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=350 // bookHistory=2_1_5 3 bookHistory=3_2_151 // bookHistory=2 3 3 bookHistory=3_252 // bookHistory=2_3 3 bookHistory=3_253 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; } }新闻热点
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