adddvdaction.java

使用Servlet和JSP进行Web组件开发

/*
 * AddDVDAction.java
 *
 *
 */

package com.dvd.controller;

import com.dvd.model.DVDItem;
import com.dvd.model.DVDLibrary;
import java.util.LinkedList;
import java.util.List;
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.ActionMapping;
import org.apache.struts.action.ActionForward;
/**
 *
 * @author
 * @version
 */

public class AddDVDAction extends Action {
    
    /* forward name="success" path="" */
    private final static String SUCCESS = "success";
    
    /**
     * This is the action called from the Struts framework.
     * @param mapping The ActionMapping used to select this instance.
     * @param form The optional ActionForm bean for this request.
     * @param request The HTTP Request we are processing.
     * @param response The HTTP Response we are processing.
     * @throws java.lang.Exception
     * @return
     */
    public ActionForward execute(ActionMapping mapping, ActionForm  form,
            HttpServletRequest request, HttpServletResponse response)
            throws Exception {
        List errorMsgs = new LinkedList();
        
        try {
            
            // Retrieve form parameters
            String title = request.getParameter("title");
            String year = request.getParameter("year");
            // Did the user type in a genre?
            String genre = request.getParameter("newGenre");
            // If not, use the drop-down list value
            if ( (genre == null) || (genre.trim().length() == 0) ) {
                genre = request.getParameter("genre").trim();
            }
            
            // Form verification
            if ( title == null || title.trim().length() == 0 ) {
                errorMsgs.add("Please enter the DVD title.");
            }
            if ( year == null || year.trim().length() == 0 ) {
                errorMsgs.add("Please enter the year of release for the DVD.");
            } else if ( !year.trim().matches("\\d\\d\\d\\d")) {
                errorMsgs.add("Please enter a valid year.");
            }
            if ( ! errorMsgs.isEmpty() ) {
                request.setAttribute("errorMsgs", errorMsgs);
                return mapping.findForward("error");
            }
            
            // retrieve the "library" attribute from the session-scope
            HttpSession session = request.getSession();
            DVDLibrary model = (DVDLibrary)session.getAttribute("library");
            DVDItem item = model.addDVD(title, year, genre);
            
            // Store the item on the request-scope
            request.setAttribute("dvdItem", item);
            return mapping.findForward("success");
            // Handle any unexpected expections
        } catch (RuntimeException e) {
            errorMsgs.add("An unexpected error: " + e.getMessage());
            request.setAttribute("errorMsgs", errorMsgs);
            return mapping.findForward("error");
        }
    }
}