JAVAEE model1模型实现商品浏览记录(去除重复的浏览记录)(一)
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2024-03-12 10:18:02
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:
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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