【Servlet】通过Cookie实现Servlet之间数据共享（实现案例）

男娘i 2023-10-08 15:16 15阅读 0赞

### 通过Cookie实现Servlet之间数据共享（实现案例） ###

#### 前言 ####

*  本文内容主要为【Cookie实现Servlet之间数据共享】的实现代码。
 *  关于Servlet之间数据共享的实现方案与Cookie详细内容可参考文章【多个Servlet之间数据共享实现方案】。
 *  本文为《多个Servlet之间数据共享实现方案》中第二节的代码实现部分。
 *  建议阅读本文前先去阅读《多个Servlet之间数据共享实现方案》。

#### 一、项目运行环境 ####

*  本案例使用的编译器为idea。

##### 1、Tomcat环境 #####

![在这里插入图片描述][watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBARXR1adu5KO-9peC8pe-9pcK0KdmIIMyRzJE_size_20_color_FFFFFF_t_70_g_se_x_16]![在这里插入图片描述][watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBARXR1adu5KO-9peC8pe-9pcK0KdmIIMyRzJE_size_20_color_FFFFFF_t_70_g_se_x_16 1]

##### 2、api环境 #####

![在这里插入图片描述][watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBARXR1adu5KO-9peC8pe-9pcK0KdmIIMyRzJE_size_20_color_FFFFFF_t_70_g_se_x_16 2]

##### 3、项目目录结构 #####

![在这里插入图片描述][watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBARXR1adu5KO-9peC8pe-9pcK0KdmIIMyRzJE_size_11_color_FFFFFF_t_70_g_se_x_16]

#### 二、项目源码解析 ####

*  index.html
    
        <!DOCTYPE html>
        <html lang="en">
        <head>
            <meta charset="UTF-8">
            <title>卡片充值</title>
        </head>
        <body>
            <center>
                <h1 style="color: tomato;">用户会员卡充值</h1>
                <form action="/myWeb/one" method="get">
                    <table border="2">
                        <tr>
                            <td>用户名：</td>
                            <td><input type="text" name="userName" /></td>
                        </tr>
                        <tr>
                            <td>金额：</td>
                            <td><input type="text" name="money" /></td>
                        </tr>
                        <tr>
                            <td><input type="submit" value="确认充值" /></td>
                            <td><input type="reset" /></td>
                        </tr>
                    </table>
                </form>
            </center>
        </body>
        </html>
 *  orderFood.html
    
        <!DOCTYPE html>
        <html lang="en">
        <head>
            <meta charset="UTF-8">
            <title>点餐</title>
        </head>
        <body>
        <center>
            <h1 style="color: tomato;">用户点餐</h1>
            <form action="/myWeb/two" method="get">
                <table border="2">
                    <tr>
                        <td>饺子-20元：</td>
                        <td><input type="radio" name="food" value="饺子" />
                    </tr>
                    <tr>
                        <td>油条-10元：</td>
                        <td><input type="radio" name="food" value="油条"/></td>
                    </tr>
                    <tr>
                        <td>米饭-15元：</td>
                        <td><input type="radio" name="food" value="米饭"/></td>
                    </tr>
                    <tr>
                        <td><input type="submit" value="提交" /></td>
                        <td><input type="reset" /></td>
                    </tr>
                </table>
            </form>
        </center>
        </body>
        </html>
 *  OneServlet.java
    
        package com.Etui.controller;
        
        import javax.servlet.*;
        import javax.servlet.http.*;
        import javax.servlet.annotation.*;
        import java.io.IOException;
        import java.net.CookieStore;
        
        @WebServlet(name = "OneServlet", value = "/one")
        public class OneServlet extends HttpServlet {
              
            @Override
            protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
              
                // 获取参数
                String userName = request.getParameter("userName");
                String money = request.getParameter("money");
        
                // 开卡，即将信息存入Cookie
                Cookie card1 = new Cookie("userName", userName);
                Cookie card2 = new Cookie("money", money);
                response.addCookie(card1);
                response.addCookie(card2);
        
                // 请求转发“orderFood”页面
                request.getRequestDispatcher("/orderFood.html").forward(request, response);
        
                System.out.println(userName + "," + money);
            }
        
        }
 *  TwoServlet.java
    
        package com.Etui.controller;
        
        import javax.servlet.*;
        import javax.servlet.http.*;
        import javax.servlet.annotation.*;
        import java.io.IOException;
        import java.io.PrintWriter;
        
        @WebServlet(name = "TwoServlet", value = "/two")
        public class TwoServlet extends HttpServlet {
              
            @Override
            protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
              
                String userName = null;
                String food = null;
                Cookie[] cookies = null;
                response.setContentType("text/html;charset=utf-8");
                PrintWriter out = response.getWriter();
                // 食物定价
                int jiaoziPrice = 20;
                int youtiaoPrice = 10;
                int mifanPrice = 15;
                int money = 0;
                // 获取参数
                food = request.getParameter("food");
        
                // 获取Cookie
                cookies = request.getCookies();
        
                for (Cookie cookie : cookies) {
              
                    String key = cookie.getName();
                    String value = cookie.getValue();
                    if("userName".equals(key)) {
              
                        userName = value;
                    } else if("money".equals(key)) {
              
                        money = Integer.parseInt(value);
                        if("饺子".equals(food)) {
              
                            if(jiaoziPrice <= money) {
              
                                Cookie newCookie = new Cookie("money", (money - jiaoziPrice) + "");
                                out.print("<h2 plugin='center'>点餐成功！当前余额为" + newCookie.getValue() + "元</h2>");
                                // 添加money的Cookie，覆盖原来的Cookie
                                response.addCookie(newCookie);
                            } else {
              
                                out.print("<h2>余额不足，请充值！</h2>");
                            }
                        } else if ("油条".equals(food)) {
              
                            if(youtiaoPrice <= money) {
              
                                Cookie newCookie = new Cookie("money", (money - youtiaoPrice) + "");
                                out.print("<h2 plugin='center'>点餐成功！当前余额为" + newCookie.getValue()+ "元</h2>");
                                // 添加money的Cookie，覆盖原来的Cookie
                                response.addCookie(newCookie);
                            } else {
              
                                out.print("<h2>余额不足，请充值！</h2>");
                            }
                        } else if ("米饭".equals(food)) {
              
                            if(mifanPrice <= money) {
              
                                Cookie newCookie = new Cookie("money", money - mifanPrice + "");
                                out.print("<h2 plugin='center'>点餐成功！当前余额为" + newCookie.getValue() + "元</h2>");
                                // 添加money的Cookie，覆盖原来的Cookie
                                response.addCookie(newCookie);
                            } else {
              
                                out.print("<h2>余额不足，请充值！</h2>");
                            }
                        }
                    }
                }
        
        
        //        System.out.println("用户名" + userName + "的余额为");
            }
        }

#### 三、原理图 ####

![请添加图片描述][watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBARXR1adu5KO-9peC8pe-9pcK0KdmIIMyRzJE_size_20_color_FFFFFF_t_70_g_se_x_16 3]

#### 四、运行结果 ####

##### 1、用户名：李华，金额：100元 #####

![在这里插入图片描述][watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBARXR1adu5KO-9peC8pe-9pcK0KdmIIMyRzJE_size_20_color_FFFFFF_t_70_g_se_x_16 4]

##### 2、选择饺子20元 #####

![在这里插入图片描述][watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBARXR1adu5KO-9peC8pe-9pcK0KdmIIMyRzJE_size_20_color_FFFFFF_t_70_g_se_x_16 5]

##### 3、交易结果 #####

![在这里插入图片描述][watermark_type_d3F5LXplbmhlaQ_shadow_50_text_Q1NETiBARXR1adu5KO-9peC8pe-9pcK0KdmIIMyRzJE_size_20_color_FFFFFF_t_70_g_se_x_16 6]

#### Over！ ####

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