购物车项目（五）——编写CartServlet类

购物车项目（五）——编写CartServlet类

编写思路：

1.创建CartServlet类，并继承HttpServlet

2.设置属性：action，并创建商品业务逻辑类对象

3.doGe()方法写为doPost(request,response)

4.写doPost()方法，并判断action动作

5.编写添加，删除商品的方法，并利用购物车类中的方法。

代码如下：

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);

ab43
}
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) //getsession.getAttribute(String name)返回session对象中与指定名称绑定的对象，如果不存在则返回null
{
Cart cart = new Cart();
request.getSession().setAttribute("cart",cart);
}
Cart cart = (Cart)request.getSession().getAttribute("cart");
if(cart.addGoodinCart(item, Integer.parseInt(number)))//字符类型转换成整型
{
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.removeGoodfromCart(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
}

}