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From "Givler, Eric" <>
Subject Code reduction for Action classes
Date Wed, 11 Oct 2006 18:32:56 GMT
I've been trying to get the hang of struts now for the past few months, and am wondering how
people write "re-usable" base classes for Struts.  If you have the time, I'd really appreciate
your thoughts on this - bear with me, as it's a lot of reading:

My actions tend to be "similar" but making them "reusable" seems to be eluding me.

What I would like to have is a set of reusable actions that handle the following standard
application features:

1. A wizard (multiple jsps, one form bean, data formatting, validation specific per page,
with persistence when any navigation occurs, not just at the end).  I've seen an example of
an "at-the-end" wizard in the sample Chapter from Struts Recipes by George Franciscus and
Danilo Gurovich.
2. A multi-record screen ( one jsp, array of items, formatting of data, validation w/ messages,
and persistence)

Are these already written, so I can save some time?

So far, I've tried to write a re-usable piece of code for #2.
Based on ideas in the ObjectSource Struts Survival Guide, Chapter 10:

#1: I wrote my own mapping.  Here are the properties:

public class CRUDActionMapping extends ActionMapping{
   private String formType;
   private String formMultiRecordProperty;
   private String formDefConfig;
   private String databaseBeanClassName;
   private String saveServiceMethod;
   private String retrieveServiceMethod;
   private String serviceName;
#2: My struts-config.xml for the action for this class is defined as:

         <action path="/cbdeqr_engcodehours"
                <set-property property="cancellable" value="true"/>
                <set-property property="formType" value="MultiRecord"/>
                <set-property property="formMultiRecordProperty" value="codehours"/>
                <set-property property="formDefConfig" value="CbdeqrEngCodeHoursForm"/>
                <set-property property="databaseBeanClassName" value="dep.ccdreporting.model.vo.cbp.CbdeqrCodeHours"/>
                <set-property property="saveServiceMethod" value="saveCbdeqrCodeHours"/>
                <set-property property="retrieveServiceMethod" value="getEngCodeHours"/>
                <set-property property="serviceName" value="dep.ccdreporting.model.service.cbp.CBPDaoService"/>
                <forward name="hourspercounty" path="/"/>
                <forward name="cbdeqr_main" path="/"/>
                <forward name="success" path="/WEB-INF/jsp/cbp/cbdeqr_engcodehours.jsp"/>

#3: The action class CbdeqrEngCodeHoursAction is reduced to two overridden methods (save and
initializePage, due to calling a calculation) of a base class, and one method that gets the
parameters to retrieve the data, which is:

   public HashMap getRetrieveServiceMethodParams( HttpServletRequest request ) {
       HttpSession session = request.getSession();
       UserBean userbean = (UserBean) session.getAttribute("usrbean");
       HashMap codeparams = new HashMap();
       codeparams.put("report_id" , userbean.getReport_id()); 
       return codeparams;
   } // getRetrieveServiceMethodParams

#4: The base class handles the initialization of the page and the save.  Here's the save()
call so this message doesn't get too wordy:

public ActionForward save(ActionMapping mapping, 
                          ActionForm form, 
                          HttpServletRequest request, 
                          HttpServletResponse response) 
  throws Exception, 
   ActionForward fwd = mapping.getInputForward();
   if (isFormValid(mapping, form, request)) {
      if ( mapping instanceof CRUDActionMapping ) {
         CRUDActionMapping myMapping = (CRUDActionMapping) mapping;
         if (myMapping.getFormType().equalsIgnoreCase("MULTIRECORD")) {
             saveMultiRecordForm ( mapping, form, request );

and the save code -- this is where I'm confused - is this a reasonable approach, or am I really
missing the boat.  Specifically:  Should I be creating the service like this?  Also, I really
want the ability to log who is performing the service methods as well - i.e. request.getRemoteUser(),
so do I have to pass this to the service method, or can I get it another way??

public void saveMultiRecordForm ( ActionMapping mapping,
                                  ActionForm form,
                                  HttpServletRequest request ) 
   throws Exception
   // get all the action-mapping properties
   CRUDActionMapping crudMapping = (CRUDActionMapping) mapping;
   String formPropertyName = crudMapping.getFormMultiRecordProperty();
   String formDefConfigName = crudMapping.getFormDefConfig();
   String databaseBeanClass = crudMapping.getDatabaseBeanClassName();
   String saveServiceMethodName = crudMapping.getSaveServiceMethod();
   // form-def returns an array of dynaActionForms, which is stored in the: formPropertyName
   DynaActionForm dynaform = (DynaActionForm ) form;
   ArrayList listOfFormDetails = (ArrayList) dynaform.get( formPropertyName );

   // db bean array needed for all our service method calls
   Class classOfDbBean = Class.forName( databaseBeanClass );
   Object[] details = (Object[]) Array.newInstance( classOfDbBean, listOfFormDetails.size()

   // Create an instance of the service class.
   Class serviceClass = Class.forName( crudMapping.getServiceName() ); 
   Object service = serviceClass.newInstance();

   // find the method that takes an array of data, and invoke it.
   Object arguments[] = new Object[] { details };
   Method svcMethod = serviceClass.getMethod(saveServiceMethodName, new Class[] { details.getClass()}
   Object result = svcMethod.invoke( service, arguments );
} // saveMultiRecordForm 

Thanks for anyone who has made it this far!

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