ASP.NET购物车实现过程详解

1、 将test数据库附加到数据库管理系统中；数据库中的book_info包含下列数据：

2、 新建一个网站，将images文件夹复制到网站中；
3、 在Default.aspx中，通过DataList控件展示数据库中的所有数据，以行为主序，每行3列，单击购买按钮时，将商品的ID和数量保存到HashTable中，并将HashTable放置到Session中。

protected void DataList1_ItemCommand(object source, DataListCommandEventArgs e)
  {
    string id = e.CommandArgument.ToString();
    Hashtable ht;
    if (Session["shopcar"] == null)
    {
      ht = new Hashtable();
      ht.Add(id, 1);
      Session["shopcar"] = ht;
    }
    else
    {
      ht = (Hashtable)Session["shopcar"];
      if (ht.Contains(id))
      {
        int count = int.Parse(ht[id].ToString());
        ht[id] = count + 1;
        Session["shopcar"] = ht;
        Response.Write(count + 1);
      }
      else
      {
        ht.Add(id, 1);
        Session["shopcar"] = ht;
      }
    }
  } 

4、 在Default.aspx中添加一个超链接，链接到shopcart.aspx,在shopcart.aspx中显示用户购买的商品信息。
提示：

A、在shopcart中先定义下列变量：

Hashtable ht;
  DataTable dt;
  string connstring=@"DataSource=.\SQLEXPRESS;Initial Catalog=test;Integrated Security=True";
  SqlConnection conn;
  SqlCommand cmd;
 SqlDataReader sdr;

B、页面中添加一个GridView。
C、在page_load中，将dt实例化，建立各列。

protected void Page_Load(object sender, EventArgs e)
  {
    dt = new DataTable();
    DataColumn col = new DataColumn();
    col.ColumnName= "id";
    col.DataType =System.Type.GetType("System.String");
    dt.Columns.Add(col);
    col = new DataColumn();
    col.ColumnName= "name";
    col.DataType =System.Type.GetType("System.String");
    dt.Columns.Add(col);
    col = new DataColumn();
    col.ColumnName= "Num";
    col.DataType =System.Type.GetType("System.Int32");
    dt.Columns.Add(col);
    col = new DataColumn();
    col.ColumnName= "price";
    col.DataType =System.Type.GetType("System.Single");
    dt.Columns.Add(col);
    col = new DataColumn();
    col.ColumnName= "Total";
    col.DataType =System.Type.GetType("System.Single");
    dt.Columns.Add(col);
    if (!IsPostBack)
    {
      Bind();
    }
  }

  public void Bind()
  {

    if (Session["shopcar"] == null)
    {
      Response.Write("<script>if(confirm('你没有登录')window.location='Default15.aspx';else window.close();</script>");
    }
    else
    {
      ht = (Hashtable)Session["shopcar"];
      foreach (object item in ht.Keys)
      {
        string id = item.ToString();
        int num = int.Parse(ht[item].ToString());
        string sql = "selectbook_name,price from book_info where book_id='" + id + "'";
        conn = new SqlConnection(connstring);
        cmd = new SqlCommand(sql, conn);
        conn.Open();
        sdr =cmd.ExecuteReader();
        if (sdr.HasRows)
        {
          sdr.Read();
          DataRow row = dt.NewRow();
          row["id"] = id;
          row["Num"] = num;
          row["name"] = sdr.GetString(0);
          row["price"] =float.Parse(sdr[1].ToString());
          row["total"] =num*(float.Parse(sdr[1].ToString()));
          dt.Rows.Add(row);
        }
        sdr.Close();
        conn.Close();

      }
      GridView1.DataSource = dt.DefaultView;
      GridView1.DataBind();
    }
}

D、这时可以看到用户购买的商品，但不能修改数量，也不能删除。
E、添加修改数量，删除商品功能，在aspx页面中定义GridView中的各列：

 <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False">
     <Columns>
       <asp:BoundField DataField="id" HeaderText="ID" />
       <asp:BoundField DataField="name" HeaderText="名称" />
       <asp:BoundField DataField="price" HeaderText="价格" />
       <asp:TemplateField>
        <ItemTemplate>
         <asp:TextBox runat="server" ID="textbox1" Text='<%# Eval("Num") %>'
            ontextchanged="textbox1_TextChanged" AutoPostBack="True" ></asp:TextBox>
        </ItemTemplate>
       </asp:TemplateField>
      <asp:BoundField DataField="total" HeaderText="总计" />
      <asp:TemplateField>
       <ItemTemplate>
        <asp:Button runat="server" ID="button1" CommandArgument='<%# Eval("id") %>'
           Text="删除" onclick="button1_Click" />

       </ItemTemplate>

      </asp:TemplateField>
     </Columns>
    </asp:GridView>

F、为GridView中的文本框添加TextChanged事件：

protected void textbox1_TextChanged(object sender, EventArgs e)
  {

    Hashtable ht =(Hashtable)Session["shopcar"];
    if (ht == null) return;
    for (int i = 0; i < GridView1.Rows.Count;i++)
    {
      string id =GridView1.Rows[i].Cells[0].Text.ToString();
      Response.Write(id);
      string num = ((TextBox)GridView1.Rows[i].FindControl("textbox1")).Text;
      Response.Write("  "+num+"<br />");
      ht[id] = num;
    }
    Session["shopcar"] = ht;
    Bind();

  }

G、为按钮添加单击事件：

protected void button1_Click(object sender, EventArgs e)
  {
    string id = ((Button)sender).CommandArgument;
    Hashtable ht = (Hashtable)Session["shopcar"];
    if (ht == null) return;
    ht.Remove(id);
    Bind();
}

购物车代码：showcart.aspx.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Collections;
using System.Data;
using System.Data.SqlClient; 

public partial class shopcart : System.Web.UI.Page
{
  Hashtable ht;
  DataTable dt;
  string connstr = "Data Source=.\\SQLEXPRESS;AttachDbFilename=F:

\\test.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True";
  SqlConnection conn;
  SqlCommand cmd;
  SqlDataReader sdr;
  protected void Page_Load(object sender, EventArgs e)
  {
    dt = new DataTable();
    DataColumn col = new DataColumn();
    col.ColumnName = "id";
    col.DataType = System.Type.GetType("System.String");
    dt.Columns.Add(col);
    col = new DataColumn();
    col.ColumnName = "name";
    col.DataType = System.Type.GetType("System.String");
    dt.Columns.Add(col);
    col = new DataColumn();
    col.ColumnName = "Num";
    col.DataType = System.Type.GetType("System.Int32");
    dt.Columns.Add(col);
    col = new DataColumn();
    col.ColumnName = "price";
    col.DataType = System.Type.GetType("System.Single");
    dt.Columns.Add(col);
    col = new DataColumn();
    col.ColumnName = "Total";
    col.DataType = System.Type.GetType("System.Single");
    dt.Columns.Add(col); 

    if (!IsPostBack)
    {
      Bind();
    } 

  } 

  public void Bind()
  {
    if (Session["shopcar"] == null)
    {
      Response.Write("<script>if(confirm('你没有登录')window.location='Default.aspx';else window.close();</script>");
    }
    else
    {
      ht = (Hashtable)Session["shopcar"];
      foreach (object item in ht.Keys)
      {
        string id = item.ToString(); 

        int num = int.Parse((ht[item].ToString()));
        string sql = "select book_name,price from book_info where book_id='" + id + "'";
        conn = new SqlConnection(connstr); 

        cmd = new SqlCommand(sql, conn);
        conn.Open(); 

        sdr = cmd.ExecuteReader();
        if (sdr.HasRows)
        {
          sdr.Read();
          DataRow row = dt.NewRow();
          row["id"] = id;
          row["Num"] = num;
          row["name"] = sdr.GetString(0);
          row["price"] = float.Parse(sdr[1].ToString());
          row["total"] = num * (float.Parse(sdr[1].ToString()));
          dt.Rows.Add(row); 

        }
        sdr.Close();
        conn.Close();
      }
    }
    GridView1.DataSource = dt.DefaultView;
    GridView1.DataBind(); 

  }
  protected void textbox1_TextChanged(object sender, EventArgs e)
  {
    Hashtable ht = (Hashtable)Session["shopcar"];
    if (ht == null) return;
    for (int i = 0; i < GridView1.Rows.Count; i++)
    {
      string id = GridView1.Rows[i].Cells[0].Text.ToString();
      Response.Write(id);
      string num = ((TextBox)GridView1.Rows[i].FindControl("textbox1")).Text;
      Response.Write("  " + num + "<br />");
      ht[id] = num;
    }
    Session["shopcar"] = ht;
    Bind(); 

  }
  protected void button1_Click(object sender, EventArgs e)
  {
    string id = ((Button)sender).CommandArgument;
    Hashtable ht = (Hashtable)Session["shopcar"];
    if (ht == null) return;
    ht.Remove(id);
    Bind(); 

  }
}

制作一个简单的购物车就是这么简单，大家可以按照我的思路进行创作，在此基础上在添加一些功能。