package com.ivan.web;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.ivan.model.Book;
/**
* 购物车实现方案:
* 1.把商品书存在session中
* 问题:1.浏览器重新打开,以前数据不在了【把书的id放在cookie】
* 2.当服务重启后,以前数据也不在【1.把书的id放在cookie,2.把session保存起来】
* @author exp
*
*/
@WebServlet("/BuyBookServlet")
public class BuyBookServlet extends HttpServlet{
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
response.setHeader("content-type","text/html;charset=utf-8");
//用户买书-书放在购物车【掌握】
//1.获取书的ID
String bookId = request.getParameter("id");
//2.通过书id找到这本书
Book book = Dbutils.findBookId(Integer.parseInt(bookId));
//3.把这个书放在购物车List<Book> cart
//3.1先从session取出购物车
List<Book> cart = (List<Book>)request.getSession().getAttribute("cart");
//3.2如果没有购物车对象,就创建一个
if(cart == null){
System.out.println("当前session没有购物车");
cart = new ArrayList<Book>();
}else{
System.out.println("当前session有购物车");
}
cart.add(book);
//4.把这个list放在session中
request.getSession().setAttribute("cart", cart);
//5.显示购物车的信息
PrintWriter writer = response.getWriter();
writer.write("购物车信息:");
for(Book b : cart){
writer.write("<br>" + b.getName());
}
}
}