使用Cookie获取最近浏览商品

我就是我 2022-05-16 06:15 224阅读 0赞

**Cookie**是客户端技术，当一个用户访问WEB资源时，web可以返回cookie数据，当用户再次访问web资源时会携带自己独享的cookie数据

import java.io.IOException;
 import java.io.PrintWriter;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
 
 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;
 
 /**
 * 商品展示首页
 */
 @WebServlet("/ProductServlet")
 public class ProductServlet extends HttpServlet {
 
 private static final long serialVersionUID = 1L;
 
 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 response.setContentType("text/html;character='UTF-8'");
 response.setCharacterEncoding("UTF-8");
 PrintWriter writer = response.getWriter();
 //展示所有商品
 writer.write("所有商品列表：");
 DB db = new DB();
 Map<String,Product> products = db.GetProducts();
 Set<Entry<String, Product>> product_set = products.entrySet();
 for(Entry e:product_set){
 Product p = (Product) e.getValue();
 writer.write("<a href = '/CookieGetProduct/ProductInfoServlet?ID="+p.getID()+"' target = '_blank'>"+p.getProductName()+"</a>");
 }
 //展示最近浏览商品从cookie中取出商品号
 Cookie cookies[] = request.getCookies();
 Cookie ProductHistory = null;
 for(int i=0;cookies!=null&&i<cookies.length;i++){
 ProductHistory = cookies[i];
 if(ProductHistory.getName()=="ProductHistory"){
 break;
 }
 }
 writer.write("最近访问商品列表：");
 if(ProductHistory!=null){
 String ids[] = ProductHistory.getValue().split("_");
 for(int i=0;i<ids.length;i++){
 Product p = products.get(ids[i]);
 writer.write("<a href = '/CookieGetProduct/ProductInfoServlet?ID="+p.getID()+"' target = '_blank'>"+p.getProductName()+"</a>");
 }
 }
 
 }
 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 doGet(request, response);
 }
 }
 /**
 * 使用类来模拟数据库
 */
 class DB{
 private Map<String, Product> products = new HashMap();
 public DB(){
 this.products.put("1", new Product("1","马丁靴","冬季保暖"));
 this.products.put("2", new Product("2","马丁靴2","冬季保暖2"));
 this.products.put("3", new Product("3","马丁靴3","冬季保暖3"));
 this.products.put("4", new Product("4","马丁靴4","冬季保暖4"));
 this.products.put("5", new Product("5","马丁靴5","冬季保暖5"));
 this.products.put("6", new Product("6","马丁靴6","冬季保暖6"));
 }
 public Map GetProducts(){
 return products;
 }
 }
 /**
 * 使用类Product来模拟数据库记录
 */
 class Product{
 private String ID;
 private String ProductName;
 private String ProductDecs;
 public Product(String iD, String productName, String productDecs) {
 super();
 ID = iD;
 ProductName = productName;
 ProductDecs = productDecs;
 }
 public String getID() {
 return ID;
 }
 public void setID(String iD) {
 ID = iD;
 }
 public String getProductName() {
 return ProductName;
 }
 public void setProductName(String productName) {
 ProductName = productName;
 }
 public String getProductDecs() {
 return ProductDecs;
 }
 public void setProductDecs(String productDecs) {
 ProductDecs = productDecs;
 }
 
 }

import java.io.IOException;
 import java.io.PrintWriter;
 import java.util.Arrays;
 import java.util.LinkedList;
 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;
 
 /**
 * 商品详情展示页
 */
 @WebServlet("/ProductInfoServlet")
 public class ProductInfoServlet extends HttpServlet {
 
 private static final long serialVersionUID = 1L;
 
 protected void doGet(HttpServletRequest request, HttpServletResponse response)
 throws ServletException, IOException {
 response.setContentType("text/html;character='UTF-8'");
 response.setCharacterEncoding("UTF-8");
 String id = request.getParameter("ID");
 PrintWriter writer = response.getWriter();
 DB db = new DB();
 Map<String, Product> products = db.GetProducts();
 Product product = products.get(id);
 // 显示商品
 writer.write(product.getID() + "\t" + product.getProductName() + "\t" + product.getProductDecs() + "");
 String ProductHistory = GetProductHistory(id, request);
 // 添加新的cookie
 Cookie cookie = new Cookie("ProductHistory", ProductHistory);
 cookie.setMaxAge(10000);
 response.addCookie(cookie);
 }
 
 /**
 * 生成新的cookie
 * 
 * @return
 */
 private String GetProductHistory(String id, HttpServletRequest request) {
 // bookHistory=null 3 bookHistory=3
 // bookHistory=2_1_5 3 bookHistory=3_2_1
 // bookHistory=2 3 bookHistory=3_2
 // bookHistory=2_3 3 bookHistory=3_2
 //得到用户之前浏览过的商品
 Cookie cookies[] = request.getCookies();
 Cookie hp = null;
 for(int i=0;cookies!=null&&i<cookies.length;i++){
 hp = cookies[i];
 if(hp.getName()=="ProductHistory"){
 break;
 }
 }
 if(hp==null){
 return id;
 }else{
 String ids[] = hp.getValue().split("_");
 LinkedList<String> list = new LinkedList<String>(Arrays.asList(ids));
 for(int i=0;i<ids.length;i++){
 if(id.equals(ids[i])){
 list.remove(id);
 }
 }
 if(list.size()>=3){
 list.removeLast();
 }
 list.addFirst(id);;
 StringBuffer result=new StringBuffer();
 for(String i:list){
 result.append(i+"_");
 }
 result.deleteCharAt(result.length()-1);
 return result.toString();
 }
 }
 
 protected void doPost(HttpServletRequest request, HttpServletResponse response)
 throws ServletException, IOException {
 doGet(request, response);
 }
 
 }