shangrila-xiu

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ServletCart2

下面继续学习购物车的servlet层的一些设计

准备工作是：在刚才创建的购物车的web工程点击new、servlet就可以创建一个servlet了。创建好之后，那就开始吧

1、先给出ItemsDAO.java的代码吧

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package dao;
import java.sql.*;
import java.util.ArrayList;
import cn.itcast.DB.DBHelper;
import entity.Items;
//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;//不可以释放
		PreparedStatement stmt=null;//其次释放
		ResultSet rs=null;//最先释放
		ArrayList<Items> list = new ArrayList<Items>();//商品集合
		try{
			conn=DBHelper.getConnection();
			String sql="select * from Items;";
			stmt=conn.prepareStatement(sql);//获取数据
			rs=stmt.executeQuery();//直接执行
			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.getInt("price"));
				item.setNumber(rs.getInt("number"));
				item.setPicture(rs.getString("picture"));
				list.add(item);//把商品加到集合
			}
			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();//会抛出异常
					rs=null;
				}catch(Exception ex){
					ex.printStackTrace();
				}
			}
			//释放语句对象
			if(stmt!=null){
				try{
					stmt.close();//会抛出异常
					stmt=null;
				}catch(Exception ex){
					ex.printStackTrace();
				}
			}
			
		}
	}
		//根据商品编号获得商品资料
	public Items getItermsById(int id){
		Connection conn=null;//不可以释放
		PreparedStatement stmt=null;//其次释放
		ResultSet rs=null;//最先释放
		try{
			conn=DBHelper.getConnection();
			String sql="select * from Items where id=?;";
			stmt=conn.prepareStatement(sql);//获取数据
			stmt.setInt(1,id);
			rs=stmt.executeQuery();//直接执行
			if(rs.next()){
				Items item = new Items();
				item.setId(rs.getInt("id"));
				item.setName(rs.getString("name"));
				item.setCity(rs.getString("city"));
				item.setPrice(rs.getInt("price"));
				item.setNumber(rs.getInt("number"));
				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();//会抛出异常
					rs=null;
				}catch(Exception ex){
					ex.printStackTrace();
				}
			}
			//释放语句对象
			if(stmt!=null){
				try{
					stmt.close();//会抛出异常
					stmt=null;
				}catch(Exception ex){
					ex.printStackTrace();
				}
			}
			
	}
	
	}
	
	//获取最近浏览的钱五条信息
	public ArrayList<Items> getViewList(String list){
		ArrayList<Items> itemlist =new ArrayList<Items>();
		int iCount=5;//每次返回前五条
		if(list!=null&&list.length()>0){
			String[] arr=list.split(",");//分隔成字符数组
			//如果商品记录大于等于五条，就倒叙输出
			if(arr.length>=5){
				for(int i=arr.length-1;i>=arr.length-iCount;i--)
				{
					itemlist.add(getItermsById(Integer.parseInt(arr[i])));
				}
			}else{
				for(int i=arr.length-1;i>=0;i--)
				{
					itemlist.add(getItermsById(Integer.parseInt(arr[i])));
				}
			}
			return itemlist;
		}else{
			return null;
		}
	}
}

2、还没有完。还得把cn.itcast.DB包下面的DBHelper.java写一下。否则上面的代码会报错哦！

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package cn.itcast.DB;
import java.sql.Connection;
import java.sql.DriverManager;
public class DBHelper {
  //我用的是mysql，这个是看用的啥了。
	private static final String driver = "com.mysql.jdbc.Driver";
  //定义一个静态类型的变量url，看是要连接哪个数据库并指定了字符编码
	private static final String url="jdbc:mysql://localhost:3306/checkmysql?useUnicode=true&characterEncoding=UTF-8";
  //连接数据库所使用的用户，一般情况下是root
	private static final String username="root";
  //下面就是个人使用数据库的密码了。每个人的可能不同
	private static final String password="xxxxx";
	//定义一个连接数据库的变量
	private static Connection conn=null;
	
	//静态代码快，负责加载驱动
	static
	{
      //对数据库的操作容易抛出异常
		try{
			Class.forName(driver);
		  }catch(Exception ex){
			ex.printStackTrace();
		   }
		}
	//单例模式返回数据库
	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();
		}
	}
}

3、对上面准备的时候创建的servletCart.java进行编写。

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package Servlet;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import dao.ItemsDAO;
import entity.Cart;
import entity.Items;
public class CartServlet extends HttpServlet {
	private String action;//显示购物车动作
	//商品业务逻辑类的对象
	private ItemsDAO idao =new ItemsDAO();
	
	
	/**
	 * Constructor of the object.
	 */
	public CartServlet() {
		super();
	}
	/**
	 * Destruction of the servlet. <br>
	 */
	public void destroy() {
		super.destroy(); // Just puts "destroy" string in log
		// Put your code here
	}
	/**
	 * The doGet method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to get.
	 * 
	 * @param request the request send by the client to the server
	 * @param response the response send by the server to the client
	 * @throws ServletException if an error occurred
	 * @throws IOException if an error occurred
	 */
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doPost(request,response);
	}
	/**
	 * The doPost method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to post.
	 * 
	 * @param request the request send by the client to the server
	 * @param response the response send by the server to the client
	 * @throws ServletException if an error occurred
	 * @throws IOException if an error occurred
	 */
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		response.setContentType("text/html;charset=utf-8");
		PrintWriter out = response.getWriter();
		if(request.getParameter("action")!=null){//判断动作类型
			this.action=request.getParameter("action");
			if(action.equals("add")){//如果是添加商品进购物车
			//	addToCart(request,response);
				if(addToCart(request,response)){
					//服务器跳转
					request.getRequestDispatcher("/success.jsp").forward(request, response);
				}else{
					request.getRequestDispatcher("/faliure.jsp").forward(request, response);
				}
				addToCart(request,response);
			}
			if(action.equals("show")){//如果是显示购物车
				
					//服务器跳转
					request.getRequestDispatcher("/cart.jsp").forward(request, response);
				//showCart(request,response);
			}
		}
	}
	//添加商品进购物车
	private boolean addToCart(HttpServletRequest request, HttpServletResponse response){
		String id=request.getParameter("id");//获得商品的id
		String number =request.getParameter("num");//获得商品的数量
		//获得商品的资料。id是整型的，需要进行转换成整型
		Items item=idao.getItemsById(Integer.parseInt(id));
		//判断是不是第一次给狗驱车添加商品,需要给session中创建新的购物车对象
		if(request.getSession().getAttribute("cart")==null){
			Cart cart =new Cart(); 
			//典型的session保存
			request.getSession().setAttribute("cart", cart);
		}
		//获得session保存的购物车对象，这里也用到了强制类型转换
		Cart cart =(Cart)request.getSession().getAttribute("cart");
		//调用添加商品进购物车的方法
		if(cart.addGoodsInCart(item, Integer.parseInt(number))){
			return true;//添加成功
		}else{
			return false;//添加失败
		}
	}
	/**
	 * Initialization of the servlet. <br>
	 *
	 * @throws ServletException if an error occurs
	 */
	public void init() throws ServletException {
		// Put your code here
	}
}

4、编写的details.jsp代码如下：

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<%@ 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 'details.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">
	-->
	<link href="css/main.css" rel="stylesheet" type="text/css">
	<script type="text/javascript" src="js/lhgcore.js"></script>
    <script type="text/javascript" src="js/lhgdialog.js"></script>
    <script type="text/javascript">
      function selflog_show(id)
      { 
         var num =  document.getElementById("number").value; 
         J.dialog.get({id: 'haoyue_creat',title: '购物成功',width: 600,height:400, link: '<%=path%>/servlet/CartServlet?id='+id+'&num='+num+'&action=add', cover:true});
      }
      function add()
      {
         var num = parseInt(document.getElementById("number").value);
         if(num<100)
         {
            document.getElementById("number").value = ++num;
         }
      }
      function sub()
      {
         var num = parseInt(document.getElementById("number").value);
         if(num>1)
         {
            document.getElementById("number").value = --num;
         }
      }
     
    </script>
	
    <style type="text/css">
	   hr{
	     
	     border-color:FF7F00; 
	   }
	   
	   div{
	      float:left;
	      margin-left: 30px;
	      margin-right:30px;
	      margin-top: 5px;
	      margin-bottom: 5px;
	     
	   }
	   div dd{
	      margin:0px;
	      font-size:10pt;
	   }
	   div dd.dd_name
	   {
	      color:blue;
	   }
	   div dd.dd_city
	   {
	      color:#000;
	   }
	   div #cart
	   {
	     margin:0px auto;
	     text-align:right; 
	   }
	   span{
	     padding:0 2px;border:1px #c0c0c0 solid;cursor:pointer;
	   }
	   a{
	      text-decoration: none; 
	   }
	</style>
  </head>
  
  <body>
    <h1>商品详情</h1>
    <a href="index.jsp">首页</a> >> <a href="index.jsp">商品列表</a>
    <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="5"><img src="image/<%=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>
               <tr>
                 <td>购买数量：<span id="sub" onclick="sub();">-</span><input type="text" id="number" name="number" value="1" size="2"/><span id="add" onclick="add();">+</span></td>
               </tr> 
             </table>
             <div id="cart">
               <img src="images/buy_now.png"><a href="javascript:selflog_show(<%=item.getId()%>)"><img src="images/in_cart.png"></a><a href="servlet/CartServlet?action=show"><img src="images/view_cart.jpg"/></a>
             </div>
          </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><font color="#FF7F00">您浏览过的商品</font></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="image/<%=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() %>&nbsp;&nbsp;价格:<%=i.getPrice() %> ￥ </dd> 
             </dl>
             </div>
             <% 
                   }
                }
             %>
             <!-- 循环结束 -->
          </td>
        </tr>
      </table>
    </center>
  </body>
</html>

5、跳转成功的success.jsp。只给出了关键的代码

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<center>
     <img src="images/add_cart_success.jpg"/>
     <hr>
     <% 
        String id = request.getParameter("id");
        String num = request.getParameter("num");
     %>
            您成功购买了<%=num%>件商品编号为<%=id%>的商品&nbsp;&nbsp;&nbsp;&nbsp;
     <br>
     <br>
     <br>
     
   </center>

6、failure.jsp的关键的代码如下

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<center>
     <img src="images/add_cart_failure.jpg"/>
     <hr>
     
     <br>
     <br>![add_cart_failure](C:\Users\Administrator\Desktop\images\add_cart_failure.jpg)
     <br>
     
   </center>

7、index.jsp的代码

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<%@ 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">
	   hr{
	    border-color:FF7F00; 
	   }
	   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="image/<%=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() %>&nbsp;&nbsp;价格:￥ <%=item.getPrice() %></dd> 
             </dl>
          </div>
          <!-- 商品循环结束 -->
        
          <%
                   }
              } 
          %>
        </td>
      </tr>
    </table>
    </center>
  </body>
</html>

在上面使用到的图片大概就是下面这些。

001

002

003

006

add_cart_success

buy_now

go_shopping

in_cart

view_cart