buyservlet.java

网上订餐系统的源码

package com.tx.web;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;

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 com.tx.entity.Book;

public class BuyServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doPost(request, response);
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		String id = request.getParameter("bookId");
		HttpSession session = request.getSession();
		ShopCar car = null;
		// 首先查看有无购物车
		Object obj = session.getAttribute("shopCar");
		// 如果没有新建购物车
		if (obj == null) {
			car = new ShopCar();
		} else {
			// 如果有继续使用
			car = (ShopCar) obj;
		}
		Book book = null;
		// 随后在从购物车中查看有没有买过当前要买的商品
		book = car.findBookById(id);
		// 如果没有买过当前的要买的书，新建书籍对象
		if (book == null) {
			ArrayList list = (ArrayList) session.getAttribute("bookList");
			for (int i = 0; i < list.size(); i++) {
				Book temp = (Book) list.get(i);
				if (temp.getBookId().equals(id)) {
					temp.setCount(1);
					book = temp;
					break;
				}
			}

		} else {// 买过此书将数量更新
			book.setCount(book.getCount() + 1);
		}
		car.addBook(book);
		// 保存购物车，进行购物列表的显示
		session.setAttribute("shopCar", car);
		response.sendRedirect("shopCarList.jsp");
	}

}