.NET开发：购物车的实现及结算处理

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购物车的实现及结算处理

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本示例利用Session对象来实现一个简单的购物车。主要用于教学演示。

Book类
此类主是代表购物车的一本书
using System;

namespace CartTest
{
/// <summary>
/// Books 的摘要说明。
/// </summary>
public class Book
{
  string bookid;
  string title;
  decimal price;
  int num;

  public Book()
  {
  }

  /// <summary>
  /// ID
  /// </summary>
  public string BookID
  {
   get{return bookid;}
   set{bookid=value;}
  }
  /// <summary>
  /// 书名
  /// </summary>
  public string Title
  {
   get{return title;}
   set{title=value;}
  }

  /// <summary>
  /// 金额
  /// </summary>
  public decimal Price
  {
   get{return price;}
   set{price=value;
   sum=price*num;
   }
  }
  /// <summary>
  /// 数量
  /// </summary>
  public int Num
  {
   get{return num;}
   set{num=value;
   sum=price*num;
   }
  }
  decimal sum=0m;
  //一种书的总金额
  public decimal Sum
  {
   get{return sum;}
   set{sum=value;}
  }
}

}

//购物车集合
//Books 用户所有订购的书 ,实现IEnumerable接口，我们可以将其绑定到datagrid控件
using System;
using System.Collections;
namespace CartTest
{
/// <summary>
///
/// </summary>
public class Books :IEnumerable
{
  Hashtable ht=null;
  public Books()
  {
   ht=new Hashtable();

  }

  public Books(int count)
  {
   ht=new Hashtable(count);
  }

  public void Add(Book b)
  {
   //如果集合中有相同ID的书，则对书的数量进行相加
   if(ht.ContainsKey(b.BookID))
   {
((Book)ht[b.BookID]).Num=((Book)ht[b.BookID]).Num+b.Num;

   }
   else
   {
    ht.Add(b.BookID,b);
   }
  }

  public void Remove(string bookid)
  {
   if(ht.ContainsKey(bookid))
   ht.Remove(bookid);
  }
//统计有多少种书
  public int Count
  {
   get
   {
    return ht.Count;
   }
  }

  public void Clear()
  {
   ht.Clear();
  }

  public Book this[string bookid]
  {
   get
   {
    if(ht.ContainsKey(bookid))
     return (Book)ht[bookid];
    return null;
   }
  }
  #region IEnumerable 成员

  public IEnumerator GetEnumerator()
  {
   // TODO: 添加 Books.GetEnumerator 实现
   return ht.Values.GetEnumerator();
  }

#endregion
}
}

//此页面主要是用于显示所有的书。用的是DataList来自定义显示模板。但是实际上可以使用DataGrid来处理。DataGrid也可以实现分页功能及自定义模板。只要将dDatagrid设为一个模板列，然后将DataList里的模板列代码Copy过去即可。
//此页面中每本书都要显示封面。这个问题我们可以通过一个过渡页来处理图片数据

<%@ Page language="c#" Codebehind="BookList.aspx.cs" AutoEventWireup="false" Inherits="CartTest.BookList" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" >
<HTML>
<HEAD>
  <title>BookList</title>
  <meta content="Microsoft Visual Studio .NET 7.1" name="GENERATOR">
  <meta content="C#" name="CODE_LANGUAGE">
  <meta content="JavaScript" name="vs_defaultClientScript">
  <meta content="http://schemas.microsoft.com/intellisense/ie5" name="vs_targetSchema">
  <LINK href="http://localhost/CartTest/StyleSheet1.css" type="text/css" rel="stylesheet">
</HEAD>
<body MS_POSITIONING="GridLayout">
  <form id="Form1" method="post" runat="server">
   <asp:datalist id="DataList1" style="Z-INDEX: 101; LEFT: 16px; POSITION: absolute; TOP: 56px" runat="server"
    DataKeyField="BookGuid" Width="650">
    <ItemTemplate>
     <TABLE id="Table14" cellSpacing="1" cellPadding="1" border="0">
      <TR>
       <TD>
        <a href='<%# "BookView.aspx?BookID="+DataBinder.Eval(Container, "DataItem.BookGuid") %>'>
      <asp:Image id=Image1 runat="server" Width="120px" Height="144px" ImageUrl='<%# "ImageView.aspx?imgid="+DataBinder.Eval(Container, "DataItem.BookGuid") %>'>
         </asp:Image>
        </a>
       </TD>
       <TD vAlign="top">
        <TABLE id="Table15" cellSpacing="1" cellPadding="1" width="300" border="1">
         <TR>
          <TD>书名：
           <asp:Label id=Label1 runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.BookTitle") %>'>
           </asp:Label></TD>
         </TR>
         <TR>
          <TD>图书简介：
           <asp:Label id=Label2 style="OVERFLOW: hidden; TEXT-OVERFLOW: ellipsis" runat="server" Width="496" Text='<%# "<nobr>"+DataBinder.Eval(Container, "DataItem.BookComment")+"/<nobr>"%>' Height="50px">
           </asp:Label></TD>
         </TR>
         <TR>
          <TD>金额：
           <asp:Label id=Label3 runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.Price","{0:C}") %>'>
           </asp:Label></TD>
         </TR>
        </TABLE>
       </TD>
      </TR>
      <TR>
       <TD>
        <asp:Label id="Label4" runat="server">日期：</asp:Label>
        <asp:Label id=Label5 runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.PublishDate", "{0:D}") %>'>
        </asp:Label></TD>
       <TD align="right">
        <asp:ImageButton id="Imagebutton1" runat="server" ImageUrl="a.gif" CommandName="AddCart"></asp:ImageButton></TD>
      </TR>
     </TABLE>
    </ItemTemplate>
    <AlternatingItemTemplate>
     <TABLE id="Table4" cellSpacing="1" cellPadding="1" bgColor="#eefeff" border="0">
      <TR>
       <TD>
        <a href='<%# "BookView.aspx?BookID="+DataBinder.Eval(Container, "DataItem.BookGuid") %>'>
        <asp:Image id=Image2 runat="server" Width="120px" Height="144px" ImageUrl='<%# "ImageView.aspx?imgid="+DataBinder.Eval(Container, "DataItem.BookGuid") %>'>
         </asp:Image></a></TD>
       <TD vAlign="top">
        <TABLE id="Table5" cellSpacing="1" cellPadding="1" width="300" border="1">
         <TR>
          <TD>书名：
           <asp:Label id=Label6 runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.BookTitle") %>'>
           </asp:Label></TD>
         </TR>
         <TR>
          <TD>图书简介：
           <asp:Label id=Label7 style="OVERFLOW: hidden; TEXT-OVERFLOW: ellipsis" runat="server" Width="496px" Text='<%# DataBinder.Eval(Container, "DataItem.BookComment") %>' Height="50px">
           </asp:Label></TD>
         </TR>
         <TR>
          <TD>金额：
           <asp:Label id=Label8 runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.Price") %>'>
           </asp:Label></TD>
         </TR>
        </TABLE>
       </TD>
      </TR>
      <TR>
       <TD>
        <asp:Label id="Label9" runat="server">日期：</asp:Label>
        <asp:Label id=Label10 runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.PublishDate") %>'>
        </asp:Label></TD>
       <TD align="right">
        <asp:ImageButton id="Imagebutton2" runat="server" ImageUrl="a.gif"></asp:ImageButton></TD>
      </TR>
     </TABLE>
    </AlternatingItemTemplate>
   </asp:datalist></form>
</body>
</HTML>

//CS CODE
using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;
namespace CartTest
{
/// <summary>
/// BookList 的摘要说明。
/// </summary>
public class BookList : System.Web.UI.Page
{
  protected System.Web.UI.WebControls.DataList DataList1;

  private void Page_Load(object sender, System.EventArgs e)
  {
   if(!this.IsPostBack)
   {
    SqlConnection cn=new SqlConnection();
    cn.ConnectionString="server=.;uid=sa;pwd=;database=p1";
    cn.Open();
    SqlCommand cmd=new SqlCommand();
    cmd.Connection=cn;
    cmd.CommandText="select * from books ";
    SqlDataAdapter da=new SqlDataAdapter();
    da.SelectCommand=cmd;
    DataSet ds=new DataSet();
    da.Fill(ds);
    cn.Close();
    this.DataList1.DataSource=ds.Tables[0];
    this.DataBind();
   }
  }

  #region Web 窗体设计器生成的代码
  override protected void OnInit(EventArgs e)
  {
   //
   // CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。
   //
   InitializeComponent();
   base.OnInit(e);
  }

  /// <summary>
  /// 设计器支持所需的方法 - 不要使用代码编辑器修改
  /// 此方法的内容。
  /// </summary>
  private void InitializeComponent()
  {
   this.DataList1.ItemCommand += new System.Web.UI.WebControls.DataListCommandEventHandler(this.DataList1_ItemCommand);
   this.Load += new System.EventHandler(this.Page_Load);

}
#endregion

  private void DataList1_ItemCommand(object source, System.Web.UI.WebControls.DataListCommandEventArgs e)
  {

   //用户选中一本书后，默认订一本书
   string bookGuid=this.DataList1.DataKeys[e.Item.ItemIndex].ToString();
   Book b=new Book();
   //首先获得自己的购物车
   Books bs=(Books)Session["MyCart"];
   b.BookID=bookGuid;
   b.Num=1;
   //根据ITEM的类型取值
   if(e.Item.ItemType==ListItemType.Item)
   {
    b.Price=Convert.ToDecimal(((Label)e.Item.FindControl("Label3")).Text.Substring(1));
    b.Title=((Label)e.Item.FindControl("Label1")).Text;
   }
   else if(e.Item.ItemType==ListItemType.AlternatingItem)
   {
    b.Price=Convert.ToDecimal(((Label)e.Item.FindControl("Label8")).Text.Substring(1));
    b.Title=((Label)e.Item.FindControl("Label6")).Text;
   }
   //将书加入到购物车
   bs.Add(b);
   Session["MyCart"]=bs;
   //打开购物车页面。
   Response.Write("<script>window.open('webform1.aspx')</script>");
  }

}
}

//图片处理页
using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;
namespace CartTest
{
/// <summary>
/// ImageView 的摘要说明。
/// </summary>
public class ImageView : System.Web.UI.Page
{

  private void Page_Load(object sender, System.EventArgs e)
  {
   SqlConnection cn=new SqlConnection();
   cn.ConnectionString="server=.;uid=sa;pwd=;database=p1";
   cn.Open();
   SqlCommand cmd=new SqlCommand();
   cmd.Connection=cn;
   cmd.CommandText="select cover from books where bookguid='"+ this.Request.QueryString["imgid"].ToString() +"'";
   //cmd.CommandText="select cover from books where bookguid='350bc228-a12d-4c15-b8e0-1e625e40403e'";
   SqlDataAdapter da=new SqlDataAdapter();
   da.SelectCommand=cmd;
   DataSet ds=new DataSet();
   da.Fill(ds);
   cn.Close();
   Response.Clear();
   Response.ClearContent();
   Response.ContentType="Image/jpg";
   Response.BinaryWrite((byte[])ds.Tables[0].Rows[0][0]);

}

}
#endregion
}
}

//当用户选取其中一本书时，获得用户当前选中书的ID，将此ID传到具体察看页面
<%@ Page language="c#" Codebehind="BookView.aspx.cs" AutoEventWireup="false" Inherits="CartTest.BookView" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" >
<HTML>
<HEAD>
  <title>BookView</title>
  <meta name="GENERATOR" Content="Microsoft Visual Studio .NET 7.1">
  <meta name="CODE_LANGUAGE" Content="C#">
  <meta name="vs_defaultClientScript" content="JavaScript">
  <meta name="vs_targetSchema" content="http://schemas.microsoft.com/intellisense/ie5">
</HEAD>
<body MS_POSITIONING="GridLayout">
  <form id="Form1" method="post" runat="server">
   <FONT face="宋体">
    <asp:Label id="Label1" style="Z-INDEX: 101; LEFT: 32px; POSITION: absolute; TOP: 24px" runat="server"
     Width="302px" Height="35px"></asp:Label>
    <asp:Image id="Image1" style="Z-INDEX: 102; LEFT: 24px; POSITION: absolute; TOP: 72px" runat="server"
     Width="120px" Height="136px"></asp:Image>
    <asp:Label id="Label2" style="Z-INDEX: 103; LEFT: 192px; POSITION: absolute; TOP: 88px" runat="server"
     Width="280px"></asp:Label>
    <asp:Label id="Label4" style="Z-INDEX: 104; LEFT: 200px; POSITION: absolute; TOP: 128px" runat="server" Width="328px">Label</asp:Label>
<asp:Panel id=Panel2 style="Z-INDEX: 105; LEFT: 24px; POSITION: absolute; TOP: 220px" runat="server" Height="172px" Width="456px"></asp:Panel>
<asp:Label id=Label5 style="Z-INDEX: 106; LEFT: 200px; POSITION: absolute; TOP: 168px" runat="server" Width="336px">Label</asp:Label></FONT>

  </form>
</body>
</HTML>

namespace CartTest
{
/// <summary>
/// BookView 的摘要说明。
/// </summary>
public class BookView : System.Web.UI.Page
{
  protected System.Web.UI.WebControls.Label Label1;
  protected System.Web.UI.WebControls.Image Image1;
  protected System.Web.UI.WebControls.Label Label2;
  protected System.Web.UI.WebControls.Label Label3;
  protected System.Web.UI.WebControls.TextBox TextBox1;
  protected System.Web.UI.WebControls.Label Label4;
  protected System.Web.UI.WebControls.Panel Panel2;
  protected System.Web.UI.WebControls.Label Label5;
  protected System.Web.UI.WebControls.Panel Panel1;

  private void Page_Load(object sender, System.EventArgs e)
  {
   if(!this.IsPostBack)
   {
    if(this.Request["BookID"]!=null)
    {
     this.Image1.ImageUrl="ImageView.aspx?imgid="+this.Request["BookID"].ToString();
     SqlConnection cn=new SqlConnection();
     cn.ConnectionString="server=.;uid=sa;pwd=;database=p1";
     cn.Open();
     SqlCommand cmd=new SqlCommand();
     cmd.Connection=cn;
     cmd.CommandText="select * from books where bookguid='"+ this.Request.QueryString["BookID"].ToString() +"'";
     //cmd.CommandText="select cover from books where bookguid='350bc228-a12d-4c15-b8e0-1e625e40403e'";
     SqlDataAdapter da=new SqlDataAdapter();
     da.SelectCommand=cmd;
     DataSet ds=new DataSet();
     da.Fill(ds);
     cn.Close();
     this.Label1.Text=ds.Tables[0].Rows[0][1].ToString();
     this.Label2.Text=ds.Tables[0].Rows[0][2].ToString();
     this.Label4.Text=ds.Tables[0].Rows[0][3].ToString();
     this.Panel2.Controls.Add(new LiteralControl(ds.Tables[0].Rows[0][4].ToString()));
    }
   }
  }

}
#endregion
}
}

//购物车页面。实现此功能主要使用DataGrid来显示总计功能。

<%@ Page language="c#" Codebehind="WebForm1.aspx.cs" AutoEventWireup="false" Inherits="CartTest.WebForm1" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" >
<HTML>
<HEAD>
  <title>WebForm1</title>
  <meta name="GENERATOR" Content="Microsoft Visual Studio .NET 7.1">
  <meta name="CODE_LANGUAGE" Content="C#">
  <meta name="vs_defaultClientScript" content="JavaScript">
  <meta name="vs_targetSchema" content="http://schemas.microsoft.com/intellisense/ie5">
  <script>
//此JS主要是防止用户输入非数字
   function checkNum()
   {
    var chr=String.fromCharCode(event.keyCode);

    if(isNaN(chr))
    {
    event.keyCode=0;
    }
   }

  </script>
</HEAD>
<body MS_POSITIONING="GridLayout">
  <form id="Form1" method="post" runat="server">
   <asp:DataGrid id="DataGrid1" runat="server" AutoGenerateColumns="False" PageSize="15" Font-Size="XX-Small"
    CellPadding="4" DataKeyField="BookID" BorderStyle="Solid" BorderColor="SkyBlue" BorderWidth="1px"
    ShowFooter="True" Width="680px">
    <ItemStyle BackColor="#EEEEEE"></ItemStyle>
    <HeaderStyle Font-Size="9pt" Font-Bold="True" BackColor="SkyBlue"></HeaderStyle>
    <Columns>
     <asp:TemplateColumn HeaderText="书名">
      <ItemTemplate>
       <asp:Label id=Label2 runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.Title") %>'>
       </asp:Label>
      </ItemTemplate>
     </asp:TemplateColumn>
     <asp:TemplateColumn HeaderText="单价">
      <ItemTemplate>
       <asp:TextBox id=txtPrice runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.Price") %>' ReadOnly="True">
       </asp:TextBox>
      </ItemTemplate>
     </asp:TemplateColumn>
     <asp:TemplateColumn HeaderText="数量">
      <ItemTemplate>
       <asp:TextBox id=txtNum onkeypress="checkNum()" runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.Num") %>'>
       </asp:TextBox>
      </ItemTemplate>
     </asp:TemplateColumn>
     <asp:TemplateColumn HeaderText="总金额">
      <ItemTemplate>
       <asp:TextBox id=txtSum runat="server" ReadOnly="True" Text='<%# DataBinder.Eval(Container, "DataItem.Sum") %>'>
       </asp:TextBox>
      </ItemTemplate>
      <FooterTemplate>
       <asp:TextBox id="txtSumPrice" runat="server" ReadOnly="True"></asp:TextBox>
      </FooterTemplate>
     </asp:TemplateColumn>
     <asp:TemplateColumn HeaderText="操作">
      <ItemTemplate>
       <asp:LinkButton id="LinkButton1" runat="server" CommandName="editBook">修改</asp:LinkButton><FONT face="宋体"> </FONT>
       <asp:LinkButton id="LinkButton2" runat="server" CommandName="delBook">删除</asp:LinkButton>
      </ItemTemplate>
     </asp:TemplateColumn>
    </Columns>
    <PagerStyle NextPageText="4" Font-Size="10pt" Font-Names="webdings" PrevPageText="3" BackColor="SkyBlue"></PagerStyle>
   </asp:DataGrid>
  </form>
</body>
</HTML>

//购物车察看页里的数据是Session里所存放的Books集合对象。可以将其绑定到网格控件

using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;
namespace CartTest
{
/// <summary>
/// WebForm1 的摘要说明。
/// </summary>
public class WebForm1 : System.Web.UI.Page
{
  protected System.Web.UI.WebControls.DataGrid DataGrid1;

  private void Page_Load(object sender, System.EventArgs e)
  {
   if(!this.IsPostBack)
   {
    Books bs=(Books)Session["MyCart"];
    this.DataGrid1.DataSource=bs;
    this.DataBind();
   }
  }

  #region Web 窗体设计器生成的代码
  override protected void OnInit(EventArgs e)
  {
   //
   // CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。
   //
   InitializeComponent();
   base.OnInit(e);
  }

  /// <summary>
  /// 设计器支持所需的方法 - 不要使用代码编辑器修改
  /// 此方法的内容。
  /// </summary>
  private void InitializeComponent()
  {
   this.DataGrid1.ItemCreated += new System.Web.UI.WebControls.DataGridItemEventHandler(this.DataGrid1_ItemCreated);
   this.DataGrid1.ItemCommand += new System.Web.UI.WebControls.DataGridCommandEventHandler(this.DataGrid1_ItemCommand);
   this.DataGrid1.ItemDataBound += new System.Web.UI.WebControls.DataGridItemEventHandler(this.DataGrid1_ItemDataBound);
   this.Load += new System.EventHandler(this.Page_Load);

}
#endregion

  //利用此事件对网格控件的外观进行控件（合并列）
  private void DataGrid1_ItemCreated(object sender, System.Web.UI.WebControls.DataGridItemEventArgs e)
  {
   ListItemType itemType = e.Item.ItemType;
   if (itemType == ListItemType.Footer)
   {
//    e.Item.BackColor = Color.SeaGreen;
//    e.Item.Font.Bold = true;
    e.Item.Cells.RemoveAt(0);
    e.Item.Cells.RemoveAt(0);
    e.Item.Cells[0].ColumnSpan = 3;
    e.Item.Cells[0].HorizontalAlign = HorizontalAlign.Right;

   }
  }

  private void DataGrid1_ItemCommand(object source, System.Web.UI.WebControls.DataGridCommandEventArgs e)
  {
   Books bs=(Books)Session["MyCart"];
   if(e.CommandName=="editBook")
   {
     int num=Convert.ToInt16(((TextBox)e.Item.FindControl("txtNum")).Text);
     decimal p=Convert.ToDecimal(((TextBox)e.Item.FindControl("txtPrice")).Text);
     bs[this.DataGrid1.DataKeys[e.Item.ItemIndex].ToString()].Sum=p*num;
    bs[this.DataGrid1.DataKeys[e.Item.ItemIndex].ToString()].Num=num;
   }
   else if(e.CommandName=="delBook")
   {
    bs.Remove(this.DataGrid1.DataKeys[e.Item.ItemIndex].ToString());
   }
   this.DataGrid1.DataSource=bs;
   this.DataBind();
   Session["MyCart"]=bs;
  }

  private void DataGrid1_ItemDataBound(object sender, System.Web.UI.WebControls.DataGridItemEventArgs e)
  {
   ListItemType itemType = e.Item.ItemType;
   if (itemType == ListItemType.Footer)
   {
    decimal sum=0;
    foreach(DataGridItem item in this.DataGrid1.Items)
    {
     decimal p=Convert.ToDecimal(((TextBox) item.FindControl("txtPrice")).Text);
     int n=Convert.ToInt16(((TextBox) item.FindControl("txtNum")).Text);
     sum+=p*n;
    }
    ((TextBox)e.Item.FindControl("txtSumPrice")).Text=sum.ToString();



   }
  }
}
}

此外我们还要在Global.asax.CS文件中将变量进行初始化，确保每个客户端访问网站时都有一个购物车，当然里面是没有书的。

此购物车实现的原理很简单.首先自己定义一个货物类，及货物集合类（实现IEnumerable集合）.当每个用户进入到网站时，首先给其分配一个空的购物车。当用户在购物页面选取一个货物时，取得该货物，同时获得自己的购物车，将货物保存到购物车中，最后再保存购物车。如果用户要对购物车中的内容进行修改也是一样的原理。而且在购物车察看页。我们则将自己生成的集合类对象绑定到我们的页面中。利用网格窗控年的一此事件来处理货物统计的问题。

希望这样一个思路能对您有所帮助。

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