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JAVAEE model1模型实现商品浏览记录（去除重复的浏览记录）（一）

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; 
  } 
}

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