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Javaweb （MVC购物车01）

您好 2022-04-22 阅读 41
javaeclipse

MVC

MVC模式（Model-View-Controller）是软件工程中的一种软件架构模式，把软件系统分为三个基本部分：模型（Model）、视图（View）和控制器（Controller）。

MVC模式最早为Trygve Reenskaug提出，为施乐帕罗奥多研究中心（Xerox PARC）的Smalltalk语言发明的一种软件设计模式。

MVC可对程序的后期维护和扩展提供了方便，并且使程序某些部分的重用提供了方便。而且MVC也使程序简化，更加直观。

控制器Controller：对请求进行处理，负责请求转发；Servlet

特点：控制器接收用户输入并调用模型和视图去完成用户的需求


视图View：界面设计人员进行图形界面设计；JSP

特点：a、视图是用户看到并与之交互的界面

b、向用户显示相关的数据

c、接受用户的输入

d、不进行任何实际的业务处理


模型Model：程序编写程序应用的功能（实现算法等等）、数据库管理；Java对象
用于处理管理数据库、处理业务逻辑、封装实体数据 JavaBean

特点：一个模型能为多个视图提供数据
 

注意，MVC不是Java的东西，几乎现在所有B/S结构的软件都采用了MVC设计模式。但是要注意，MVC在B/S结构软件并没有完全实现，例如在我们今后的B/S软件中并不会有事件驱动！

实现MVC购物车的绑值和加入购物车初始版：

实体类和数据库辅助类该怎么写还是怎么写

//实体类：商品类
package com.zking.mvc.cart.entity;

import java.io.Serializable;

public class Goods implements Serializable{

	private static final long serialVersionUID = -2858362891359151911L;
	
	private int gid;
	private String gname;
	private int gprice;
	private String ginfo;
	private String gpath;
	private int gkc;
	private String gtype;
	
	public Goods() {
		// TODO Auto-generated constructor stub
	}

	public Goods(int gid, String gname, int gprice, String ginfo, String gpath, int gkc, String gtype) {
		super();
		this.gid = gid;
		this.gname = gname;
		this.gprice = gprice;
		this.ginfo = ginfo;
		this.gpath = gpath;
		this.gkc = gkc;
		this.gtype = gtype;
	}

	public Goods(String gname, int gprice, String ginfo, String gpath, int gkc, String gtype) {
		super();
		this.gname = gname;
		this.gprice = gprice;
		this.ginfo = ginfo;
		this.gpath = gpath;
		this.gkc = gkc;
		this.gtype = gtype;
	}

	public int getGid() {
		return gid;
	}

	public void setGid(int gid) {
		this.gid = gid;
	}

	public String getGname() {
		return gname;
	}

	public void setGname(String gname) {
		this.gname = gname;
	}

	public int getGprice() {
		return gprice;
	}

	public void setGprice(int gprice) {
		this.gprice = gprice;
	}

	public String getGinfo() {
		return ginfo;
	}

	public void setGinfo(String ginfo) {
		this.ginfo = ginfo;
	}

	public String getGpath() {
		return gpath;
	}

	public void setGpath(String gpath) {
		this.gpath = gpath;
	}

	public int getGkc() {
		return gkc;
	}

	public void setGkc(int gkc) {
		this.gkc = gkc;
	}

	public String getGtype() {
		return gtype;
	}

	public void setGtype(String gtype) {
		this.gtype = gtype;
	}

	@Override
	public String toString() {
		return "Goods [gid=" + gid + ", gname=" + gname + ", gprice=" + gprice + ", ginfo=" + ginfo + ", gpath=" + gpath
				+ ", gkc=" + gkc + ", gtype=" + gtype + "]";
	}
	
	
	
	

}

//购物车类
package com.zking.mvc.cart.entity;

import java.io.Serializable;

public class Cart  implements Serializable{
	
	private static final long serialVersionUID = 5969840860422993319L;
	private int cid;
	private Goods goods;
	private User user;
	private int count;
	private int ctotal;
	
	public Cart() {
		// TODO Auto-generated constructor stub
	}

	public int getCid() {
		return cid;
	}

	public void setCid(int cid) {
		this.cid = cid;
	}

	public Goods getGoods() {
		return goods;
	}

	public void setGoods(Goods goods) {
		this.goods = goods;
	}

	public User getUsers() {
		return user;
	}

	public void setUsers(User user) {
		this.user = user;
	}

	public int getCount() {
		return count;
	}

	public void setCount(int count) {
		this.count = count;
	}

	public int getCtotal() {
		return ctotal;
	}

	public void setCtotal() {
		this.ctotal = this.getGoods().getGprice() * this.getCount();
	}

	public Cart(int cid, Goods goods, User user, int count, int ctotal) {
		this.cid = cid;
		this.goods = goods;
		this.user = user;
		this.count = count;
		this.ctotal = ctotal;
	}

	@Override
	public String toString() {
		return "Cart [cid=" + cid + ", goods=" + goods + ", users=" + user + ", count=" + count + ", ctotal=" + ctotal
				+ "]";
	}
	
}

三层架构该怎么写就怎么写

下面是servlet里面的代码用来实现绑值和加入购物车：

绑值代码：

package com.zking.mvc.cart.servlet;

import java.io.IOException;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import com.zking.mvc.cart.biz.IGoodsBiz;
import com.zking.mvc.cart.biz.impl.GoodsBizImpl;
import com.zking.mvc.cart.entity.Goods;
import com.zking.mvc.cart.entity.User;

@WebServlet("/GoodsListServlet")
public class GoodsListServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
   
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doPost(request, response);
	}

	
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		//servlet作用：负责处理用户的请求以及响应
		
		//1.设置字符编码
		request.setCharacterEncoding("utf-8");
		response.setCharacterEncoding("utf-8");
		response.setContentType("utf-8");
		//2.获取参数  省略
		//3.封装  调用biz判断
		IGoodsBiz igb=new GoodsBizImpl();
		List<Goods> listGoods = igb.queryGoodsAll();


		//数据保存在域对象中
		//获取域对象 session
		HttpSession session =  request.getSession();
		session.setAttribute("listGoods", listGoods);
	
		
		//获取当前项目的绝对路径
		String path =  request.getServletContext().getContextPath();// /web_mvc_cart_t280
		//4.响应
		response.sendRedirect("index.jsp");
		
	}

}

页面代码：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
    <!--通过taglib引入JSTL标准标签库  -->
    <%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
	<!--通过c标签判断是否在域对象中存在数据-->
	<c:if test="${empty listGoods }">
		<jsp:forward page="GoodsListServlet"></jsp:forward>
	</c:if>

	<h2 style="text-align:center">zkingzz购物首页</h2>
	<hr/>
	<p>欢迎您！大佬先生--${users.username}</p>
	<table border="1" cellspacing="0" cellpadding="0" width="100%" >
		<tr>
			<th>商品编码</th>
			<th>商品名称</th>
			<th>商品价格</th>
			<th>操作</th>
		</tr>
		<!--通过c标签遍历数据  -->
		<c:forEach items="${listGoods}" var="goods">
			<tr>
				<td>${goods.gid}</td>
				<td>${goods.gname}</td>
				<td>${goods.gprice}</td>
				<td>
					<button onclick="addCart(${goods.gid})">加入购物车</button>
				</td>
			</tr>
		</c:forEach>
	</table>
	
	<script type="text/javascript">
	//加入购物车的点击事件
	function addCart(gid) {
		//alert(gid);
		window.location.href="AddCartServlet?gid="+gid;
	}
	
	</script>
</body>
</html>

加入购物车：

package com.zking.mvc.cart.servlet;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import com.zking.mvc.cart.biz.ICartBiz;
import com.zking.mvc.cart.biz.IGoodsBiz;
import com.zking.mvc.cart.biz.impl.CartBizImpl;
import com.zking.mvc.cart.biz.impl.GoodsBizImpl;
import com.zking.mvc.cart.entity.Cart;
import com.zking.mvc.cart.entity.Goods;
import com.zking.mvc.cart.entity.User;


@WebServlet("/AddCartServlet")
public class AddCartServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    
	
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doPost(request, response);
	}

	
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		//jrebel  热部署插件
				//加入加购物车的servlet
				//System.out.println("进来了！");
				//1.设置字符集编码
				request.setCharacterEncoding("utf-8");
				response.setCharacterEncoding("utf-8");
				response.setContentType("text/html;charset=utf-8");
				
				//2.获取location带过来的gid
				String id = request.getParameter("gid");
				int gid = 0;
				if(null!=id) {
					gid = Integer.valueOf(id);
				}
				//数据封装
				Cart c = new Cart();
				//将gid Userid ccount ctotal 封装到cart实体对象中
				IGoodsBiz igb = new GoodsBizImpl();
				Goods goods = igb.getGoodsByGid(gid);
				
				//userid
				HttpSession session = request.getSession();
				User user = (User)session.getAttribute("users");
				
				c.setGoods(goods);
				c.setUsers(user);
				c.setCount(1);
				c.setCtotal();
				
				//System.out.println(c);
				
				//要想将封装好的购物车信息 保存到数据库中
				//先获取当前这个登录用户的购物车
				ICartBiz icb = new CartBizImpl();
				List<Cart> listCarts =  icb.getCartByUsersid(user.getUserid());
				//如果购物车List<Cart> listCarts = null;
				boolean flag = true;
				//如果该用户第一次进入 构建一个新的购物车 实例化
				if(null == listCarts ) {
					listCarts = new ArrayList<Cart>();
				}
				else {//非第一次
					//遍历所有的商品
					for (Cart cart : listCarts) {
						//判断当前加入的与购物车已有的进行匹配
						if(cart.getGoods().getGid() == c.getGoods().getGid()) {
							//不需要重复添加 修改数量和总价格
							cart.setCount(cart.getCount()+1);
							cart.setCtotal();
							//进行一个数据库的更新
							icb.editCartByCidAndUserid(cart);
							flag = false;
							break;
						}
					}
				}
				
				//问题：加入购物车 不是加入集合 而是加到数据库
				//listCarts.add(c);
				if(flag) {
					icb.addCart(c);
				}
				//加入后数据要继续更新
				listCarts =  icb.getCartByUsersid(user.getUserid());
				
				session.setAttribute("listCarts", listCarts);
				
				response.sendRedirect("cart.jsp");
	}

}

页面代码：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
	<h1>我的购物车</h1>
	<p><a href="index.jsp">返回首页</a></p>
	<hr/>
	<table border="1" cellspacing="0" cellpadding="0" width="100%" >
		<tr>
			<th>购物车编码</th>
			<th>商品名称</th>
			<th>商品单价</th>
			<th>商品数量</th>
			<th>商品总价</th>
			<th>操作</th>
		</tr>
		<!--通过c标签遍历数据  -->
		<c:forEach items="${listCarts}" var="cart">
			<tr>
				<td>${cart.cid}</td>
				<td>${cart.goods.gname}</td>
				<td>${cart.goods.gprice}</td>
				<td>${goods.ccount}</td>
				<td>${goods.ctotal}</td>
				<td>
					<button>删除</button><button>修改</button>
				</td>
			</tr>
		</c:forEach>
	</table>
</body>
</html>

以上就是初始版的MVC购物车项目

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