简单购物车的实现（JSP+Servlet+JDBC）

package cn.edu.cg.controller;

import java.io.IOException;
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 cn.edu.cg.dao.BookDaoImpl;
import cn.edu.cg.domain.Book;
import cn.edu.cg.domain.Cart;

@WebServlet("/BuyServlet")
public class BuyServlet extends HttpServlet {

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html; charset=UTF-8");
        String id=request.getParameter("id");
        BookDaoImpl dao=new BookDaoImpl();
        Book book = dao.find(id);
        Cart cart = (Cart) request.getSession().getAttribute("cart");
        if(cart==null){
            cart = new Cart();
            request.getSession().setAttribute("cart", cart);
        }
       
        cart.add(book);
        
        request.getRequestDispatcher("/listcart.jsp").forward(request, response);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }
}

 

package cn.edu.cg.controller;

import java.io.IOException;
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 cn.edu.cg.domain.Cart;
import cn.edu.cg.domain.CartItem;

@WebServlet("/ChangeQuantityServlet")
public class ChangeQuantityServlet extends HttpServlet {

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html; charset=UTF-8");
        String id=request.getParameter("id");
        String quantity=request.getParameter("quantity");
        Cart cart=(Cart) request.getSession().getAttribute("cart");
        CartItem item = cart.getMap().get(id);
        item.setQuantity(Double.parseDouble(quantity));//int 转化时不能带小数点
        request.getRequestDispatcher("/listcart.jsp").forward(request, response);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }
}

 

package cn.edu.cg.controller;

import java.io.IOException;
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 cn.edu.cg.domain.Cart;

@WebServlet("/ClearCartServlet")
public class ClearCartServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html; charset=UTF-8");
      Cart cart=  (Cart) request.getSession().getAttribute("cart");
      cart.getMap().clear();
      request.getRequestDispatcher("/listcart.jsp").forward(request, response);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }
}

package cn.edu.cg.controller;

import java.io.IOException;

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 cn.edu.cg.domain.Cart;

@WebServlet("/DeleteItemServlet")
public class DeleteItemServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html; charset=UTF-8");
        String id=request.getParameter("id");
        

        Cart cart = (Cart) request.getSession().getAttribute("cart");
        cart.getMap().remove(id);
        System.out.println("len:"+cart.getMap().size());
        request.getRequestDispatcher("/listcart.jsp").forward(request, response);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }
}

package cn.edu.cg.controller;

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 cn.edu.cg.dao.BookDaoImpl;
import cn.edu.cg.domain.Book;

@WebServlet("/index.do")
public class ListBookServlet extends HttpServlet {

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html; charset=UTF-8");
        
        BookDaoImpl bookDao=new BookDaoImpl();
        List books = bookDao.getAll();
        request.setAttribute("books", books);
        
        request.getRequestDispatcher("/index.jsp").forward(request, response);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }
}

package cn.edu.cg.dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;

import cn.edu.cg.domain.Book;
import cn.edu.cg.utils.JdbcUtils;

public class BookDaoImpl {
    public Book find(String id) {
        Book book=null;
        Connection conn=null;
        PreparedStatement ps=null;
        ResultSet rs=null;
        try {
            conn=JdbcUtils.getConn();
            String FINDBYID = "SELECT * FROM book WHERE id=?";
            ps=conn.prepareStatement(FINDBYID);
            ps.setString(1, id);
            rs  = ps.executeQuery();
            book=new Book();
            if(rs.next()) {
                book.setId(rs.getString("id"));
                book.setName(rs.getString("name"));
                book.setPrice(rs.getDouble("price"));                        
            }
            return book;
        } catch (Exception e) {
            throw new RuntimeException(e);
        }finally {
            JdbcUtils.closeAll(ps, rs, conn);
        }
    }
    public List getAll() {
        Book book=null;
        Connection conn=null;
        PreparedStatement pstmt=null;
        ResultSet rs=null;
        try {
            conn=JdbcUtils.getConn();
            String sql="select * from book";
            pstmt=conn.prepareStatement(sql);
            rs  = pstmt.executeQuery();            
            List books=new ArrayList<>();
            while(rs.next()) {
                book=new Book();
                book.setId(rs.getString("id"));
                book.setName(rs.getString("name"));
                book.setPrice(rs.getDouble("price"));
                books.add(book);
                book=null;
            }
            return books;
        } catch (Exception e) {
            throw new RuntimeException(e);
        }finally {
            JdbcUtils.closeAll(pstmt, rs, conn);
        }
    }

}

package cn.edu.cg.domain;
public class Book {
    private String id;
    private String name;
    private double price;
    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public double getPrice() {
        return price;
    }
    public void setPrice(double price) {
        this.price = price;
    }
}

package cn.edu.cg.domain;

import java.util.LinkedHashMap;
import java.util.Map;

public class Cart {
    private Map map = new LinkedHashMap<>();
    private double price;
    public void add(Book book) {
        CartItem item=map.get(book.getId());
        if(item==null) {
            item=new CartItem();
            item.setBook(book);
            item.setQuantity(1);
            map.put(book.getId(), item);            
        }else {
            item.setQuantity(item.getQuantity()+1);
        }
    }
    public Map getMap() {
        return map;
    }

    public void setMap(Map map) {
        this.map = map;
    }

    public double getPrice() {
        double totalPrice = 0;
        for (Map.Entry entry : map.entrySet()) {
            totalPrice += entry.getValue().getPrice();
        }
        this.price = totalPrice;
        return price;
    }

}

package cn.edu.cg.domain;

public class CartItem {
    private Book book;
    private double quantity;
    private double price;

    public Book getBook() {
        return book;
    }

    public void setBook(Book book) {
        this.book = book;
    }

    public double getQuantity() {
        return quantity;
    }

    public void setQuantity(double quantity) {
        this.quantity = quantity;
        this.price=this.quantity*book.getPrice();
    }

    public double getPrice() {
        return price;
    }

    
    @Override
    public String toString() {
        return "CartItem [book=" + book + ", quantity=" + quantity + ", price="
                + price + "]";
    }
}

package cn.edu.cg.utils;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class JdbcUtils {
    public static Connection getConn() {
        Connection conn=null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            String url="jdbc:mysql://localhost:3306/cart?useUnicode=true&characterEncoding=UTF-8";
            conn = DriverManager.getConnection(url, "root", "root");
            return conn;
        } catch (Exception e) {
            throw new ExceptionInInitializerError("连接错误");
        }
    }
    public static void closeAll(PreparedStatement pstmt,ResultSet rs,Connection conn) {
        if(pstmt!=null) {
            try {
                pstmt.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
            pstmt=null;
        }
        if(rs!=null) {
            try {
                rs.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
            rs=null;
        }
        if(conn!=null) {
            try {
                conn.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
            conn=null;
        }
        
    }

}

<%@ 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>选书title>
head>
<body>
<table frame="border" border="2px" cellpadding="0" cellspacing="0" width="90%" align="center">
           <caption><h2>图书信息h2>caption>
           <tr align="center">
               <td>书名td>
               <td>价格td>
             <td>操作td>
           tr>
           <c:forEach var="book" items="${books}" >
            <tr align="center">
                   <td>${book.name}td>
                   <td>${book.price}td>
                   <td>
                       <a href="${pageContext.request.contextPath}/BuyServlet?id=${book.id}" target="_blank">购买a>
                   td>
               tr>
           c:forEach>
           
       table>
body>
html>

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>购物车列表title>
    
    <script type="text/javascript" >
        
        function deleteitem(id){
            var b = window.confirm("您确认删除吗？？");
            if(b){
                window.location.href="${pageContext.request.contextPath }/DeleteItemServlet?id="+id;
            }
        }
        
        function clearcart(){
            var b = window.confirm("您确认清空吗？？");
            if(b){
                window.location.href="${pageContext.request.contextPath}/ClearCartServlet";
            }
        }
        
        function changeQuantity(input,id,oldvalue){
            var quantity = input.value;
            
            if(quantity<0 || quantity!=parseInt(quantity)){
                alert("请输入正整数！！");
                input.value = oldvalue;
                
                return;
            }
            
            
            
            var b = window.confirm("您确认把书的数量修改为:" + quantity);
            if(b){
                window.location.href="${pageContext.request.contextPath}/ChangeQuantityServlet?id=" + id + "&quantity=" + quantity;
            }
        }
    script>
    
  head>
  
  <body style="text-align: center">
   
    <h1>购物车列表h1><a href="${pageContext.request.contextPath}/index.do">继续购买a>
    
    <c:if test="${empty(cart.map)}"> 
        您没有购买任何商品！！！
    c:if>
   
   
       <c:if test="${!empty(cart.map)}"> 
    <table width="70%" border="1" align="center">
        <tr>
            <td>书名td>
            <td>单价td>
            <td>数量 td>
            <td>小计td>
            <td>操作td>
        tr>
        <c:forEach var="entry" items="${cart.map}">
            <tr>
                <td>${entry.value.book.name}td>
                <td>${entry.value.book.price}td>
                <td>
                    <input type="text" name="quantity" value="${entry.value.quantity }" style="width:35px" onchange="changeQuantity(this,${entry.key},${entry.value.quantity})">
                td>
                <td>${entry.value.price }td>
                <td>
                    <a href="javascript:void(0)" onclick="deleteitem(${entry.key})">删除a>  
                    
                td>
            tr>
        c:forEach>
        
        <tr>
            <td colspan="3">总价td>
            <td colspan="2">${cart.price}元td>
        tr>    
    table>
    <a href="javascript:void(0)" onclick="clearcart()">清空购物车a>
     c:if>
    
  body>
html>