package servlet;

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import dao.ItemsDAO;

import entity.Cart;

import entity.Items;

public class CartServlet extends HttpServlet {

private String action ; //表示购物车的动作 ,add,show,delete

//商品业务逻辑类的对象

private ItemsDAO idao = new ItemsDAO();

/**

* Constructor of the object.

*/

public CartServlet() {

super();

}

/**

* Destruction of the servlet. <br>

*/

public void destroy() {

super.destroy(); // Just puts "destroy" string in log

// Put your code here

}

/**

* 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 {

        doPost(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 {

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

PrintWriter out = response.getWriter();

if(request.getParameter("action")!=null)

{

this.action = request.getParameter("action");

if(action.equals("add")) //如果是添加商品进购物车

{

if(addToCart(request,response))

{

request.getRequestDispatcher("/success.jsp").forward(request, response);

}

else

{

request.getRequestDispatcher("/failure.jsp").forward(request, response);

}

}

if(action.equals("show"))//如果是显示购物车

{

request.getRequestDispatcher("/cart.jsp").forward(request, response);

}

if(action.equals("delete")) //如果是执行删除购物车中的商品

{

if(deleteFromCart(request,response))

{

request.getRequestDispatcher("/cart.jsp").forward(request, response);

}

else

{

request.getRequestDispatcher("/cart.jsp").forward(request, response);

}

}

}

}

//添加商品进购物车的方法

private boolean addToCart(HttpServletRequest request, HttpServletResponse response)

{

String id = request.getParameter("id");

String number = request.getParameter("num");

Items item = idao.getItemsById(Integer.parseInt(id));

//是否是第一次给购物车添加商品,需要给session中创建一个新的购物车对象

if(request.getSession().getAttribute("cart")==null)

{

Cart cart = new Cart();

request.getSession().setAttribute("cart",cart);

}

Cart cart = (Cart)request.getSession().getAttribute("cart");

if(cart.addGoodsInCart(item, Integer.parseInt(number)))

{

return true;

}

else

{

return false;

}

}

//从购物车中删除商品

private boolean deleteFromCart(HttpServletRequest request, HttpServletResponse response)

{

String id = request.getParameter("id");

Cart cart = (Cart)request.getSession().getAttribute("cart");

   Items item = idao.getItemsById(Integer.parseInt(id));

   if(cart.removeGoodsFromCart(item))

   {

    return true;

   }

   else

   {

    return false;

   }

}

/**

* Initialization of the servlet. <br>

*

* @throws ServletException if an error occurs

*/

public void init() throws ServletException {

// Put your code here

}

}

private boolean addToCart(HttpServletRequest request, HttpServletResponse response)

为什么这个方法的参数是HttpServletRequest request, HttpServletResponse response，不太懂，而且为什么返回值要弄成布尔类型？