Cookie案例-記錄使用者上次訪問的時間+商品的瀏覽記錄
阿新 • • 發佈：2019-01-10
使用cookie來記錄使用者上次訪問瀏覽器的時間
cookie工具類：從cookie陣列中獲取指定名稱的cookie
package com.utils; import javax.servlet.http.Cookie; public class MyCookieUtil { public static Cookie getCookieByName(Cookie[] cookies,String name){ if(cookies==null){ return null; }else{ for (Cookie c : cookies) { if(name.equals(c.getName())==true) return c; } return null; } } }
訪問的servlet
package com.servlet; import java.io.IOException; import java.text.SimpleDateFormat; import java.util.Date; 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; import com.utils.MyCookieUtil; /** * 顯示使用者上次訪問的時間 * @author 58351 * */ @WebServlet("/lasttime") public class LastTimeServlet extends HttpServlet { private static final long serialVersionUID = 1L; protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charset=UTF-8"); Date date = new Date(); SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); String sDate = sdf.format(date); /* * 1、先判斷是否是第一次訪問servlet，第一次和第n次處理的業務是不一樣的 * 2、如果是第一次訪問，向客戶端輸出一句歡迎，並且記錄當前的時間，儲存到cookie中，回寫到瀏覽器 * 3、如果不是第一次訪問，獲取cookie中的值（上次的訪問時間），把時間輸出到頁面上，並且記錄到當前的時間，儲存到cookie中，回寫到瀏覽器 */ //判斷是否是第一次訪問 //獲取cookie的陣列 Cookie[] cookies = request.getCookies(); //查詢自己定義的cookie，查詢指定名稱的cookie（Cookie c = new Cookie("cookie的名稱","cookie的值");） Cookie cookie = MyCookieUtil.getCookieByName(cookies, "last"); if(cookie==null){ //說明是第一次訪問 //列印一句歡迎 response.getWriter().write("<h3>第一次訪問，歡迎！</h3>"); //建立一個cookie，並將當前的時間儲存到cookie中去 Cookie c = new Cookie("last",sDate); response.addCookie(c); } else{ //不是第一次訪問了，獲取上一次訪問的時間 String lastTime = cookie.getValue(); response.getWriter().write("<h3>上次訪問的時間是:"+lastTime+"</h3>"); cookie.setValue(sDate); response.addCookie(cookie); } } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
商品的瀏覽記錄
JSP頁面
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Insert title here</title> </head> <style type="text/css"> .img1{ width:160px; height:140px; } .img2{ width:80px; height:70px; } </style> <body> <img class="img1" src="/Product/img/1.jpg"><a href="/Product/product?id=1">手電筒</a> <img class="img1" src="/Product/img/2.jpg"><a href="/Product/product?id=2">電話</a> <img class="img1" src="/Product/img/3.jpg"><a href="/Product/product?id=3">電視</a> <br/> <img class="img1" src="/Product/img/4.jpg"><a href="/Product/product?id=4">冰箱</a> <img class="img1" src="/Product/img/5.jpg"><a href="/Product/product?id=5">手錶</a> <img class="img1" src="/Product/img/6.jpg"><a href="/Product/product?id=6">電腦</a> <h3>商品的瀏覽記錄</h3> <% //從cookie中獲取值 Cookie[] cookies = request.getCookies(); Cookie cookie = com.utils.MyCookieUtils.getCookieByName(cookies, "product"); if(cookie!=null){ String longId = cookie.getValue(); //切割 String[] ids = longId.split(","); String path = request.getContextPath(); //遍歷 for(String id:ids){ %> <img class="img2" src="<%=path%>/img/<%= id %>.jpg"> <% } } %> </body> </html>
servlet響應
package com.servlet;
import java.io.IOException;
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;
import com.utils.MyCookieUtils;
@WebServlet("/product")
public class ProductServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//response.getWriter().write("111");
/*
* 1、獲取從客戶端傳過來的id值
* 2、判斷是否是第一次訪問（通過在cookie陣列中查詢指定名稱的cookie來判斷）
* 如果是第一次訪問（獲取的cookie為null），建立一個指定名稱的cookie，將獲取的id值存入cookie，向客戶端回寫cookie
* 如果不是第一次訪問，判斷獲取的id值是否已經存在於cookie中，如果是，則不操作，否則將這個id值存入cookie中
*/
//獲取id值
String id = request.getParameter("id");
//獲取cookie陣列
Cookie[] cookies = request.getCookies();
//查詢指定名稱的cookie
Cookie cookie = MyCookieUtils.getCookieByName(cookies, "product");
//判斷cookie
if(cookie==null){
Cookie c = new Cookie("product",id);
//設定cookie的有效時間
//c.setMaxAge(60*60);
//設定訪問路徑
c.setPath("/Product");
//回寫到客戶端
response.addCookie(c);
}else{
//獲取cookie的值
String longId = cookie.getValue();
//把cookie的值切割為字串陣列
String[] ids = longId.split(",");
//判斷longId中是否包含當前id
//longId中不包含當前id，將當前id加入到cookie的值中
if(!checkId(ids,id)){
cookie.setValue(id+","+longId);
//cookie.setMaxAge(60*60);
cookie.setPath("/Product");
//回寫到客戶端
response.addCookie(cookie);
}
}
//重定向或者轉發到商品顯示頁面，用request.getContextPath()獲取虛擬路徑，預設和專案名相同
response.sendRedirect(request.getContextPath()+"/cookie/productList.jsp");
}
//判斷longId中是否包含當前id
public boolean checkId(String[] ids,String id){
for(String s:ids){
if(s.equals(id)){
return true;
}
}
return false;
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
效果：
清楚商品的瀏覽記錄servlet
package com.servlet;
import java.io.IOException;
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;
import com.utils.MyCookieUtils;
@WebServlet("/removeProduct")
public class RemoveProductServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//獲取cookie
Cookie[] cookies = request.getCookies();
Cookie cookie = MyCookieUtils.getCookieByName(cookies, "product");
if(cookie!=null){
cookie.setMaxAge(0);
response.addCookie(cookie);
}
response.sendRedirect(request.getContextPath()+"/cookie/productList.jsp");
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}