JAVAEE model1模型实现商品浏览记录(去除重复的浏

      2020-02-15 05:43      JAVA编程
这篇文章主要为大家详细介绍了JAVAEE model1模型实现商品浏览记录,去除重复的浏览记录,具有一定的参考价值,感兴趣的小伙伴们可以参考一下

在javaee中Model1模型是以jsp页面为中心的,jsp既要对浏览器的request做出逻辑处理(使用javabean),访问数据库也要显示出相关的页面。
在model1模型中,没有servlet。
Model1结果图如下:

Model1的可维护性 可扩展性都是较差的 只适合小项目。

首先运行结果

goods.jsp

<%@page import="entity.Items"%> <%@page import="dao.ItemsDao"%> <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <%   String path = request.getContextPath();   String basePath = request.getScheme() + "://"       + request.getServerName() + ":" + request.getServerPort()       + path + "/"; %>  <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <base href="<%=basePath%>">  <title>My JSP 'index.jsp' starting page</title> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="This is my page"> <!--   <link rel="stylesheet" type="text/css" href="styles.css">   --> <style type="text/css"> div {   float: left;   margin: 10px; }  div dd {   margin: 0px;   font-size: 10pt; }  div dd.dd_name {   color: blue; }  div dd.dd_city {   color: #000; } </style> </head>  <body>   <center>     <h1>商品展示</h1>     <hr>     <table width="800" height="60" cellpadding="0" cellspacing="0"       border="0">       <tr>         <td>           <%             ItemsDao dao = new ItemsDao();             ArrayList<Items> list = new ArrayList<Items>();             //从dao中获取所有的商品 并保存到list集合中             list = dao.getAllItems();             if (list != null && list.size() > 0) {               //循环遍历集合 并显示               for (int i = 0; i < list.size(); i++) {                 Items item = list.get(i);           %>           <div>             <dl>               <dt>                 <a href="details.jsp?id=<%=item.getId()%>"><img                   src="images/<%=item.getPicture()%>" width="120" height="90"                   border="1" />                 </a>               </dt>               <dd class="dd_name"><%=item.getName()%></dd>               <dd class="dd_city">                 产地:<%=item.getCity()%> 价格:¥                 <%=item.getPrice()%></dd>             </dl>           </div> <%   }   }  %>         </td>        </tr>     </table>   </center> </body> </html>

在代码中 表示商品的图片

<span style="white-space:pre">               </span><a href="details.jsp?id=<%=item.getId()%>"><img src="images/<%=item.getPicture()%>" width="120" height="90"  border="1" />  </a> 

通过点击商品的图片 把当前商品的id传值给details页面
details.jsp通过商品的id来显示详细商品 ,而浏览记录由cookies维护

<%@page import="org.apache.taglibs.standard.tag.common.xml.ForEachTag"%> <%@page import="entity.Items"%> <%@page import="dao.ItemsDao"%> <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <%   String path = request.getContextPath();   String basePath = request.getScheme() + "://"       + request.getServerName() + ":" + request.getServerPort()       + path + "/"; %>  <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <base href="<%=basePath%>">  <title>My JSP 'index.jsp' starting page</title> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="This is my page"> <style type="text/css"> #historyview {   border: 1;   background: #EAEAEE; }  #historyview td {   font-size: 10px; } </style> </head>  <body>   <center>     <h1>商品详情</h1>     <hr>     <table width="750" border="0" cellpadding="0" cellspacing="0">       <tr>         <td width="70%">           <center>             <table border="0">               <%                 ItemsDao dao = new ItemsDao();                 //根据request传来的商品id 向dao中获得相对应的商品对象                 Items item = dao.getItemById(Integer.parseInt(request                     .getParameter("id")));                 if (item != null) {               %>               <tr>                 <td rowspan="5"><img src="images/<%=item.getPicture()%>"                   width="200" height="150"></td>               </tr>               <tr>                 <td><b><%=item.getName()%></b>                 </td>               </tr>               <tr>                 <td id="cityname">产地:<%=item.getCity()%></td>               </tr>               <tr>                 <td id="pricename">价格:<%=item.getPrice()%> ¥</td>               </tr>               <tr>                 <td id="pricename">价格:<%=item.getPrice()%> ¥</td>               </tr>               <%                 }                 //将该商品加入cookies                 Cookie[] cookies = request.getCookies();                 String historyStr = "";                 for (Cookie c : cookies) {                   if (c.getName().equals("history")) {                     historyStr = c.getValue();                   }                 }                 historyStr += item.getId() + ",";                 Cookie c = new Cookie("history", historyStr);                 //重新设置cookies                 response.addCookie(c);               %>             </table>           </center></td>          <td width="30%" valign="top" id="historyview">           <center>             <table>               <tr>                 <td><b>你浏览过的商品</b></td>               </tr>               <%                 //根据cookie 从dao获取最后浏览的三次记录 并保存到list集合                 ArrayList<Items> historyItems = dao.getHistoryView(historyStr);                 if (historyItems != null && historyItems.size() > 0) {                   //遍历集合                   for (Items historyItem : historyItems) {               %>               <tr>                 <td><a href="details.jsp?id=<%=historyItem.getId()%>"><img                     src="images/<%=historyItem.getPicture()%>" width="100"                     height="80" border="1"> </a></td>               </tr>               <tr>                 <td><b><%=historyItem.getName()%></b>                 </td>               </tr>               <tr>                 <td>产地:<%=historyItem.getCity()%></td>               </tr>               <%                 }                 }               %>             </table>           </center>         </td>       </tr>     </table>    </center> </body> </html>

dao层 负责商品在数据库中的查询操作

package dao;  import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.util.ArrayList; import util.DBHelper; import entity.Items;  //商品的业务逻辑类 public class ItemsDao {   // 获得所有商品信息   public ArrayList<Items> getAllItems() {     // 商品集合     ArrayList<Items> list = new ArrayList<Items>();     Connection conn = null;     PreparedStatement ps = null;     ResultSet rs = null;      try {       conn = DBHelper.getConnection();       String sql = "select * from items";// sql 语句       ps = conn.prepareStatement(sql);       rs = ps.executeQuery();       // 将查询的结果依次加入集合       while (rs.next()) {         Items item = new Items();         item.setId(rs.getInt("id"));         item.setName(rs.getString("name"));         item.setCity(rs.getString("city"));         item.setPrice(rs.getDouble("price"));         item.setPicture(rs.getString("picture"));         item.setNumber(rs.getInt("number"));         list.add(item);       }     } catch (SQLException e) {        e.printStackTrace();     } finally {       // 关闭资源       if (rs != null) {         try {           rs.close();         } catch (SQLException e) {           // TODO Auto-generated catch block           e.printStackTrace();         }       }       if (ps != null) {         try {           ps.close();         } catch (SQLException e) {           // TODO Auto-generated catch block           e.printStackTrace();         }       }      }     return list;   }    // 根据商品编号获取商品资料    public Items getItemById(int id) {     Items item = new Items();     Connection con = null;     PreparedStatement ps = null;     ResultSet rs = null;     String sql = "select * from items where id = ?";     try {       con = DBHelper.getConnection();       ps = con.prepareStatement(sql);       ps.setInt(1, id);       rs = ps.executeQuery();       // 如果找到该id 为item对象初始化       if (rs.next()) {         item.setId(rs.getInt("id"));         item.setName(rs.getString("name"));         item.setCity(rs.getString("city"));         item.setPrice(rs.getDouble("price"));         item.setPicture(rs.getString("picture"));         item.setNumber(rs.getInt("number"));       }      } catch (SQLException e) {       // TODO Auto-generated catch block       e.printStackTrace();     } finally {       // 关闭资源       if (rs != null) {         try {           rs.close();         } catch (SQLException e) {           // TODO Auto-generated catch block           e.printStackTrace();         }       }       if (ps != null) {         try {           ps.close();         } catch (SQLException e) {           // TODO Auto-generated catch block           e.printStackTrace();         }       }     }     return item;   }    // 根据cookie 获得浏览的最后三个商品   public ArrayList<Items> getHistoryView(String cookie) {     ArrayList<Items> list = new ArrayList<Items>();     String ids[] = cookie.split(",");     int counts = 3;// 浏览的最后三条记录     if (ids != null && ids.length > 0) {       for (int i = ids.length - 1; i >= 0 && i > ids.length - counts - 1; i--) {         Items item = getItemById(Integer.parseInt(ids[i]));         /*          * 首先判断集合中是否存在当前物品 如果存在 counts+1 多读取一次(保证list集合中有3个对象) 不添加此物品          */         if (list.contains(item)) {           counts++;           continue;         }         list.add(item);       }     }     return list;   } } 

商品的实体类 Items

package entity;  public class Items {   private int id;   private String name;   private String city;   private double price;   private int number;   private String picture;    public int getId() {     return id;   }    public void setId(int id) {     this.id = id;   }    public String getName() {     return name;   }    public void setName(String name) {     this.name = name;   }    public String getCity() {     return city;   }    public void setCity(String city) {     this.city = city;   }    public double getPrice() {     return price;   }    public void setPrice(double price) {     this.price = price;   }    public int getNumber() {     return number;   }    public void setNumber(int number) {     this.number = number;   }    public String getPicture() {     return picture;   }    public void setPicture(String picture) {     this.picture = picture;   }      @Override   public int hashCode() {     // TODO Auto-generated method stub     return this.getId()+this.getName().hashCode();   }   @Override   public boolean equals(Object obj) {     if(this==obj)     {       return true;     }     else     {       if(obj instanceof Items)       {         Items item=(Items) obj;         if(this.getId()==item.getId()&&this.getName().equals(item.getName()))         {           return true;         }       }     }     return false;   } } 

在这里 重写了hasCode和equals方法 来修改比较方式(所有的item都是一个新的对象 即使两个商品的内容全部一样也不会相等 。所以要修改比较方式)
因为对于浏览记录而言 我们不能通过刷新当前商品 浏览记录全部都是该商品 我们只要保证该商品在浏览记录中 只有一个即可
所以在dao层中的getHistoryView方法有这句代码

<span style="white-space:pre">       </span>if (list.contains(item)) {           counts++;           continue;         } 

然后是工具类
DBHelpher单例模式获得connection对象

package util;  import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException;  public class DBHelper {   private static final String driver = "com.mysql.jdbc.Driver";   private static final String url = "jdbc:mysql://localhost:3306/shopping?useUnicode=true&charcterEncoding=UTF-8";   private static final String username = "root";   private static final String password = "123";   private static Connection con = null;   // 静态块代码负责加载驱动   static {     try {       Class.forName(driver);     } catch (ClassNotFoundException e) {       // TODO Auto-generated catch block       e.printStackTrace();     }   }    public static Connection getConnection() {      if (con == null) {       try {         con = DriverManager.getConnection(url, username, password);       } catch (SQLException e) {         // TODO Auto-generated catch block         e.printStackTrace();       }     }     return con;   } } 

以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持。


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