javaWeb_04-Cookie案例-显示商品浏览历史纪录

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04-Cookie案例-显示商品浏览历史纪录

显示用户上次浏览过的商品

首页：进入本页可选择要看的商品，刷新之后会有记录

[java] view plain copy print ?

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.LinkedHashMap;
import java.util.Map;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class CookieDemo4_1
*/
@WebServlet("/CookieDemo4_1")
public class CookieDemo4_1 extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
response.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
//1,输出网站所有商品
out.write("本网站有如下商品：");
Map map = Db.getAll();
for(Map.Entry entry:map.entrySet()){
Book book = entry.getValue();
out.print("<a href="/day07/CookieDemo4_2?id='+book.getId()+'" target="_blank">"+book.getName()+"</a>");
}
//2，显示用户曾经看过的商品
out.write("您看过的商品如下：");
Cookie cookies[] = request.getCookies();
for(int i = 0;cookies != null && i < cookies.length;i++){
if(cookies[i].getName().equals("bookHistory")){
String ids[] = cookies[i].getValue().split("\\,");//2,3,1
System.out.println(Arrays.asList(ids));
for(String id:ids){
Book book = Db.getAll().get(id);
out.print(book.getName());
}
}
}
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
}
}
/*-------------------模拟数据库，存储书籍信息---------------------*/
class Db{
private static LinkedHashMap map = new LinkedHashMap();
static {
map.put("1",new Book("1", "数学", "张三", "math"));
map.put("2",new Book("2", "语文", "里斯", "chinese"));
map.put("3",new Book("3", "英语", "王五", "english"));
map.put("4",new Book("4", "化学", "赵六", "chemistry"));
}
public static Map getAll(){
return map;
}
}
/*-------------------维护对象---------------------*/
class Book{
public Book() {
super();
// TODO Auto-generated constructor stub
}
public Book(String id, String name, String author, String description) {
super();
this.id = id;
this.name = name;
this.author = author;
this.description = description;
}
private String id;
private String name;
private String author;
private String description;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getAuthor() {
return author;
}
public void setAuthor(String author) {
this.author = author;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
}

显示商品详细信息，并处理cookie

[java] view plain copy print ?

import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.LinkedList;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class CookieDemo4_1
*/
@WebServlet("/CookieDemo4_2")
public class CookieDemo4_2 extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
// 根据用户带来的id，显示商品的详细信息
String id = request.getParameter("id");
System.out.println(id);
Book book = Db.getAll().get(id);
out.write(book.getId());
out.write(book.getName());
out.write(book.getAuthor());
out.write(book.getDescription());
//2，构建cookie，回写给浏览器
String cookieValue = BuildCookie(id,request );
Cookie cookie =new Cookie("bookHistory",cookieValue);
cookie.setMaxAge(3600*1000);
cookie.setPath("/day07");
response.addCookie(cookie);
}
private String BuildCookie(String id, HttpServletRequest request) {
/**
* 传进来的cookies可能的情况：
* 1,2,3 == 2===>2,1,3
* 1,2 == 3==> 3,1,2
* null == 2==> 2
* 1,2,3 ==4==> 4 1 2
*
*
*/
Cookie cookies[] = request.getCookies();
StringBuilder sb = new StringBuilder();
String bookHistory = null;
for(int i = 0 ;cookies != null && i < cookies.length;i++){
if(cookies[i].getName().equals("bookHistory")){
bookHistory = cookies[i].getValue();
break;
}
}
if(bookHistory == null){
return id;
}
/*怪不得找不到 addFirst方法，原来，不是用的链 linkedList*/
//ArrayList list = (ArrayList) Arrays.asList(bookHistory.split("\\,"));
LinkedList list = new LinkedList(Arrays.asList(bookHistory.split("\\,")));
/* if(list.contains(id)){
list.remove(id);
list.addFirst(id)
}else{
if(list.size()>=3){
list.removeLast();
list.addFirst(id);
}else{
list.addFirst(id);
}
}*/
if(list.contains(id)){
list.remove(id);
}else if(list.size()>=3){
list.removeLast();
}
list.addFirst(id);
for(String bid:list){
sb.append(bid+",");
}
return sb.deleteCharAt(sb.length()-1).toString();
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
}
}