java用servlet、cookie实现一个阅读记录

效果如图

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代码1

 package com.xiaostudy.servlet;

 import java.io.IOException;
 import java.io.PrintWriter;

 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;

 @WebServlet("/Cookie_1")
 public class Cookie_1 extends HttpServlet {
     private static final long serialVersionUID = 1L;

     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
         PrintWriter out = response.getWriter();
         response.setContentType("text/html;charset=UTF-8");

         out.print("<a href=" + request.getContextPath() + "/Cookie_2?book=java>java</a><br/>");
         out.print("<a href=" + request.getContextPath() + "/Cookie_2?book=python>python</a><br/>");
         out.print("<a href=" + request.getContextPath() + "/Cookie_2?book=c#>c#</a><br/>");
         out.print("<a href=" + request.getContextPath() + "/Cookie_2?book=php>php</a><br/>");
         out.print("<hr/>");
         Cookie[] cookies = request.getCookies();//获取cookie集合
         for(int i=0; cookies!=null && i<cookies.length; i++) {//循环cookie集合
             if("book".equals(cookies[i].getName())) {//判断cookie是否有自己存放的name和value
                 String[] books = cookies[i].getValue().split("-");//拿到所有的点击value集合
                 for(int j=0; j<books.length; j++) {//循环输出显示
                     out.print(books[j] + "<br/>");
                 }
             }
         }

     }

     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
         doGet(request, response);
     }

 }

代码2

 package com.xiaostudy.servlet;

 import java.io.IOException;
 import java.io.PrintWriter;

 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;

 @WebServlet("/Cookie_2")
 public class Cookie_2 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");
         PrintWriter out = response.getWriter();
         String book = (String)request.getParameter("book");
         String str = book;
         Cookie[] cookies = request.getCookies();//得到cookie的集合数组
         for(int i=0; cookies!=null && i<cookies.length; i++) {//循环cookie
             if("book".equals(cookies[i].getName())) {//看看以前有没有放过
                 String[] books = cookies[i].getValue().split("-");//做切割
                 for(int j=0; j<books.length; j++) {//循环元素
                     if(!book.equals(books[j])) {//排除已经点击过的
                         str = str + "-" + books[j];
                     }
                 }
             }
         }
         Cookie ck = new Cookie("book", str);//创建一个cookie，并且添加name和value
         ck.setPath("/");//说明为当前的应用
         ck.setMaxAge(5);//保存cookie的时间，单位为秒
         response.addCookie(ck);//服务器向浏览器添加cookie
         out.print("成功添加书籍：" + book + "<br/>2秒后返回主页。。。");//输出到浏览器的信息

         //响应消息头，2秒后跳转到指定页面
         response.setHeader("refresh", "2;url=" + request.getContextPath() + "/Cookie_1");
     }

     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
         doGet(request, response);
     }

 }

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