searchcustomeraction.java

struts的一些用的书籍

package app18b.action;

import app18b.dao.CustomerDAO;
import app18b.dao.DAOFactory;
import app18b.form.CustomerSearchCriteriaForm;
import app18b.util.Config;
import app18b.to.CustomerSearchCriteriaTO;
import java.util.ArrayList;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;

public class SearchCustomerAction extends Action {

  private static int maxRecordsPerPage;
  private static int maxPagesPerRetrieve;
  private static int maxRecordsPerRetrieve;
  private static String CUSTOMER_LIST = "customerList";
  static {
      maxRecordsPerPage = Integer.parseInt(Config.getInstance().getStringValue("maxRecordsPerPage"));
      maxPagesPerRetrieve = Integer.parseInt(Config.getInstance().getStringValue("maxPagesPerRetrieve"));
  		maxRecordsPerRetrieve = maxRecordsPerPage * maxPagesPerRetrieve;
  }
    
  public ActionForward execute(ActionMapping mapping, ActionForm form,
    HttpServletRequest request, HttpServletResponse response) {

      CustomerSearchCriteriaForm criteria = (CustomerSearchCriteriaForm) form;
      int currentPage = 1; // the page number requested
      try {
          currentPage = Integer.parseInt(request.getParameter("page"));
      }
      catch (NumberFormatException e) {
      }
      criteria.setCurrentPage(currentPage);
      criteria.setNextPage(currentPage + 1);
      criteria.setPreviousPage(currentPage - 1);
      HttpSession session = request.getSession();

      if (request.getMethod().equalsIgnoreCase("POST") ||
        session.getAttribute(CUSTOMER_LIST)==null) {
          ArrayList customerList = retrieveDataFromDB(criteria, 0, maxRecordsPerRetrieve);
          session.setAttribute(CUSTOMER_LIST, customerList);
          criteria.setCachedStartPage(1);
      }
      else {
          // retrieve the cached result
          if (currentPage<criteria.getCachedStartPage() ||  
                  currentPage >= criteria.getCachedStartPage() + maxPagesPerRetrieve) {
              ArrayList customerList = retrieveDataFromDB(criteria, (currentPage - 1) * maxRecordsPerPage, maxRecordsPerRetrieve);
              session.setAttribute(CUSTOMER_LIST, customerList);
              criteria.setCachedStartPage(currentPage);
          }
      }
      criteria.setStartRecord((currentPage - criteria.getCachedStartPage()) * maxRecordsPerPage);
      criteria.setEndRecord(criteria.getStartRecord() + maxRecordsPerPage - 1);
      
    return mapping.getInputForward();
  }
  
  private ArrayList retrieveDataFromDB (CustomerSearchCriteriaForm criteria, int offset, int maxRecordsPerRetrieve) {
		CustomerSearchCriteriaTO customerSearch = new CustomerSearchCriteriaTO();
		ArrayList customerList = new ArrayList();      
		customerSearch.setName(criteria.getName()); 	
		customerSearch.setAddress(criteria.getAddress());   
		customerSearch.setPhone(criteria.getPhone());
		CustomerDAO customerDAO = DAOFactory.getInstance().getCustomerDAO();
         
		try {
			customerList = customerDAO.searchCustomers(customerSearch, offset, maxRecordsPerRetrieve +1);
			int size = customerList.size();
			if (size < maxRecordsPerRetrieve + 1) 
			    criteria.setHighestPageNumber(criteria.getCurrentPage() + (int) Math.ceil(size/maxRecordsPerPage));
			else 
				  criteria.setHighestPageNumber(-1);
		}
		catch (Exception ex) {  
		} 
		return customerList;
  }
  
}