shoppingcartservlet.java

一个完整的网上书店

package com.ascenttech.ebookstore.servlet;

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

import com.ascenttech.ebookstore.bean.Book;
import com.ascenttech.ebookstore.shopcart.BookDetails;
import com.ascenttech.ebookstore.shopcart.ShoppingCart;
import com.ascenttech.ebookstore.util.*;

import java.io.*;
import java.util.*;
import java.sql.*;

public class ShoppingCartServlet
    extends HttpServlet {
  private ServletContext sc;
  private static final String CONTENT_TYPE = "text/html; charset=GBK";

  public ShoppingCartServlet() {
    
  }
  
  //Initialize global variables
  public void init() throws ServletException {
    super.init();
    sc=this.getServletContext();
    
  }
  // service method, the main control method
  protected void service(HttpServletRequest request ,HttpServletResponse response)throws ServletException, IOException{
   response.setContentType("text/html");
   String operation=request.getParameter("operation");

   if(operation==null){
     operation="";
   }
   if(operation.equalsIgnoreCase("addItem")){
     this.doAdd(request,response);
     return;
   }
   if(operation.equalsIgnoreCase("removeItem")){
     this.doRemove(request,response);
     return;
   }
   if(operation.equalsIgnoreCase("removeAll")){
     this.doRemoveAll(request,response);
     return;
   }
   this.doUnknown(request,response);
     return;
  }
  
  private void doBrower(HttpServletRequest request, HttpServletResponse response)throws ServletException,IOException{
    RequestDispatcher rd=sc.getRequestDispatcher("/showcart.jsp");
    rd.forward(request,response);
  }
  
  private void doBrowseErr(HttpServletRequest request, HttpServletResponse response) throws
           ServletException, IOException{
     RequestDispatcher rd=sc.getRequestDispatcher("/login.jsp");
     rd.forward(request,response);

  }

  private void doAdd(HttpServletRequest request, HttpServletResponse response)throws ServletException,IOException{
    HttpSession session=request.getSession(false);
    String user = (String) session.getAttribute("username");
    ShoppingCart cartmap=(ShoppingCart) session.getAttribute(user);
  
    if(cartmap==null){
     this.doBrowseErr(request, response);
    }

    String itemisdn=request.getParameter("isdn");
    Book  book = new Book();
    BookDetails bd= null;
    try {
      bd= book.findBookByISBN(itemisdn);
    }
    catch (SQLException ex) {
      ex.printStackTrace();
    }

    cartmap.add(itemisdn, bd);
    doBrower(request,response);
  }
  
  private void doRemove(HttpServletRequest request, HttpServletResponse response)throws ServletException,IOException{
   HttpSession session=request.getSession();
   String user = (String) session.getAttribute("username");
   ShoppingCart cartmap=(ShoppingCart) session.getAttribute(user);
   if(cartmap==null){
     cartmap=new ShoppingCart();
    session.setAttribute("shoppingcart",cartmap);
   }

   String itemisdn=request.getParameter("isdn");

   cartmap.remove(itemisdn);
   session.setAttribute("shoppingcart",cartmap);
   doBrower(request,response);

  }
  
  private void doRemoveAll(HttpServletRequest request, HttpServletResponse response)throws ServletException,IOException{

  }
  
  private void doUnknown(HttpServletRequest request, HttpServletResponse response)throws ServletException,IOException{

  }
  //Clean up resources
  public void destroy() {
  }

}