Cookie案例-显示商品浏览历史纪录

 1 package cn.itcast.cookie;
 2 
 3 import java.io.IOException;
 4 import java.io.PrintWriter;
 5 import java.util.Date;
 6 import java.util.HashMap;
 7 import java.util.LinkedHashMap;
 8 import java.util.Map;
 9 
10 import javax.servlet.ServletException;
11 import javax.servlet.http.Cookie;
12 import javax.servlet.http.HttpServlet;
13 import javax.servlet.http.HttpServletRequest;
14 import javax.servlet.http.HttpServletResponse;
15 
16 import cn.itcast.Book;
17 import cn.itcast.Db;
18 
19 public class CookieDemo extends HttpServlet {
20 
21     public void doGet(HttpServletRequest request, HttpServletResponse response)
22             throws ServletException, IOException {
23 
24         response.setCharacterEncoding("UTF-8");
25         response.setContentType("text/html;charset=UTF-8");
26         PrintWriter out = response.getWriter();
27 
28         // 1.输出网站的商品
29         out.write("本网站有如下商品：<br/>");
30         Db db = new Db();
31         Map<String, Book> map = db.getAll();
32 
33         for (Map.Entry<String, Book> entry : map.entrySet()) {
34             Book book = entry.getValue();
35             out.print("<a href=‘/ServletDemo/servlet/CookieDemo2?id="
36                     + book.getId() + "‘target=‘_blank‘>" + book.getName()
37                     + "</a><br/>");
38         }
39 
40         // 2.显示用户曾经看过的商品
41         out.print("<br/>您曾经看过如下商品：<br/>");
42         Cookie cookies[] = request.getCookies();
43         for (int i = 0; cookies != null && i < cookies.length; i++) {
44             if (cookies[i].getName().equals("bookHistory")) {
45                 String ids[] = cookies[i].getValue().split("\\,");
46                 for(String id:ids){
47                     Book book = (Book) Db.getAll().get(id);
48                     out.print(book.getName()+"<br/>");
49                 }
50             }
51         }
52 
53     }
54 
55     public void doPost(HttpServletRequest request, HttpServletResponse response)
56             throws ServletException, IOException {
57 
58     }
59 
60 }

 1 package cn.itcast.cookie;
 2 
 3 import java.io.IOException;
 4 import java.io.PrintWriter;
 5 import java.util.Arrays;
 6 import java.util.LinkedList;
 7 import java.util.List;
 8 
 9 import javax.servlet.ServletException;
10 import javax.servlet.http.Cookie;
11 import javax.servlet.http.HttpServlet;
12 import javax.servlet.http.HttpServletRequest;
13 import javax.servlet.http.HttpServletResponse;
14 
15 import cn.itcast.Book;
16 import cn.itcast.Db;
17 
18 public class CookieDemo2 extends HttpServlet {
19 
20     public void doGet(HttpServletRequest request, HttpServletResponse response)
21             throws ServletException, IOException {
22 
23         response.setCharacterEncoding("UTF-8");
24         response.setContentType("text/html;charset=UTF-8");
25         PrintWriter out = response.getWriter();
26 
27         // 1.给据用户带来的id，显示相应商品的详细信息。
28         String id = request.getParameter("id");
29         Book book = (Book) Db.getAll().get(id);
30         out.write(book.getId() + "<br/>");
31         out.write(book.getName() + "<br/>");
32         out.write(book.getAuthor() + "<br/>");
33         out.write(book.getDescription() + "<br/>");
34 
35         // 2.构建cookie，会写给浏览器
36         String cookieValue = buildCookie(id, request);
37         Cookie cookie = new Cookie("bookHistory", cookieValue);
38         cookie.setMaxAge(1 * 30 * 24 * 60 * 60);
39         cookie.setPath("/ServletDemo");
40         response.addCookie(cookie);
41     }
42 
43     private String buildCookie(String id, HttpServletRequest request) {
44 
45         String bookHistory = null;
46         Cookie cookies[] = request.getCookies();
47         for (int i = 0; cookies != null && i < cookies.length; i++) {
48             if (cookies[i].getName().equals("bookHistory")) {
49                 bookHistory = cookies[i].getValue();
50             }
51 
52         }
53 
54         if (bookHistory == null) {
55             return id;
56         }
57 
58         LinkedList<String> list = new LinkedList(Arrays
59                 .asList(bookHistory.split("\\,")));
60         
61         if (list.contains(id)) {
62             list.remove(id);
63         } else {
64             if (list.size() >= 3) {
65                 list.removeLast();
66             }
67         }
68         
69         list.addFirst(id);
70         
71         StringBuffer sb = new StringBuffer();
72         for (String bid : list) {
73             sb.append(bid+",");
74         }
75         
76         return sb.deleteCharAt(sb.length()-1).toString();
77     }
78 
79     public void doPost(HttpServletRequest request, HttpServletResponse response)
80             throws ServletException, IOException {
81 
82     }
83 
84 }

 1 package cn.itcast;
 2 
 3 import java.util.LinkedHashMap;
 4 import java.util.Map;
 5 
 6 public class Db {
 7     private static Map<String, Book> map = new LinkedHashMap();
 8     
 9     static{
10         map.put("1", new Book("1","javaweb开发","Zero","一本好书！！"));
11         map.put("2", new Book("2","jdbc开发","one","一本好书！！"));
12         map.put("3", new Book("3","spring开发","two","一本好书！！"));
13         map.put("4", new Book("4","struks开发","three","一本好书！！"));
14         map.put("5", new Book("5","hibernate开发","four","一本好书！！"));
15     }
16     
17     public static Map getAll(){
18         return map;
19     }
20 }

 1 package cn.itcast;
 2 
 3 
 4 public class Book {
 5     private String id;
 6     private String name;
 7     private String author;
 8     private String description;
 9     
10     public Book(String id, String name, String author, String description) {
11         super();
12         this.id = id;
13         this.name = name;
14         this.author = author;
15         this.description = description;
16     }
17 
18     public String getId() {
19         return id;
20     }
21 
22     public void setId(String id) {
23         this.id = id;
24     }
25 
26     public String getName() {
27         return name;
28     }
29 
30     public void setName(String name) {
31         this.name = name;
32     }
33 
34     public String getAuthor() {
35         return author;
36     }
37 
38     public void setAuthor(String author) {
39         this.author = author;
40     }
41 
42     public String getDescription() {
43         return description;
44     }
45 
46     public void setDescription(String description) {
47         this.description = description;
48     }
49 }