adddvdservlet.java

使用Servlet和JSP进行Web组件开发

/*
 * AddDVDServlet.java
 *
 * 
 */

package com.dvd.controller;

import com.dvd.model.DVDItem;
import java.io.*;
import java.util.LinkedList;
import java.util.List;

import javax.servlet.*;
import javax.servlet.http.*;

/**
 *
 * @author 
 * @version
 */
public class AddDVDServlet extends HttpServlet {
    public void doPost(HttpServletRequest request,
            HttpServletResponse response)
            throws IOException, ServletException {
        
        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);
                RequestDispatcher view = request.getRequestDispatcher("/error.view");
                view.forward(request, response);
                return;
            }
            
            // Business logic
            DVDItem item = new DVDItem(title, year, genre);
            
            // Store the item on the request-scope
            request.setAttribute("dvdItem", item);
            
            // Dispatch to Success view
            RequestDispatcher view = request.getRequestDispatcher("/success.view");
            view.forward(request, response);
            
            // Handle any unexpected expections
        } catch (RuntimeException e) {
            errorMsgs.add("An unexpected error: " + e.getMessage());
            request.setAttribute("errorMsgs", errorMsgs);
            RequestDispatcher view = request.getRequestDispatcher("/error.view");
            view.forward(request, response);
        }
    }
}