servlet-cookie和session应用示例：模拟购物车

时间：2022-08-25 20:49:41
思路分析：
1. 根据需求抽象出业务对象
User{
usrename;
password;
}


ShoppingCarItem{
product;
num;
}

ShoppingCar{
List<ShoppingCarItem>
}

2. 写Servlet处理请求
...


domain:
Java代码 servlet-cookie和session应用示例：模拟购物车 servlet-cookie和session应用示例：模拟购物车
  1. package cn.itcast.cd.domain;
  3. import java.util.ArrayList;
  4. import java.util.List;
  5. import java.util.UUID;
  7. public class ShoppingCar {
  8. private List<ShoppingCarItem> list = new ArrayList<ShoppingCarItem>();
  10. /**
  11. * 根据货品和数量往购物车中添加
  12. * @param product
  13. * @param num
  14. */
  15. public void add(String product,Integer num){
  16. ShoppingCarItem carItem = new ShoppingCarItem();
  17. carItem.setNum(num);
  18. carItem.setProduct(product);
  19. carItem.setId(UUID.randomUUID().toString());
  20. list.add(carItem);
  21. }
  23. /**
  24. * 根据唯一的标示删除购物车中对应的明细
  25. * @param id
  26. */
  27. public void remove(String id){
  28. for (ShoppingCarItem item : list) {
  29. if(id.equals(item.getId())){
  30. list.remove(item);
  31. break;
  32. }
  33. }
  34. }
  36. public List<ShoppingCarItem> getList() {
  37. return list;
  38. }
  40. }
  42. package cn.itcast.cd.domain;
  44. public class ShoppingCarItem {
  45. private String product;
  46. private Integer num;
  47. private String id; //给每一个明细生成一个唯一的id
  48. public String getProduct() {
  49. return product;
  50. }
  51. public void setProduct(String product) {
  52. this.product = product;
  53. }
  54. public Integer getNum() {
  55. return num;
  56. }
  57. public void setNum(Integer num) {
  58. this.num = num;
  59. }
  60. public String getId() {
  61. return id;
  62. }
  63. public void setId(String id) {
  64. this.id = id;
  65. }
  67. }
  69. package cn.itcast.cd.domain;
  71. public class User {
  72. private String username;
  73. private String password;
  74. public String getUsername() {
  75. return username;
  76. }
  77. public void setUsername(String username) {
  78. this.username = username;
  79. }
  80. public String getPassword() {
  81. return password;
  82. }
  83. public void setPassword(String password) {
  84. this.password = password;
  85. }
  86. }


servlet:

Java代码 servlet-cookie和session应用示例：模拟购物车 servlet-cookie和session应用示例：模拟购物车
  1. package cn.itcast.cd.servlet;
  3. import java.io.IOException;
  4. import java.io.PrintWriter;
  6. import javax.servlet.ServletException;
  7. import javax.servlet.http.HttpServlet;
  8. import javax.servlet.http.HttpServletRequest;
  9. import javax.servlet.http.HttpServletResponse;
  10. import javax.servlet.http.HttpSession;
  12. import cn.itcast.cd.domain.ShoppingCar;
  14. public class BuyServlet extends HttpServlet {
  15. @Override
  16. protected void service(HttpServletRequest request, HttpServletResponse response)
  17. throws ServletException, IOException {
  18. request.setCharacterEncoding("UTF-8");
  19. response.setContentType("text/html;charset=utf-8");
  20. //1. 获取请求中的参数.
  21. String product = request.getParameter("product");
  22. String num = request.getParameter("num");
  23. //2. 获取到购物车
  24. //2.1 首先要到session中找一下是否已经有了购物车. 如果有的话就不需要创建了... 直接把货品放到购物车中就可以了
  25. HttpSession httpSession = request.getSession();
  26. ShoppingCar shoppingCar = (ShoppingCar)httpSession.getAttribute("SHOPINGCAR_IN_SESSION");
  27. if(shoppingCar==null){ //说明是第一次购物. 还没有购物车的
  28. //2.2 如果从session中没有找到购物车. 需要新创建一个购物车并且放到session中.为了下次购物使用这个购物车
  29. shoppingCar = new ShoppingCar();
  30. httpSession.setAttribute("SHOPINGCAR_IN_SESSION", shoppingCar);
  31. }
  32. shoppingCar.add(product, Integer.parseInt(num));
  33. PrintWriter pw = response.getWriter();
  34. pw.println("添加成功<br/>");
  35. pw.println("<a href='/buy.html'>继续购物</a><br/>");
  36. pw.println("<a href='/list'>管理购物</a><br/>");
  38. }
  39. }
  41. package cn.itcast.cd.servlet;
  43. import java.io.IOException;
  44. import java.io.PrintWriter;
  46. import javax.servlet.ServletException;
  47. import javax.servlet.http.HttpServlet;
  48. import javax.servlet.http.HttpServletRequest;
  49. import javax.servlet.http.HttpServletResponse;
  50. import javax.servlet.http.HttpSession;
  52. import cn.itcast.cd.domain.ShoppingCar;
  53. import cn.itcast.cd.domain.ShoppingCarItem;
  54. import cn.itcast.cd.domain.User;
  56. public class ListServlet extends HttpServlet {
  57. @Override
  58. protected void service(HttpServletRequest request, HttpServletResponse response)
  59. throws ServletException, IOException {
  60. request.setCharacterEncoding("UTF-8");
  61. response.setContentType("text/html;charset=utf-8");
  63. HttpSession httpSession = request.getSession();
  64. //1. 先获取session中的User
  65. User user = (User) httpSession.getAttribute("USER_IN_SESSION");
  66. PrintWriter pw = response.getWriter();
  67. pw.println("当前用户为:"+user.getUsername()+"<br/>");
  68. //2. 获取session的购物车
  69. ShoppingCar shoppingCar = (ShoppingCar) httpSession.getAttribute("SHOPINGCAR_IN_SESSION");
  70. //2.1 如果在session中购物车的话,列出购物车中的明细
  71. if(shoppingCar!=null){
  72. for (ShoppingCarItem item : shoppingCar.getList()) {
  73. pw.println("货品:"+item.getProduct()+" 数量:"+item.getNum()+"<br/>");
  74. }
  75. }else{
  76. //2.2 在session中没有购物车的话.提示用户没有当前用户名购物车
  77. pw.println("当前用户没有购物车.");
  78. }
  82. }
  83. }
  85. package cn.itcast.cd.servlet;
  87. import java.io.IOException;
  88. import java.io.PrintWriter;
  90. import javax.servlet.ServletException;
  91. import javax.servlet.http.HttpServlet;
  92. import javax.servlet.http.HttpServletRequest;
  93. import javax.servlet.http.HttpServletResponse;
  94. import javax.servlet.http.HttpSession;
  96. import cn.itcast.cd.domain.User;
  98. public class LoginServlet extends HttpServlet {
  100. @Override
  101. protected void service(HttpServletRequest request, HttpServletResponse response)
  102. throws ServletException, IOException {
  103. request.setCharacterEncoding("UTF-8");
  104. response.setContentType("text/html;charset=utf-8");
  106. //1. 接收请求中的数据封装对象
  107. String username = request.getParameter("username");
  108. String password = request.getParameter("password");
  109. User user = new User();
  110. user.setPassword(password);
  111. user.setUsername(username);
  113. //2. 将用户方到session*ListServlet从session中访问到User
  114. HttpSession httpSession = request.getSession();
  115. httpSession.setAttribute("USER_IN_SESSION", user);
  117. PrintWriter pw = response.getWriter();
  118. pw.println("欢迎:"+username+"<br/>");
  119. pw.println("<a href='/buy.html'>购物</a><br/>");
  120. pw.println("<a href='/list'>管理购物</a><br/>");
  121. }
  124. }


用户登录页面：
Html代码 servlet-cookie和session应用示例：模拟购物车 servlet-cookie和session应用示例：模拟购物车
  1. <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
  2. <html>
  3. <head>
  4. <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
  5. <title>用户登录</title>
  6. </head>
  7. <body>
  9. <form action="/login" method="post">
  10. 用户名：<input type="text" name="username"><br/>
  11. 密码：<input type="text" name="password"><br/>
  12. <input type="submit" value="登录">
  13. </form>
  14. </body>
  15. </html>


购买页面：
Html代码 servlet-cookie和session应用示例：模拟购物车 servlet-cookie和session应用示例：模拟购物车
  1. <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
  2. <html>
  3. <head>
  4. <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
  5. <title>购物货品</title>
  6. </head>
  7. <body>
  9. <form action="/buy" method="post">
  10. 货品：<select name="product">
  11. <option value="鼠标">鼠标</option>
  12. <option value="键盘">键盘</option>
  13. <option value="内存">内存</option>
  14. <option value="显示器">显示器</option>
  15. </select> <br/>
  16. 数量：<input type="text" name="num"><br/>
  17. <input type="submit" value="购买">
  18. </form>
  19. </body>
  20. </html>


web.xml配置：
Xml代码 servlet-cookie和session应用示例：模拟购物车 servlet-cookie和session应用示例：模拟购物车
  1. <?xml version="1.0" encoding="UTF-8"?>
  3. <web-app xmlns="http://java.sun.com/xml/ns/javaee"
  4. xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  5. xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
  6. version="2.5">
  8. <servlet>
  9. <servlet-name>LoginServlet</servlet-name>
  10. <servlet-class>cn.itcast.cd.servlet.LoginServlet</servlet-class>
  11. </servlet>
  13. <servlet-mapping>
  14. <servlet-name>LoginServlet</servlet-name>
  15. <url-pattern>/login</url-pattern>
  16. </servlet-mapping>
  18. <servlet>
  19. <servlet-name>BuyServlet</servlet-name>
  20. <servlet-class>cn.itcast.cd.servlet.BuyServlet</servlet-class>
  21. </servlet>
  23. <servlet-mapping>
  24. <servlet-name>BuyServlet</servlet-name>
  25. <url-pattern>/buy</url-pattern>
  26. </servlet-mapping>
  28. <servlet>
  29. <servlet-name>ListServlet</servlet-name>
  30. <servlet-class>cn.itcast.cd.servlet.ListServlet</servlet-class>
  31. </servlet>
  33. <servlet-mapping>
  34. <servlet-name>ListServlet</servlet-name>
  35. <url-pattern>/list</url-pattern>
  36. </servlet-mapping>
  37. </web-app>
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