Session简单实现购物车功能

这个小程序主要就3个页面，一个商品列表页面(HomeServlet)，一个是提示加入购物车页面(AddCartTipServlet)，一个是显示购物车清单页面(ShowCartServlet)。

HomeServlet页面：

@WebServlet({ "/HomeServlet", "/home" })
public class HomeServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public HomeServlet() {
        super();
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        request.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
        PrintWriter out = response.getWriter();
        out.print("<h2>书单</h2><hr/><br/>");
        out.print("人类简史<a href='"+request.getContextPath()+"/addCartTip?id=1'>加入购物车</a><br/>");
        out.print("未来简史<a href='"+request.getContextPath()+"/addCartTip?id=2'>加入购物车</a><br/>");
        out.print("世界简史<a href='"+request.getContextPath()+"/addCartTip?id=3'>加入购物车</a><br/>");
        out.print("时间简史<a href='"+request.getContextPath()+"/addCartTip?id=4'>加入购物车</a><br/>");
        out.print("<a href='"+request.getContextPath()+"/show/cart'>查看购物车</a><br/>");
    }

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

}
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AddCartTipServlet页面：

@WebServlet({ "/AddCartTipsServlet", "/addCartTip" })
public class AddCartTipsServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;


    public AddCartTipsServlet() {
        super();
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        request.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");

        HttpSession session = request.getSession();
        List<String> list = (List<String>) session.getAttribute("cart");
        if(list==null){
            list=new ArrayList<>();
        }

        String id = request.getParameter("id");
        list.add(id);
        session.setAttribute("cart", list);

        System.out.println(list.toString());
        response.getWriter().println("已加入购物车<br/>"
                + "<a href='"+request.getContextPath()+"/home'>继续购物</a><br/>"
                + "<a href='"+request.getContextPath()+"/show/cart'>查看购物车</a><br/>");
    }

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

}
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ShowCartSevlet页面

@WebServlet({ "/ShowCartServlet", "/show/cart" })
public class ShowCartServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public ShowCartServlet() {
        super();
    }


    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
        PrintWriter out = response.getWriter();
        List<String> list = (List<String>)request.getSession().getAttribute("cart");
        if(list!=null){     
            out.print("你的购物清单：<br/>");
            for (String string : list) {
                out.println(DBUtils.findById(string)+"<br/>");
            }
            out.println("<br/><a href='"+request.getContextPath()+"/home'>继续购物</a><br/>");
        }else{
            out.println("你还没有将商品添加到购物车<br/>"
                    + "<a href='"+request.getContextPath()+"/home'>返回商品列表</a><br/>");
        }
    }

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

}
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DBUtils：存储着商品信息

public class DBUtils {
    private static Map<String,String> map = new HashMap<>();

    static{
        map.put("1", "人类简史");
        map.put("2", "未来简史");
        map.put("3", "世界简史");
        map.put("4", "时间简史");
    }

    public static String findById(String id){
        return map.get(id);
    }

}
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【转载】
作者：张行之
来源：CSDN
原文：https://blog.csdn.net/qq_33689414/article/details/59102339
版权声明：本文为博主原创文章，转载请附上博文链接！

奈斯，感谢分享