JavaWeb程序设计之JSP实现购物车功能全过程

package com.ryx.web.sy7;

import lombok.allargsconstructor;
import lombok.builder;
import lombok.data;
import lombok.noargsconstructor;

@noargsconstructor
@allargsconstructor
@data
@builder
public class user {
    private string username;
    private string password;
}

package com.ryx.web.sy7;

import lombok.allargsconstructor;
import lombok.builder;
import lombok.data;
import lombok.noargsconstructor;

import java.math.bigdecimal;

@data
@builder
@noargsconstructor
@allargsconstructor
public class product {
    integer id;
    string name;
    string imagepath;
    bigdecimal price;
    string description;
}

package com.ryx.web.sy7;

import lombok.getter;
import lombok.setter;
import java.math.bigdecimal;

public class productvo extends product {
    @getter
    @setter
    integer count; //统计数量

    public productvo(integer id, integer count, string name, double price, string imagepath) {
        super();
        this.id = id;
        this.count = count;
        this.name = name;
        this.price = bigdecimal.valueof(price);
        this.imagepath=imagepath;
    }
}

package com.ryx.web.sy7;

import lombok.sneakythrows;
import org.springframework.util.objectutils;
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 java.io.ioexception;
import java.sql.*;
import java.util.hashmap;
import java.util.map;

@webservlet(name = "shoppingcart", value = "/shoppingcart")
public class cartcontroller extends httpservlet {
//    连接数据库
    private static final string db_url = "jdbc:mysql://localhost:3306/test";
    private static final string db_username = "root";
    private static final string db_password = "abc1234";

    @sneakythrows
    protected void doget(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {
        integer id = integer.valueof(request.getparameter("id"));
        string op = request.getparameter("op");
        string wherecome = request.getheader("referer");
        string redirectpath = null;
//        如果在主页点击加入购物车超链接，不跳转
        if (wherecome.equals("http://localhost:8080/sy7/home.jsp")) {
            redirectpath = request.getcontextpath() + "/sy7/home.jsp";
        } else {
//            如果在购物车页面增加或删除商品也不跳转
            redirectpath = request.getcontextpath() + "/sy7/cart.jsp";
        }
        httpsession session = request.getsession();
        map<integer, productvo> cart = (map<integer, productvo>) session.getattribute("cart");
        if (objectutils.isempty(cart)) {
            cart = new hashmap();
        }
        switch (op) {
//            添加商品
            case "add":
                if (!objectutils.isempty(cart.get(id))) {
                    productvo productvo = cart.get(id);
                    productvo.setcount(productvo.getcount() + 1);
                    cart.put(id, productvo);
                } else {
                    class.forname("com.mysql.jdbc.driver");
                    try (connection conn = drivermanager.getconnection(db_url, db_username, db_password)) {
                        string query = "select * from product where id = ?";
                        try (preparedstatement stmt = conn.preparestatement(query)) {
                            stmt.setint(1, id);
                            try (resultset rs = stmt.executequery()) {
                                if (rs.next()) {
                                    string name = rs.getstring("name");
                                    double price = rs.getdouble("price");
                                    string imagepath = rs.getstring("image_path");
                                    integer iid = rs.getint("id");
                                    productvo productvo = new productvo(iid, 1, name, price, imagepath);
                                    cart.put(id, productvo);
                                }
                            }
                        }
                    } catch (sqlexception e) {
                        e.printstacktrace();
                    }
                }
                break;
//          减少商品
            case "sub":
                if (!objectutils.isempty(cart.get(id))) {
                    productvo productvo = cart.get(id);
//                    防止出现负数
                    if (productvo.getcount() > 1) {
                        productvo.setcount(productvo.getcount() - 1);
                        cart.put(id, productvo);
                    } else {
//                        如果小于1则移除商品
                        cart.remove(id);
                    }

                }
                break;
        }
        session.setattribute("cart", cart);
        response.sendredirect(redirectpath);
    }
}

table {
    border-collapse: collapse;
    width: 86%;
}

table, th, td {
    border: 1px solid gainsboro;
}

td {
    width: 200px;
}

.redtext {
    color: #ff0000;
}

.pinktest {
    color: lightpink;
}

<%@ page import="java.sql.connection" %>
<%@ page import="java.sql.preparedstatement" %>
<%@ page import="java.sql.resultset" %>
<%@ page import="java.sql.drivermanager" %>
<%--
  created by intellij idea.
  user: 86189
  date: 2023/10/23
  主页面展示商品
--%>
<%@ page language="java" contenttype="text/html; charset=utf-8" pageencoding="utf-8" %>
<!doctype html>
<html>
<head>
    <meta charset="utf-8">
    <title>小煊的美妆铺</title>
   
</head>
<body>
<h1 align="center" class="pinktest">欢迎来到小煊的美妆铺~</h1>
<div align="right" style="width: 90%"><a href="login.jsp" rel="external nofollow" >登录</a></div>
<div align="right" style="width: 90%"><a href="checkout.jsp" rel="external nofollow"  rel="external nofollow" >结算</a></div>
<div align="right" style="width: 90%"><a href="cart.jsp" rel="external nofollow" >查看购物车</a></div>
<br>

<table align="center">
    <%---------------------- 获取商品数据 -----------------------------%>
    <%
        connection conn = null;
        preparedstatement stmt = null;
        resultset rs = null;
        try {
            //连接数据库
            class.forname("com.mysql.cj.jdbc.driver");
            conn = drivermanager.getconnection("jdbc:mysql://localhost:3306/test", "root", "abc1234");
            string query = "select * from product";
            stmt = conn.preparestatement(query);
            rs = stmt.executequery();

            int count = 0;
            while (rs.next()) {
                int id = rs.getint("id"); //商品编号
                string name = rs.getstring("name"); //商品名
                double price = rs.getdouble("price"); //价格
                string description = rs.getstring("description"); //描述
                string imagepath = rs.getstring("image_path"); // 图片路径
                //五个商品即换行
                if (count % 5 == 0) {
                    out.println("<tr>");
                }
    %>
    <td><br>
        <%--------------------------图片-----------------------%>
        <div align="center"><img src="<%=request.getcontextpath()+imagepath%>" width="180px" height="240px"></div>
        <%--------------------------商品描述-----------------------%>
        <div> <%=name%><%=description%> </div>
        <%--------------------------价格-----------------------%>
        <div class="redtext" align="left"> ￥：<%=price%> </div>
        <%--------------------------加购-----------------------%>
        <div align="right">
            <form action="home.jsp" method="post">
                <button onclick="void(0)"><a style="text-decoration: none"
                                             href="<%=request.getcontextpath()+" rel="external nofollow" /shoppingcart?id="+id+"&op=add"%>"/>加入购物车
                </button>
            </form>
        </div>
    </td>
    <%
                //闭合标签
                if (count % 5 == 4) {
                    out.println("</tr>");
                }
                count++;
            }
            //最后不足五个，自动闭合
            if (count % 5 != 0) {
                out.println("</tr>");
            }
        } catch (exception e) {
            e.printstacktrace();
        } finally {
            try {
                rs.close();
            } catch (exception e) {
            }
            try {
                stmt.close();
            } catch (exception e) {
            }
            try {
                conn.close();
            } catch (exception e) {
            }
        }
    %>
</table>
<br>
<%
//    初始化历史访问人数
    integer accesscount = (integer) session.getattribute("accesscount");
    if (accesscount == null) {
        accesscount = new integer(0);
    } else {
        accesscount = new integer(accesscount.intvalue() + 1);
    }
    session.setattribute("accesscount", accesscount);
%>

<div>历史访问人数：<%= accesscount %> </div>
</body>
</html>

<%-----------------------jsp程序段---------------------------%>
<%
    request.setcharacterencoding("utf-8");
    //一次性登录
    string msg = request.getparameter("msg");
%>
<%
    if (msg != null) {
        string errormessage = "账号或密码有误，请重新输入！";
%>
<script>
    var error = '<%= errormessage %>';
    alert(error);
</script>
<%
    }
%>

<%-- 读取cookie --%>
<%
    cookie[] cookies = request.getcookies();
    string savedusername = null;
    string savedpassword = null;

    if (cookies != null) {
        for (cookie cookie : cookies) {
            if (cookie.getname().equals("username")) {
                savedusername = cookie.getvalue();
            } else if (cookie.getname().equals("password")) {
                savedpassword = cookie.getvalue();
            }
        }
    }
%>

<%--
  created by intellij idea.
  user: 86189
  date: 2023/10/13
  登录页面
--%>
<%@ page contenttype="text/html;charset=utf-8" language="java" pageencoding="utf-8" %>
<html>
<head>
    <style>
        body {
            display: flex;
            justify-content: center;
            padding-top: 40px;
        }
        .titlecolor{
            color: lightpink;
        }
    </style>
    <title>登录页面</title>
</head>
<body>
<%-----------------------登录表单--------------------------%>
<form action="loginaction.jsp" method="post">
    <h1 align="center" class="titlecolor">登录账号</h1>
    <br>
    <table width="300px">
        <tr>
            <td>
                <laber for="username">用户名：</laber>
            </td>
            <td><input type="text" value="<%= savedusername==null?"":savedusername%>" id="username" name="username" required></td>
        </tr>
        <tr>
            <td><label for="password">密码：</label></td>
            <td><input type="password" value="<%= savedpassword==null?"":savedpassword%>" id="password" name="password" required></td>
            <td align="right"><input type="submit" value="登录"></td>
        </tr>
        <tr>
            <td></td>
           <td><input type="checkbox" name="remember" value="member">记住密码</td>
        </tr>
    </table>
</form>

</body>
</html>

<%@ page import="com.ryx.web.sy7.user" %>
<%@ page import="java.sql.*" %>
<%--
  created by intellij idea.
  user: 86189
  date: 2023/10/13
  判断输入的用户信息是否存在数据库
--%>
<%@ page contenttype="text/html;charset=utf-8" language="java" %>

<%!
    public boolean validateuser(string username, string password) {
        // 使用jdbc连接数据库
        connection connection = null;
        preparedstatement statement = null;
        resultset resultset = null;

        string driver = "com.mysql.cj.jdbc.driver";
        string url = "jdbc:mysql://localhost:3306/test";  //数据库
        string user = "root"; //账户
        string psword = "abc1234"; //密码

        try {
            try {
                try {
                    class.forname(driver);
                } catch (classnotfoundexception e) {
                    throw new runtimeexception(e);
                }
                // 获取数据库连接
                connection = drivermanager.getconnection(url, user, psword);
            } catch (sqlexception e) {
                e.printstacktrace();
            }

            try {
                // 构造查询语句
                string query = "select * from test.user where username =  ? ";

                // 创建preparedstatement对象，并设置参数
                statement = connection.preparestatement(query);
                statement.setstring(1, username);

                // 执行查询
                resultset = statement.executequery();
                // 验证用户名和密码
                if (resultset.next()) {
                    string storedpassword = resultset.getstring("password");
                    if (storedpassword.equals(password)) {
                        return true;
                    }
                }
            } catch (sqlexception e) {
                e.printstacktrace();
            }

        } finally {
            // 关闭连接和释放资源
            try {
                if (resultset != null) {
                    resultset.close();
                }
                if (statement != null) {
                    statement.close();
                }
                if (connection != null) {
                    connection.close();
                }
            } catch (sqlexception e) {
                e.printstacktrace();
            }
        }
        return false;
    }
 %>

<%
    request.setcharacterencoding("utf-8");
    string username = request.getparameter("username");
    string password = request.getparameter("password");

    boolean isvaliduser = validateuser(username, password);
    //验证成功
    if (isvaliduser) {
        // 创建形 builder 构造者模式，链式编程
        user user = user.builder()
                    .username(username)
                    .password(password)
                    .build();

        string remember = request.getparameter("remember");

        if (remember != null && remember.equals("member")) {
            // 创建存储用户名和密码的cookie对象
            cookie usernamecookie = new cookie("username", username);
            cookie passwordcookie = new cookie("password", password);

            // 设置cookie的有效期（设置为7天）
            usernamecookie.setmaxage(7 * 24 * 60 * 60); // 7天
            passwordcookie.setmaxage(7 * 24 * 60 * 60); // 7天

            // 将cookie添加到响应中
            response.addcookie(usernamecookie);
            response.addcookie(passwordcookie);
        } else {
            // 删除之前保存的cookie
            cookie[] cookies = request.getcookies();
            if (cookies != null) {
                for (cookie cookie : cookies) {
                    if (cookie.getname().equals("username") || cookie.getname().equals("password")) {
                        cookie.setmaxage(0); // 设置有效期为0，即立即删除
                        response.addcookie(cookie);
                    }
                }
            }
        }

        session.setattribute("user", user);
        //跳转到其他页面
        response.sendredirect("home.jsp");
    } else {
        //验证失败，提示出错
        response.sendredirect("login.jsp?msg=failed");
    }
 %>

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ page import="com.ryx.web.sy7.user" %>
<%@ page import="java.util.map" %>
<%--
  created by intellij idea.
  user: 86189
  date: 2023/10/21
  结算页面
--%>
<%@ page contenttype="text/html;charset=utf-8" language="java" pageencoding="utf-8" %>
<!doctype html>
<html>
<%--------------------判断用户是否登录-----------------------%>
<%
    //存储变量
    user user = (user) session.getattribute("user");
    //    未登录用户跳转到登录页面
    if (user == null) {
        response.sendredirect("login.jsp");
    }
%>
<head>
    <meta charset="utf-8">
    <title>结算</title>
</head>
<body>
<%----------------- 获取购物车中的商品 ------------------------%>
<h1 align="center" style="color: lightpink">订单信息</h1>
<%
    session = request.getsession();
    map<integer, integer> cart = (map<integer, integer>) session.getattribute("cart");
    if (cart == null) {
        out.println("购物车为空");
        return;
    }
%>
<%--计算总价钱--%>
<c:set var="totalamount" value="0"/>
<c:foreach var="entry" items="${cart.entryset()}">
    <c:set var="product" value="${entry.value}"/>
    <%--单个商品的总额--%>
    <c:set var="amount" value="${product.price * product.count}"/>
    <%--所有商品的总额--%>
    <c:set var="totalamount" value="${totalamount + amount}"/>
</c:foreach>
<div align="center">
    <h2>您应支付:￥${totalamount}</h2>
    <form action="checkout.jsp" method="post">
        <input type="submit" value="确认订单">
    </form>
</div>

</body>
</html>

table {
    border-collapse: collapse;
}

table, th, td {
    border: 1px solid gainsboro;
}

.titletest {
    color: lightpink;
}

td {
    width: 20%;
}

a {
   text-decoration: none;
}

<%@ page language="java" contenttype="text/html; charset=utf-8" pageencoding="utf-8" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>
<%--
  created by intellij idea.
  user: 86189
  date: 2023/10/21
  购物车页面
--%>
<!doctype html>
<html>
<head>
    <meta charset="utf-8">
    <title>购物车</title>

</head>
<body>
<h1 align="center" class="titletest">我的购物车</h1>
<c:if test="${cart!=null && cart.size()>0}">
    <table style="width: 1000px" align="center">
        <tr>
            <th>商品信息</th>
            <th>单价</th>
            <th>数量</th>
            <th>金额</th>
        </tr>
        <c:foreach var="entry" items="${cart.entryset()}">
            <tr>
                <c:set var="product" value="${entry.value}"/>
                <%----------------------商品信息--------------------%>
                <td><img src="${request.contextpath}${product.imagepath}" width="60px" height="80px">${product.name}</td>
                <%----------------------单价--------------------%>
                <td align="center">￥：${product.price}</td>
                <%----------------------数量-/+--------------------%>
                <td align="center">
                    <button onclick="void(0)"><a href="
                <%=request.getcontextpath()+"/shoppingcart?op=sub&id="%>${product.id}
               "/>-
                    </button>
                        ${product.count}
                    <button onclick="void(0)"><a href="
                <%=request.getcontextpath()+"/shoppingcart?op=add&id="%>${product.id}
               "/>+
                    </button>
                </td>
                <%----------------------金额--------------------%>
                <td align="center">￥：${product.count*product.price}</td>

            </tr>

        </c:foreach>
    </table>
</c:if>

<br><br>
<div style="width: 90%" align="right">
    <a href="home.jsp" rel="external nofollow" >继续购物</a>
    <a href="checkout.jsp" rel="external nofollow"  rel="external nofollow" >去结算</a>

</div>
</body>
</html>