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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）

程序员文章站 2024-03-11 11:23:43
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mod...

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：

JAVAEE model1模型实现商品浏览记录（去除重复的浏览记录）（一）

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

JAVAEE model1模型实现商品浏览记录（去除重复的浏览记录）（一）

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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