这是本次项目结果,商品展示页面和浏览历史记录页面。
1,先从数据库入手:创建商品数据库。
CREATE TABLE `items` ( `id` int(11) NOT NULL auto_increment, `name` varchar(50) default NULL, `city` varchar(50) default NULL, `price` int(11) default NULL, `number` int(11) default NULL, `picture` varchar(500) default NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=11 DEFAULT CHARSET=utf8; -- ---------------------------- -- Records of items -- ---------------------------- INSERT INTO `items` VALUES ('1', '沃特篮球鞋', '佛山', '180', '500', '001.jpg'); INSERT INTO `items` VALUES ('2', '安踏运动鞋', '福州', '120', '800', '002.jpg'); INSERT INTO `items` VALUES ('3', '耐克运动鞋', '广州', '500', '1000', '003.jpg'); INSERT INTO `items` VALUES ('4', '阿迪达斯T血衫', '上海', '388', '600', '004.jpg'); INSERT INTO `items` VALUES ('5', '李宁文化衫', '广州', '180', '900', '005.jpg'); INSERT INTO `items` VALUES ('6', '小米3', '北京', '1999', '3000', '006.jpg'); INSERT INTO `items` VALUES ('7', '小米2S', '北京', '1299', '1000', '007.jpg'); INSERT INTO `items` VALUES ('8', 'thinkpad笔记本', '北京', '6999', '500', '008.jpg'); INSERT INTO `items` VALUES ('9', 'dell笔记本', '北京', '3999', '500', '009.jpg'); INSERT INTO `items` VALUES ('10', 'ipad5', '北京', '5999', '500', '010.jpg');
2,创建商品实体类和数据库相对应:
//商品类 public class Items { private int id; // 商品编号 private String name; // 商品名称 private String city; // 产地 private int price; // 价格 private int number; // 库存 private String picture; // 商品图片 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 int getPrice() { return price; } public void setPrice(int 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; } }
3,创建数据库帮助类,用于连接数据库: 这里用到了我平时没怎么用过的静态代码块(跟静态属性类似,代码属于类,不属于对象;静态代码,在构造方法之前执行 。在程序启动的时候执行 一般用来初始化只用一次的对象 ),和单例模式(保证内存中只有一个对象)返回数据连接,
public class DBHelper { private static final String driver = "com.mysql.jdbc.Driver"; //数据库驱动 //连接数据库的URL地址 private static final String url="jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=UTF-8"; private static final String username="root";//数据库的用户名 private static final String password="root";//数据库的密码 private static Connection conn=null; //静态代码块负责加载驱动 static { try { Class.forName(driver); } catch(Exception ex) { ex.printStackTrace(); } } //单例模式返回数据库连接对象 public static Connection getConnection() throws Exception { if(conn==null) { conn = DriverManager.getConnection(url, username, password); return conn; } return conn; } public static void main(String[] args) { try { Connection conn = DBHelper.getConnection(); if(conn!=null) { System.out.println("数据库连接正常!"); } else { System.out.println("数据库连接异常!"); } } catch(Exception ex) { ex.printStackTrace(); } } }
4,数据库操作类:
//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>(); // 商品集合 try { conn = DBHelper.getConnection(); String sql = "select * from items;"; // SQL语句 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);// 把一个商品加入集合 } return list; // 返回集合。 } catch (Exception ex) { ex.printStackTrace(); return null; } finally { // 释放数据集对象 if (rs != null) { try { rs.close(); rs = null; } catch (Exception ex) { ex.printStackTrace(); } } // 释放语句对象 if (stmt != null) { try { stmt.close(); stmt = null; } catch (Exception ex) { ex.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=?;"; // SQL语句 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 ex) { ex.printStackTrace(); return null; } finally { // 释放数据集对象 if (rs != null) { try { rs.close(); rs = null; } catch (Exception ex) { ex.printStackTrace(); } } // 释放语句对象 if (stmt != null) { try { stmt.close(); stmt = null; } catch (Exception ex) { ex.printStackTrace(); } } } } //获取最近浏览的前五条商品信息 public ArrayList<Items> getViewList(String list) { System.out.println("list:"+list); ArrayList<Items> itemlist = new ArrayList<Items>(); int iCount=5; //每次返回前五条记录 if(list!=null&&list.length()>0) { String[] arr = list.split(","); System.out.println("arr.length="+arr.length); //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; } } }
5,商品展示页面,即第一页显示所有商品信息:
<%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%> <%@ page import="entity.Items"%> <%@ page import="dao.ItemsDAO"%> <% 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> <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 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> <!-- 商品循环结束 --> <% } } %> </td> </tr> </table> </center> </body> </html>
6,商品详细页面显示,商品浏览记录,显示前五条记录,这里用Cookie记录,用户点击商品id,把它存在一个字符串中,然后从字符串中取出最后添加的五条商品信息ID,然后根据ID查找显示商品信息。(这里设置了字符串长度最长为1000,超过了清零)
<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 --> <% ItemsDAO itemDao = new ItemsDAO(); Items item = itemDao.getItemsById(Integer.parseInt(request.getParameter("id"))); if(item!=null) { %> <td width="70%" valign="top"> <table> <tr> <td rowspan="4"><img src="images/<%=item.getPicture()%>" width="200" height="160"/></td> </tr> <tr> <td><B><%=item.getName() %></B></td> </tr> <tr> <td>产地:<%=item.getCity()%></td> </tr> <tr> <td>价格:<%=item.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="30%" bgcolor="#EEE" align="center"> <br> <b>您浏览过的商品</b><br> <!-- 循环开始 --> <% ArrayList<Items> itemlist = itemDao.getViewList(list); if(itemlist!=null&&itemlist.size()>0 ) { System.out.println("itemlist.size="+itemlist.size()); for(Items i:itemlist) { %> <div> <dl> <dt> <a href="details.jsp?id=<%=i.getId()%>"><img src="images/<%=i.getPicture() %>" width="120" height="90" border="1"/></a> </dt> <dd class="dd_name"><%=i.getName() %></dd> <dd class="dd_city">产地:<%=i.getCity() %> 价格:<%=i.getPrice() %> ¥ </dd> </dl> </div> <% } } %> <!-- 循环结束 --> </td> </tr> </table>