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这是什么情况？？

来源：8-8 使用Cookie实现保存商品浏览记录
weixin_慕仙1176837
2020-10-24 11:02
就是删掉response.addCookie(cookie)就不会了,不过不循环了
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1回答

weixin_慕仙1176837: 2020-10-24 11:09:22
这是index.jsp的
<%@ page import="java.util.ArrayList" %>
<%@ page import="list.entity.Items" %>
<%@ page import="list.dao.ItemsDAO" %><%--
  Created by IntelliJ IDEA.
  User: zz
  Date: 2020/10/21
  Time: 10:50
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>商品展示</title>
    <style type="text/css">
        div{
            float:left;
            margin:10px;
        }
        div dd{
            margin:0px;
            font-siez:10pt;
        }
        div dd.dd_name{
            color:blue;
        }
        div dd.dd_city{
            color: #000;
        }
    </style>
</head>
<body>
<h1>商品展示</h1>
<hr>
<center>
    <table width="750" height="60" cellpadding="0" cellspacing="0" border="0">
        <tr>
            <td>
                <!--商品循环开始-->
                <%
                    ItemsDAO itemsDAO=new ItemsDAO();
                    ArrayList<Items>list=itemsDAO.getAllItems();
                    if(list!=null&&list.size()>0){
                    for(int i=0;i<list.size();i++){
                    Items items=list.get(i);
                %>
                <div>
                    <dl>
                        <dt>
                            <a href="details.jsp?id=<%=items.getId()%>"><img src="images/<%=items.getPicture()%>" width="120" height="80"></a>
                        </dt>
                        <dd class="dd_name"><%=items.getName()%></dd>
                        <dd class="dd_city">产地:<%=items.getCity()%>&nbsp;&nbsp;价格:￥<%=items.getPrice()%></dd>
                    </dl>
                </div>
                <!--商品循环结束-->
                <%
                        }
                    }
                %>
            </td>
        </tr>
    </table>
</center>
</body>
</html>
这是ItemsDAO的
package list.dao;

import list.entity.Items;
import list.util.DBHelper;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;

//商品的业务逻辑类
public class ItemsDAO {
    //获得所有的商品信息
    public ArrayList<Items> getAllItems(){
        Connection conn=null;
        PreparedStatement stmt=null;
        ResultSet rs=null;
        ArrayList<Items> list=new ArrayList<Items>();
        try{
            conn= DBHelper.getConnection();
            String sql="SELECT * from items";
            stmt=conn.prepareStatement(sql);
            rs=stmt.executeQuery();
            while (rs.next()){
                Items item=new Items();
                item.setId(rs.getInt("id"));
                item.setName(rs.getString("name"));
                item.setCity(rs.getString("city"));
                item.setNumber(rs.getInt("number"));
                item.setPrice(rs.getInt("price"));
                item.setPicture(rs.getString("picture"));
                list.add(item);//把一个对象加入集合
            }
            return list;
        }catch (Exception e){
            e.printStackTrace();
            return null;
        }finally {
            //释放数据集对象
            if(rs!=null){
                try{
                    rs.close();
                    rs=null;
                }catch (Exception e){
                    e.printStackTrace();
                }
            }
            //释放语句对象
            if(stmt!=null){
                try{
                    stmt.close();
                    stmt=null;
                }catch (Exception e){
                    e.printStackTrace();
                }
            }
        }
    }
        //根据商品编号获得商品资料
    public Items getItemsById(int id){
        Connection conn=null;
        PreparedStatement stmt=null;
        ResultSet rs=null;
        try{
            conn= DBHelper.getConnection();
            String sql="SELECT * from items where id=?";
            stmt=conn.prepareStatement(sql);
            stmt.setInt(1,id);
            rs=stmt.executeQuery();
            if (rs.next()){
                Items item=new Items();
                item.setId(rs.getInt("id"));
                item.setName(rs.getString("name"));
                item.setCity(rs.getString("city"));
                item.setNumber(rs.getInt("number"));
                item.setPrice(rs.getInt("price"));
                item.setPicture(rs.getString("picture"));
                return  item;
            }else{
                return null;
            }
        }catch (Exception e){
            e.printStackTrace();
            return null;
        }finally {
            //释放数据集对象
            if(rs!=null) {
                try {
                    rs.close();
                    rs = null;
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
            //释放语句对象
            if (stmt != null) {
                try {
                    stmt.close();
                    stmt = null;
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
    }
    //获取最近浏览的签5条商品信息
    public ArrayList<Items> getViewList(String list){
        ArrayList<Items> itemlist=new ArrayList<Items>();
        int iCount=5;//每次返回前5条记录
        if(list!=null&&list.length()>0) {
            String[] arr = list.split(",");
            //如果商品记录大于等于5条
            if (arr.length >= 5) {
                for(int i=arr.length-1;i>=arr.length-iCount;i--){
                    itemlist.add(getItemsById(Integer.parseInt(arr[i])));
                }
            }else{
                for(int i=arr.length-1;i>=0;i--){
                    itemlist.add(getItemsById(Integer.parseInt(arr[i])));
                }
            }
                return itemlist;
            } else {
                return null;
            }
        }
    }
    这是detals.jsp的
    <%@ page import="list.dao.ItemsDAO" %>
<%@ page import="list.entity.Items" %>
<%@ page import="java.util.ArrayList" %><%--
  Created by IntelliJ IDEA.
  User: zz
  Date: 2020/10/21
  Time: 10:01
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>商品详情</title>
    <style type="text/css">
        div{
            float:left;
            margin-left:30px;
            margin-right:30px;
            margin-top:5px;
            margin-bottom:5px;
        }
        div dd{
            margin:0px;
            font-size:10pt;
        }
        div dd.dd_name{
            color:blue;
        }
        div dd.dd_city{
            color:#000;
        }
    </style>
</head>
<body>
<h1>商品详情</h1>
<hr>
<center>
    <table width="750" height="60" cellpadding="0" cellspacing="0"border="0">
        <tr>
            <!--商品详情-->
            <%
                Items items=new Items();
                ItemsDAO itemsDAO=new ItemsDAO();
                items=itemsDAO.getItemsById(Integer.parseInt(request.getParameter("id")));
                if(items!=null){
            %>
            <td width="70%" valign="top">
                <table>
                    <tr>
                        <td rowspan="4"><img src="images/<%=items.getPicture()%>" width="200" height="160"/> </td>
                    </tr>
                    <tr>
                        <td><B><%=items.getName()%></B></td>
                    </tr>
                    <tr>
                        <td>产地:<%=items.getCity()%></td>
                    </tr>
                    <tr>
                        <td>价格:<%=items.getPrice()%>￥</td>
                    </tr>
                </table>
            </td>
            <%
                }
            %>
            <%
                String list="";
                //从客户端获得Cookies集合
                Cookie[] cookies=request.getCookies();
                //遍历这个Cookies集合
                if(cookies!=null&&cookies.length>0) {
                    for (Cookie c : cookies) {
                        if (c.getName().equals("ListViewCookie")) {
                            list = c.getValue();
                        }
                    }
                }
                list+=request.getParameter("id")+",";
                //如果浏览记录超过1000条,清零
                String [] arr=list.split(",");
                if(arr!=null&&arr.length>0){
                    if(arr.length>=1000){
                        list="";
                    }
                }
                Cookie cookie=new Cookie("ListViewCookie",list);
                response.addCookie(cookie);

            %>
            <!--浏览过的商品-->
            <td width="308" bgcolor="#EEE" align="center">
                <br>
                <b>您浏览过的商品</b><br/>
                <!--循环开始-->
                <%
                    ArrayList<Items> itemlist=itemsDAO.getViewList(list);
                    if(itemlist!=null&&itemlist.size()>0){
                        for(Items i:itemlist){
                %>
                <div>
                    <dl>
                        <dt>
                            <a href="details.jsp?id=<%=i.getId()%>"><img src="images/<%=i.getPicture()%>" width="120" height="120"></a>
                        </dt>
                        <dd class="dd_name"><%=i.getName()%></dd>
                        <dd class="dd_city">产地:<%=i.getCity()%>&nbsp;&nbsp;价格:<%=i.getPrice()%>￥</dd>
                    </dl>
                </div>
                <%
                        }
                    }
                %>
                <!--循环结束-->
            </td>
        </tr>
    </table>
</center>
</body>
</html>
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