MVC框架实现购物车

最新推荐文章于 2022-05-15 23:20:59 发布

原创最新推荐文章于 2022-05-15 23:20:59 发布 · 8.4k 阅读

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文章标签：

#mvc #框架 #string #list #session #servlet

java笔记专栏收录该内容

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1.服务器端在每接收到一次request请求时,都建立一个request对象,

2.服务器端在第一次和某client端建立会话时(可以http请求为标识)建立Session对象,并在Session的存活时间内留在内存中,当结束会话时(如关掉IE浏览器)或其存活时间过期时Session对象消亡

3.Application对象在启动服务器建立,服务器关闭时消亡

用MVC思想实现购物车

//Control.java实现控制

package servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import cart.*;
import java.util.*;
/**
* Servlet implementation class for Servlet: Control
*
*/
public class Control extends javax.servlet.http.HttpServlet implements javax.servlet.Servlet {
   static final long serialVersionUID = 1L;
MyDb md=new MyDb();

    /* (non-Java-doc)
* @see javax.servlet.http.HttpServlet#HttpServlet()
*/
public Control() {
  super();
}

/* (non-Java-doc)
* @see javax.servlet.http.HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  String oper=request.getParameter("oper");
  String _id=request.getParameter("id");
  int id=-1;
  if(_id!=null)
  id=Integer.parseInt(_id);

  HttpSession session=request.getSession();

  ShoppingCart sc=(ShoppingCart)session.getAttribute("cart");
  if(sc==null){
   sc=new ShoppingCart();
   session.setAttribute("cart",sc);
  }
  if("view".equals(oper)){
   request.getRequestDispatcher("/showCart.jsp").forward(request,response);
   return;
  }
  if("buy".equals(oper)){
   sc.addItem(md.getById(id));
   request.getRequestDispatcher("/showCart.jsp").forward(request,response);
   return;
  }

  List aL=md.getAll();
  request.setAttribute("items",aL);
  request.getRequestDispatcher("/showItems.jsp").forward(request,response);
}

/* (non-Java-doc)
* @see javax.servlet.http.HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  // TODO Auto-generated method stub
}
}

//Item.java商品类

package cart;

public class Item {
private int id;
private String name;
private float price;

public Item(){}
public Item(int id,String name,float price){
  this.id=id;
  this.name=name;
  this.price=price;
}

public int getId() {
  return id;
}

public void setId(int id) {
this.id = id;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public float getPrice() {
return price;
}

public void setPrice(float price) {
this.price = price;
}
public String toString(){
return "[id:"+id+",name:"+name+",price:"+price+"]";
}
}
//MyDb.java作为数据源

package cart;
import java.util.*;
public class MyDb {
List aL=new ArrayList();
public MyDb(){
  aL.add(new Item(1,"Apple",10));
  aL.add(new Item(2,"Banana",20));
  aL.add(new Item(3,"Orange",30));
  aL.add(new Item(4,"Pear",10));
}
public List getAll(){
  return aL;
}
public Item getById(int id){
  for(int i=0;i<aL.size();i++){
   Item item=(Item)aL.get(i);
   if(item.getId()==id)return item;
  }
  return null;
}

}
//ShoppingCart.java实现购物操作

package cart;

import java.util.*;
public class ShoppingCart {
private List aL=new ArrayList();

public void empty(){
  aL.clear();
}
public void addItem(Item item){
  aL.add(item);
}
public void removeItem(int id){
  for(int i=0;i<aL.size();i++){
   Item item=(Item)aL.get(i);
   if(item.getId()==id){
    aL.remove(i);
    return;
   }
  }
}
public List getAllItem(){
  return aL;
}
}

//ShowItems.jsp显示商品页面

<body>
<%
List aL=(List)request.getAttribute("items");
for(int i=0;i<aL.size();i++){
Item item=(Item)aL.get(i);
out.println("<a href='?oper=buy&id="+item.getId()+"'>"+item.getName()+"</a>");
out.println("价钱:"+item.getPrice()+"<br/>");
}
%>
<br/>
<a href="?oper=view">查看购物车</a>
</body>

//ShowCart.jsp显示购物车页面

<body>
<%
ShoppingCart sc=(ShoppingCart)session.getAttribute("cart");
List aL=sc.getAllItem();
for(int i=0;i<aL.size();i++){
Item item=(Item)aL.get(i);
out.println("<a href='?oper=buy&id="+item.getId()+"'>"+item.getName()+"</a>");
out.println("价钱:"+item.getPrice()+"<br/>");
}
%>
<a href="Control">继续购物</a>
</body>