shoppingcartservlet.java

网上书店 。根据对网上书店系统的需求分析

package web.servlet;

import java.io.IOException;
import java.sql.SQLException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import dao.BookDao;
import entity.Book;
import entity.ShoppingCart;

public class ShoppingCartServlet extends HttpServlet {

	public static final String CART_NAME = "cart";
	private BookDao bookDao = new BookDao();
	
	/**
	 * The doGet method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to get.
	 * 
	 * @param request the request send by the client to the server
	 * @param response the response send by the server to the client
	 * @throws ServletException if an error occurred
	 * @throws IOException if an error occurred
	 */
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		HttpSession session = request.getSession();
		Object obj = session.getAttribute(CART_NAME);
		ShoppingCart cart;
		if( obj == null )
		{
			cart = new ShoppingCart();
			session.setAttribute(CART_NAME, cart);
		}
		else
		{
			cart = (ShoppingCart) obj;
		}
		
		//获得op参数
		String op = request.getParameter("op");
		//获得isbn参数
		String isbn = request.getParameter("isbn");
		if( "doAdd".equals(op) )
		{
			//查书
			Book book = null;
			try {
				book = bookDao.findByIsbn(isbn);
			} catch (SQLException e) {
				e.printStackTrace();
			}
			if(book!=null)
			{
				//添加到购物车中（购物车本身放在会话中）
				cart.addItem(isbn, book);
			}
		}
		else if( "doDelete".equals( op )) // op.equals( "doDelete")
		{
			cart.deleteItem(isbn);
		}
		else if( "doUpdate".equals( op ) )
		{
			try
			{
				int amount = Integer.parseInt( request.getParameter("amount"));
				cart.updateAmount(isbn, amount);
			}
			catch(Exception ex)
			{
				//
			}
		}
		//转发到cart.jsp，显示购物信息
		request.getRequestDispatcher("cart.jsp").forward(request, response);
	}

	/**
	 * The doPost method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to post.
	 * 
	 * @param request the request send by the client to the server
	 * @param response the response send by the server to the client
	 * @throws ServletException if an error occurred
	 * @throws IOException if an error occurred
	 */
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		this.doGet(request, response);
	}

}