selectleagueaction.java

使用Servlet和JSP进行Web组件开发

package sl314.controller;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
// Struts classes
import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.action.ActionForm;
// Model classes
import sl314.model.RegisterService;
import sl314.model.League;
import sl314.model.ObjectNotFoundException;
import java.util.List;
import java.util.LinkedList;


public class SelectLeagueAction extends Action {

  public ActionForward execute(ActionMapping mapping, ActionForm form,
                               HttpServletRequest request,
                               HttpServletResponse response) {

    // Keep a set of strings to record form processing errors.
    List errorMsgs = new LinkedList();
    // Store this set in the request scope, in case we need to
    // send the ErrorPage view.
    request.setAttribute("errorMsgs", errorMsgs);

    try {

      // Retrieve form parameters.
      String season = request.getParameter("season").trim();
      String yearStr = request.getParameter("year").trim();

      // Perform data conversions.
      int year = -1;
      try {
        year = Integer.parseInt(yearStr);
      } catch (NumberFormatException nfe) {
        errorMsgs.add("The 'year' field must be a positive integer.");
      }

      // Verify 'Select League' form fields
      if ( (year != -1) && ((year < 2000) || (year > 2010)) ) {
        errorMsgs.add("The 'year' field must within 2000 to 2010.");
      }
      if ( season.equals("UNKNOWN") ) {
        errorMsgs.add("Please select a league season.");
      }

      // Send the ErrorPage view if there were errors
      if ( ! errorMsgs.isEmpty() ) {
        return mapping.findForward("error");
      }

      // Perform business logic
      RegisterService registerSvc = new RegisterService();

      // Retrieve the league
      League league = registerSvc.getLeague(year, season);

      // Store the league object in the session-scope
      HttpSession session = request.getSession();
      session.setAttribute("league", league);

      // Send the Success view
      return mapping.findForward("success");

    // Handle business exceptions
    } catch (ObjectNotFoundException onfe) {
      errorMsgs.add("The league you selected does not yet exist."
                    + " Please select another.");
      return mapping.findForward("error");

    // Handle any unusual exceptions
    } catch (RuntimeException e) {
      // Log stack trace
      e.printStackTrace(System.err);

      // Send the Error view if there were errors
      errorMsgs.add(e.getMessage());
      return mapping.findForward("error");

    } // END of try-catch block

  } // END of execute method

} // END of RegisterAction class