1、在DisPlay的servlet中主要做两件事情
1.1显示在出售的商品
1.2显示顾客曾经浏览的商品
DisPlay的代码如下：
package com.baowei.cookie;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class Display extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
resp.setCharacterEncoding("utf-8");
resp.setContentType("text/html;charset=utf-8");
//显示所有的图书
PrintWriter out = resp.getWriter();
out.print("本书店出售的图书如下:<br/>");
Map<String,Book> books = DB.getDBMap();
Set<Entry<String, Book>> set = books.entrySet();
Iterator<Entry<String, Book>> it = set.iterator();
while(it.hasNext()){
Entry<String, Book> entry = it.next();
Book book = entry.getValue();
out.print("<a href=‘/HuiHuaTest/BookDetail?id="+book.getId()+"‘ target=‘_blank‘>"+book.getName()+"</a><br/>");
}
//用户最近看过的图书
out.print("你最近浏览过的图书如下:<br/>");
Cookie cookie = null;
Cookie [] cookies = req.getCookies();
for (int i = 0; cookies != null && i < cookies.length; i++) {
if(cookies[i].getName().equals("bookHistory")){
cookie = cookies[i];
}
}
if(cookie!=null){
//找到了bookHistory这个cookie
String bookHistory = cookie.getValue(); //4_6_1
String ids[] = bookHistory.split("\\_"); //这样划分更好
for(String id: ids){
Book book = (Book) DB.getDBMap().get(id);
out.print(book.getName() + "<br/>");
}
}
}
}
2. 对于图书的详细介绍的BookDetail的servlet，也是两个功能
2.1 介绍商品的详细信息
2.2 将浏览过的商品的信息加入到Cookie中，并且将Cookie写回浏览器
BookDetail的实现代码如下：
1 package com.baowei.cookie;
2
3 import java.io.IOException;
4 import java.io.PrintWriter;
5 import java.util.Arrays;
6 import java.util.LinkedList;
7
8 import javax.servlet.ServletException;
9 import javax.servlet.http.Cookie;
10 import javax.servlet.http.HttpServlet;
11 import javax.servlet.http.HttpServletRequest;
12 import javax.servlet.http.HttpServletResponse;
13
14 public class BookDetail extends HttpServlet {
15
16 public void doGet(HttpServletRequest request, HttpServletResponse response)
17 throws ServletException, IOException {
18
19 doPost(request, response);
20
21 }
22
23 public void doPost(HttpServletRequest request, HttpServletResponse response)
24 throws ServletException, IOException {
25
26 response.setContentType("text/html;charset=UTF-8");
27 response.setCharacterEncoding("UTF-8");
28 PrintWriter out = response.getWriter();
29
30 // 1.根据用户带过来的id值，显示相应商品的信息
31 out.print("您想看的书的详细信息为：<br/>");
32 String id = request.getParameter("id");
33 Book book = (Book) DB.getDBMap().get(id);
34 out.print(book.getId() + "<br/>");
35 out.print(book.getName() + "<br/>");
36 out.print(book.getAuthor() + "<br/>");
37
38 // 2.以cookie的形式回写该商品的id号给浏览器
39 String bookHistory = makeCookie(book.getId(), request);
40 Cookie cookie = new Cookie("bookHistory", bookHistory);
41 //cookie.setMaxAge(10000); //将Cookie保存在硬盘内
42 response.addCookie(cookie);
43
44 }
45
46 // 根据用户原来看过的书，以及现在看的书的id，构建新的cookie值
47 private String makeCookie(String id, HttpServletRequest request) {
48
49 // bookHistory=null 3 bookHistory=3
50 // bookHistory=2_1_5 3 bookHistory=3_2_1
51 // bookHistory=2 3 3 bookHistory=3_2
52 // bookHistory=2_3 3 bookHistory=3_2
53
54 // 1.得到用户曾经看过的书
55 String bookHistory = null;
56 Cookie cookies[] = request.getCookies();
57 for (int i = 0; cookies != null && i < cookies.length; i++) {
58 if (cookies[i].getName().equals("bookHistory")) {
59 bookHistory = cookies[i].getValue();
60 }
61 }
62
63 if (bookHistory == null) {
64 bookHistory = id;
65 return bookHistory;
66 }
67
68 // bookHistory=1_2_5 代表用户曾经看一些书，接着程序要得到用户曾经看过什么书
69 String ids[] = bookHistory.split("_");
70 // 为了检测数组中是否包含当前id，我们应该把数据转成集合，并且还要转成链表结构的集合
71 LinkedList<String> idList = new LinkedList(Arrays.asList(ids));
72
73 if (idList.contains(id)) {
74 idList.remove(id);
75 } else {
76 if (idList.size() >= 5) {
77 idList.removeLast();
78 }
79 }
80 idList.addFirst(id);
81
82 StringBuffer sb = new StringBuffer();
83 for (String lid : idList) { // 1_2_3_
84 sb.append(lid + "_");
85 }
86
87 return sb.deleteCharAt(sb.length() - 1).toString();
88 }
89
90 }
上面两个程序中用到的Book类和DB类如下：
Book类的代码：
1 package com.baowei.cookie;
2
3 public class Book {
4
5 private String id;
6 private String name;
7 private String author;
8
9 public Book() {
10
11 }
12
13 public Book(String id, String name, String author) {
14 this.id = id;
15 this.name = name;
16 this.author = author;
17 }
18 public String getId() {
19 return id;
20 }
21 public void setId(String id) {
22 this.id = id;
23 }
24 public String getName() {
25 return name;
26 }
27 public void setName(String name) {
28 this.name = name;
29 }
30 public String getAuthor() {
31 return author;
32 }
33 public void setAuthor(String author) {
34 this.author = author;
35 }
36
37
38
39 }
DB类的代码如下：
package com.baowei.cookie;
import java.util.HashMap;
import java.util.Map;
public class DB {
static Map<String,Book> map = new HashMap<String,Book>();
static {
map.put("1", new Book("1","JavaWeb开发","张保卫") );
map.put("2", new Book("2","操作系统","张保卫") );
map.put("3", new Book("3","Spring开发","张保卫") );
map.put("4", new Book("4","Struts2开发","张保卫") );
map.put("5", new Book("5","Java基础开发","张保卫") );
map.put("6", new Book("6","数据结构","张保卫") );
map.put("7", new Book("7","ACM","张保卫") );
map.put("8", new Book("8","计算机网络","张保卫") );
map.put("9", new Book("9","软件工程","张保卫") );
map.put("10", new Book("10","Android开发","张保卫") );
}
public static Map<String,Book> getDBMap(){
return map;
}
}
时间： 2024-08-04 14:08:43