The realization of the shopping cart function _java by Java Web Development

In order to facilitate their own later review, so write more carefully, record their growth.
Since it is a shopping cart, then the prerequisite is to first need a series of goods, that is, to build an entity, here built a commodity table,

Display on the browser through a query

The basic show has been done, now into our plays, the Servlet
When clicked into the shopping cart, the servlet is accessed

Shopping Cart Code

Package com.servlet;
Import java.io.IOException;
Import Java.io.PrintWriter;
Import Java.util.HashMap;

Import Java.util.Map;
Import javax.servlet.ServletException;
Import Javax.servlet.http.HttpServlet;
Import Javax.servlet.http.HttpServletRequest;

Import Javax.servlet.http.HttpServletResponse;
Import Com.dao.GoodsDAO;
Import Com.entity.Goods;

Import Com.entity.GoodsItem; public class Putcarservlet extends HttpServlet {public void doget (HttpServletRequest request, HttpServletResponse Respo
  NSE) throws Servletexception, IOException {response.setcontenttype ("text/html");
  
  PrintWriter out = Response.getwriter ();
 DoPost (request, response); 

  public void DoPost (HttpServletRequest request, httpservletresponse response) throws Servletexception, IOException {
  Response.setcontenttype ("text/html");
  PrintWriter out = Response.getwriter ();
  
  Gets the number String id = request.getparameter ("Goodsid");
  Get all the information of the merchandise object by number Goodsdao DAO = new Goodsdao (); Goods g = DAO.GEtgoodsbyid (ID);
  Put the goods into the shopping cart//map collection is the cart//map< key, Value > Item number as the key commodity item as the value//1. Determine if a shopping cart//cart is in session//from session to fetch cart
  Map<string,goodsitem> GWC = (map<string,goodsitem>) request.getsession (). GetAttribute ("GWC");
  Determine if there is an if (gwc==null) {//create cart GWC = new hashmap<string, goodsitem> (); ///Put items into Cart//put (item number, item) add data to the GWC collection//You want to have the product in the shopping cart//Plainly it is in the GWC set to match whether there is such a commodity = = "Go to the collection to match whether there is such a commodity Number key//To determine if the existence of the item number keys if (Gwc.containskey (ID)) {//presence//Set quantity +1//key to get value//keys for commodity number value for commodity item items contain commodity objects
   Information and quantity information Goodsitem SPX = Gwc.get (ID);
   Get the original quantity int yldsl = Spx.getcount ();
   
In the original quantity +1 Gwc.get (id). SetCount (yldsl+1);
   
  Gwc.get (ID). SetCount (Gwc.get (ID). GetCount () +1);
   
   }else{//does not exist//create a new item quantity of 1 Goodsitem gi = new Goodsitem (g, 1);
  Put this item into the GWC gwc.put (ID, GI);
  
  ///place cart into session request.getsession () setattribute ("GWC", GWC); Continue shopping Response.sendreDirect ("index.jsp");

 }

}

Execution results:

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