', 'REW_<%= thisPage %>')" >
<%
if(headPointer - nrOfHitsOnPage > 0){
out.print(" << ");
if(tailPointer - nrOfHitsOnPage <= 0 ){
out.print(1);
} else {
out.print(tailPointer - nrOfHitsOnPage);
}
out.print("-");
out.print(tailPointer);
} %>
</a>
<% if(resultListSize > 0 ) { %>
<%=(tailPointer + 1)%> - <%= headPointer %>
<%}%>
<a class="link" href="javascript:doSubmit('MenyNavigation', 'FWD_<%= thisPage %>')" >
<%
if(headPointer < resultListSize){
out.print(1 + headPointer);
out.print("-");
if(headPointer + nrOfHitsOnPage > resultListSize){
out.print(resultListSize);
} else {
out.print(nrOfHitsOnPage + headPointer);
}
out.print(" >> ");
} %>
</a>
Appearantly this code displays the text “Display 1-10 of 20” when there are 10 elements per page and 20 in total and likewise for other settings but I think this solution is not very reusable. The code is already used in one place in our project and we decided that if we haveone solution for a problem we are going to use the same solution for the same problems if they appear in different places and now I must do pagination for > 5 popups(!) that have search functions and I wonder whether to use this code, to make an analgue solution or build from scratch.
The controller Java class has also not that high cohesion:
public class MenyNavigationActionHandler extends PandoraActionHandler {
private ArendeProcessSessionData sessionData;
private final static Logger logger = Logger
.getLogger(MenyNavigationActionHandler.class);
protected IFormData getFormData() {
return null;
}
protected IFormPattern getPattern() {
return EmptyFormPattern.getInstance();
}
protected void performAction(ISessionHandler sessionHandler, Action action) {
String returnPage = null;
try {
sessionData = (ArendeProcessSessionData) sessionHandler.getSessionData();
if(sessionData.returnToUnsavedData(sessionHandler, action)){
return;
}
if (sessionData.getMenuManager() == null) {
MenuManager menuManager = new MenuManager();
sessionData.setMenuManager(menuManager);
}
// Om man bläddar i träfflista på formell kontrollista
if (action.getActionCommand().endsWith(ArendeProcessLocator.getFormellKontrollLista())) {
FormellKontrollInfo fInfo = sessionData.getFormellKontrollInfo();
FormellKontrollSearchAdmin fSearch = fInfo.getFormellKontrollSearchAdmin();
if(fInfo != null) {
if (action.getActionCommand().startsWith("FWD")) {
fSearch.setDirection(PandoraConstants.FWD_DIRECTION);
} else if (action.getActionCommand().startsWith("REW")) {
fSearch.setDirection(PandoraConstants.REW_DIRECTION);
} else {
fSearch.setDirection(PandoraConstants.NO_DIRECTION);
}
}
returnPage = ArendeProcessLocator.getFormellKontrollLista();
action.setReturnPage(returnPage);
} else if (action.getActionCommand().equalsIgnoreCase(
ArendeProcessLabelConstants.SUB_MENU_VISA_REGISTRERADE)) {
sessionData.setNyinkomnaLista(null);
MenuManager menuManager = sessionData.getMenuManager();
returnPage = menuManager.getLatestDestination(action.getActionTarget());
if (returnPage == null) {
returnPage = action.getCurrPage();
}
action.setReturnPage(returnPage);
} else {
// Standard hantering av menyval. Target från Navigation-objekt hämtas från action.getActionModifier
MenuManager menuManager = sessionData.getMenuManager();
if(action.getActionTarget() != null && !action.getActionTarget().trim().equals("")){
returnPage = menuManager.getLatestDestination(action.getActionTarget());
}else{
returnPage = menuManager.getLatestDestination(sessionData.getLatestActionTarget());
}
if (returnPage == null) {
returnPage = action.getCurrPage();
}
action.setReturnPage(returnPage);
}
if(action.getCurrPage().endsWith(ArendeProcessLocator.getNyregistrering())){
// Nytt önskemål, Kom ihåg innehållet på registrera sidan när vi går till listan 2010-12-02
sessionData.getNyregistrering().setKundReferens(sessionHandler.getRequestParameter(PandoraFieldConstants.FIELD_KUNDREFERENS));
sessionData.getNyregistrering().setSokEfternamn(sessionHandler.getRequestParameter(PandoraFieldConstants.FIELD_SOKEFTERNAMN));
sessionData.getNyregistrering().setSokFornamn(sessionHandler.getRequestParameter(PandoraFieldConstants.FIELD_SOKFORNAMN));
sessionData.getNyregistrering().setForetag(sessionHandler.getRequestParameter(PandoraFieldConstants.FIELD_FORETAG));
sessionData.getNyregistrering().setSokandeLandKod(sessionHandler.getRequestParameter(PandoraFieldConstants.FIELD_SELECT_SOKANDELAND));
sessionData.getNyregistrering().setAnkomstDatum(sessionHandler.getRequestParameter(PandoraFieldConstants.FIELD_ANKOMSTDAG));
sessionData.getNyregistrering().setOriginal("original".equals(sessionHandler.getRequestParameter(PandoraFieldConstants.FIELD_HANDLINGSFORM))? true : false);
sessionData.getNyregistrering().setArendeNummer(sessionHandler.getRequestParameter(PandoraFieldConstants.FIELD_ARENDENUMMER));
//printer ??
}
if(!action.getCurrPage().endsWith(ArendeProcessLocator.getNyinkomnaLista2()) && action.getReturnPage().endsWith((ArendeProcessLocator.getNyregistrering()))){
// Rensa minnet av registrera sidan om det inte är listan med registrerade man kommer ifrån
sessionData.getNyregistrering().setKundReferens("");
sessionData.getNyregistrering().setSokEfternamn("");
sessionData.getNyregistrering().setSokFornamn("");
sessionData.getNyregistrering().setForetag("");
sessionData.getNyregistrering().setSokandeLandKod("");
sessionData.getNyregistrering().setAnkomstDatum("");
sessionData.getNyregistrering().setOriginal(true);
sessionData.getNyregistrering().setArendeNummer("");
}
if(action.getActionCommand().equals(ArendeProcessLocator.getNyinkomnaLista())){
sessionData.setNyinkomnaLista(null);
}
} catch (Exception e) {
logger.error("MenyNavigationActionHandler: performAction() ", e);
}
}
}
I have access to my colleague who write the code and can ask him to guide me what files I should have so the pagination will work but I want a clean and lean solution with no scriplets and that would be a lot of work starting this from scratch instead of using the scriplets.
What do you think I should do? Just use the scriplets above, make them work for my use case and then refactor the most I can to JSTL tags and EL? Any other comment how to reuse Java / JSP code for pagination? Our framework is rather special and custom and we are not using struts or spring or jsf but our own framework which kind of oomplicates things since it relies on session data much.
Any answer or comment is appreciated.
I think it depends on how much of this code there is, and whether you have time to spend on making it more maintainable. I don’t think anyone but you (and your boss) can answer that question.
On the question of how to implement this kind of thing, you can choose between the standard JSTL tag libraries or implementing your own, or a combination. And you can do more if you combine taglibs with EL. And session attributes shouldn’t be a particular problem.
One piece of advice though. JSTL and JSP EL are getting more expressive, so it could be worthwhile upgrading to a servlet container that implements a recent edition of the Servlet specs.